2 # (C) Copyright 2000 - 2013
3 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5 # SPDX-License-Identifier: GPL-2.0+
11 This directory contains the source code for U-Boot, a boot loader for
12 Embedded boards based on PowerPC, ARM, MIPS and several other
13 processors, which can be installed in a boot ROM and used to
14 initialize and test the hardware or to download and run application
17 The development of U-Boot is closely related to Linux: some parts of
18 the source code originate in the Linux source tree, we have some
19 header files in common, and special provision has been made to
20 support booting of Linux images.
22 Some attention has been paid to make this software easily
23 configurable and extendable. For instance, all monitor commands are
24 implemented with the same call interface, so that it's very easy to
25 add new commands. Also, instead of permanently adding rarely used
26 code (for instance hardware test utilities) to the monitor, you can
27 load and run it dynamically.
33 In general, all boards for which a configuration option exists in the
34 Makefile have been tested to some extent and can be considered
35 "working". In fact, many of them are used in production systems.
37 In case of problems see the CHANGELOG file to find out who contributed
38 the specific port. In addition, there are various MAINTAINERS files
39 scattered throughout the U-Boot source identifying the people or
40 companies responsible for various boards and subsystems.
42 Note: As of August, 2010, there is no longer a CHANGELOG file in the
43 actual U-Boot source tree; however, it can be created dynamically
44 from the Git log using:
52 In case you have questions about, problems with or contributions for
53 U-Boot, you should send a message to the U-Boot mailing list at
54 <u-boot@lists.denx.de>. There is also an archive of previous traffic
55 on the mailing list - please search the archive before asking FAQ's.
56 Please see http://lists.denx.de/pipermail/u-boot and
57 http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
60 Where to get source code:
61 =========================
63 The U-Boot source code is maintained in the Git repository at
64 git://www.denx.de/git/u-boot.git ; you can browse it online at
65 http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
67 The "snapshot" links on this page allow you to download tarballs of
68 any version you might be interested in. Official releases are also
69 available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
72 Pre-built (and tested) images are available from
73 ftp://ftp.denx.de/pub/u-boot/images/
79 - start from 8xxrom sources
80 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
82 - make it easier to add custom boards
83 - make it possible to add other [PowerPC] CPUs
84 - extend functions, especially:
85 * Provide extended interface to Linux boot loader
88 * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
89 - create ARMBoot project (http://sourceforge.net/projects/armboot)
90 - add other CPU families (starting with ARM)
91 - create U-Boot project (http://sourceforge.net/projects/u-boot)
92 - current project page: see http://www.denx.de/wiki/U-Boot
98 The "official" name of this project is "Das U-Boot". The spelling
99 "U-Boot" shall be used in all written text (documentation, comments
100 in source files etc.). Example:
102 This is the README file for the U-Boot project.
104 File names etc. shall be based on the string "u-boot". Examples:
106 include/asm-ppc/u-boot.h
108 #include <asm/u-boot.h>
110 Variable names, preprocessor constants etc. shall be either based on
111 the string "u_boot" or on "U_BOOT". Example:
113 U_BOOT_VERSION u_boot_logo
114 IH_OS_U_BOOT u_boot_hush_start
120 Starting with the release in October 2008, the names of the releases
121 were changed from numerical release numbers without deeper meaning
122 into a time stamp based numbering. Regular releases are identified by
123 names consisting of the calendar year and month of the release date.
124 Additional fields (if present) indicate release candidates or bug fix
125 releases in "stable" maintenance trees.
128 U-Boot v2009.11 - Release November 2009
129 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
130 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
136 /arch Architecture specific files
137 /arc Files generic to ARC architecture
138 /arm Files generic to ARM architecture
139 /m68k Files generic to m68k architecture
140 /microblaze Files generic to microblaze architecture
141 /mips Files generic to MIPS architecture
142 /nds32 Files generic to NDS32 architecture
143 /nios2 Files generic to Altera NIOS2 architecture
144 /openrisc Files generic to OpenRISC architecture
145 /powerpc Files generic to PowerPC architecture
146 /riscv Files generic to RISC-V architecture
147 /sandbox Files generic to HW-independent "sandbox"
148 /sh Files generic to SH architecture
149 /x86 Files generic to x86 architecture
150 /api Machine/arch independent API for external apps
151 /board Board dependent files
152 /cmd U-Boot commands functions
153 /common Misc architecture independent functions
154 /configs Board default configuration files
155 /disk Code for disk drive partition handling
156 /doc Documentation (don't expect too much)
157 /drivers Commonly used device drivers
158 /dts Contains Makefile for building internal U-Boot fdt.
159 /examples Example code for standalone applications, etc.
160 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
161 /include Header Files
162 /lib Library routines generic to all architectures
163 /Licenses Various license files
165 /post Power On Self Test
166 /scripts Various build scripts and Makefiles
167 /test Various unit test files
168 /tools Tools to build S-Record or U-Boot images, etc.
170 Software Configuration:
171 =======================
173 Configuration is usually done using C preprocessor defines; the
174 rationale behind that is to avoid dead code whenever possible.
176 There are two classes of configuration variables:
178 * Configuration _OPTIONS_:
179 These are selectable by the user and have names beginning with
182 * Configuration _SETTINGS_:
183 These depend on the hardware etc. and should not be meddled with if
184 you don't know what you're doing; they have names beginning with
187 Previously, all configuration was done by hand, which involved creating
188 symbolic links and editing configuration files manually. More recently,
189 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
190 allowing you to use the "make menuconfig" command to configure your
194 Selection of Processor Architecture and Board Type:
195 ---------------------------------------------------
197 For all supported boards there are ready-to-use default
198 configurations available; just type "make <board_name>_defconfig".
200 Example: For a TQM823L module type:
203 make TQM823L_defconfig
205 Note: If you're looking for the default configuration file for a board
206 you're sure used to be there but is now missing, check the file
207 doc/README.scrapyard for a list of no longer supported boards.
212 U-Boot can be built natively to run on a Linux host using the 'sandbox'
213 board. This allows feature development which is not board- or architecture-
214 specific to be undertaken on a native platform. The sandbox is also used to
215 run some of U-Boot's tests.
217 See board/sandbox/README.sandbox for more details.
220 Board Initialisation Flow:
221 --------------------------
223 This is the intended start-up flow for boards. This should apply for both
224 SPL and U-Boot proper (i.e. they both follow the same rules).
226 Note: "SPL" stands for "Secondary Program Loader," which is explained in
227 more detail later in this file.
229 At present, SPL mostly uses a separate code path, but the function names
230 and roles of each function are the same. Some boards or architectures
231 may not conform to this. At least most ARM boards which use
232 CONFIG_SPL_FRAMEWORK conform to this.
234 Execution typically starts with an architecture-specific (and possibly
235 CPU-specific) start.S file, such as:
237 - arch/arm/cpu/armv7/start.S
238 - arch/powerpc/cpu/mpc83xx/start.S
239 - arch/mips/cpu/start.S
241 and so on. From there, three functions are called; the purpose and
242 limitations of each of these functions are described below.
245 - purpose: essential init to permit execution to reach board_init_f()
246 - no global_data or BSS
247 - there is no stack (ARMv7 may have one but it will soon be removed)
248 - must not set up SDRAM or use console
249 - must only do the bare minimum to allow execution to continue to
251 - this is almost never needed
252 - return normally from this function
255 - purpose: set up the machine ready for running board_init_r():
256 i.e. SDRAM and serial UART
257 - global_data is available
259 - BSS is not available, so you cannot use global/static variables,
260 only stack variables and global_data
262 Non-SPL-specific notes:
263 - dram_init() is called to set up DRAM. If already done in SPL this
267 - you can override the entire board_init_f() function with your own
269 - preloader_console_init() can be called here in extremis
270 - should set up SDRAM, and anything needed to make the UART work
271 - these is no need to clear BSS, it will be done by crt0.S
272 - must return normally from this function (don't call board_init_r()
275 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
276 this point the stack and global_data are relocated to below
277 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
281 - purpose: main execution, common code
282 - global_data is available
284 - BSS is available, all static/global variables can be used
285 - execution eventually continues to main_loop()
287 Non-SPL-specific notes:
288 - U-Boot is relocated to the top of memory and is now running from
292 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
293 CONFIG_SPL_STACK_R_ADDR points into SDRAM
294 - preloader_console_init() can be called here - typically this is
295 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
296 spl_board_init() function containing this call
297 - loads U-Boot or (in falcon mode) Linux
301 Configuration Options:
302 ----------------------
304 Configuration depends on the combination of board and CPU type; all
305 such information is kept in a configuration file
306 "include/configs/<board_name>.h".
308 Example: For a TQM823L module, all configuration settings are in
309 "include/configs/TQM823L.h".
312 Many of the options are named exactly as the corresponding Linux
313 kernel configuration options. The intention is to make it easier to
314 build a config tool - later.
316 - ARM Platform Bus Type(CCI):
317 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
318 provides full cache coherency between two clusters of multi-core
319 CPUs and I/O coherency for devices and I/O masters
321 CONFIG_SYS_FSL_HAS_CCI400
323 Defined For SoC that has cache coherent interconnect
326 CONFIG_SYS_FSL_HAS_CCN504
328 Defined for SoC that has cache coherent interconnect CCN-504
330 The following options need to be configured:
332 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
334 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
336 - Marvell Family Member
337 CONFIG_SYS_MVFS - define it if you want to enable
338 multiple fs option at one time
339 for marvell soc family
344 Specifies that the core is a 64-bit PowerPC implementation (implements
345 the "64" category of the Power ISA). This is necessary for ePAPR
346 compliance, among other possible reasons.
348 CONFIG_SYS_FSL_TBCLK_DIV
350 Defines the core time base clock divider ratio compared to the
351 system clock. On most PQ3 devices this is 8, on newer QorIQ
352 devices it can be 16 or 32. The ratio varies from SoC to Soc.
354 CONFIG_SYS_FSL_PCIE_COMPAT
356 Defines the string to utilize when trying to match PCIe device
357 tree nodes for the given platform.
359 CONFIG_SYS_FSL_ERRATUM_A004510
361 Enables a workaround for erratum A004510. If set,
362 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
363 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
365 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
366 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
368 Defines one or two SoC revisions (low 8 bits of SVR)
369 for which the A004510 workaround should be applied.
371 The rest of SVR is either not relevant to the decision
372 of whether the erratum is present (e.g. p2040 versus
373 p2041) or is implied by the build target, which controls
374 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
376 See Freescale App Note 4493 for more information about
379 CONFIG_A003399_NOR_WORKAROUND
380 Enables a workaround for IFC erratum A003399. It is only
381 required during NOR boot.
383 CONFIG_A008044_WORKAROUND
384 Enables a workaround for T1040/T1042 erratum A008044. It is only
385 required during NAND boot and valid for Rev 1.0 SoC revision
387 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
389 This is the value to write into CCSR offset 0x18600
390 according to the A004510 workaround.
392 CONFIG_SYS_FSL_DSP_DDR_ADDR
393 This value denotes start offset of DDR memory which is
394 connected exclusively to the DSP cores.
396 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
397 This value denotes start offset of M2 memory
398 which is directly connected to the DSP core.
400 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
401 This value denotes start offset of M3 memory which is directly
402 connected to the DSP core.
404 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
405 This value denotes start offset of DSP CCSR space.
407 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
408 Single Source Clock is clocking mode present in some of FSL SoC's.
409 In this mode, a single differential clock is used to supply
410 clocks to the sysclock, ddrclock and usbclock.
412 CONFIG_SYS_CPC_REINIT_F
413 This CONFIG is defined when the CPC is configured as SRAM at the
414 time of U-Boot entry and is required to be re-initialized.
417 Indicates this SoC supports deep sleep feature. If deep sleep is
418 supported, core will start to execute uboot when wakes up.
420 - Generic CPU options:
421 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
423 Defines the endianess of the CPU. Implementation of those
424 values is arch specific.
427 Freescale DDR driver in use. This type of DDR controller is
428 found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
431 CONFIG_SYS_FSL_DDR_ADDR
432 Freescale DDR memory-mapped register base.
434 CONFIG_SYS_FSL_DDR_EMU
435 Specify emulator support for DDR. Some DDR features such as
436 deskew training are not available.
438 CONFIG_SYS_FSL_DDRC_GEN1
439 Freescale DDR1 controller.
441 CONFIG_SYS_FSL_DDRC_GEN2
442 Freescale DDR2 controller.
444 CONFIG_SYS_FSL_DDRC_GEN3
445 Freescale DDR3 controller.
447 CONFIG_SYS_FSL_DDRC_GEN4
448 Freescale DDR4 controller.
450 CONFIG_SYS_FSL_DDRC_ARM_GEN3
451 Freescale DDR3 controller for ARM-based SoCs.
454 Board config to use DDR1. It can be enabled for SoCs with
455 Freescale DDR1 or DDR2 controllers, depending on the board
459 Board config to use DDR2. It can be enabled for SoCs with
460 Freescale DDR2 or DDR3 controllers, depending on the board
464 Board config to use DDR3. It can be enabled for SoCs with
465 Freescale DDR3 or DDR3L controllers.
468 Board config to use DDR3L. It can be enabled for SoCs with
472 Board config to use DDR4. It can be enabled for SoCs with
475 CONFIG_SYS_FSL_IFC_BE
476 Defines the IFC controller register space as Big Endian
478 CONFIG_SYS_FSL_IFC_LE
479 Defines the IFC controller register space as Little Endian
481 CONFIG_SYS_FSL_IFC_CLK_DIV
482 Defines divider of platform clock(clock input to IFC controller).
484 CONFIG_SYS_FSL_LBC_CLK_DIV
485 Defines divider of platform clock(clock input to eLBC controller).
487 CONFIG_SYS_FSL_PBL_PBI
488 It enables addition of RCW (Power on reset configuration) in built image.
489 Please refer doc/README.pblimage for more details
491 CONFIG_SYS_FSL_PBL_RCW
492 It adds PBI(pre-boot instructions) commands in u-boot build image.
493 PBI commands can be used to configure SoC before it starts the execution.
494 Please refer doc/README.pblimage for more details
497 It adds a target to create boot binary having SPL binary in PBI format
498 concatenated with u-boot binary.
500 CONFIG_SYS_FSL_DDR_BE
501 Defines the DDR controller register space as Big Endian
503 CONFIG_SYS_FSL_DDR_LE
504 Defines the DDR controller register space as Little Endian
506 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
507 Physical address from the view of DDR controllers. It is the
508 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
509 it could be different for ARM SoCs.
511 CONFIG_SYS_FSL_DDR_INTLV_256B
512 DDR controller interleaving on 256-byte. This is a special
513 interleaving mode, handled by Dickens for Freescale layerscape
516 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
517 Number of controllers used as main memory.
519 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
520 Number of controllers used for other than main memory.
522 CONFIG_SYS_FSL_HAS_DP_DDR
523 Defines the SoC has DP-DDR used for DPAA.
525 CONFIG_SYS_FSL_SEC_BE
526 Defines the SEC controller register space as Big Endian
528 CONFIG_SYS_FSL_SEC_LE
529 Defines the SEC controller register space as Little Endian
532 CONFIG_SYS_INIT_SP_OFFSET
534 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
535 pointer. This is needed for the temporary stack before
538 CONFIG_SYS_MIPS_CACHE_MODE
540 Cache operation mode for the MIPS CPU.
541 See also arch/mips/include/asm/mipsregs.h.
543 CONF_CM_CACHABLE_NO_WA
546 CONF_CM_CACHABLE_NONCOHERENT
550 CONF_CM_CACHABLE_ACCELERATED
552 CONFIG_SYS_XWAY_EBU_BOOTCFG
554 Special option for Lantiq XWAY SoCs for booting from NOR flash.
555 See also arch/mips/cpu/mips32/start.S.
557 CONFIG_XWAY_SWAP_BYTES
559 Enable compilation of tools/xway-swap-bytes needed for Lantiq
560 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
561 be swapped if a flash programmer is used.
564 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
566 Select high exception vectors of the ARM core, e.g., do not
567 clear the V bit of the c1 register of CP15.
570 Generic timer clock source frequency.
572 COUNTER_FREQUENCY_REAL
573 Generic timer clock source frequency if the real clock is
574 different from COUNTER_FREQUENCY, and can only be determined
578 CONFIG_TEGRA_SUPPORT_NON_SECURE
580 Support executing U-Boot in non-secure (NS) mode. Certain
581 impossible actions will be skipped if the CPU is in NS mode,
582 such as ARM architectural timer initialization.
584 - Linux Kernel Interface:
587 U-Boot stores all clock information in Hz
588 internally. For binary compatibility with older Linux
589 kernels (which expect the clocks passed in the
590 bd_info data to be in MHz) the environment variable
591 "clocks_in_mhz" can be defined so that U-Boot
592 converts clock data to MHZ before passing it to the
594 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
595 "clocks_in_mhz=1" is automatically included in the
598 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
600 When transferring memsize parameter to Linux, some versions
601 expect it to be in bytes, others in MB.
602 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
606 New kernel versions are expecting firmware settings to be
607 passed using flattened device trees (based on open firmware
611 * New libfdt-based support
612 * Adds the "fdt" command
613 * The bootm command automatically updates the fdt
615 OF_TBCLK - The timebase frequency.
616 OF_STDOUT_PATH - The path to the console device
618 boards with QUICC Engines require OF_QE to set UCC MAC
621 CONFIG_OF_BOARD_SETUP
623 Board code has addition modification that it wants to make
624 to the flat device tree before handing it off to the kernel
626 CONFIG_OF_SYSTEM_SETUP
628 Other code has addition modification that it wants to make
629 to the flat device tree before handing it off to the kernel.
630 This causes ft_system_setup() to be called before booting
635 U-Boot can detect if an IDE device is present or not.
636 If not, and this new config option is activated, U-Boot
637 removes the ATA node from the DTS before booting Linux,
638 so the Linux IDE driver does not probe the device and
639 crash. This is needed for buggy hardware (uc101) where
640 no pull down resistor is connected to the signal IDE5V_DD7.
642 CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
644 This setting is mandatory for all boards that have only one
645 machine type and must be used to specify the machine type
646 number as it appears in the ARM machine registry
647 (see http://www.arm.linux.org.uk/developer/machines/).
648 Only boards that have multiple machine types supported
649 in a single configuration file and the machine type is
650 runtime discoverable, do not have to use this setting.
652 - vxWorks boot parameters:
654 bootvx constructs a valid bootline using the following
655 environments variables: bootdev, bootfile, ipaddr, netmask,
656 serverip, gatewayip, hostname, othbootargs.
657 It loads the vxWorks image pointed bootfile.
659 Note: If a "bootargs" environment is defined, it will overwride
660 the defaults discussed just above.
662 - Cache Configuration:
663 CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
664 CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
665 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
667 - Cache Configuration for ARM:
668 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
670 CONFIG_SYS_PL310_BASE - Physical base address of PL310
671 controller register space
676 Define this if you want support for Amba PrimeCell PL010 UARTs.
680 Define this if you want support for Amba PrimeCell PL011 UARTs.
684 If you have Amba PrimeCell PL011 UARTs, set this variable to
685 the clock speed of the UARTs.
689 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
690 define this to a list of base addresses for each (supported)
691 port. See e.g. include/configs/versatile.h
693 CONFIG_SERIAL_HW_FLOW_CONTROL
695 Define this variable to enable hw flow control in serial driver.
696 Current user of this option is drivers/serial/nsl16550.c driver
699 CONFIG_BAUDRATE - in bps
700 Select one of the baudrates listed in
701 CONFIG_SYS_BAUDRATE_TABLE, see below.
705 Only needed when CONFIG_BOOTDELAY is enabled;
706 define a command string that is automatically executed
707 when no character is read on the console interface
708 within "Boot Delay" after reset.
