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
1423 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1425 The clock frequency of the MII bus
1427 CONFIG_PHY_RESET_DELAY
1429 Some PHY like Intel LXT971A need extra delay after
1430 reset before any MII register access is possible.
1431 For such PHY, set this option to the usec delay
1432 required. (minimum 300usec for LXT971A)
1434 CONFIG_PHY_CMD_DELAY (ppc4xx)
1436 Some PHY like Intel LXT971A need extra delay after
1437 command issued before MII status register can be read
1442 Define a default value for the IP address to use for
1443 the default Ethernet interface, in case this is not
1444 determined through e.g. bootp.
1445 (Environment variable "ipaddr")
1447 - Server IP address:
1450 Defines a default value for the IP address of a TFTP
1451 server to contact when using the "tftboot" command.
1452 (Environment variable "serverip")
1454 CONFIG_KEEP_SERVERADDR
1456 Keeps the server's MAC address, in the env 'serveraddr'
1457 for passing to bootargs (like Linux's netconsole option)
1459 - Gateway IP address:
1462 Defines a default value for the IP address of the
1463 default router where packets to other networks are
1465 (Environment variable "gatewayip")
1470 Defines a default value for the subnet mask (or
1471 routing prefix) which is used to determine if an IP
1472 address belongs to the local subnet or needs to be
1473 forwarded through a router.
1474 (Environment variable "netmask")
1476 - Multicast TFTP Mode:
1479 Defines whether you want to support multicast TFTP as per
1480 rfc-2090; for example to work with atftp. Lets lots of targets
1481 tftp down the same boot image concurrently. Note: the Ethernet
1482 driver in use must provide a function: mcast() to join/leave a
1485 - BOOTP Recovery Mode:
1486 CONFIG_BOOTP_RANDOM_DELAY
1488 If you have many targets in a network that try to
1489 boot using BOOTP, you may want to avoid that all
1490 systems send out BOOTP requests at precisely the same
1491 moment (which would happen for instance at recovery
1492 from a power failure, when all systems will try to
1493 boot, thus flooding the BOOTP server. Defining
1494 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1495 inserted before sending out BOOTP requests. The
1496 following delays are inserted then:
1498 1st BOOTP request: delay 0 ... 1 sec
1499 2nd BOOTP request: delay 0 ... 2 sec
1500 3rd BOOTP request: delay 0 ... 4 sec
1502 BOOTP requests: delay 0 ... 8 sec
1504 CONFIG_BOOTP_ID_CACHE_SIZE
1506 BOOTP packets are uniquely identified using a 32-bit ID. The
1507 server will copy the ID from client requests to responses and
1508 U-Boot will use this to determine if it is the destination of
1509 an incoming response. Some servers will check that addresses
1510 aren't in use before handing them out (usually using an ARP
1511 ping) and therefore take up to a few hundred milliseconds to
1512 respond. Network congestion may also influence the time it
1513 takes for a response to make it back to the client. If that
1514 time is too long, U-Boot will retransmit requests. In order
1515 to allow earlier responses to still be accepted after these
1516 retransmissions, U-Boot's BOOTP client keeps a small cache of
1517 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1518 cache. The default is to keep IDs for up to four outstanding
1519 requests. Increasing this will allow U-Boot to accept offers
1520 from a BOOTP client in networks with unusually high latency.
1522 - DHCP Advanced Options:
1523 You can fine tune the DHCP functionality by defining
1524 CONFIG_BOOTP_* symbols:
1526 CONFIG_BOOTP_NISDOMAIN
1527 CONFIG_BOOTP_BOOTFILESIZE
1528 CONFIG_BOOTP_SEND_HOSTNAME
1529 CONFIG_BOOTP_NTPSERVER
1530 CONFIG_BOOTP_TIMEOFFSET
1531 CONFIG_BOOTP_VENDOREX
1532 CONFIG_BOOTP_MAY_FAIL
1534 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1535 environment variable, not the BOOTP server.
1537 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1538 after the configured retry count, the call will fail
1539 instead of starting over. This can be used to fail over
1540 to Link-local IP address configuration if the DHCP server
1543 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1544 to do a dynamic update of a DNS server. To do this, they
1545 need the hostname of the DHCP requester.
1546 If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1547 of the "hostname" environment variable is passed as
1548 option 12 to the DHCP server.
1550 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1552 A 32bit value in microseconds for a delay between
1553 receiving a "DHCP Offer" and sending the "DHCP Request".