710 CONFIG_RAMBOOT and CONFIG_NFSBOOT
711 The value of these goes into the environment as
712 "ramboot" and "nfsboot" respectively, and can be used
713 as a convenience, when switching between booting from
719 When this option is #defined, the existence of the
720 environment variable "preboot" will be checked
721 immediately before starting the CONFIG_BOOTDELAY
722 countdown and/or running the auto-boot command resp.
723 entering interactive mode.
725 This feature is especially useful when "preboot" is
726 automatically generated or modified. For an example
727 see the LWMON board specific code: here "preboot" is
728 modified when the user holds down a certain
729 combination of keys on the (special) keyboard when
732 - Serial Download Echo Mode:
734 If defined to 1, all characters received during a
735 serial download (using the "loads" command) are
736 echoed back. This might be needed by some terminal
737 emulations (like "cu"), but may as well just take
738 time on others. This setting #define's the initial
739 value of the "loads_echo" environment variable.
741 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
743 Select one of the baudrates listed in
744 CONFIG_SYS_BAUDRATE_TABLE, see below.
746 - Removal of commands
747 If no commands are needed to boot, you can disable
748 CONFIG_CMDLINE to remove them. In this case, the command line
749 will not be available, and when U-Boot wants to execute the
750 boot command (on start-up) it will call board_run_command()
751 instead. This can reduce image size significantly for very
752 simple boot procedures.
754 - Regular expression support:
756 If this variable is defined, U-Boot is linked against
757 the SLRE (Super Light Regular Expression) library,
758 which adds regex support to some commands, as for
759 example "env grep" and "setexpr".
763 If this variable is defined, U-Boot will use a device tree
764 to configure its devices, instead of relying on statically
765 compiled #defines in the board file. This option is
766 experimental and only available on a few boards. The device
767 tree is available in the global data as gd->fdt_blob.
769 U-Boot needs to get its device tree from somewhere. This can
770 be done using one of the three options below:
773 If this variable is defined, U-Boot will embed a device tree
774 binary in its image. This device tree file should be in the
775 board directory and called <soc>-<board>.dts. The binary file
776 is then picked up in board_init_f() and made available through
777 the global data structure as gd->fdt_blob.
780 If this variable is defined, U-Boot will build a device tree
781 binary. It will be called u-boot.dtb. Architecture-specific
782 code will locate it at run-time. Generally this works by:
784 cat u-boot.bin u-boot.dtb >image.bin
786 and in fact, U-Boot does this for you, creating a file called
787 u-boot-dtb.bin which is useful in the common case. You can
788 still use the individual files if you need something more
792 If this variable is defined, U-Boot will use the device tree
793 provided by the board at runtime instead of embedding one with
794 the image. Only boards defining board_fdt_blob_setup() support
795 this option (see include/fdtdec.h file).
799 If this variable is defined, it enables watchdog
800 support for the SoC. There must be support in the SoC
801 specific code for a watchdog. For the 8xx
802 CPUs, the SIU Watchdog feature is enabled in the SYPCR
803 register. When supported for a specific SoC is
804 available, then no further board specific code should
808 When using a watchdog circuitry external to the used
809 SoC, then define this variable and provide board
810 specific code for the "hw_watchdog_reset" function.
812 CONFIG_AT91_HW_WDT_TIMEOUT
813 specify the timeout in seconds. default 2 seconds.
816 CONFIG_VERSION_VARIABLE
817 If this variable is defined, an environment variable
818 named "ver" is created by U-Boot showing the U-Boot
819 version as printed by the "version" command.
820 Any change to this variable will be reverted at the
825 When CONFIG_CMD_DATE is selected, the type of the RTC
826 has to be selected, too. Define exactly one of the
829 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
830 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
831 CONFIG_RTC_MC146818 - use MC146818 RTC
832 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
833 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
834 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
835 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
836 CONFIG_RTC_DS164x - use Dallas DS164x RTC
837 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
838 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
839 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
840 CONFIG_SYS_RV3029_TCR - enable trickle charger on
843 Note that if the RTC uses I2C, then the I2C interface
844 must also be configured. See I2C Support, below.
847 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
849 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
850 chip-ngpio pairs that tell the PCA953X driver the number of
851 pins supported by a particular chip.
853 Note that if the GPIO device uses I2C, then the I2C interface
854 must also be configured. See I2C Support, below.
857 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
858 accesses and can checksum them or write a list of them out
859 to memory. See the 'iotrace' command for details. This is
860 useful for testing device drivers since it can confirm that
861 the driver behaves the same way before and after a code
862 change. Currently this is supported on sandbox and arm. To
863 add support for your architecture, add '#include <iotrace.h>'
864 to the bottom of arch/<arch>/include/asm/io.h and test.
866 Example output from the 'iotrace stats' command is below.
867 Note that if the trace buffer is exhausted, the checksum will
868 still continue to operate.
871 Start: 10000000 (buffer start address)
872 Size: 00010000 (buffer size)
873 Offset: 00000120 (current buffer offset)
874 Output: 10000120 (start + offset)
875 Count: 00000018 (number of trace records)
876 CRC32: 9526fb66 (CRC32 of all trace records)
880 When CONFIG_TIMESTAMP is selected, the timestamp
881 (date and time) of an image is printed by image
882 commands like bootm or iminfo. This option is
883 automatically enabled when you select CONFIG_CMD_DATE .
885 - Partition Labels (disklabels) Supported:
886 Zero or more of the following:
887 CONFIG_MAC_PARTITION Apple's MacOS partition table.
888 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
889 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
890 bootloader. Note 2TB partition limit; see
892 CONFIG_MTD_PARTITIONS Memory Technology Device partition table.
894 If IDE or SCSI support is enabled (CONFIG_IDE or
895 CONFIG_SCSI) you must configure support for at
896 least one non-MTD partition type as well.
899 CONFIG_IDE_RESET_ROUTINE - this is defined in several
900 board configurations files but used nowhere!
902 CONFIG_IDE_RESET - is this is defined, IDE Reset will
903 be performed by calling the function
904 ide_set_reset(int reset)
905 which has to be defined in a board specific file
910 Set this to enable ATAPI support.
915 Set this to enable support for disks larger than 137GB
916 Also look at CONFIG_SYS_64BIT_LBA.
917 Whithout these , LBA48 support uses 32bit variables and will 'only'
918 support disks up to 2.1TB.
920 CONFIG_SYS_64BIT_LBA:
921 When enabled, makes the IDE subsystem use 64bit sector addresses.
925 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
926 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
927 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
928 maximum numbers of LUNs, SCSI ID's and target
931 The environment variable 'scsidevs' is set to the number of
932 SCSI devices found during the last scan.
934 - NETWORK Support (PCI):
936 Support for Intel 8254x/8257x gigabit chips.
939 Utility code for direct access to the SPI bus on Intel 8257x.
940 This does not do anything useful unless you set at least one
941 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
943 CONFIG_E1000_SPI_GENERIC
944 Allow generic access to the SPI bus on the Intel 8257x, for
945 example with the "sspi" command.
948 Support for Intel 82557/82559/82559ER chips.
949 Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
950 write routine for first time initialisation.
953 Support for Digital 2114x chips.
954 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
955 modem chip initialisation (KS8761/QS6611).
958 Support for National dp83815 chips.
961 Support for National dp8382[01] gigabit chips.
963 - NETWORK Support (other):
965 CONFIG_DRIVER_AT91EMAC
966 Support for AT91RM9200 EMAC.
969 Define this to use reduced MII inteface
971 CONFIG_DRIVER_AT91EMAC_QUIET
972 If this defined, the driver is quiet.
973 The driver doen't show link status messages.
976 Support for the Calxeda XGMAC device
979 Support for SMSC's LAN91C96 chips.
981 CONFIG_LAN91C96_USE_32_BIT
982 Define this to enable 32 bit addressing
985 Support for SMSC's LAN91C111 chip
988 Define this to hold the physical address
989 of the device (I/O space)
991 CONFIG_SMC_USE_32_BIT
992 Define this if data bus is 32 bits
994 CONFIG_SMC_USE_IOFUNCS
995 Define this to use i/o functions instead of macros
996 (some hardware wont work with macros)
998 CONFIG_DRIVER_TI_EMAC
999 Support for davinci emac
1001 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1002 Define this if you have more then 3 PHYs.
1005 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1007 CONFIG_FTGMAC100_EGIGA
1008 Define this to use GE link update with gigabit PHY.
1009 Define this if FTGMAC100 is connected to gigabit PHY.
1010 If your system has 10/100 PHY only, it might not occur
1011 wrong behavior. Because PHY usually return timeout or
1012 useless data when polling gigabit status and gigabit
1013 control registers. This behavior won't affect the
1014 correctnessof 10/100 link speed update.
1017 Support for Renesas on-chip Ethernet controller
1019 CONFIG_SH_ETHER_USE_PORT
1020 Define the number of ports to be used
1022 CONFIG_SH_ETHER_PHY_ADDR
1023 Define the ETH PHY's address
1025 CONFIG_SH_ETHER_CACHE_WRITEBACK
1026 If this option is set, the driver enables cache flush.
1030 Support for PWM module on the imx6.
1034 Support TPM devices.
1036 CONFIG_TPM_TIS_INFINEON
1037 Support for Infineon i2c bus TPM devices. Only one device
1038 per system is supported at this time.
1040 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1041 Define the burst count bytes upper limit
1044 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
1046 CONFIG_TPM_ST33ZP24_I2C
1047 Support for STMicroelectronics ST33ZP24 I2C devices.
1048 Requires TPM_ST33ZP24 and I2C.
1050 CONFIG_TPM_ST33ZP24_SPI
1051 Support for STMicroelectronics ST33ZP24 SPI devices.
1052 Requires TPM_ST33ZP24 and SPI.
1054 CONFIG_TPM_ATMEL_TWI
1055 Support for Atmel TWI TPM device. Requires I2C support.
1058 Support for generic parallel port TPM devices. Only one device
1059 per system is supported at this time.
1061 CONFIG_TPM_TIS_BASE_ADDRESS
1062 Base address where the generic TPM device is mapped
1063 to. Contemporary x86 systems usually map it at
1067 Define this to enable the TPM support library which provides
1068 functional interfaces to some TPM commands.
1069 Requires support for a TPM device.
1071 CONFIG_TPM_AUTH_SESSIONS
1072 Define this to enable authorized functions in the TPM library.
1073 Requires CONFIG_TPM and CONFIG_SHA1.
1076 At the moment only the UHCI host controller is
1077 supported (PIP405, MIP405); define
1078 CONFIG_USB_UHCI to enable it.
1079 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1080 and define CONFIG_USB_STORAGE to enable the USB
1083 Supported are USB Keyboards and USB Floppy drives
1086 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1087 txfilltuning field in the EHCI controller on reset.
1089 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1090 HW module registers.
1093 Define the below if you wish to use the USB console.
1094 Once firmware is rebuilt from a serial console issue the
1095 command "setenv stdin usbtty; setenv stdout usbtty" and
1096 attach your USB cable. The Unix command "dmesg" should print
1097 it has found a new device. The environment variable usbtty
1098 can be set to gserial or cdc_acm to enable your device to
1099 appear to a USB host as a Linux gserial device or a
1100 Common Device Class Abstract Control Model serial device.
1101 If you select usbtty = gserial you should be able to enumerate
1103 # modprobe usbserial vendor=0xVendorID product=0xProductID
1104 else if using cdc_acm, simply setting the environment
1105 variable usbtty to be cdc_acm should suffice. The following
1106 might be defined in YourBoardName.h
1109 Define this to build a UDC device
1112 Define this to have a tty type of device available to
1113 talk to the UDC device
1116 Define this to enable the high speed support for usb
1117 device and usbtty. If this feature is enabled, a routine
1118 int is_usbd_high_speed(void)
1119 also needs to be defined by the driver to dynamically poll
1120 whether the enumeration has succeded at high speed or full
1123 CONFIG_SYS_CONSOLE_IS_IN_ENV
1124 Define this if you want stdin, stdout &/or stderr to
1127 If you have a USB-IF assigned VendorID then you may wish to
1128 define your own vendor specific values either in BoardName.h
1129 or directly in usbd_vendor_info.h. If you don't define
1130 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1131 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1132 should pretend to be a Linux device to it's target host.
1134 CONFIG_USBD_MANUFACTURER
1135 Define this string as the name of your company for
1136 - CONFIG_USBD_MANUFACTURER "my company"
1138 CONFIG_USBD_PRODUCT_NAME
1139 Define this string as the name of your product
1140 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1142 CONFIG_USBD_VENDORID
1143 Define this as your assigned Vendor ID from the USB
1144 Implementors Forum. This *must* be a genuine Vendor ID
1145 to avoid polluting the USB namespace.
1146 - CONFIG_USBD_VENDORID 0xFFFF
1148 CONFIG_USBD_PRODUCTID
1149 Define this as the unique Product ID
1151 - CONFIG_USBD_PRODUCTID 0xFFFF
1153 - ULPI Layer Support:
1154 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1155 the generic ULPI layer. The generic layer accesses the ULPI PHY
1156 via the platform viewport, so you need both the genric layer and
1157 the viewport enabled. Currently only Chipidea/ARC based
1158 viewport is supported.
1159 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1160 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1161 If your ULPI phy needs a different reference clock than the
1162 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1163 the appropriate value in Hz.
1166 The MMC controller on the Intel PXA is supported. To
1167 enable this define CONFIG_MMC. The MMC can be
1168 accessed from the boot prompt by mapping the device
1169 to physical memory similar to flash. Command line is
1170 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1171 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1174 Support for Renesas on-chip MMCIF controller
1176 CONFIG_SH_MMCIF_ADDR
1177 Define the base address of MMCIF registers
1180 Define the clock frequency for MMCIF
1182 CONFIG_SUPPORT_EMMC_BOOT
1183 Enable some additional features of the eMMC boot partitions.
1185 CONFIG_SUPPORT_EMMC_RPMB
1186 Enable the commands for reading, writing and programming the
1187 key for the Replay Protection Memory Block partition in eMMC.
1189 - USB Device Firmware Update (DFU) class support:
1191 This enables the USB portion of the DFU USB class
1194 This enables support for exposing (e)MMC devices via DFU.
1197 This enables support for exposing NAND devices via DFU.
1200 This enables support for exposing RAM via DFU.
1201 Note: DFU spec refer to non-volatile memory usage, but
1202 allow usages beyond the scope of spec - here RAM usage,
1203 one that would help mostly the developer.
1205 CONFIG_SYS_DFU_DATA_BUF_SIZE
1206 Dfu transfer uses a buffer before writing data to the
1207 raw storage device. Make the size (in bytes) of this buffer
1208 configurable. The size of this buffer is also configurable
1209 through the "dfu_bufsiz" environment variable.
1211 CONFIG_SYS_DFU_MAX_FILE_SIZE
1212 When updating files rather than the raw storage device,
1213 we use a static buffer to copy the file into and then write
1214 the buffer once we've been given the whole file. Define
1215 this to the maximum filesize (in bytes) for the buffer.
1216 Default is 4 MiB if undefined.
1218 DFU_DEFAULT_POLL_TIMEOUT
1219 Poll timeout [ms], is the timeout a device can send to the
1220 host. The host must wait for this timeout before sending
1221 a subsequent DFU_GET_STATUS request to the device.
1223 DFU_MANIFEST_POLL_TIMEOUT
1224 Poll timeout [ms], which the device sends to the host when
1225 entering dfuMANIFEST state. Host waits this timeout, before
1226 sending again an USB request to the device.
1228 - Journaling Flash filesystem support:
1230 Define these for a default partition on a NAND device
1232 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1233 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1234 Define these for a default partition on a NOR device
1237 See Kconfig help for available keyboard drivers.
1241 Define this to enable a custom keyboard support.
1242 This simply calls drv_keyboard_init() which must be
1243 defined in your board-specific files. This option is deprecated
1244 and is only used by novena. For new boards, use driver model
1249 Enable the Freescale DIU video driver. Reference boards for
1250 SOCs that have a DIU should define this macro to enable DIU
1251 support, and should also define these other macros:
1256 CONFIG_VIDEO_SW_CURSOR
1257 CONFIG_VGA_AS_SINGLE_DEVICE
1259 CONFIG_VIDEO_BMP_LOGO
1261 The DIU driver will look for the 'video-mode' environment
1262 variable, and if defined, enable the DIU as a console during
1263 boot. See the documentation file doc/README.video for a
1264 description of this variable.
1266 - LCD Support: CONFIG_LCD
1268 Define this to enable LCD support (for output to LCD
1269 display); also select one of the supported displays
1270 by defining one of these:
1274 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1276 CONFIG_NEC_NL6448AC33:
1278 NEC NL6448AC33-18. Active, color, single scan.
1280 CONFIG_NEC_NL6448BC20
1282 NEC NL6448BC20-08. 6.5", 640x480.
1283 Active, color, single scan.
1285 CONFIG_NEC_NL6448BC33_54
1287 NEC NL6448BC33-54. 10.4", 640x480.
1288 Active, color, single scan.
1292 Sharp 320x240. Active, color, single scan.
1293 It isn't 16x9, and I am not sure what it is.
1295 CONFIG_SHARP_LQ64D341
1297 Sharp LQ64D341 display, 640x480.
1298 Active, color, single scan.
1302 HLD1045 display, 640x480.
1303 Active, color, single scan.
1307 Optrex CBL50840-2 NF-FW 99 22 M5
1309 Hitachi LMG6912RPFC-00T
1313 320x240. Black & white.
1315 CONFIG_LCD_ALIGNMENT
1317 Normally the LCD is page-aligned (typically 4KB). If this is
1318 defined then the LCD will be aligned to this value instead.
1319 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1320 here, since it is cheaper to change data cache settings on
1321 a per-section basis.
1326 Sometimes, for example if the display is mounted in portrait
1327 mode or even if it's mounted landscape but rotated by 180degree,
1328 we need to rotate our content of the display relative to the
1329 framebuffer, so that user can read the messages which are
1331 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1332 initialized with a given rotation from "vl_rot" out of
1333 "vidinfo_t" which is provided by the board specific code.
1334 The value for vl_rot is coded as following (matching to
1335 fbcon=rotate:<n> linux-kernel commandline):
1336 0 = no rotation respectively 0 degree
1337 1 = 90 degree rotation
1338 2 = 180 degree rotation
1339 3 = 270 degree rotation
1341 If CONFIG_LCD_ROTATION is not defined, the console will be
1342 initialized with 0degree rotation.
1346 Support drawing of RLE8-compressed bitmaps on the LCD.
1350 Enables an 'i2c edid' command which can read EDID
1351 information over I2C from an attached LCD display.
1353 - Splash Screen Support: CONFIG_SPLASH_SCREEN
1355 If this option is set, the environment is checked for
1356 a variable "splashimage". If found, the usual display
1357 of logo, copyright and system information on the LCD
1358 is suppressed and the BMP image at the address
1359 specified in "splashimage" is loaded instead. The
1360 console is redirected to the "nulldev", too. This
1361 allows for a "silent" boot where a splash screen is
1362 loaded very quickly after power-on.
1364 CONFIG_SPLASHIMAGE_GUARD
1366 If this option is set, then U-Boot will prevent the environment
1367 variable "splashimage" from being set to a problematic address
1368 (see doc/README.displaying-bmps).
1369 This option is useful for targets where, due to alignment
1370 restrictions, an improperly aligned BMP image will cause a data
1371 abort. If you think you will not have problems with unaligned
1372 accesses (for example because your toolchain prevents them)
1373 there is no need to set this option.
1375 CONFIG_SPLASH_SCREEN_ALIGN
1377 If this option is set the splash image can be freely positioned
1378 on the screen. Environment variable "splashpos" specifies the
1379 position as "x,y". If a positive number is given it is used as
1380 number of pixel from left/top. If a negative number is given it
1381 is used as number of pixel from right/bottom. You can also
1382 specify 'm' for centering the image.
1385 setenv splashpos m,m
1386 => image at center of screen
1388 setenv splashpos 30,20
1389 => image at x = 30 and y = 20
1391 setenv splashpos -10,m
1392 => vertically centered image
1393 at x = dspWidth - bmpWidth - 9
1395 - Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1397 If this option is set, additionally to standard BMP
1398 images, gzipped BMP images can be displayed via the
1399 splashscreen support or the bmp command.
1401 - Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1403 If this option is set, 8-bit RLE compressed BMP images
1404 can be displayed via the splashscreen support or the
1407 - Compression support:
1410 Enabled by default to support gzip compressed images.
1414 If this option is set, support for bzip2 compressed
1415 images is included. If not, only uncompressed and gzip
1416 compressed images are supported.
1418 NOTE: the bzip2 algorithm requires a lot of RAM, so
1419 the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1425 The address of PHY on MII bus.
1427 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1429 The clock frequency of the MII bus
1431 CONFIG_PHY_RESET_DELAY
1433 Some PHY like Intel LXT971A need extra delay after
1434 reset before any MII register access is possible.
1435 For such PHY, set this option to the usec delay
1436 required. (minimum 300usec for LXT971A)
1438 CONFIG_PHY_CMD_DELAY (ppc4xx)
1440 Some PHY like Intel LXT971A need extra delay after
1441 command issued before MII status register can be read
1446 Define a default value for the IP address to use for
1447 the default Ethernet interface, in case this is not
1448 determined through e.g. bootp.
1449 (Environment variable "ipaddr")
1451 - Server IP address:
1454 Defines a default value for the IP address of a TFTP
1455 server to contact when using the "tftboot" command.
1456 (Environment variable "serverip")
1458 CONFIG_KEEP_SERVERADDR
1460 Keeps the server's MAC address, in the env 'serveraddr'
1461 for passing to bootargs (like Linux's netconsole option)
1463 - Gateway IP address:
1466 Defines a default value for the IP address of the
1467 default router where packets to other networks are
1469 (Environment variable "gatewayip")
1474 Defines a default value for the subnet mask (or
1475 routing prefix) which is used to determine if an IP
1476 address belongs to the local subnet or needs to be
1477 forwarded through a router.
1478 (Environment variable "netmask")
1480 - Multicast TFTP Mode:
1483 Defines whether you want to support multicast TFTP as per
1484 rfc-2090; for example to work with atftp. Lets lots of targets
1485 tftp down the same boot image concurrently. Note: the Ethernet
1486 driver in use must provide a function: mcast() to join/leave a
1489 - BOOTP Recovery Mode:
1490 CONFIG_BOOTP_RANDOM_DELAY
1492 If you have many targets in a network that try to
1493 boot using BOOTP, you may want to avoid that all
1494 systems send out BOOTP requests at precisely the same
1495 moment (which would happen for instance at recovery
1496 from a power failure, when all systems will try to
1497 boot, thus flooding the BOOTP server. Defining
1498 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1499 inserted before sending out BOOTP requests. The
1500 following delays are inserted then:
1502 1st BOOTP request: delay 0 ... 1 sec
1503 2nd BOOTP request: delay 0 ... 2 sec
1504 3rd BOOTP request: delay 0 ... 4 sec
1506 BOOTP requests: delay 0 ... 8 sec
1508 CONFIG_BOOTP_ID_CACHE_SIZE
1510 BOOTP packets are uniquely identified using a 32-bit ID. The
1511 server will copy the ID from client requests to responses and
1512 U-Boot will use this to determine if it is the destination of
1513 an incoming response. Some servers will check that addresses
1514 aren't in use before handing them out (usually using an ARP
1515 ping) and therefore take up to a few hundred milliseconds to
1516 respond. Network congestion may also influence the time it
1517 takes for a response to make it back to the client. If that
1518 time is too long, U-Boot will retransmit requests. In order
1519 to allow earlier responses to still be accepted after these
1520 retransmissions, U-Boot's BOOTP client keeps a small cache of
1521 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1522 cache. The default is to keep IDs for up to four outstanding
1523 requests. Increasing this will allow U-Boot to accept offers
1524 from a BOOTP client in networks with unusually high latency.
1526 - DHCP Advanced Options:
1527 You can fine tune the DHCP functionality by defining
1528 CONFIG_BOOTP_* symbols:
1530 CONFIG_BOOTP_NISDOMAIN
1531 CONFIG_BOOTP_BOOTFILESIZE
1532 CONFIG_BOOTP_SEND_HOSTNAME
1533 CONFIG_BOOTP_NTPSERVER
1534 CONFIG_BOOTP_TIMEOFFSET
1535 CONFIG_BOOTP_VENDOREX
1536 CONFIG_BOOTP_MAY_FAIL
1538 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1539 environment variable, not the BOOTP server.
1541 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1542 after the configured retry count, the call will fail
1543 instead of starting over. This can be used to fail over
1544 to Link-local IP address configuration if the DHCP server
1547 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1548 to do a dynamic update of a DNS server. To do this, they
1549 need the hostname of the DHCP requester.
1550 If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1551 of the "hostname" environment variable is passed as
1552 option 12 to the DHCP server.
1554 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1556 A 32bit value in microseconds for a delay between
1557 receiving a "DHCP Offer" and sending the "DHCP Request".
1558 This fixes a problem with certain DHCP servers that don't
1559 respond 100% of the time to a "DHCP request". E.g. On an
1560 AT91RM9200 processor running at 180MHz, this delay needed
1561 to be *at least* 15,000 usec before a Windows Server 2003
1562 DHCP server would reply 100% of the time. I recommend at
1563 least 50,000 usec to be safe. The alternative is to hope
1564 that one of the retries will be successful but note that
1565 the DHCP timeout and retry process takes a longer than
1568 - Link-local IP address negotiation:
1569 Negotiate with other link-local clients on the local network
1570 for an address that doesn't require explicit configuration.
1571 This is especially useful if a DHCP server cannot be guaranteed
1572 to exist in all environments that the device must operate.
1574 See doc/README.link-local for more information.
1576 - MAC address from environment variables
1578 FDT_SEQ_MACADDR_FROM_ENV
1580 Fix-up device tree with MAC addresses fetched sequentially from
1581 environment variables. This config work on assumption that
1582 non-usable ethernet node of device-tree are either not present
1583 or their status has been marked as "disabled".
1586 CONFIG_CDP_DEVICE_ID
1588 The device id used in CDP trigger frames.
1590 CONFIG_CDP_DEVICE_ID_PREFIX
1592 A two character string which is prefixed to the MAC address
1597 A printf format string which contains the ascii name of
1598 the port. Normally is set to "eth%d" which sets
1599 eth0 for the first Ethernet, eth1 for the second etc.
1601 CONFIG_CDP_CAPABILITIES
1603 A 32bit integer which indicates the device capabilities;
1604 0x00000010 for a normal host which does not forwards.
1608 An ascii string containing the version of the software.
1612 An ascii string containing the name of the platform.
1616 A 32bit integer sent on the trigger.
1618 CONFIG_CDP_POWER_CONSUMPTION
1620 A 16bit integer containing the power consumption of the
1621 device in .1 of milliwatts.
1623 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1625 A byte containing the id of the VLAN.
1627 - Status LED: CONFIG_LED_STATUS
1629 Several configurations allow to display the current
1630 status using a LED. For instance, the LED will blink
1631 fast while running U-Boot code, stop blinking as
1632 soon as a reply to a BOOTP request was received, and
1633 start blinking slow once the Linux kernel is running
1634 (supported by a status LED driver in the Linux
1635 kernel). Defining CONFIG_LED_STATUS enables this
1640 CONFIG_LED_STATUS_GPIO
1641 The status LED can be connected to a GPIO pin.
1642 In such cases, the gpio_led driver can be used as a
1643 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1644 to include the gpio_led driver in the U-Boot binary.
1646 CONFIG_GPIO_LED_INVERTED_TABLE
1647 Some GPIO connected LEDs may have inverted polarity in which
1648 case the GPIO high value corresponds to LED off state and
1649 GPIO low value corresponds to LED on state.
1650 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1651 with a list of GPIO LEDs that have inverted polarity.
1653 - I2C Support: CONFIG_SYS_I2C
1655 This enable the NEW i2c subsystem, and will allow you to use
1656 i2c commands at the u-boot command line (as long as you set
1657 CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
1658 based realtime clock chips or other i2c devices. See
1659 common/cmd_i2c.c for a description of the command line
1662 ported i2c driver to the new framework:
1663 - drivers/i2c/soft_i2c.c:
1664 - activate first bus with CONFIG_SYS_I2C_SOFT define
1665 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1666 for defining speed and slave address
1667 - activate second bus with I2C_SOFT_DECLARATIONS2 define
1668 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1669 for defining speed and slave address
1670 - activate third bus with I2C_SOFT_DECLARATIONS3 define
1671 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1672 for defining speed and slave address
1673 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1674 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1675 for defining speed and slave address
1677 - drivers/i2c/fsl_i2c.c:
1678 - activate i2c driver with CONFIG_SYS_I2C_FSL
1679 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1680 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1681 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1683 - If your board supports a second fsl i2c bus, define
1684 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1685 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1686 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1689 - drivers/i2c/tegra_i2c.c:
1690 - activate this driver with CONFIG_SYS_I2C_TEGRA
1691 - This driver adds 4 i2c buses with a fix speed from
1692 100000 and the slave addr 0!
1694 - drivers/i2c/ppc4xx_i2c.c
1695 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1696 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1697 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1699 - drivers/i2c/i2c_mxc.c
1700 - activate this driver with CONFIG_SYS_I2C_MXC
1701 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1702 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1703 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1704 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1705 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1706 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1707 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1708 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1709 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1710 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1711 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1712 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1713 If those defines are not set, default value is 100000
1714 for speed, and 0 for slave.
1716 - drivers/i2c/rcar_i2c.c:
1717 - activate this driver with CONFIG_SYS_I2C_RCAR
1718 - This driver adds 4 i2c buses
1720 - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
1721 - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
1722 - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
1723 - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
1724 - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
1725 - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
1726 - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
1727 - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
1728 - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
1730 - drivers/i2c/sh_i2c.c:
1731 - activate this driver with CONFIG_SYS_I2C_SH
1732 - This driver adds from 2 to 5 i2c buses
1734 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1735 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1736 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1737 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1738 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1739 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1740 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1741 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1742 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1743 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1744 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1746 - drivers/i2c/omap24xx_i2c.c
1747 - activate this driver with CONFIG_SYS_I2C_OMAP24XX
1748 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
1749 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
1750 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
1751 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
1752 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
1753 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
1754 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
1755 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
1756 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
1757 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
1759 - drivers/i2c/zynq_i2c.c
1760 - activate this driver with CONFIG_SYS_I2C_ZYNQ
1761 - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
1762 - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
1764 - drivers/i2c/s3c24x0_i2c.c:
1765 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1766 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1767 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1768 with a fix speed from 100000 and the slave addr 0!
1770 - drivers/i2c/ihs_i2c.c
1771 - activate this driver with CONFIG_SYS_I2C_IHS
1772 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1773 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1774 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1775 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1776 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1777 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1778 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1779 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1780 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1781 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1782 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1783 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1784 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1785 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1786 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1787 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1788 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1789 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1790 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1791 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1792 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1796 CONFIG_SYS_NUM_I2C_BUSES
1797 Hold the number of i2c buses you want to use.
1799 CONFIG_SYS_I2C_DIRECT_BUS
1800 define this, if you don't use i2c muxes on your hardware.
1801 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1804 CONFIG_SYS_I2C_MAX_HOPS
1805 define how many muxes are maximal consecutively connected
1806 on one i2c bus. If you not use i2c muxes, omit this
1809 CONFIG_SYS_I2C_BUSES
1810 hold a list of buses you want to use, only used if
1811 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1812 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1813 CONFIG_SYS_NUM_I2C_BUSES = 9:
1815 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1816 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1817 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1818 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1819 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1820 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1821 {1, {I2C_NULL_HOP}}, \
1822 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1823 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1827 bus 0 on adapter 0 without a mux
1828 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1829 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1830 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1831 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1832 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1833 bus 6 on adapter 1 without a mux
1834 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1835 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1837 If you do not have i2c muxes on your board, omit this define.
1839 - Legacy I2C Support:
1840 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1841 then the following macros need to be defined (examples are
1842 from include/configs/lwmon.h):
1846 (Optional). Any commands necessary to enable the I2C
1847 controller or configure ports.
1849 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1853 The code necessary to make the I2C data line active
1854 (driven). If the data line is open collector, this
1857 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1861 The code necessary to make the I2C data line tri-stated
1862 (inactive). If the data line is open collector, this
1865 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1869 Code that returns true if the I2C data line is high,
1872 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1876 If <bit> is true, sets the I2C data line high. If it
1877 is false, it clears it (low).
1879 eg: #define I2C_SDA(bit) \
1880 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1881 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1885 If <bit> is true, sets the I2C clock line high. If it
1886 is false, it clears it (low).
1888 eg: #define I2C_SCL(bit) \
1889 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1890 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1894 This delay is invoked four times per clock cycle so this
1895 controls the rate of data transfer. The data rate thus
1896 is 1 / (I2C_DELAY * 4). Often defined to be something
1899 #define I2C_DELAY udelay(2)
1901 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1903 If your arch supports the generic GPIO framework (asm/gpio.h),
1904 then you may alternatively define the two GPIOs that are to be
1905 used as SCL / SDA. Any of the previous I2C_xxx macros will
1906 have GPIO-based defaults assigned to them as appropriate.
1908 You should define these to the GPIO value as given directly to
1909 the generic GPIO functions.
1911 CONFIG_SYS_I2C_INIT_BOARD
1913 When a board is reset during an i2c bus transfer
1914 chips might think that the current transfer is still
1915 in progress. On some boards it is possible to access
1916 the i2c SCLK line directly, either by using the
1917 processor pin as a GPIO or by having a second pin
1918 connected to the bus. If this option is defined a
1919 custom i2c_init_board() routine in boards/xxx/board.c
1920 is run early in the boot sequence.
1922 CONFIG_I2C_MULTI_BUS
1924 This option allows the use of multiple I2C buses, each of which
1925 must have a controller. At any point in time, only one bus is
1926 active. To switch to a different bus, use the 'i2c dev' command.
1927 Note that bus numbering is zero-based.
1929 CONFIG_SYS_I2C_NOPROBES
1931 This option specifies a list of I2C devices that will be skipped
1932 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1933 is set, specify a list of bus-device pairs. Otherwise, specify
1934 a 1D array of device addresses
1937 #undef CONFIG_I2C_MULTI_BUS
1938 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1940 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1942 #define CONFIG_I2C_MULTI_BUS
1943 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1945 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1947 CONFIG_SYS_SPD_BUS_NUM
1949 If defined, then this indicates the I2C bus number for DDR SPD.
1950 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1952 CONFIG_SYS_RTC_BUS_NUM
1954 If defined, then this indicates the I2C bus number for the RTC.
1955 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1957 CONFIG_SOFT_I2C_READ_REPEATED_START
1959 defining this will force the i2c_read() function in
1960 the soft_i2c driver to perform an I2C repeated start
1961 between writing the address pointer and reading the
1962 data. If this define is omitted the default behaviour
1963 of doing a stop-start sequence will be used. Most I2C
1964 devices can use either method, but some require one or
1967 - SPI Support: CONFIG_SPI
1969 Enables SPI driver (so far only tested with
1970 SPI EEPROM, also an instance works with Crystal A/D and
1971 D/As on the SACSng board)
1975 Enables a software (bit-bang) SPI driver rather than
1976 using hardware support. This is a general purpose
1977 driver that only requires three general I/O port pins
1978 (two outputs, one input) to function. If this is
1979 defined, the board configuration must define several
1980 SPI configuration items (port pins to use, etc). For
1981 an example, see include/configs/sacsng.h.
1985 Enables a hardware SPI driver for general-purpose reads
1986 and writes. As with CONFIG_SOFT_SPI, the board configuration
1987 must define a list of chip-select function pointers.
1988 Currently supported on some MPC8xxx processors. For an
1989 example, see include/configs/mpc8349emds.h.
1991 CONFIG_SYS_SPI_MXC_WAIT
1992 Timeout for waiting until spi transfer completed.
1993 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1995 - FPGA Support: CONFIG_FPGA
1997 Enables FPGA subsystem.
1999 CONFIG_FPGA_<vendor>
2001 Enables support for specific chip vendors.
2004 CONFIG_FPGA_<family>
2006 Enables support for FPGA family.
2007 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2011 Specify the number of FPGA devices to support.
2013 CONFIG_SYS_FPGA_PROG_FEEDBACK
2015 Enable printing of hash marks during FPGA configuration.
2017 CONFIG_SYS_FPGA_CHECK_BUSY
2019 Enable checks on FPGA configuration interface busy
2020 status by the configuration function. This option
2021 will require a board or device specific function to
2026 If defined, a function that provides delays in the FPGA
2027 configuration driver.
2029 CONFIG_SYS_FPGA_CHECK_CTRLC
2030 Allow Control-C to interrupt FPGA configuration
2032 CONFIG_SYS_FPGA_CHECK_ERROR
2034 Check for configuration errors during FPGA bitfile
2035 loading. For example, abort during Virtex II
2036 configuration if the INIT_B line goes low (which
2037 indicated a CRC error).
2039 CONFIG_SYS_FPGA_WAIT_INIT
2041 Maximum time to wait for the INIT_B line to de-assert
2042 after PROB_B has been de-asserted during a Virtex II
2043 FPGA configuration sequence. The default time is 500
2046 CONFIG_SYS_FPGA_WAIT_BUSY
2048 Maximum time to wait for BUSY to de-assert during
2049 Virtex II FPGA configuration. The default is 5 ms.
2051 CONFIG_SYS_FPGA_WAIT_CONFIG
2053 Time to wait after FPGA configuration. The default is
2056 - Configuration Management:
2059 Some SoCs need special image types (e.g. U-Boot binary
2060 with a special header) as build targets. By defining
2061 CONFIG_BUILD_TARGET in the SoC / board header, this
2062 special image will be automatically built upon calling
2067 If defined, this string will be added to the U-Boot
2068 version information (U_BOOT_VERSION)
2070 - Vendor Parameter Protection:
2072 U-Boot considers the values of the environment
2073 variables "serial#" (Board Serial Number) and
2074 "ethaddr" (Ethernet Address) to be parameters that
2075 are set once by the board vendor / manufacturer, and
2076 protects these variables from casual modification by
2077 the user. Once set, these variables are read-only,
2078 and write or delete attempts are rejected. You can
2079 change this behaviour:
2081 If CONFIG_ENV_OVERWRITE is #defined in your config
2082 file, the write protection for vendor parameters is
2083 completely disabled. Anybody can change or delete
2086 Alternatively, if you define _both_ an ethaddr in the
2087 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2088 Ethernet address is installed in the environment,
2089 which can be changed exactly ONCE by the user. [The
2090 serial# is unaffected by this, i. e. it remains
2093 The same can be accomplished in a more flexible way
2094 for any variable by configuring the type of access
2095 to allow for those variables in the ".flags" variable
2096 or define CONFIG_ENV_FLAGS_LIST_STATIC.
2101 Define this variable to enable the reservation of
2102 "protected RAM", i. e. RAM which is not overwritten
2103 by U-Boot. Define CONFIG_PRAM to hold the number of
2104 kB you want to reserve for pRAM. You can overwrite
2105 this default value by defining an environment
2106 variable "pram" to the number of kB you want to
2107 reserve. Note that the board info structure will
2108 still show the full amount of RAM. If pRAM is
2109 reserved, a new environment variable "mem" will
2110 automatically be defined to hold the amount of
2111 remaining RAM in a form that can be passed as boot
2112 argument to Linux, for instance like that:
2114 setenv bootargs ... mem=\${mem}
2117 This way you can tell Linux not to use this memory,
2118 either, which results in a memory region that will
2119 not be affected by reboots.