1554 This fixes a problem with certain DHCP servers that don't
1555 respond 100% of the time to a "DHCP request". E.g. On an
1556 AT91RM9200 processor running at 180MHz, this delay needed
1557 to be *at least* 15,000 usec before a Windows Server 2003
1558 DHCP server would reply 100% of the time. I recommend at
1559 least 50,000 usec to be safe. The alternative is to hope
1560 that one of the retries will be successful but note that
1561 the DHCP timeout and retry process takes a longer than
1564 - Link-local IP address negotiation:
1565 Negotiate with other link-local clients on the local network
1566 for an address that doesn't require explicit configuration.
1567 This is especially useful if a DHCP server cannot be guaranteed
1568 to exist in all environments that the device must operate.
1570 See doc/README.link-local for more information.
1572 - MAC address from environment variables
1574 FDT_SEQ_MACADDR_FROM_ENV
1576 Fix-up device tree with MAC addresses fetched sequentially from
1577 environment variables. This config work on assumption that
1578 non-usable ethernet node of device-tree are either not present
1579 or their status has been marked as "disabled".
1582 CONFIG_CDP_DEVICE_ID
1584 The device id used in CDP trigger frames.
1586 CONFIG_CDP_DEVICE_ID_PREFIX
1588 A two character string which is prefixed to the MAC address
1593 A printf format string which contains the ascii name of
1594 the port. Normally is set to "eth%d" which sets
1595 eth0 for the first Ethernet, eth1 for the second etc.
1597 CONFIG_CDP_CAPABILITIES
1599 A 32bit integer which indicates the device capabilities;
1600 0x00000010 for a normal host which does not forwards.
1604 An ascii string containing the version of the software.
1608 An ascii string containing the name of the platform.
1612 A 32bit integer sent on the trigger.
1614 CONFIG_CDP_POWER_CONSUMPTION
1616 A 16bit integer containing the power consumption of the
1617 device in .1 of milliwatts.
1619 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1621 A byte containing the id of the VLAN.
1623 - Status LED: CONFIG_LED_STATUS
1625 Several configurations allow to display the current
1626 status using a LED. For instance, the LED will blink
1627 fast while running U-Boot code, stop blinking as
1628 soon as a reply to a BOOTP request was received, and
1629 start blinking slow once the Linux kernel is running
1630 (supported by a status LED driver in the Linux
1631 kernel). Defining CONFIG_LED_STATUS enables this
1636 CONFIG_LED_STATUS_GPIO
1637 The status LED can be connected to a GPIO pin.
1638 In such cases, the gpio_led driver can be used as a
1639 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1640 to include the gpio_led driver in the U-Boot binary.
1642 CONFIG_GPIO_LED_INVERTED_TABLE
1643 Some GPIO connected LEDs may have inverted polarity in which
1644 case the GPIO high value corresponds to LED off state and
1645 GPIO low value corresponds to LED on state.
1646 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1647 with a list of GPIO LEDs that have inverted polarity.
1649 - I2C Support: CONFIG_SYS_I2C
1651 This enable the NEW i2c subsystem, and will allow you to use
1652 i2c commands at the u-boot command line (as long as you set
1653 CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
1654 based realtime clock chips or other i2c devices. See
1655 common/cmd_i2c.c for a description of the command line
1658 ported i2c driver to the new framework:
1659 - drivers/i2c/soft_i2c.c:
1660 - activate first bus with CONFIG_SYS_I2C_SOFT define
1661 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1662 for defining speed and slave address
1663 - activate second bus with I2C_SOFT_DECLARATIONS2 define
1664 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1665 for defining speed and slave address
1666 - activate third bus with I2C_SOFT_DECLARATIONS3 define
1667 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1668 for defining speed and slave address
1669 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1670 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1671 for defining speed and slave address
1673 - drivers/i2c/fsl_i2c.c:
1674 - activate i2c driver with CONFIG_SYS_I2C_FSL
1675 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1676 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1677 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1679 - If your board supports a second fsl i2c bus, define
1680 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1681 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1682 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1685 - drivers/i2c/tegra_i2c.c:
1686 - activate this driver with CONFIG_SYS_I2C_TEGRA
1687 - This driver adds 4 i2c buses with a fix speed from
1688 100000 and the slave addr 0!
1690 - drivers/i2c/ppc4xx_i2c.c
1691 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1692 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1693 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1695 - drivers/i2c/i2c_mxc.c
1696 - activate this driver with CONFIG_SYS_I2C_MXC
1697 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1698 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1699 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1700 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1701 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1702 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1703 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1704 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1705 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1706 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1707 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1708 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1709 If those defines are not set, default value is 100000
1710 for speed, and 0 for slave.