2121 *WARNING* If your board configuration uses automatic
2122 detection of the RAM size, you must make sure that
2123 this memory test is non-destructive. So far, the
2124 following board configurations are known to be
2127 IVMS8, IVML24, SPD8xx,
2128 HERMES, IP860, RPXlite, LWMON,
2131 - Access to physical memory region (> 4GB)
2132 Some basic support is provided for operations on memory not
2133 normally accessible to U-Boot - e.g. some architectures
2134 support access to more than 4GB of memory on 32-bit
2135 machines using physical address extension or similar.
2136 Define CONFIG_PHYSMEM to access this basic support, which
2137 currently only supports clearing the memory.
2140 CONFIG_NET_RETRY_COUNT
2142 This variable defines the number of retries for
2143 network operations like ARP, RARP, TFTP, or BOOTP
2144 before giving up the operation. If not defined, a
2145 default value of 5 is used.
2149 Timeout waiting for an ARP reply in milliseconds.
2153 Timeout in milliseconds used in NFS protocol.
2154 If you encounter "ERROR: Cannot umount" in nfs command,
2155 try longer timeout such as
2156 #define CONFIG_NFS_TIMEOUT 10000UL
2158 - Command Interpreter:
2159 CONFIG_SYS_PROMPT_HUSH_PS2
2161 This defines the secondary prompt string, which is
2162 printed when the command interpreter needs more input
2163 to complete a command. Usually "> ".
2167 In the current implementation, the local variables
2168 space and global environment variables space are
2169 separated. Local variables are those you define by
2170 simply typing `name=value'. To access a local
2171 variable later on, you have write `$name' or
2172 `${name}'; to execute the contents of a variable
2173 directly type `$name' at the command prompt.
2175 Global environment variables are those you use
2176 setenv/printenv to work with. To run a command stored
2177 in such a variable, you need to use the run command,
2178 and you must not use the '$' sign to access them.
2180 To store commands and special characters in a
2181 variable, please use double quotation marks
2182 surrounding the whole text of the variable, instead
2183 of the backslashes before semicolons and special
2186 - Command Line Editing and History:
2187 CONFIG_CMDLINE_PS_SUPPORT
2189 Enable support for changing the command prompt string
2190 at run-time. Only static string is supported so far.
2191 The string is obtained from environment variables PS1
2194 - Default Environment:
2195 CONFIG_EXTRA_ENV_SETTINGS
2197 Define this to contain any number of null terminated
2198 strings (variable = value pairs) that will be part of
2199 the default environment compiled into the boot image.
2201 For example, place something like this in your
2202 board's config file:
2204 #define CONFIG_EXTRA_ENV_SETTINGS \
2208 Warning: This method is based on knowledge about the
2209 internal format how the environment is stored by the
2210 U-Boot code. This is NOT an official, exported
2211 interface! Although it is unlikely that this format
2212 will change soon, there is no guarantee either.
2213 You better know what you are doing here.
2215 Note: overly (ab)use of the default environment is
2216 discouraged. Make sure to check other ways to preset
2217 the environment like the "source" command or the
2220 CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2222 Define this in order to add variables describing certain
2223 run-time determined information about the hardware to the
2224 environment. These will be named board_name, board_rev.
2226 CONFIG_DELAY_ENVIRONMENT
2228 Normally the environment is loaded when the board is
2229 initialised so that it is available to U-Boot. This inhibits
2230 that so that the environment is not available until
2231 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2232 this is instead controlled by the value of
2233 /config/load-environment.
2235 - Serial Flash support
2236 Usage requires an initial 'sf probe' to define the serial
2237 flash parameters, followed by read/write/erase/update
2240 The following defaults may be provided by the platform
2241 to handle the common case when only a single serial
2242 flash is present on the system.
2244 CONFIG_SF_DEFAULT_BUS Bus identifier
2245 CONFIG_SF_DEFAULT_CS Chip-select
2246 CONFIG_SF_DEFAULT_MODE (see include/spi.h)
2247 CONFIG_SF_DEFAULT_SPEED in Hz
2250 - TFTP Fixed UDP Port:
2253 If this is defined, the environment variable tftpsrcp
2254 is used to supply the TFTP UDP source port value.
2255 If tftpsrcp isn't defined, the normal pseudo-random port
2256 number generator is used.
2258 Also, the environment variable tftpdstp is used to supply
2259 the TFTP UDP destination port value. If tftpdstp isn't
2260 defined, the normal port 69 is used.
2262 The purpose for tftpsrcp is to allow a TFTP server to
2263 blindly start the TFTP transfer using the pre-configured
2264 target IP address and UDP port. This has the effect of
2265 "punching through" the (Windows XP) firewall, allowing
2266 the remainder of the TFTP transfer to proceed normally.
2267 A better solution is to properly configure the firewall,
2268 but sometimes that is not allowed.
2270 - bootcount support:
2272 enable special bootcounter support on at91sam9xe based boards.
2273 CONFIG_BOOTCOUNT_RAM
2274 enable support for the bootcounter in RAM
2275 CONFIG_BOOTCOUNT_I2C
2276 enable support for the bootcounter on an i2c (like RTC) device.
2277 CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2278 CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2280 CONFIG_BOOTCOUNT_ALEN = address len
2281 CONFIG_BOOTCOUNT_EXT
2282 enable support for the bootcounter in EXT filesystem
2283 CONFIG_SYS_BOOTCOUNT_ADDR = RAM address used for read
2285 CONFIG_SYS_BOOTCOUNT_EXT_INTERFACE = interface
2286 CONFIG_SYS_BOOTCOUNT_EXT_DEVPART = device and part
2287 CONFIG_SYS_BOOTCOUNT_EXT_NAME = filename
2289 - Show boot progress:
2290 CONFIG_SHOW_BOOT_PROGRESS
2292 Defining this option allows to add some board-
2293 specific code (calling a user-provided function
2294 "show_boot_progress(int)") that enables you to show
2295 the system's boot progress on some display (for
2296 example, some LED's) on your board. At the moment,
2297 the following checkpoints are implemented:
2300 Legacy uImage format:
2303 1 common/cmd_bootm.c before attempting to boot an image
2304 -1 common/cmd_bootm.c Image header has bad magic number
2305 2 common/cmd_bootm.c Image header has correct magic number
2306 -2 common/cmd_bootm.c Image header has bad checksum
2307 3 common/cmd_bootm.c Image header has correct checksum
2308 -3 common/cmd_bootm.c Image data has bad checksum
2309 4 common/cmd_bootm.c Image data has correct checksum
2310 -4 common/cmd_bootm.c Image is for unsupported architecture
2311 5 common/cmd_bootm.c Architecture check OK
2312 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi)
2313 6 common/cmd_bootm.c Image Type check OK
2314 -6 common/cmd_bootm.c gunzip uncompression error
2315 -7 common/cmd_bootm.c Unimplemented compression type
2316 7 common/cmd_bootm.c Uncompression OK
2317 8 common/cmd_bootm.c No uncompress/copy overwrite error
2318 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
2320 9 common/image.c Start initial ramdisk verification
2321 -10 common/image.c Ramdisk header has bad magic number
2322 -11 common/image.c Ramdisk header has bad checksum
2323 10 common/image.c Ramdisk header is OK
2324 -12 common/image.c Ramdisk data has bad checksum
2325 11 common/image.c Ramdisk data has correct checksum
2326 12 common/image.c Ramdisk verification complete, start loading
2327 -13 common/image.c Wrong Image Type (not PPC Linux ramdisk)
2328 13 common/image.c Start multifile image verification
2329 14 common/image.c No initial ramdisk, no multifile, continue.
2331 15 arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2333 -30 arch/powerpc/lib/board.c Fatal error, hang the system
2334 -31 post/post.c POST test failed, detected by post_output_backlog()
2335 -32 post/post.c POST test failed, detected by post_run_single()
2337 34 common/cmd_doc.c before loading a Image from a DOC device
2338 -35 common/cmd_doc.c Bad usage of "doc" command
2339 35 common/cmd_doc.c correct usage of "doc" command
2340 -36 common/cmd_doc.c No boot device
2341 36 common/cmd_doc.c correct boot device
2342 -37 common/cmd_doc.c Unknown Chip ID on boot device
2343 37 common/cmd_doc.c correct chip ID found, device available
2344 -38 common/cmd_doc.c Read Error on boot device
2345 38 common/cmd_doc.c reading Image header from DOC device OK
2346 -39 common/cmd_doc.c Image header has bad magic number
2347 39 common/cmd_doc.c Image header has correct magic number
2348 -40 common/cmd_doc.c Error reading Image from DOC device
2349 40 common/cmd_doc.c Image header has correct magic number
2350 41 common/cmd_ide.c before loading a Image from a IDE device
2351 -42 common/cmd_ide.c Bad usage of "ide" command
2352 42 common/cmd_ide.c correct usage of "ide" command
2353 -43 common/cmd_ide.c No boot device
2354 43 common/cmd_ide.c boot device found
2355 -44 common/cmd_ide.c Device not available
2356 44 common/cmd_ide.c Device available
2357 -45 common/cmd_ide.c wrong partition selected
2358 45 common/cmd_ide.c partition selected
2359 -46 common/cmd_ide.c Unknown partition table
2360 46 common/cmd_ide.c valid partition table found
2361 -47 common/cmd_ide.c Invalid partition type
2362 47 common/cmd_ide.c correct partition type
2363 -48 common/cmd_ide.c Error reading Image Header on boot device
2364 48 common/cmd_ide.c reading Image Header from IDE device OK
2365 -49 common/cmd_ide.c Image header has bad magic number
2366 49 common/cmd_ide.c Image header has correct magic number
2367 -50 common/cmd_ide.c Image header has bad checksum
2368 50 common/cmd_ide.c Image header has correct checksum
2369 -51 common/cmd_ide.c Error reading Image from IDE device
2370 51 common/cmd_ide.c reading Image from IDE device OK
2371 52 common/cmd_nand.c before loading a Image from a NAND device
2372 -53 common/cmd_nand.c Bad usage of "nand" command
2373 53 common/cmd_nand.c correct usage of "nand" command
2374 -54 common/cmd_nand.c No boot device
2375 54 common/cmd_nand.c boot device found
2376 -55 common/cmd_nand.c Unknown Chip ID on boot device
2377 55 common/cmd_nand.c correct chip ID found, device available
2378 -56 common/cmd_nand.c Error reading Image Header on boot device
2379 56 common/cmd_nand.c reading Image Header from NAND device OK
2380 -57 common/cmd_nand.c Image header has bad magic number
2381 57 common/cmd_nand.c Image header has correct magic number
2382 -58 common/cmd_nand.c Error reading Image from NAND device
2383 58 common/cmd_nand.c reading Image from NAND device OK
2385 -60 common/env_common.c Environment has a bad CRC, using default
2387 64 net/eth.c starting with Ethernet configuration.
2388 -64 net/eth.c no Ethernet found.
2389 65 net/eth.c Ethernet found.
2391 -80 common/cmd_net.c usage wrong
2392 80 common/cmd_net.c before calling net_loop()
2393 -81 common/cmd_net.c some error in net_loop() occurred
2394 81 common/cmd_net.c net_loop() back without error
2395 -82 common/cmd_net.c size == 0 (File with size 0 loaded)
2396 82 common/cmd_net.c trying automatic boot
2397 83 common/cmd_net.c running "source" command
2398 -83 common/cmd_net.c some error in automatic boot or "source" command
2399 84 common/cmd_net.c end without errors
2404 100 common/cmd_bootm.c Kernel FIT Image has correct format
2405 -100 common/cmd_bootm.c Kernel FIT Image has incorrect format
2406 101 common/cmd_bootm.c No Kernel subimage unit name, using configuration
2407 -101 common/cmd_bootm.c Can't get configuration for kernel subimage
2408 102 common/cmd_bootm.c Kernel unit name specified
2409 -103 common/cmd_bootm.c Can't get kernel subimage node offset
2410 103 common/cmd_bootm.c Found configuration node
2411 104 common/cmd_bootm.c Got kernel subimage node offset
2412 -104 common/cmd_bootm.c Kernel subimage hash verification failed
2413 105 common/cmd_bootm.c Kernel subimage hash verification OK
2414 -105 common/cmd_bootm.c Kernel subimage is for unsupported architecture
2415 106 common/cmd_bootm.c Architecture check OK
2416 -106 common/cmd_bootm.c Kernel subimage has wrong type
2417 107 common/cmd_bootm.c Kernel subimage type OK
2418 -107 common/cmd_bootm.c Can't get kernel subimage data/size
2419 108 common/cmd_bootm.c Got kernel subimage data/size
2420 -108 common/cmd_bootm.c Wrong image type (not legacy, FIT)
2421 -109 common/cmd_bootm.c Can't get kernel subimage type
2422 -110 common/cmd_bootm.c Can't get kernel subimage comp
2423 -111 common/cmd_bootm.c Can't get kernel subimage os
2424 -112 common/cmd_bootm.c Can't get kernel subimage load address
2425 -113 common/cmd_bootm.c Image uncompress/copy overwrite error
2427 120 common/image.c Start initial ramdisk verification
2428 -120 common/image.c Ramdisk FIT image has incorrect format
2429 121 common/image.c Ramdisk FIT image has correct format
2430 122 common/image.c No ramdisk subimage unit name, using configuration
2431 -122 common/image.c Can't get configuration for ramdisk subimage
2432 123 common/image.c Ramdisk unit name specified
2433 -124 common/image.c Can't get ramdisk subimage node offset
2434 125 common/image.c Got ramdisk subimage node offset
2435 -125 common/image.c Ramdisk subimage hash verification failed
2436 126 common/image.c Ramdisk subimage hash verification OK
2437 -126 common/image.c Ramdisk subimage for unsupported architecture
2438 127 common/image.c Architecture check OK
2439 -127 common/image.c Can't get ramdisk subimage data/size
2440 128 common/image.c Got ramdisk subimage data/size
2441 129 common/image.c Can't get ramdisk load address
2442 -129 common/image.c Got ramdisk load address
2444 -130 common/cmd_doc.c Incorrect FIT image format
2445 131 common/cmd_doc.c FIT image format OK
2447 -140 common/cmd_ide.c Incorrect FIT image format
2448 141 common/cmd_ide.c FIT image format OK
2450 -150 common/cmd_nand.c Incorrect FIT image format
2451 151 common/cmd_nand.c FIT image format OK
2453 - legacy image format:
2454 CONFIG_IMAGE_FORMAT_LEGACY
2455 enables the legacy image format support in U-Boot.
2458 enabled if CONFIG_FIT_SIGNATURE is not defined.
2460 CONFIG_DISABLE_IMAGE_LEGACY
2461 disable the legacy image format
2463 This define is introduced, as the legacy image format is
2464 enabled per default for backward compatibility.
2466 - Standalone program support:
2467 CONFIG_STANDALONE_LOAD_ADDR
2469 This option defines a board specific value for the
2470 address where standalone program gets loaded, thus
2471 overwriting the architecture dependent default
2474 - Frame Buffer Address:
2477 Define CONFIG_FB_ADDR if you want to use specific
2478 address for frame buffer. This is typically the case
2479 when using a graphics controller has separate video
2480 memory. U-Boot will then place the frame buffer at
2481 the given address instead of dynamically reserving it
2482 in system RAM by calling lcd_setmem(), which grabs
2483 the memory for the frame buffer depending on the
2484 configured panel size.
2486 Please see board_init_f function.
2488 - Automatic software updates via TFTP server
2490 CONFIG_UPDATE_TFTP_CNT_MAX
2491 CONFIG_UPDATE_TFTP_MSEC_MAX
2493 These options enable and control the auto-update feature;
2494 for a more detailed description refer to doc/README.update.
2496 - MTD Support (mtdparts command, UBI support)
2499 Adds the MTD device infrastructure from the Linux kernel.
2500 Needed for mtdparts command support.
2502 CONFIG_MTD_PARTITIONS
2504 Adds the MTD partitioning infrastructure from the Linux
2505 kernel. Needed for UBI support.
2508 CONFIG_UBI_SILENCE_MSG
2510 Make the verbose messages from UBI stop printing. This leaves
2511 warnings and errors enabled.
2514 CONFIG_MTD_UBI_WL_THRESHOLD
2515 This parameter defines the maximum difference between the highest
2516 erase counter value and the lowest erase counter value of eraseblocks
2517 of UBI devices. When this threshold is exceeded, UBI starts performing
2518 wear leveling by means of moving data from eraseblock with low erase
2519 counter to eraseblocks with high erase counter.
2521 The default value should be OK for SLC NAND flashes, NOR flashes and
2522 other flashes which have eraseblock life-cycle 100000 or more.
2523 However, in case of MLC NAND flashes which typically have eraseblock
2524 life-cycle less than 10000, the threshold should be lessened (e.g.,
2525 to 128 or 256, although it does not have to be power of 2).
2529 CONFIG_MTD_UBI_BEB_LIMIT
2530 This option specifies the maximum bad physical eraseblocks UBI
2531 expects on the MTD device (per 1024 eraseblocks). If the
2532 underlying flash does not admit of bad eraseblocks (e.g. NOR
2533 flash), this value is ignored.
2535 NAND datasheets often specify the minimum and maximum NVM
2536 (Number of Valid Blocks) for the flashes' endurance lifetime.
2537 The maximum expected bad eraseblocks per 1024 eraseblocks
2538 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2539 which gives 20 for most NANDs (MaxNVB is basically the total
2540 count of eraseblocks on the chip).
2542 To put it differently, if this value is 20, UBI will try to
2543 reserve about 1.9% of physical eraseblocks for bad blocks
2544 handling. And that will be 1.9% of eraseblocks on the entire
2545 NAND chip, not just the MTD partition UBI attaches. This means
2546 that if you have, say, a NAND flash chip admits maximum 40 bad
2547 eraseblocks, and it is split on two MTD partitions of the same
2548 size, UBI will reserve 40 eraseblocks when attaching a
2553 CONFIG_MTD_UBI_FASTMAP
2554 Fastmap is a mechanism which allows attaching an UBI device
2555 in nearly constant time. Instead of scanning the whole MTD device it
2556 only has to locate a checkpoint (called fastmap) on the device.
2557 The on-flash fastmap contains all information needed to attach
2558 the device. Using fastmap makes only sense on large devices where
2559 attaching by scanning takes long. UBI will not automatically install
2560 a fastmap on old images, but you can set the UBI parameter
2561 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2562 that fastmap-enabled images are still usable with UBI implementations
2563 without fastmap support. On typical flash devices the whole fastmap
2564 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2566 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2567 Set this parameter to enable fastmap automatically on images
2571 CONFIG_MTD_UBI_FM_DEBUG
2572 Enable UBI fastmap debug
2576 CONFIG_UBIFS_SILENCE_MSG
2578 Make the verbose messages from UBIFS stop printing. This leaves
2579 warnings and errors enabled.
2583 Enable building of SPL globally.
2586 LDSCRIPT for linking the SPL binary.
2588 CONFIG_SPL_MAX_FOOTPRINT
2589 Maximum size in memory allocated to the SPL, BSS included.
2590 When defined, the linker checks that the actual memory
2591 used by SPL from _start to __bss_end does not exceed it.
2592 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2593 must not be both defined at the same time.
2596 Maximum size of the SPL image (text, data, rodata, and
2597 linker lists sections), BSS excluded.
2598 When defined, the linker checks that the actual size does
2601 CONFIG_SPL_TEXT_BASE
2602 TEXT_BASE for linking the SPL binary.
2604 CONFIG_SPL_RELOC_TEXT_BASE
2605 Address to relocate to. If unspecified, this is equal to
2606 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2608 CONFIG_SPL_BSS_START_ADDR
2609 Link address for the BSS within the SPL binary.
2611 CONFIG_SPL_BSS_MAX_SIZE
2612 Maximum size in memory allocated to the SPL BSS.
2613 When defined, the linker checks that the actual memory used
2614 by SPL from __bss_start to __bss_end does not exceed it.
2615 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2616 must not be both defined at the same time.
2619 Adress of the start of the stack SPL will use
2621 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2622 When defined, SPL will panic() if the image it has
2623 loaded does not have a signature.
2624 Defining this is useful when code which loads images
2625 in SPL cannot guarantee that absolutely all read errors
2627 An example is the LPC32XX MLC NAND driver, which will
2628 consider that a completely unreadable NAND block is bad,
2629 and thus should be skipped silently.
2631 CONFIG_SPL_RELOC_STACK
2632 Adress of the start of the stack SPL will use after
2633 relocation. If unspecified, this is equal to
2636 CONFIG_SYS_SPL_MALLOC_START
2637 Starting address of the malloc pool used in SPL.
2638 When this option is set the full malloc is used in SPL and
2639 it is set up by spl_init() and before that, the simple malloc()
2640 can be used if CONFIG_SYS_MALLOC_F is defined.
2642 CONFIG_SYS_SPL_MALLOC_SIZE
2643 The size of the malloc pool used in SPL.
2646 Enable booting directly to an OS from SPL.
2647 See also: doc/README.falcon
2649 CONFIG_SPL_DISPLAY_PRINT
2650 For ARM, enable an optional function to print more information
2651 about the running system.
2653 CONFIG_SPL_INIT_MINIMAL
2654 Arch init code should be built for a very small image
2656 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2657 Partition on the MMC to load U-Boot from when the MMC is being
2660 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2661 Sector to load kernel uImage from when MMC is being
2662 used in raw mode (for Falcon mode)
2664 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2665 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2666 Sector and number of sectors to load kernel argument
2667 parameters from when MMC is being used in raw mode
2670 CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
2671 Partition on the MMC to load U-Boot from when the MMC is being
2674 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2675 Filename to read to load U-Boot when reading from filesystem
2677 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2678 Filename to read to load kernel uImage when reading
2679 from filesystem (for Falcon mode)
2681 CONFIG_SPL_FS_LOAD_ARGS_NAME
2682 Filename to read to load kernel argument parameters
2683 when reading from filesystem (for Falcon mode)
2685 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2686 Set this for NAND SPL on PPC mpc83xx targets, so that
2687 start.S waits for the rest of the SPL to load before
2688 continuing (the hardware starts execution after just
2689 loading the first page rather than the full 4K).
2691 CONFIG_SPL_SKIP_RELOCATE
2692 Avoid SPL relocation
2694 CONFIG_SPL_NAND_BASE
2695 Include nand_base.c in the SPL. Requires
2696 CONFIG_SPL_NAND_DRIVERS.
2698 CONFIG_SPL_NAND_DRIVERS
2699 SPL uses normal NAND drivers, not minimal drivers.
2702 Include standard software ECC in the SPL
2704 CONFIG_SPL_NAND_SIMPLE
2705 Support for NAND boot using simple NAND drivers that
2706 expose the cmd_ctrl() interface.
2709 Support for a lightweight UBI (fastmap) scanner and
2712 CONFIG_SPL_NAND_RAW_ONLY
2713 Support to boot only raw u-boot.bin images. Use this only
2714 if you need to save space.
2716 CONFIG_SPL_COMMON_INIT_DDR
2717 Set for common ddr init with serial presence detect in
2720 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2721 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2722 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2723 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2724 CONFIG_SYS_NAND_ECCBYTES
2725 Defines the size and behavior of the NAND that SPL uses
2728 CONFIG_SPL_NAND_BOOT
2729 Add support NAND boot
2731 CONFIG_SYS_NAND_U_BOOT_OFFS
2732 Location in NAND to read U-Boot from
2734 CONFIG_SYS_NAND_U_BOOT_DST
2735 Location in memory to load U-Boot to
2737 CONFIG_SYS_NAND_U_BOOT_SIZE
2738 Size of image to load
2740 CONFIG_SYS_NAND_U_BOOT_START
2741 Entry point in loaded image to jump to
2743 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2744 Define this if you need to first read the OOB and then the
2745 data. This is used, for example, on davinci platforms.
2747 CONFIG_SPL_RAM_DEVICE
2748 Support for running image already present in ram, in SPL binary
2751 Image offset to which the SPL should be padded before appending
2752 the SPL payload. By default, this is defined as
2753 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2754 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2755 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2758 Final target image containing SPL and payload. Some SPLs
2759 use an arch-specific makefile fragment instead, for
2760 example if more than one image needs to be produced.
2762 CONFIG_FIT_SPL_PRINT
2763 Printing information about a FIT image adds quite a bit of
2764 code to SPL. So this is normally disabled in SPL. Use this
2765 option to re-enable it. This will affect the output of the
2766 bootm command when booting a FIT image.
2770 Enable building of TPL globally.
2773 Image offset to which the TPL should be padded before appending
2774 the TPL payload. By default, this is defined as
2775 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2776 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2777 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2779 - Interrupt support (PPC):
2781 There are common interrupt_init() and timer_interrupt()
2782 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2783 for CPU specific initialization. interrupt_init_cpu()
2784 should set decrementer_count to appropriate value. If
2785 CPU resets decrementer automatically after interrupt
2786 (ppc4xx) it should set decrementer_count to zero.
2787 timer_interrupt() calls timer_interrupt_cpu() for CPU
2788 specific handling. If board has watchdog / status_led
2789 / other_activity_monitor it works automatically from
2790 general timer_interrupt().
2793 Board initialization settings:
2794 ------------------------------
2796 During Initialization u-boot calls a number of board specific functions
2797 to allow the preparation of board specific prerequisites, e.g. pin setup
2798 before drivers are initialized. To enable these callbacks the
2799 following configuration macros have to be defined. Currently this is
2800 architecture specific, so please check arch/your_architecture/lib/board.c
2801 typically in board_init_f() and board_init_r().
2803 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2804 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2805 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2806 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2808 Configuration Settings:
2809 -----------------------
2811 - CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2812 Optionally it can be defined to support 64-bit memory commands.
2814 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2815 undefine this when you're short of memory.
2817 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2818 width of the commands listed in the 'help' command output.
2820 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2821 prompt for user input.
2823 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2825 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2827 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2829 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2830 the application (usually a Linux kernel) when it is
2833 - CONFIG_SYS_BAUDRATE_TABLE:
2834 List of legal baudrate settings for this board.
2836 - CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2837 Begin and End addresses of the area used by the
2840 - CONFIG_SYS_ALT_MEMTEST:
2841 Enable an alternate, more extensive memory test.
2843 - CONFIG_SYS_MEMTEST_SCRATCH:
2844 Scratch address used by the alternate memory test
2845 You only need to set this if address zero isn't writeable
2847 - CONFIG_SYS_MEM_RESERVE_SECURE
2848 Only implemented for ARMv8 for now.
2849 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2850 is substracted from total RAM and won't be reported to OS.
2851 This memory can be used as secure memory. A variable
2852 gd->arch.secure_ram is used to track the location. In systems
2853 the RAM base is not zero, or RAM is divided into banks,
2854 this variable needs to be recalcuated to get the address.
2856 - CONFIG_SYS_MEM_TOP_HIDE:
2857 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2858 this specified memory area will get subtracted from the top
2859 (end) of RAM and won't get "touched" at all by U-Boot. By
2860 fixing up gd->ram_size the Linux kernel should gets passed
2861 the now "corrected" memory size and won't touch it either.
2862 This should work for arch/ppc and arch/powerpc. Only Linux
2863 board ports in arch/powerpc with bootwrapper support that
2864 recalculate the memory size from the SDRAM controller setup
2865 will have to get fixed in Linux additionally.
2867 This option can be used as a workaround for the 440EPx/GRx
2868 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2871 WARNING: Please make sure that this value is a multiple of
2872 the Linux page size (normally 4k). If this is not the case,
2873 then the end address of the Linux memory will be located at a
2874 non page size aligned address and this could cause major
2877 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2878 Enable temporary baudrate change while serial download
2880 - CONFIG_SYS_SDRAM_BASE:
2881 Physical start address of SDRAM. _Must_ be 0 here.
2883 - CONFIG_SYS_FLASH_BASE:
2884 Physical start address of Flash memory.
2886 - CONFIG_SYS_MONITOR_BASE:
2887 Physical start address of boot monitor code (set by
2888 make config files to be same as the text base address
2889 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2890 CONFIG_SYS_FLASH_BASE when booting from flash.
2892 - CONFIG_SYS_MONITOR_LEN:
2893 Size of memory reserved for monitor code, used to
2894 determine _at_compile_time_ (!) if the environment is
2895 embedded within the U-Boot image, or in a separate
2898 - CONFIG_SYS_MALLOC_LEN:
2899 Size of DRAM reserved for malloc() use.
2901 - CONFIG_SYS_MALLOC_F_LEN
2902 Size of the malloc() pool for use before relocation. If
2903 this is defined, then a very simple malloc() implementation
2904 will become available before relocation. The address is just
2905 below the global data, and the stack is moved down to make
2908 This feature allocates regions with increasing addresses
2909 within the region. calloc() is supported, but realloc()
2910 is not available. free() is supported but does nothing.
2911 The memory will be freed (or in fact just forgotten) when
2912 U-Boot relocates itself.
2914 - CONFIG_SYS_MALLOC_SIMPLE
2915 Provides a simple and small malloc() and calloc() for those
2916 boards which do not use the full malloc in SPL (which is
2917 enabled with CONFIG_SYS_SPL_MALLOC_START).
2919 - CONFIG_SYS_NONCACHED_MEMORY:
2920 Size of non-cached memory area. This area of memory will be
2921 typically located right below the malloc() area and mapped
2922 uncached in the MMU. This is useful for drivers that would
2923 otherwise require a lot of explicit cache maintenance. For
2924 some drivers it's also impossible to properly maintain the
2925 cache. For example if the regions that need to be flushed
2926 are not a multiple of the cache-line size, *and* padding
2927 cannot be allocated between the regions to align them (i.e.
2928 if the HW requires a contiguous array of regions, and the
2929 size of each region is not cache-aligned), then a flush of
2930 one region may result in overwriting data that hardware has
2931 written to another region in the same cache-line. This can
2932 happen for example in network drivers where descriptors for
2933 buffers are typically smaller than the CPU cache-line (e.g.
2934 16 bytes vs. 32 or 64 bytes).
2936 Non-cached memory is only supported on 32-bit ARM at present.
2938 - CONFIG_SYS_BOOTM_LEN:
2939 Normally compressed uImages are limited to an
2940 uncompressed size of 8 MBytes. If this is not enough,
2941 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2942 to adjust this setting to your needs.
2944 - CONFIG_SYS_BOOTMAPSZ:
2945 Maximum size of memory mapped by the startup code of
2946 the Linux kernel; all data that must be processed by
2947 the Linux kernel (bd_info, boot arguments, FDT blob if
2948 used) must be put below this limit, unless "bootm_low"
2949 environment variable is defined and non-zero. In such case
2950 all data for the Linux kernel must be between "bootm_low"
2951 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2952 variable "bootm_mapsize" will override the value of
2953 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2954 then the value in "bootm_size" will be used instead.
2956 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2957 Enable initrd_high functionality. If defined then the
2958 initrd_high feature is enabled and the bootm ramdisk subcommand
2961 - CONFIG_SYS_BOOT_GET_CMDLINE:
2962 Enables allocating and saving kernel cmdline in space between
2963 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2965 - CONFIG_SYS_BOOT_GET_KBD:
2966 Enables allocating and saving a kernel copy of the bd_info in
2967 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2969 - CONFIG_SYS_MAX_FLASH_BANKS:
2970 Max number of Flash memory banks
2972 - CONFIG_SYS_MAX_FLASH_SECT:
2973 Max number of sectors on a Flash chip
2975 - CONFIG_SYS_FLASH_ERASE_TOUT:
2976 Timeout for Flash erase operations (in ms)
2978 - CONFIG_SYS_FLASH_WRITE_TOUT:
2979 Timeout for Flash write operations (in ms)
2981 - CONFIG_SYS_FLASH_LOCK_TOUT
2982 Timeout for Flash set sector lock bit operation (in ms)
2984 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2985 Timeout for Flash clear lock bits operation (in ms)
2987 - CONFIG_SYS_FLASH_PROTECTION
2988 If defined, hardware flash sectors protection is used
2989 instead of U-Boot software protection.
2991 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2993 Enable TFTP transfers directly to flash memory;
2994 without this option such a download has to be
2995 performed in two steps: (1) download to RAM, and (2)
2996 copy from RAM to flash.
2998 The two-step approach is usually more reliable, since
2999 you can check if the download worked before you erase
3000 the flash, but in some situations (when system RAM is
3001 too limited to allow for a temporary copy of the
3002 downloaded image) this option may be very useful.
3004 - CONFIG_SYS_FLASH_CFI:
3005 Define if the flash driver uses extra elements in the
3006 common flash structure for storing flash geometry.
3008 - CONFIG_FLASH_CFI_DRIVER
3009 This option also enables the building of the cfi_flash driver
3010 in the drivers directory
3012 - CONFIG_FLASH_CFI_MTD
3013 This option enables the building of the cfi_mtd driver
3014 in the drivers directory. The driver exports CFI flash
3017 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3018 Use buffered writes to flash.
3020 - CONFIG_FLASH_SPANSION_S29WS_N
3021 s29ws-n MirrorBit flash has non-standard addresses for buffered
3024 - CONFIG_SYS_FLASH_QUIET_TEST
3025 If this option is defined, the common CFI flash doesn't
3026 print it's warning upon not recognized FLASH banks. This
3027 is useful, if some of the configured banks are only
3028 optionally available.
3030 - CONFIG_FLASH_SHOW_PROGRESS
3031 If defined (must be an integer), print out countdown
3032 digits and dots. Recommended value: 45 (9..1) for 80
3033 column displays, 15 (3..1) for 40 column displays.
3035 - CONFIG_FLASH_VERIFY
3036 If defined, the content of the flash (destination) is compared
3037 against the source after the write operation. An error message
3038 will be printed when the contents are not identical.
3039 Please note that this option is useless in nearly all cases,
3040 since such flash programming errors usually are detected earlier
3041 while unprotecting/erasing/programming. Please only enable
3042 this option if you really know what you are doing.
3044 - CONFIG_SYS_RX_ETH_BUFFER:
3045 Defines the number of Ethernet receive buffers. On some
3046 Ethernet controllers it is recommended to set this value
3047 to 8 or even higher (EEPRO100 or 405 EMAC), since all
3048 buffers can be full shortly after enabling the interface
3049 on high Ethernet traffic.
3050 Defaults to 4 if not defined.
3052 - CONFIG_ENV_MAX_ENTRIES
3054 Maximum number of entries in the hash table that is used
3055 internally to store the environment settings. The default
3056 setting is supposed to be generous and should work in most
3057 cases. This setting can be used to tune behaviour; see
3058 lib/hashtable.c for details.
3060 - CONFIG_ENV_FLAGS_LIST_DEFAULT
3061 - CONFIG_ENV_FLAGS_LIST_STATIC
3062 Enable validation of the values given to environment variables when
3063 calling env set. Variables can be restricted to only decimal,
3064 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
3065 the variables can also be restricted to IP address or MAC address.
3067 The format of the list is:
3068 type_attribute = [s|d|x|b|i|m]
3069 access_attribute = [a|r|o|c]
3070 attributes = type_attribute[access_attribute]
3071 entry = variable_name[:attributes]
3074 The type attributes are:
3075 s - String (default)
3078 b - Boolean ([1yYtT|0nNfF])
3082 The access attributes are:
3088 - CONFIG_ENV_FLAGS_LIST_DEFAULT
3089 Define this to a list (string) to define the ".flags"
3090 environment variable in the default or embedded environment.
3092 - CONFIG_ENV_FLAGS_LIST_STATIC
3093 Define this to a list (string) to define validation that
3094 should be done if an entry is not found in the ".flags"
3095 environment variable. To override a setting in the static
3096 list, simply add an entry for the same variable name to the
3099 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3100 regular expression. This allows multiple variables to define the same
3101 flags without explicitly listing them for each variable.
3103 - CONFIG_ENV_ACCESS_IGNORE_FORCE
3104 If defined, don't allow the -f switch to env set override variable
3108 If stdint.h is available with your toolchain you can define this
3109 option to enable it. You can provide option 'USE_STDINT=1' when
3110 building U-Boot to enable this.
3112 The following definitions that deal with the placement and management
3113 of environment data (variable area); in general, we support the
3114 following configurations:
3116 - CONFIG_BUILD_ENVCRC:
3118 Builds up envcrc with the target environment so that external utils
3119 may easily extract it and embed it in final U-Boot images.
3121 BE CAREFUL! The first access to the environment happens quite early
3122 in U-Boot initialization (when we try to get the setting of for the
3123 console baudrate). You *MUST* have mapped your NVRAM area then, or
3126 Please note that even with NVRAM we still use a copy of the
3127 environment in RAM: we could work on NVRAM directly, but we want to
3128 keep settings there always unmodified except somebody uses "saveenv"
3129 to save the current settings.
3131 BE CAREFUL! For some special cases, the local device can not use
3132 "saveenv" command. For example, the local device will get the
3133 environment stored in a remote NOR flash by SRIO or PCIE link,
3134 but it can not erase, write this NOR flash by SRIO or PCIE interface.
3136 - CONFIG_NAND_ENV_DST
3138 Defines address in RAM to which the nand_spl code should copy the
3139 environment. If redundant environment is used, it will be copied to
3140 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3142 Please note that the environment is read-only until the monitor
3143 has been relocated to RAM and a RAM copy of the environment has been
3144 created; also, when using EEPROM you will have to use env_get_f()
3145 until then to read environment variables.
3147 The environment is protected by a CRC32 checksum. Before the monitor
3148 is relocated into RAM, as a result of a bad CRC you will be working
3149 with the compiled-in default environment - *silently*!!! [This is
3150 necessary, because the first environment variable we need is the
3151 "baudrate" setting for the console - if we have a bad CRC, we don't
3152 have any device yet where we could complain.]
3154 Note: once the monitor has been relocated, then it will complain if
3155 the default environment is used; a new CRC is computed as soon as you
3156 use the "saveenv" command to store a valid environment.
3158 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3159 Echo the inverted Ethernet link state to the fault LED.
3161 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3162 also needs to be defined.
3164 - CONFIG_SYS_FAULT_MII_ADDR:
3165 MII address of the PHY to check for the Ethernet link state.
3167 - CONFIG_NS16550_MIN_FUNCTIONS:
3168 Define this if you desire to only have use of the NS16550_init
3169 and NS16550_putc functions for the serial driver located at
3170 drivers/serial/ns16550.c. This option is useful for saving
3171 space for already greatly restricted images, including but not
3172 limited to NAND_SPL configurations.
3174 - CONFIG_DISPLAY_BOARDINFO
3175 Display information about the board that U-Boot is running on
3176 when U-Boot starts up. The board function checkboard() is called
3179 - CONFIG_DISPLAY_BOARDINFO_LATE
3180 Similar to the previous option, but display this information
3181 later, once stdio is running and output goes to the LCD, if
3184 - CONFIG_BOARD_SIZE_LIMIT:
3185 Maximum size of the U-Boot image. When defined, the
3186 build system checks that the actual size does not
3189 Low Level (hardware related) configuration options:
3190 ---------------------------------------------------
3192 - CONFIG_SYS_CACHELINE_SIZE:
3193 Cache Line Size of the CPU.
3195 - CONFIG_SYS_CCSRBAR_DEFAULT:
3196 Default (power-on reset) physical address of CCSR on Freescale
3199 - CONFIG_SYS_CCSRBAR:
3200 Virtual address of CCSR. On a 32-bit build, this is typically
3201 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3203 - CONFIG_SYS_CCSRBAR_PHYS:
3204 Physical address of CCSR. CCSR can be relocated to a new
3205 physical address, if desired. In this case, this macro should
3206 be set to that address. Otherwise, it should be set to the
3207 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
3208 is typically relocated on 36-bit builds. It is recommended
3209 that this macro be defined via the _HIGH and _LOW macros:
3211 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3212 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3214 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3215 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
3216 either 0 (32-bit build) or 0xF (36-bit build). This macro is
3217 used in assembly code, so it must not contain typecasts or
3218 integer size suffixes (e.g. "ULL").
3220 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
3221 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
3222 used in assembly code, so it must not contain typecasts or
3223 integer size suffixes (e.g. "ULL").
3225 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3226 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3227 forced to a value that ensures that CCSR is not relocated.
3229 - Floppy Disk Support:
3230 CONFIG_SYS_FDC_DRIVE_NUMBER
3232 the default drive number (default value 0)
3234 CONFIG_SYS_ISA_IO_STRIDE
3236 defines the spacing between FDC chipset registers
3239 CONFIG_SYS_ISA_IO_OFFSET
3241 defines the offset of register from address. It
3242 depends on which part of the data bus is connected to
3243 the FDC chipset. (default value 0)
3245 If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3246 CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3249 if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3250 fdc_hw_init() is called at the beginning of the FDC
3251 setup. fdc_hw_init() must be provided by the board
3252 source code. It is used to make hardware-dependent
3256 Most IDE controllers were designed to be connected with PCI
3257 interface. Only few of them were designed for AHB interface.
3258 When software is doing ATA command and data transfer to
3259 IDE devices through IDE-AHB controller, some additional
3260 registers accessing to these kind of IDE-AHB controller
3263 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
3264 DO NOT CHANGE unless you know exactly what you're
3265 doing! (11-4) [MPC8xx systems only]
3267 - CONFIG_SYS_INIT_RAM_ADDR:
3269 Start address of memory area that can be used for
3270 initial data and stack; please note that this must be
3271 writable memory that is working WITHOUT special
3272 initialization, i. e. you CANNOT use normal RAM which
3273 will become available only after programming the
3274 memory controller and running certain initialization
3277 U-Boot uses the following memory types:
3278 - MPC8xx: IMMR (internal memory of the CPU)
3280 - CONFIG_SYS_GBL_DATA_OFFSET:
3282 Offset of the initial data structure in the memory
3283 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3284 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3285 data is located at the end of the available space
3286 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3287 GENERATED_GBL_DATA_SIZE), and the initial stack is just
3288 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3289 CONFIG_SYS_GBL_DATA_OFFSET) downward.
3292 On the MPC824X (or other systems that use the data
3293 cache for initial memory) the address chosen for
3294 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3295 point to an otherwise UNUSED address space between
3296 the top of RAM and the start of the PCI space.
3298 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
3300 - CONFIG_SYS_OR_TIMING_SDRAM:
3303 - CONFIG_SYS_MAMR_PTA:
3304 periodic timer for refresh
3306 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3307 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3308 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3309 CONFIG_SYS_BR1_PRELIM:
3310 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3312 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3313 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3314 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3315 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3317 - CONFIG_PCI_ENUM_ONLY
3318 Only scan through and get the devices on the buses.
3319 Don't do any setup work, presumably because someone or
3320 something has already done it, and we don't need to do it
3321 a second time. Useful for platforms that are pre-booted
3322 by coreboot or similar.
3324 - CONFIG_PCI_INDIRECT_BRIDGE:
3325 Enable support for indirect PCI bridges.
3328 Chip has SRIO or not
3331 Board has SRIO 1 port available
3334 Board has SRIO 2 port available
3336 - CONFIG_SRIO_PCIE_BOOT_MASTER
3337 Board can support master function for Boot from SRIO and PCIE
3339 - CONFIG_SYS_SRIOn_MEM_VIRT:
3340 Virtual Address of SRIO port 'n' memory region
3342 - CONFIG_SYS_SRIOn_MEM_PHYS:
3343 Physical Address of SRIO port 'n' memory region
3345 - CONFIG_SYS_SRIOn_MEM_SIZE:
3346 Size of SRIO port 'n' memory region
3348 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
3349 Defined to tell the NAND controller that the NAND chip is using
3351 Not all NAND drivers use this symbol.
3352 Example of drivers that use it:
3353 - drivers/mtd/nand/ndfc.c
3354 - drivers/mtd/nand/mxc_nand.c
3356 - CONFIG_SYS_NDFC_EBC0_CFG
3357 Sets the EBC0_CFG register for the NDFC. If not defined
3358 a default value will be used.
3361 Get DDR timing information from an I2C EEPROM. Common
3362 with pluggable memory modules such as SODIMMs
3365 I2C address of the SPD EEPROM
3367 - CONFIG_SYS_SPD_BUS_NUM
3368 If SPD EEPROM is on an I2C bus other than the first
3369 one, specify here. Note that the value must resolve
3370 to something your driver can deal with.
3372 - CONFIG_SYS_DDR_RAW_TIMING
3373 Get DDR timing information from other than SPD. Common with
3374 soldered DDR chips onboard without SPD. DDR raw timing
3375 parameters are extracted from datasheet and hard-coded into
3376 header files or board specific files.
3378 - CONFIG_FSL_DDR_INTERACTIVE
3379 Enable interactive DDR debugging. See doc/README.fsl-ddr.
3381 - CONFIG_FSL_DDR_SYNC_REFRESH
3382 Enable sync of refresh for multiple controllers.
3384 - CONFIG_FSL_DDR_BIST
3385 Enable built-in memory test for Freescale DDR controllers.
3387 - CONFIG_SYS_83XX_DDR_USES_CS0
3388 Only for 83xx systems. If specified, then DDR should
3389 be configured using CS0 and CS1 instead of CS2 and CS3.
3392 Enable RMII mode for all FECs.
3393 Note that this is a global option, we can't
3394 have one FEC in standard MII mode and another in RMII mode.
3396 - CONFIG_CRC32_VERIFY
3397 Add a verify option to the crc32 command.
3400 => crc32 -v <address> <count> <crc32>
3402 Where address/count indicate a memory area
3403 and crc32 is the correct crc32 which the
3407 Add the "loopw" memory command. This only takes effect if
3408 the memory commands are activated globally (CONFIG_CMD_MEMORY).
3411 Add the "mdc" and "mwc" memory commands. These are cyclic
3416 This command will print 4 bytes (10,11,12,13) each 500 ms.
3418 => mwc.l 100 12345678 10
3419 This command will write 12345678 to address 100 all 10 ms.
3421 This only takes effect if the memory commands are activated
3422 globally (CONFIG_CMD_MEMORY).
3424 - CONFIG_SKIP_LOWLEVEL_INIT
3425 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
3426 low level initializations (like setting up the memory
3427 controller) are omitted and/or U-Boot does not
3428 relocate itself into RAM.
3430 Normally this variable MUST NOT be defined. The only
3431 exception is when U-Boot is loaded (to RAM) by some
3432 other boot loader or by a debugger which performs
3433 these initializations itself.
3435 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
3436 [ARM926EJ-S only] This allows just the call to lowlevel_init()
3437 to be skipped. The normal CP15 init (such as enabling the
3438 instruction cache) is still performed.
3441 Modifies the behaviour of start.S when compiling a loader
3442 that is executed before the actual U-Boot. E.g. when
3443 compiling a NAND SPL.
3446 Modifies the behaviour of start.S when compiling a loader
3447 that is executed after the SPL and before the actual U-Boot.
3448 It is loaded by the SPL.
3450 - CONFIG_SYS_MPC85XX_NO_RESETVEC
3451 Only for 85xx systems. If this variable is specified, the section
3452 .resetvec is not kept and the section .bootpg is placed in the
3453 previous 4k of the .text section.
3455 - CONFIG_ARCH_MAP_SYSMEM
3456 Generally U-Boot (and in particular the md command) uses
3457 effective address. It is therefore not necessary to regard
3458 U-Boot address as virtual addresses that need to be translated
3459 to physical addresses. However, sandbox requires this, since
3460 it maintains its own little RAM buffer which contains all
3461 addressable memory. This option causes some memory accesses
3462 to be mapped through map_sysmem() / unmap_sysmem().
3464 - CONFIG_X86_RESET_VECTOR
3465 If defined, the x86 reset vector code is included. This is not
3466 needed when U-Boot is running from Coreboot.
3468 - CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
3469 Enables the RTC32K OSC on AM33xx based plattforms
3471 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
3472 Option to disable subpage write in NAND driver
3473 driver that uses this:
3474 drivers/mtd/nand/davinci_nand.c
3476 Freescale QE/FMAN Firmware Support:
3477 -----------------------------------
3479 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3480 loading of "firmware", which is encoded in the QE firmware binary format.
3481 This firmware often needs to be loaded during U-Boot booting, so macros
3482 are used to identify the storage device (NOR flash, SPI, etc) and the address
3485 - CONFIG_SYS_FMAN_FW_ADDR
3486 The address in the storage device where the FMAN microcode is located. The
3487 meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3490 - CONFIG_SYS_QE_FW_ADDR
3491 The address in the storage device where the QE microcode is located. The
3492 meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3495 - CONFIG_SYS_QE_FMAN_FW_LENGTH
3496 The maximum possible size of the firmware. The firmware binary format
3497 has a field that specifies the actual size of the firmware, but it
3498 might not be possible to read any part of the firmware unless some
3499 local storage is allocated to hold the entire firmware first.
3501 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
3502 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3503 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
3504 virtual address in NOR flash.
3506 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
3507 Specifies that QE/FMAN firmware is located in NAND flash.
3508 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3510 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
3511 Specifies that QE/FMAN firmware is located on the primary SD/MMC
3512 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3514 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3515 Specifies that QE/FMAN firmware is located in the remote (master)
3516 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3517 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3518 window->master inbound window->master LAW->the ucode address in
3519 master's memory space.
3521 Freescale Layerscape Management Complex Firmware Support:
3522 ---------------------------------------------------------
3523 The Freescale Layerscape Management Complex (MC) supports the loading of
3525 This firmware often needs to be loaded during U-Boot booting, so macros
3526 are used to identify the storage device (NOR flash, SPI, etc) and the address
3529 - CONFIG_FSL_MC_ENET
3530 Enable the MC driver for Layerscape SoCs.
3532 Freescale Layerscape Debug Server Support:
3533 -------------------------------------------
3534 The Freescale Layerscape Debug Server Support supports the loading of
3535 "Debug Server firmware" and triggering SP boot-rom.
3536 This firmware often needs to be loaded during U-Boot booting.
3538 - CONFIG_SYS_MC_RSV_MEM_ALIGN
3539 Define alignment of reserved memory MC requires
3544 In order to achieve reproducible builds, timestamps used in the U-Boot build
3545 process have to be set to a fixed value.
3547 This is done using the SOURCE_DATE_EPOCH environment variable.
3548 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
3549 option for U-Boot or an environment variable in U-Boot.
3551 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
3553 Building the Software:
3554 ======================
3556 Building U-Boot has been tested in several native build environments
3557 and in many different cross environments. Of course we cannot support
3558 all possibly existing versions of cross development tools in all
3559 (potentially obsolete) versions. In case of tool chain problems we
3560 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3561 which is extensively used to build and test U-Boot.
3563 If you are not using a native environment, it is assumed that you
3564 have GNU cross compiling tools available in your path. In this case,
3565 you must set the environment variable CROSS_COMPILE in your shell.
3566 Note that no changes to the Makefile or any other source files are
3567 necessary. For example using the ELDK on a 4xx CPU, please enter:
3569 $ CROSS_COMPILE=ppc_4xx-
3570 $ export CROSS_COMPILE
3572 Note: If you wish to generate Windows versions of the utilities in
3573 the tools directory you can use the MinGW toolchain
3574 (http://www.mingw.org). Set your HOST tools to the MinGW
3575 toolchain and execute 'make tools'. For example:
3577 $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3579 Binaries such as tools/mkimage.exe will be created which can
3580 be executed on computers running Windows.
3582 U-Boot is intended to be simple to build. After installing the
3583 sources you must configure U-Boot for one specific board type. This
3588 where "NAME_defconfig" is the name of one of the existing configu-
3589 rations; see boards.cfg for supported names.
3591 Note: for some board special configuration names may exist; check if
3592 additional information is available from the board vendor; for
3593 instance, the TQM823L systems are available without (standard)
3594 or with LCD support. You can select such additional "features"
3595 when choosing the configuration, i. e.
3597 make TQM823L_defconfig
3598 - will configure for a plain TQM823L, i. e. no LCD support
3600 make TQM823L_LCD_defconfig
3601 - will configure for a TQM823L with U-Boot console on LCD
3606 Finally, type "make all", and you should get some working U-Boot
3607 images ready for download to / installation on your system:
3609 - "u-boot.bin" is a raw binary image
3610 - "u-boot" is an image in ELF binary format
3611 - "u-boot.srec" is in Motorola S-Record format
3613 By default the build is performed locally and the objects are saved
3614 in the source directory. One of the two methods can be used to change
3615 this behavior and build U-Boot to some external directory:
3617 1. Add O= to the make command line invocations:
3619 make O=/tmp/build distclean
3620 make O=/tmp/build NAME_defconfig
3621 make O=/tmp/build all
3623 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3625 export KBUILD_OUTPUT=/tmp/build
3630 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3633 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3634 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3635 For example to treat all compiler warnings as errors:
3637 make KCFLAGS=-Werror
3639 Please be aware that the Makefiles assume you are using GNU make, so
3640 for instance on NetBSD you might need to use "gmake" instead of
3644 If the system board that you have is not listed, then you will need
3645 to port U-Boot to your hardware platform. To do this, follow these
3648 1. Create a new directory to hold your board specific code. Add any
3649 files you need. In your board directory, you will need at least
3650 the "Makefile" and a "<board>.c".
3651 2. Create a new configuration file "include/configs/<board>.h" for
3653 3. If you're porting U-Boot to a new CPU, then also create a new
3654 directory to hold your CPU specific code. Add any files you need.
3655 4. Run "make <board>_defconfig" with your new name.
3656 5. Type "make", and you should get a working "u-boot.srec" file
3657 to be installed on your target system.
3658 6. Debug and solve any problems that might arise.
3659 [Of course, this last step is much harder than it sounds.]
3662 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3663 ==============================================================
3665 If you have modified U-Boot sources (for instance added a new board
3666 or support for new devices, a new CPU, etc.) you are expected to
3667 provide feedback to the other developers. The feedback normally takes
3668 the form of a "patch", i. e. a context diff against a certain (latest
3669 official or latest in the git repository) version of U-Boot sources.
3671 But before you submit such a patch, please verify that your modifi-
3672 cation did not break existing code. At least make sure that *ALL* of
3673 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3674 just run the buildman script (tools/buildman/buildman), which will
3675 configure and build U-Boot for ALL supported system. Be warned, this
3676 will take a while. Please see the buildman README, or run 'buildman -H'
3680 See also "U-Boot Porting Guide" below.
3683 Monitor Commands - Overview:
3684 ============================
3686 go - start application at address 'addr'
3687 run - run commands in an environment variable
3688 bootm - boot application image from memory
3689 bootp - boot image via network using BootP/TFTP protocol
3690 bootz - boot zImage from memory
3691 tftpboot- boot image via network using TFTP protocol
3692 and env variables "ipaddr" and "serverip"
3693 (and eventually "gatewayip")
3694 tftpput - upload a file via network using TFTP protocol
3695 rarpboot- boot image via network using RARP/TFTP protocol
3696 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3697 loads - load S-Record file over serial line
3698 loadb - load binary file over serial line (kermit mode)
3700 mm - memory modify (auto-incrementing)
3701 nm - memory modify (constant address)
3702 mw - memory write (fill)
3704 cmp - memory compare
3705 crc32 - checksum calculation
3706 i2c - I2C sub-system
3707 sspi - SPI utility commands
3708 base - print or set address offset
3709 printenv- print environment variables
3710 setenv - set environment variables
3711 saveenv - save environment variables to persistent storage
3712 protect - enable or disable FLASH write protection
3713 erase - erase FLASH memory
3714 flinfo - print FLASH memory information
3715 nand - NAND memory operations (see doc/README.nand)
3716 bdinfo - print Board Info structure
3717 iminfo - print header information for application image
3718 coninfo - print console devices and informations
3719 ide - IDE sub-system
3720 loop - infinite loop on address range
3721 loopw - infinite write loop on address range
3722 mtest - simple RAM test
3723 icache - enable or disable instruction cache
3724 dcache - enable or disable data cache
3725 reset - Perform RESET of the CPU
3726 echo - echo args to console
3727 version - print monitor version
3728 help - print online help
3729 ? - alias for 'help'
3732 Monitor Commands - Detailed Description:
3733 ========================================
3737 For now: just type "help <command>".
3740 Environment Variables:
3741 ======================
3743 U-Boot supports user configuration using Environment Variables which
3744 can be made persistent by saving to Flash memory.
3746 Environment Variables are set using "setenv", printed using
3747 "printenv", and saved to Flash using "saveenv". Using "setenv"
3748 without a value can be used to delete a variable from the
3749 environment. As long as you don't save the environment you are
3750 working with an in-memory copy. In case the Flash area containing the
3751 environment is erased by accident, a default environment is provided.
3753 Some configuration options can be set using Environment Variables.
3755 List of environment variables (most likely not complete):
3757 baudrate - see CONFIG_BAUDRATE
3759 bootdelay - see CONFIG_BOOTDELAY
3761 bootcmd - see CONFIG_BOOTCOMMAND
3763 bootargs - Boot arguments when booting an RTOS image
3765 bootfile - Name of the image to load with TFTP
3767 bootm_low - Memory range available for image processing in the bootm
3768 command can be restricted. This variable is given as
3769 a hexadecimal number and defines lowest address allowed
3770 for use by the bootm command. See also "bootm_size"
3771 environment variable. Address defined by "bootm_low" is
3772 also the base of the initial memory mapping for the Linux
3773 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3776 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3777 This variable is given as a hexadecimal number and it
3778 defines the size of the memory region starting at base
3779 address bootm_low that is accessible by the Linux kernel
3780 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3781 as the default value if it is defined, and bootm_size is
3784 bootm_size - Memory range available for image processing in the bootm
3785 command can be restricted. This variable is given as
3786 a hexadecimal number and defines the size of the region
3787 allowed for use by the bootm command. See also "bootm_low"
3788 environment variable.
3790 updatefile - Location of the software update file on a TFTP server, used
3791 by the automatic software update feature. Please refer to
3792 documentation in doc/README.update for more details.
3794 autoload - if set to "no" (any string beginning with 'n'),
3795 "bootp" will just load perform a lookup of the
3796 configuration from the BOOTP server, but not try to
3797 load any image using TFTP
3799 autostart - if set to "yes", an image loaded using the "bootp",
3800 "rarpboot", "tftpboot" or "diskboot" commands will
3801 be automatically started (by internally calling
3804 If set to "no", a standalone image passed to the
3805 "bootm" command will be copied to the load address
3806 (and eventually uncompressed), but NOT be started.
3807 This can be used to load and uncompress arbitrary
3810 fdt_high - if set this restricts the maximum address that the
3811 flattened device tree will be copied into upon boot.
3812 For example, if you have a system with 1 GB memory
3813 at physical address 0x10000000, while Linux kernel
3814 only recognizes the first 704 MB as low memory, you
3815 may need to set fdt_high as 0x3C000000 to have the
3816 device tree blob be copied to the maximum address
3817 of the 704 MB low memory, so that Linux kernel can
3818 access it during the boot procedure.
3820 If this is set to the special value 0xFFFFFFFF then
3821 the fdt will not be copied at all on boot. For this
3822 to work it must reside in writable memory, have
3823 sufficient padding on the end of it for u-boot to
3824 add the information it needs into it, and the memory
3825 must be accessible by the kernel.
3827 fdtcontroladdr- if set this is the address of the control flattened
3828 device tree used by U-Boot when CONFIG_OF_CONTROL is
3831 i2cfast - (PPC405GP|PPC405EP only)
3832 if set to 'y' configures Linux I2C driver for fast
3833 mode (400kHZ). This environment variable is used in
3834 initialization code. So, for changes to be effective
3835 it must be saved and board must be reset.
3837 initrd_high - restrict positioning of initrd images:
3838 If this variable is not set, initrd images will be
3839 copied to the highest possible address in RAM; this
3840 is usually what you want since it allows for
3841 maximum initrd size. If for some reason you want to
3842 make sure that the initrd image is loaded below the
3843 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3844 variable to a value of "no" or "off" or "0".
3845 Alternatively, you can set it to a maximum upper
3846 address to use (U-Boot will still check that it
3847 does not overwrite the U-Boot stack and data).
3849 For instance, when you have a system with 16 MB
3850 RAM, and want to reserve 4 MB from use by Linux,
3851 you can do this by adding "mem=12M" to the value of
3852 the "bootargs" variable. However, now you must make
3853 sure that the initrd image is placed in the first
3854 12 MB as well - this can be done with
3856 setenv initrd_high 00c00000
3858 If you set initrd_high to 0xFFFFFFFF, this is an
3859 indication to U-Boot that all addresses are legal
3860 for the Linux kernel, including addresses in flash
3861 memory. In this case U-Boot will NOT COPY the
3862 ramdisk at all. This may be useful to reduce the
3863 boot time on your system, but requires that this
3864 feature is supported by your Linux kernel.
3866 ipaddr - IP address; needed for tftpboot command
3868 loadaddr - Default load address for commands like "bootp",
3869 "rarpboot", "tftpboot", "loadb" or "diskboot"
3871 loads_echo - see CONFIG_LOADS_ECHO
3873 serverip - TFTP server IP address; needed for tftpboot command
3875 bootretry - see CONFIG_BOOT_RETRY_TIME
3877 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3879 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3881 ethprime - controls which interface is used first.
3883 ethact - controls which interface is currently active.
3884 For example you can do the following
3886 => setenv ethact FEC
3887 => ping 192.168.0.1 # traffic sent on FEC
3888 => setenv ethact SCC
3889 => ping 10.0.0.1 # traffic sent on SCC
3891 ethrotate - When set to "no" U-Boot does not go through all
3892 available network interfaces.
3893 It just stays at the currently selected interface.
3895 netretry - When set to "no" each network operation will
3896 either succeed or fail without retrying.
3897 When set to "once" the network operation will
3898 fail when all the available network interfaces
3899 are tried once without success.
3900 Useful on scripts which control the retry operation
3903 npe_ucode - set load address for the NPE microcode
3905 silent_linux - If set then Linux will be told to boot silently, by
3906 changing the console to be empty. If "yes" it will be
3907 made silent. If "no" it will not be made silent. If
3908 unset, then it will be made silent if the U-Boot console
3911 tftpsrcp - If this is set, the value is used for TFTP's
3914 tftpdstp - If this is set, the value is used for TFTP's UDP
3915 destination port instead of the Well Know Port 69.
3917 tftpblocksize - Block size to use for TFTP transfers; if not set,
3918 we use the TFTP server's default block size
3920 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3921 seconds, minimum value is 1000 = 1 second). Defines
3922 when a packet is considered to be lost so it has to
3923 be retransmitted. The default is 5000 = 5 seconds.
3924 Lowering this value may make downloads succeed
3925 faster in networks with high packet loss rates or
3926 with unreliable TFTP servers.
3928 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3929 unit, minimum value = 0). Defines how many timeouts
3930 can happen during a single file transfer before that
3931 transfer is aborted. The default is 10, and 0 means
3932 'no timeouts allowed'. Increasing this value may help
3933 downloads succeed with high packet loss rates, or with
3934 unreliable TFTP servers or client hardware.
3936 vlan - When set to a value < 4095 the traffic over
3937 Ethernet is encapsulated/received over 802.1q
3940 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3941 Unsigned value, in milliseconds. If not set, the period will
3942 be either the default (28000), or a value based on
3943 CONFIG_NET_RETRY_COUNT, if defined. This value has
3944 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3946 The following image location variables contain the location of images
3947 used in booting. The "Image" column gives the role of the image and is
3948 not an environment variable name. The other columns are environment
3949 variable names. "File Name" gives the name of the file on a TFTP
3950 server, "RAM Address" gives the location in RAM the image will be
3951 loaded to, and "Flash Location" gives the image's address in NOR
3952 flash or offset in NAND flash.
3954 *Note* - these variables don't have to be defined for all boards, some
3955 boards currently use other variables for these purposes, and some
3956 boards use these variables for other purposes.
3958 Image File Name RAM Address Flash Location
3959 ----- --------- ----------- --------------
3960 u-boot u-boot u-boot_addr_r u-boot_addr
3961 Linux kernel bootfile kernel_addr_r kernel_addr
3962 device tree blob fdtfile fdt_addr_r fdt_addr
3963 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3965 The following environment variables may be used and automatically
3966 updated by the network boot commands ("bootp" and "rarpboot"),
3967 depending the information provided by your boot server:
3969 bootfile - see above
3970 dnsip - IP address of your Domain Name Server
3971 dnsip2 - IP address of your secondary Domain Name Server
3972 gatewayip - IP address of the Gateway (Router) to use
3973 hostname - Target hostname
3975 netmask - Subnet Mask
3976 rootpath - Pathname of the root filesystem on the NFS server
3977 serverip - see above
3980 There are two special Environment Variables:
3982 serial# - contains hardware identification information such
3983 as type string and/or serial number
3984 ethaddr - Ethernet address
3986 These variables can be set only once (usually during manufacturing of
3987 the board). U-Boot refuses to delete or overwrite these variables
3988 once they have been set once.
3991 Further special Environment Variables:
3993 ver - Contains the U-Boot version string as printed
3994 with the "version" command. This variable is
3995 readonly (see CONFIG_VERSION_VARIABLE).
3998 Please note that changes to some configuration parameters may take
3999 only effect after the next boot (yes, that's just like Windoze :-).
4002 Callback functions for environment variables:
4003 ---------------------------------------------
4005 For some environment variables, the behavior of u-boot needs to change
4006 when their values are changed. This functionality allows functions to
4007 be associated with arbitrary variables. On creation, overwrite, or
4008 deletion, the callback will provide the opportunity for some side
4009 effect to happen or for the change to be rejected.
4011 The callbacks are named and associated with a function using the
4012 U_BOOT_ENV_CALLBACK macro in your board or driver code.
4014 These callbacks are associated with variables in one of two ways. The
4015 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4016 in the board configuration to a string that defines a list of
4017 associations. The list must be in the following format:
4019 entry = variable_name[:callback_name]
4022 If the callback name is not specified, then the callback is deleted.
4023 Spaces are also allowed anywhere in the list.
4025 Callbacks can also be associated by defining the ".callbacks" variable
4026 with the same list format above. Any association in ".callbacks" will
4027 override any association in the static list. You can define
4028 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4029 ".callbacks" environment variable in the default or embedded environment.
4031 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
4032 regular expression. This allows multiple variables to be connected to
4033 the same callback without explicitly listing them all out.
4036 Command Line Parsing:
4037 =====================
4039 There are two different command line parsers available with U-Boot:
4040 the old "simple" one, and the much more powerful "hush" shell:
4042 Old, simple command line parser:
4043 --------------------------------
4045 - supports environment variables (through setenv / saveenv commands)
4046 - several commands on one line, separated by ';'
4047 - variable substitution using "... ${name} ..." syntax
4048 - special characters ('$', ';') can be escaped by prefixing with '\',
4050 setenv bootcmd bootm \${address}
4051 - You can also escape text by enclosing in single apostrophes, for example:
4052 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4057 - similar to Bourne shell, with control structures like
4058 if...then...else...fi, for...do...done; while...do...done,
4059 until...do...done, ...
4060 - supports environment ("global") variables (through setenv / saveenv
4061 commands) and local shell variables (through standard shell syntax
4062 "name=value"); only environment variables can be used with "run"
4068 (1) If a command line (or an environment variable executed by a "run"
4069 command) contains several commands separated by semicolon, and
4070 one of these commands fails, then the remaining commands will be
4073 (2) If you execute several variables with one call to run (i. e.
4074 calling run with a list of variables as arguments), any failing
4075 command will cause "run" to terminate, i. e. the remaining
4076 variables are not executed.
4078 Note for Redundant Ethernet Interfaces:
4079 =======================================
4081 Some boards come with redundant Ethernet interfaces; U-Boot supports
4082 such configurations and is capable of automatic selection of a
4083 "working" interface when needed. MAC assignment works as follows:
4085 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4086 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4087 "eth1addr" (=>eth1), "eth2addr", ...
4089 If the network interface stores some valid MAC address (for instance
4090 in SROM), this is used as default address if there is NO correspon-
4091 ding setting in the environment; if the corresponding environment
4092 variable is set, this overrides the settings in the card; that means:
4094 o If the SROM has a valid MAC address, and there is no address in the
4095 environment, the SROM's address is used.
4097 o If there is no valid address in the SROM, and a definition in the
4098 environment exists, then the value from the environment variable is
4101 o If both the SROM and the environment contain a MAC address, and
4102 both addresses are the same, this MAC address is used.
4104 o If both the SROM and the environment contain a MAC address, and the
4105 addresses differ, the value from the environment is used and a
4108 o If neither SROM nor the environment contain a MAC address, an error
4109 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
4110 a random, locally-assigned MAC is used.
4112 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4113 will be programmed into hardware as part of the initialization process. This
4114 may be skipped by setting the appropriate 'ethmacskip' environment variable.
4115 The naming convention is as follows:
4116 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4121 U-Boot is capable of booting (and performing other auxiliary operations on)
4122 images in two formats:
4124 New uImage format (FIT)
4125 -----------------------
4127 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4128 to Flattened Device Tree). It allows the use of images with multiple
4129 components (several kernels, ramdisks, etc.), with contents protected by
4130 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4136 Old image format is based on binary files which can be basically anything,
4137 preceded by a special header; see the definitions in include/image.h for
4138 details; basically, the header defines the following image properties:
4140 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4141 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4142 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4143 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4145 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
4146 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4147 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4148 * Compression Type (uncompressed, gzip, bzip2)
4154 The header is marked by a special Magic Number, and both the header
4155 and the data portions of the image are secured against corruption by
4162 Although U-Boot should support any OS or standalone application
4163 easily, the main focus has always been on Linux during the design of
4166 U-Boot includes many features that so far have been part of some
4167 special "boot loader" code within the Linux kernel. Also, any
4168 "initrd" images to be used are no longer part of one big Linux image;
4169 instead, kernel and "initrd" are separate images. This implementation
4170 serves several purposes:
4172 - the same features can be used for other OS or standalone
4173 applications (for instance: using compressed images to reduce the
4174 Flash memory footprint)
4176 - it becomes much easier to port new Linux kernel versions because
4177 lots of low-level, hardware dependent stuff are done by U-Boot
4179 - the same Linux kernel image can now be used with different "initrd"
4180 images; of course this also means that different kernel images can
4181 be run with the same "initrd". This makes testing easier (you don't
4182 have to build a new "zImage.initrd" Linux image when you just
4183 change a file in your "initrd"). Also, a field-upgrade of the
4184 software is easier now.
4190 Porting Linux to U-Boot based systems:
4191 ---------------------------------------
4193 U-Boot cannot save you from doing all the necessary modifications to
4194 configure the Linux device drivers for use with your target hardware
4195 (no, we don't intend to provide a full virtual machine interface to
4198 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4200 Just make sure your machine specific header file (for instance
4201 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4202 Information structure as we define in include/asm-<arch>/u-boot.h,
4203 and make sure that your definition of IMAP_ADDR uses the same value
4204 as your U-Boot configuration in CONFIG_SYS_IMMR.
4206 Note that U-Boot now has a driver model, a unified model for drivers.
4207 If you are adding a new driver, plumb it into driver model. If there
4208 is no uclass available, you are encouraged to create one. See
4212 Configuring the Linux kernel:
4213 -----------------------------
4215 No specific requirements for U-Boot. Make sure you have some root
4216 device (initial ramdisk, NFS) for your target system.
4219 Building a Linux Image:
4220 -----------------------
4222 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4223 not used. If you use recent kernel source, a new build target
4224 "uImage" will exist which automatically builds an image usable by
4225 U-Boot. Most older kernels also have support for a "pImage" target,
4226 which was introduced for our predecessor project PPCBoot and uses a
4227 100% compatible format.
4231 make TQM850L_defconfig
4236 The "uImage" build target uses a special tool (in 'tools/mkimage') to
4237 encapsulate a compressed Linux kernel image with header information,
4238 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4240 * build a standard "vmlinux" kernel image (in ELF binary format):
4242 * convert the kernel into a raw binary image:
4244 ${CROSS_COMPILE}-objcopy -O binary \
4245 -R .note -R .comment \
4246 -S vmlinux linux.bin
4248 * compress the binary image:
4252 * package compressed binary image for U-Boot:
4254 mkimage -A ppc -O linux -T kernel -C gzip \
4255 -a 0 -e 0 -n "Linux Kernel Image" \
4256 -d linux.bin.gz uImage
4259 The "mkimage" tool can also be used to create ramdisk images for use
4260 with U-Boot, either separated from the Linux kernel image, or
4261 combined into one file. "mkimage" encapsulates the images with a 64
4262 byte header containing information about target architecture,
4263 operating system, image type, compression method, entry points, time
4264 stamp, CRC32 checksums, etc.
4266 "mkimage" can be called in two ways: to verify existing images and
4267 print the header information, or to build new images.
4269 In the first form (with "-l" option) mkimage lists the information
4270 contained in the header of an existing U-Boot image; this includes
4271 checksum verification:
4273 tools/mkimage -l image
4274 -l ==> list image header information
4276 The second form (with "-d" option) is used to build a U-Boot image
4277 from a "data file" which is used as image payload:
4279 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4280 -n name -d data_file image
4281 -A ==> set architecture to 'arch'
4282 -O ==> set operating system to 'os'
4283 -T ==> set image type to 'type'
4284 -C ==> set compression type 'comp'
4285 -a ==> set load address to 'addr' (hex)
4286 -e ==> set entry point to 'ep' (hex)
4287 -n ==> set image name to 'name'
4288 -d ==> use image data from 'datafile'
4290 Right now, all Linux kernels for PowerPC systems use the same load
4291 address (0x00000000), but the entry point address depends on the
4294 - 2.2.x kernels have the entry point at 0x0000000C,
4295 - 2.3.x and later kernels have the entry point at 0x00000000.
4297 So a typical call to build a U-Boot image would read:
4299 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4300 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4301 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4302 > examples/uImage.TQM850L
4303 Image Name: 2.4.4 kernel for TQM850L
4304 Created: Wed Jul 19 02:34:59 2000
4305 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4306 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
4307 Load Address: 0x00000000
4308 Entry Point: 0x00000000
4310 To verify the contents of the image (or check for corruption):
4312 -> tools/mkimage -l examples/uImage.TQM850L
4313 Image Name: 2.4.4 kernel for TQM850L
4314 Created: Wed Jul 19 02:34:59 2000
4315 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4316 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
4317 Load Address: 0x00000000
4318 Entry Point: 0x00000000
4320 NOTE: for embedded systems where boot time is critical you can trade
4321 speed for memory and install an UNCOMPRESSED image instead: this
4322 needs more space in Flash, but boots much faster since it does not
4323 need to be uncompressed:
4325 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4326 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4327 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4328 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4329 > examples/uImage.TQM850L-uncompressed
4330 Image Name: 2.4.4 kernel for TQM850L
4331 Created: Wed Jul 19 02:34:59 2000
4332 Image Type: PowerPC Linux Kernel Image (uncompressed)
4333 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
4334 Load Address: 0x00000000
4335 Entry Point: 0x00000000
4338 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4339 when your kernel is intended to use an initial ramdisk:
4341 -> tools/mkimage -n 'Simple Ramdisk Image' \
4342 > -A ppc -O linux -T ramdisk -C gzip \
4343 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4344 Image Name: Simple Ramdisk Image
4345 Created: Wed Jan 12 14:01:50 2000
4346 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4347 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
4348 Load Address: 0x00000000
4349 Entry Point: 0x00000000
4351 The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
4352 option performs the converse operation of the mkimage's second form (the "-d"
4353 option). Given an image built by mkimage, the dumpimage extracts a "data file"
4356 tools/dumpimage -i image -T type -p position data_file
4357 -i ==> extract from the 'image' a specific 'data_file'
4358 -T ==> set image type to 'type'
4359 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
4362 Installing a Linux Image:
4363 -------------------------
4365 To downloading a U-Boot image over the serial (console) interface,
4366 you must convert the image to S-Record format:
4368 objcopy -I binary -O srec examples/image examples/image.srec
4370 The 'objcopy' does not understand the information in the U-Boot
4371 image header, so the resulting S-Record file will be relative to
4372 address 0x00000000. To load it to a given address, you need to
4373 specify the target address as 'offset' parameter with the 'loads'
4376 Example: install the image to address 0x40100000 (which on the
4377 TQM8xxL is in the first Flash bank):
4379 => erase 40100000 401FFFFF
4385 ## Ready for S-Record download ...
4386 ~>examples/image.srec
4387 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4389 15989 15990 15991 15992
4390 [file transfer complete]
4392 ## Start Addr = 0x00000000
4395 You can check the success of the download using the 'iminfo' command;
4396 this includes a checksum verification so you can be sure no data
4397 corruption happened:
4401 ## Checking Image at 40100000 ...
4402 Image Name: 2.2.13 for initrd on TQM850L
4403 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4404 Data Size: 335725 Bytes = 327 kB = 0 MB
4405 Load Address: 00000000
4406 Entry Point: 0000000c
4407 Verifying Checksum ... OK
4413 The "bootm" command is used to boot an application that is stored in
4414 memory (RAM or Flash). In case of a Linux kernel image, the contents
4415 of the "bootargs" environment variable is passed to the kernel as
4416 parameters. You can check and modify this variable using the
4417 "printenv" and "setenv" commands:
4420 => printenv bootargs
4421 bootargs=root=/dev/ram
4423 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4425 => printenv bootargs
4426 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4429 ## Booting Linux kernel at 40020000 ...
4430 Image Name: 2.2.13 for NFS on TQM850L
4431 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4432 Data Size: 381681 Bytes = 372 kB = 0 MB
4433 Load Address: 00000000
4434 Entry Point: 0000000c
4435 Verifying Checksum ... OK
4436 Uncompressing Kernel Image ... OK
4437 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
4438 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4439 time_init: decrementer frequency = 187500000/60
4440 Calibrating delay loop... 49.77 BogoMIPS
4441 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4444 If you want to boot a Linux kernel with initial RAM disk, you pass
4445 the memory addresses of both the kernel and the initrd image (PPBCOOT
4446 format!) to the "bootm" command:
4448 => imi 40100000 40200000
4450 ## Checking Image at 40100000 ...
4451 Image Name: 2.2.13 for initrd on TQM850L
4452 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4453 Data Size: 335725 Bytes = 327 kB = 0 MB
4454 Load Address: 00000000
4455 Entry Point: 0000000c
4456 Verifying Checksum ... OK
4458 ## Checking Image at 40200000 ...
4459 Image Name: Simple Ramdisk Image
4460 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4461 Data Size: 566530 Bytes = 553 kB = 0 MB
4462 Load Address: 00000000
4463 Entry Point: 00000000
4464 Verifying Checksum ... OK
4466 => bootm 40100000 40200000
4467 ## Booting Linux kernel at 40100000 ...
4468 Image Name: 2.2.13 for initrd on TQM850L
4469 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4470 Data Size: 335725 Bytes = 327 kB = 0 MB
4471 Load Address: 00000000
4472 Entry Point: 0000000c
4473 Verifying Checksum ... OK
4474 Uncompressing Kernel Image ... OK
4475 ## Loading RAMDisk Image at 40200000 ...
4476 Image Name: Simple Ramdisk Image
4477 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4478 Data Size: 566530 Bytes = 553 kB = 0 MB
4479 Load Address: 00000000
4480 Entry Point: 00000000
4481 Verifying Checksum ... OK
4482 Loading Ramdisk ... OK
4483 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
4484 Boot arguments: root=/dev/ram
4485 time_init: decrementer frequency = 187500000/60
4486 Calibrating delay loop... 49.77 BogoMIPS
4488 RAMDISK: Compressed image found at block 0
4489 VFS: Mounted root (ext2 filesystem).
4493 Boot Linux and pass a flat device tree:
4496 First, U-Boot must be compiled with the appropriate defines. See the section
4497 titled "Linux Kernel Interface" above for a more in depth explanation. The
4498 following is an example of how to start a kernel and pass an updated
4504 oft=oftrees/mpc8540ads.dtb
4505 => tftp $oftaddr $oft
4506 Speed: 1000, full duplex
4508 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4509 Filename 'oftrees/mpc8540ads.dtb'.
4510 Load address: 0x300000
4513 Bytes transferred = 4106 (100a hex)
4514 => tftp $loadaddr $bootfile
4515 Speed: 1000, full duplex
4517 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4519 Load address: 0x200000
4520 Loading:############
4522 Bytes transferred = 1029407 (fb51f hex)
4527 => bootm $loadaddr - $oftaddr
4528 ## Booting image at 00200000 ...
4529 Image Name: Linux-2.6.17-dirty
4530 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4531 Data Size: 1029343 Bytes = 1005.2 kB
4532 Load Address: 00000000
4533 Entry Point: 00000000
4534 Verifying Checksum ... OK
4535 Uncompressing Kernel Image ... OK
4536 Booting using flat device tree at 0x300000
4537 Using MPC85xx ADS machine description
4538 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4542 More About U-Boot Image Types:
4543 ------------------------------
4545 U-Boot supports the following image types:
4547 "Standalone Programs" are directly runnable in the environment
4548 provided by U-Boot; it is expected that (if they behave
4549 well) you can continue to work in U-Boot after return from
4550 the Standalone Program.
4551 "OS Kernel Images" are usually images of some Embedded OS which
4552 will take over control completely. Usually these programs
4553 will install their own set of exception handlers, device
4554 drivers, set up the MMU, etc. - this means, that you cannot
4555 expect to re-enter U-Boot except by resetting the CPU.
4556 "RAMDisk Images" are more or less just data blocks, and their
4557 parameters (address, size) are passed to an OS kernel that is
4559 "Multi-File Images" contain several images, typically an OS
4560 (Linux) kernel image and one or more data images like
4561 RAMDisks. This construct is useful for instance when you want
4562 to boot over the network using BOOTP etc., where the boot
4563 server provides just a single image file, but you want to get
4564 for instance an OS kernel and a RAMDisk image.
4566 "Multi-File Images" start with a list of image sizes, each
4567 image size (in bytes) specified by an "uint32_t" in network
4568 byte order. This list is terminated by an "(uint32_t)0".
4569 Immediately after the terminating 0 follow the images, one by
4570 one, all aligned on "uint32_t" boundaries (size rounded up to
4571 a multiple of 4 bytes).
4573 "Firmware Images" are binary images containing firmware (like
4574 U-Boot or FPGA images) which usually will be programmed to
4577 "Script files" are command sequences that will be executed by
4578 U-Boot's command interpreter; this feature is especially
4579 useful when you configure U-Boot to use a real shell (hush)
4580 as command interpreter.
4582 Booting the Linux zImage:
4583 -------------------------
4585 On some platforms, it's possible to boot Linux zImage. This is done
4586 using the "bootz" command. The syntax of "bootz" command is the same
4587 as the syntax of "bootm" command.
4589 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
4590 kernel with raw initrd images. The syntax is slightly different, the
4591 address of the initrd must be augmented by it's size, in the following
4592 format: "<initrd addres>:<initrd size>".
4598 One of the features of U-Boot is that you can dynamically load and
4599 run "standalone" applications, which can use some resources of
4600 U-Boot like console I/O functions or interrupt services.
4602 Two simple examples are included with the sources:
4607 'examples/hello_world.c' contains a small "Hello World" Demo
4608 application; it is automatically compiled when you build U-Boot.
4609 It's configured to run at address 0x00040004, so you can play with it
4613 ## Ready for S-Record download ...
4614 ~>examples/hello_world.srec
4615 1 2 3 4 5 6 7 8 9 10 11 ...
4616 [file transfer complete]
4618 ## Start Addr = 0x00040004
4620 => go 40004 Hello World! This is a test.
4621 ## Starting application at 0x00040004 ...
4632 Hit any key to exit ...
4634 ## Application terminated, rc = 0x0
4636 Another example, which demonstrates how to register a CPM interrupt
4637 handler with the U-Boot code, can be found in 'examples/timer.c'.
4638 Here, a CPM timer is set up to generate an interrupt every second.
4639 The interrupt service routine is trivial, just printing a '.'
4640 character, but this is just a demo program. The application can be
4641 controlled by the following keys:
4643 ? - print current values og the CPM Timer registers
4644 b - enable interrupts and start timer
4645 e - stop timer and disable interrupts
4646 q - quit application
4649 ## Ready for S-Record download ...
4650 ~>examples/timer.srec
4651 1 2 3 4 5 6 7 8 9 10 11 ...
4652 [file transfer complete]
4654 ## Start Addr = 0x00040004
4657 ## Starting application at 0x00040004 ...
4660 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4663 [q, b, e, ?] Set interval 1000000 us
4666 [q, b, e, ?] ........
4667 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4670 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4673 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4676 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4678 [q, b, e, ?] ...Stopping timer
4680 [q, b, e, ?] ## Application terminated, rc = 0x0
4686 Over time, many people have reported problems when trying to use the
4687 "minicom" terminal emulation program for serial download. I (wd)
4688 consider minicom to be broken, and recommend not to use it. Under
4689 Unix, I recommend to use C-Kermit for general purpose use (and
4690 especially for kermit binary protocol download ("loadb" command), and
4691 use "cu" for S-Record download ("loads" command). See
4692 http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4693 for help with kermit.
4696 Nevertheless, if you absolutely want to use it try adding this
4697 configuration to your "File transfer protocols" section:
4699 Name Program Name U/D FullScr IO-Red. Multi
4700 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4701 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4707 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4708 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4710 Building requires a cross environment; it is known to work on
4711 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4712 need gmake since the Makefiles are not compatible with BSD make).
4713 Note that the cross-powerpc package does not install include files;
4714 attempting to build U-Boot will fail because <machine/ansi.h> is
4715 missing. This file has to be installed and patched manually:
4717 # cd /usr/pkg/cross/powerpc-netbsd/include
4719 # ln -s powerpc machine
4720 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4721 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4723 Native builds *don't* work due to incompatibilities between native
4724 and U-Boot include files.
4726 Booting assumes that (the first part of) the image booted is a
4727 stage-2 loader which in turn loads and then invokes the kernel
4728 proper. Loader sources will eventually appear in the NetBSD source
4729 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4730 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4733 Implementation Internals:
4734 =========================
4736 The following is not intended to be a complete description of every
4737 implementation detail. However, it should help to understand the
4738 inner workings of U-Boot and make it easier to port it to custom
4742 Initial Stack, Global Data:
4743 ---------------------------
4745 The implementation of U-Boot is complicated by the fact that U-Boot
4746 starts running out of ROM (flash memory), usually without access to
4747 system RAM (because the memory controller is not initialized yet).
4748 This means that we don't have writable Data or BSS segments, and BSS
4749 is not initialized as zero. To be able to get a C environment working
4750 at all, we have to allocate at least a minimal stack. Implementation
4751 options for this are defined and restricted by the CPU used: Some CPU
4752 models provide on-chip memory (like the IMMR area on MPC8xx and
4753 MPC826x processors), on others (parts of) the data cache can be
4754 locked as (mis-) used as memory, etc.
4756 Chris Hallinan posted a good summary of these issues to the
4757 U-Boot mailing list:
4759 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4760 From: "Chris Hallinan" <clh@net1plus.com>
4761 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4764 Correct me if I'm wrong, folks, but the way I understand it
4765 is this: Using DCACHE as initial RAM for Stack, etc, does not
4766 require any physical RAM backing up the cache. The cleverness
4767 is that the cache is being used as a temporary supply of
4768 necessary storage before the SDRAM controller is setup. It's
4769 beyond the scope of this list to explain the details, but you
4770 can see how this works by studying the cache architecture and
4771 operation in the architecture and processor-specific manuals.
4773 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4774 is another option for the system designer to use as an
4775 initial stack/RAM area prior to SDRAM being available. Either
4776 option should work for you. Using CS 4 should be fine if your
4777 board designers haven't used it for something that would
4778 cause you grief during the initial boot! It is frequently not
4781 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4782 with your processor/board/system design. The default value
4783 you will find in any recent u-boot distribution in
4784 walnut.h should work for you. I'd set it to a value larger
4785 than your SDRAM module. If you have a 64MB SDRAM module, set
4786 it above 400_0000. Just make sure your board has no resources
4787 that are supposed to respond to that address! That code in
4788 start.S has been around a while and should work as is when
4789 you get the config right.
4794 It is essential to remember this, since it has some impact on the C
4795 code for the initialization procedures:
4797 * Initialized global data (data segment) is read-only. Do not attempt
4800 * Do not use any uninitialized global data (or implicitly initialized
4801 as zero data - BSS segment) at all - this is undefined, initiali-
4802 zation is performed later (when relocating to RAM).
4804 * Stack space is very limited. Avoid big data buffers or things like
4807 Having only the stack as writable memory limits means we cannot use
4808 normal global data to share information between the code. But it
4809 turned out that the implementation of U-Boot can be greatly
4810 simplified by making a global data structure (gd_t) available to all
4811 functions. We could pass a pointer to this data as argument to _all_
4812 functions, but this would bloat the code. Instead we use a feature of
4813 the GCC compiler (Global Register Variables) to share the data: we
4814 place a pointer (gd) to the global data into a register which we
4815 reserve for this purpose.
4817 When choosing a register for such a purpose we are restricted by the
4818 relevant (E)ABI specifications for the current architecture, and by
4819 GCC's implementation.
4821 For PowerPC, the following registers have specific use:
4823 R2: reserved for system use
4824 R3-R4: parameter passing and return values
4825 R5-R10: parameter passing
4826 R13: small data area pointer
4830 (U-Boot also uses R12 as internal GOT pointer. r12
4831 is a volatile register so r12 needs to be reset when
4832 going back and forth between asm and C)
4834 ==> U-Boot will use R2 to hold a pointer to the global data
4836 Note: on PPC, we could use a static initializer (since the
4837 address of the global data structure is known at compile time),
4838 but it turned out that reserving a register results in somewhat
4839 smaller code - although the code savings are not that big (on
4840 average for all boards 752 bytes for the whole U-Boot image,
4841 624 text + 127 data).
4843 On ARM, the following registers are used:
4845 R0: function argument word/integer result
4846 R1-R3: function argument word
4847 R9: platform specific
4848 R10: stack limit (used only if stack checking is enabled)
4849 R11: argument (frame) pointer
4850 R12: temporary workspace
4853 R15: program counter
4855 ==> U-Boot will use R9 to hold a pointer to the global data
4857 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4859 On Nios II, the ABI is documented here:
4860 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4862 ==> U-Boot will use gp to hold a pointer to the global data
4864 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4865 to access small data sections, so gp is free.
4867 On NDS32, the following registers are used:
4869 R0-R1: argument/return
4871 R15: temporary register for assembler
4872 R16: trampoline register
4873 R28: frame pointer (FP)
4874 R29: global pointer (GP)
4875 R30: link register (LP)
4876 R31: stack pointer (SP)
4877 PC: program counter (PC)
4879 ==> U-Boot will use R10 to hold a pointer to the global data
4881 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4882 or current versions of GCC may "optimize" the code too much.
4884 On RISC-V, the following registers are used:
4886 x0: hard-wired zero (zero)
4887 x1: return address (ra)
4888 x2: stack pointer (sp)
4889 x3: global pointer (gp)
4890 x4: thread pointer (tp)
4891 x5: link register (t0)
4892 x8: frame pointer (fp)
4893 x10-x11: arguments/return values (a0-1)
4894 x12-x17: arguments (a2-7)
4895 x28-31: temporaries (t3-6)
4896 pc: program counter (pc)
4898 ==> U-Boot will use gp to hold a pointer to the global data
4903 U-Boot runs in system state and uses physical addresses, i.e. the
4904 MMU is not used either for address mapping nor for memory protection.
4906 The available memory is mapped to fixed addresses using the memory
4907 controller. In this process, a contiguous block is formed for each
4908 memory type (Flash, SDRAM, SRAM), even when it consists of several
4909 physical memory banks.
4911 U-Boot is installed in the first 128 kB of the first Flash bank (on
4912 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4913 booting and sizing and initializing DRAM, the code relocates itself
4914 to the upper end of DRAM. Immediately below the U-Boot code some
4915 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4916 configuration setting]. Below that, a structure with global Board
4917 Info data is placed, followed by the stack (growing downward).
4919 Additionally, some exception handler code is copied to the low 8 kB
4920 of DRAM (0x00000000 ... 0x00001FFF).
4922 So a typical memory configuration with 16 MB of DRAM could look like
4925 0x0000 0000 Exception Vector code
4928 0x0000 2000 Free for Application Use
4934 0x00FB FF20 Monitor Stack (Growing downward)
4935 0x00FB FFAC Board Info Data and permanent copy of global data
4936 0x00FC 0000 Malloc Arena
4939 0x00FE 0000 RAM Copy of Monitor Code
4940 ... eventually: LCD or video framebuffer
4941 ... eventually: pRAM (Protected RAM - unchanged by reset)
4942 0x00FF FFFF [End of RAM]
4945 System Initialization:
4946 ----------------------
4948 In the reset configuration, U-Boot starts at the reset entry point
4949 (on most PowerPC systems at address 0x00000100). Because of the reset
4950 configuration for CS0# this is a mirror of the on board Flash memory.
4951 To be able to re-map memory U-Boot then jumps to its link address.
4952 To be able to implement the initialization code in C, a (small!)
4953 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4954 which provide such a feature like), or in a locked part of the data
4955 cache. After that, U-Boot initializes the CPU core, the caches and
4958 Next, all (potentially) available memory banks are mapped using a
4959 preliminary mapping. For example, we put them on 512 MB boundaries
4960 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4961 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4962 programmed for SDRAM access. Using the temporary configuration, a
4963 simple memory test is run that determines the size of the SDRAM
4966 When there is more than one SDRAM bank, and the banks are of
4967 different size, the largest is mapped first. For equal size, the first
4968 bank (CS2#) is mapped first. The first mapping is always for address
4969 0x00000000, with any additional banks following immediately to create
4970 contiguous memory starting from 0.
4972 Then, the monitor installs itself at the upper end of the SDRAM area
4973 and allocates memory for use by malloc() and for the global Board
4974 Info data; also, the exception vector code is copied to the low RAM
4975 pages, and the final stack is set up.
4977 Only after this relocation will you have a "normal" C environment;
4978 until that you are restricted in several ways, mostly because you are
4979 running from ROM, and because the code will have to be relocated to a
4983 U-Boot Porting Guide:
4984 ----------------------
4986 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4990 int main(int argc, char *argv[])
4992 sighandler_t no_more_time;
4994 signal(SIGALRM, no_more_time);
4995 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4997 if (available_money > available_manpower) {
4998 Pay consultant to port U-Boot;
5002 Download latest U-Boot source;
5004 Subscribe to u-boot mailing list;
5007 email("Hi, I am new to U-Boot, how do I get started?");
5010 Read the README file in the top level directory;
5011 Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5012 Read applicable doc/*.README;
5013 Read the source, Luke;
5014 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
5017 if (available_money > toLocalCurrency ($2500))
5020 Add a lot of aggravation and time;
5022 if (a similar board exists) { /* hopefully... */
5023 cp -a board/<similar> board/<myboard>
5024 cp include/configs/<similar>.h include/configs/<myboard>.h
5026 Create your own board support subdirectory;
5027 Create your own board include/configs/<myboard>.h file;
5029 Edit new board/<myboard> files
5030 Edit new include/configs/<myboard>.h
5035 Add / modify source code;
5039 email("Hi, I am having problems...");
5041 Send patch file to the U-Boot email list;
5042 if (reasonable critiques)
5043 Incorporate improvements from email list code review;
5045 Defend code as written;
5051 void no_more_time (int sig)
5060 All contributions to U-Boot should conform to the Linux kernel
5061 coding style; see the kernel coding style guide at
5062 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
5063 script "scripts/Lindent" in your Linux kernel source directory.
5065 Source files originating from a different project (for example the
5066 MTD subsystem) are generally exempt from these guidelines and are not
5067 reformatted to ease subsequent migration to newer versions of those
5070 Please note that U-Boot is implemented in C (and to some small parts in
5071 Assembler); no C++ is used, so please do not use C++ style comments (//)
5074 Please also stick to the following formatting rules:
5075 - remove any trailing white space
5076 - use TAB characters for indentation and vertical alignment, not spaces
5077 - make sure NOT to use DOS '\r\n' line feeds
5078 - do not add more than 2 consecutive empty lines to source files
5079 - do not add trailing empty lines to source files
5081 Submissions which do not conform to the standards may be returned
5082 with a request to reformat the changes.
5088 Since the number of patches for U-Boot is growing, we need to
5089 establish some rules. Submissions which do not conform to these rules
5090 may be rejected, even when they contain important and valuable stuff.
5092 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5094 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5095 see https://lists.denx.de/listinfo/u-boot
5097 When you send a patch, please include the following information with
5100 * For bug fixes: a description of the bug and how your patch fixes
5101 this bug. Please try to include a way of demonstrating that the
5102 patch actually fixes something.
5104 * For new features: a description of the feature and your
5107 * A CHANGELOG entry as plaintext (separate from the patch)
5109 * For major contributions, add a MAINTAINERS file with your
5110 information and associated file and directory references.
5112 * When you add support for a new board, don't forget to add a
5113 maintainer e-mail address to the boards.cfg file, too.
5115 * If your patch adds new configuration options, don't forget to
5116 document these in the README file.
5118 * The patch itself. If you are using git (which is *strongly*
5119 recommended) you can easily generate the patch using the
5120 "git format-patch". If you then use "git send-email" to send it to
5121 the U-Boot mailing list, you will avoid most of the common problems
5122 with some other mail clients.
5124 If you cannot use git, use "diff -purN OLD NEW". If your version of
5125 diff does not support these options, then get the latest version of
5128 The current directory when running this command shall be the parent
5129 directory of the U-Boot source tree (i. e. please make sure that
5130 your patch includes sufficient directory information for the
5133 We prefer patches as plain text. MIME attachments are discouraged,
5134 and compressed attachments must not be used.
5136 * If one logical set of modifications affects or creates several
5137 files, all these changes shall be submitted in a SINGLE patch file.
5139 * Changesets that contain different, unrelated modifications shall be
5140 submitted as SEPARATE patches, one patch per changeset.
5145 * Before sending the patch, run the buildman script on your patched
5146 source tree and make sure that no errors or warnings are reported
5147 for any of the boards.
5149 * Keep your modifications to the necessary minimum: A patch
5150 containing several unrelated changes or arbitrary reformats will be
5151 returned with a request to re-formatting / split it.
5153 * If you modify existing code, make sure that your new code does not
5154 add to the memory footprint of the code ;-) Small is beautiful!
5155 When adding new features, these should compile conditionally only
5156 (using #ifdef), and the resulting code with the new feature
5157 disabled must not need more memory than the old code without your
5160 * Remember that there is a size limit of 100 kB per message on the
5161 u-boot mailing list. Bigger patches will be moderated. If they are
5162 reasonable and not too big, they will be acknowledged. But patches
5163 bigger than the size limit should be avoided.