1712 - drivers/i2c/rcar_i2c.c:
1713 - activate this driver with CONFIG_SYS_I2C_RCAR
1714 - This driver adds 4 i2c buses
1716 - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
1717 - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
1718 - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
1719 - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
1720 - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
1721 - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
1722 - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
1723 - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
1724 - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
1726 - drivers/i2c/sh_i2c.c:
1727 - activate this driver with CONFIG_SYS_I2C_SH
1728 - This driver adds from 2 to 5 i2c buses
1730 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1731 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1732 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1733 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1734 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1735 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1736 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1737 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1738 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1739 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1740 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1742 - drivers/i2c/omap24xx_i2c.c
1743 - activate this driver with CONFIG_SYS_I2C_OMAP24XX
1744 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
1745 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
1746 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
1747 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
1748 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
1749 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
1750 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
1751 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
1752 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
1753 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
1755 - drivers/i2c/zynq_i2c.c
1756 - activate this driver with CONFIG_SYS_I2C_ZYNQ
1757 - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
1758 - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
1760 - drivers/i2c/s3c24x0_i2c.c:
1761 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1762 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1763 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1764 with a fix speed from 100000 and the slave addr 0!
1766 - drivers/i2c/ihs_i2c.c
1767 - activate this driver with CONFIG_SYS_I2C_IHS
1768 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1769 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1770 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1771 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1772 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1773 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1774 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1775 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1776 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1777 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1778 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1779 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1780 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1781 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1782 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1783 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1784 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1785 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1786 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1787 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1788 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1792 CONFIG_SYS_NUM_I2C_BUSES
1793 Hold the number of i2c buses you want to use.
1795 CONFIG_SYS_I2C_DIRECT_BUS
1796 define this, if you don't use i2c muxes on your hardware.
1797 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1800 CONFIG_SYS_I2C_MAX_HOPS
1801 define how many muxes are maximal consecutively connected
1802 on one i2c bus. If you not use i2c muxes, omit this
1805 CONFIG_SYS_I2C_BUSES
1806 hold a list of buses you want to use, only used if
1807 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1808 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1809 CONFIG_SYS_NUM_I2C_BUSES = 9:
1811 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1812 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1813 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1814 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1815 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1816 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1817 {1, {I2C_NULL_HOP}}, \
1818 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1819 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1823 bus 0 on adapter 0 without a mux
1824 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1825 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1826 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1827 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1828 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1829 bus 6 on adapter 1 without a mux
1830 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1831 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1833 If you do not have i2c muxes on your board, omit this define.
1835 - Legacy I2C Support:
1836 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1837 then the following macros need to be defined (examples are
1838 from include/configs/lwmon.h):
1842 (Optional). Any commands necessary to enable the I2C
1843 controller or configure ports.
1845 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1849 The code necessary to make the I2C data line active
1850 (driven). If the data line is open collector, this
1853 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1857 The code necessary to make the I2C data line tri-stated
1858 (inactive). If the data line is open collector, this
1861 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1865 Code that returns true if the I2C data line is high,
1868 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1872 If <bit> is true, sets the I2C data line high. If it
1873 is false, it clears it (low).
1875 eg: #define I2C_SDA(bit) \
1876 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1877 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1881 If <bit> is true, sets the I2C clock line high. If it
1882 is false, it clears it (low).
1884 eg: #define I2C_SCL(bit) \
1885 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1886 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1890 This delay is invoked four times per clock cycle so this
1891 controls the rate of data transfer. The data rate thus
1892 is 1 / (I2C_DELAY * 4). Often defined to be something
1895 #define I2C_DELAY udelay(2)
1897 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1899 If your arch supports the generic GPIO framework (asm/gpio.h),
1900 then you may alternatively define the two GPIOs that are to be
1901 used as SCL / SDA. Any of the previous I2C_xxx macros will
1902 have GPIO-based defaults assigned to them as appropriate.
1904 You should define these to the GPIO value as given directly to
1905 the generic GPIO functions.
1907 CONFIG_SYS_I2C_INIT_BOARD
1909 When a board is reset during an i2c bus transfer
1910 chips might think that the current transfer is still
1911 in progress. On some boards it is possible to access
1912 the i2c SCLK line directly, either by using the
1913 processor pin as a GPIO or by having a second pin
1914 connected to the bus. If this option is defined a
1915 custom i2c_init_board() routine in boards/xxx/board.c
1916 is run early in the boot sequence.
1918 CONFIG_I2C_MULTI_BUS
1920 This option allows the use of multiple I2C buses, each of which
1921 must have a controller. At any point in time, only one bus is
1922 active. To switch to a different bus, use the 'i2c dev' command.
1923 Note that bus numbering is zero-based.
1925 CONFIG_SYS_I2C_NOPROBES
1927 This option specifies a list of I2C devices that will be skipped
1928 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1929 is set, specify a list of bus-device pairs. Otherwise, specify
1930 a 1D array of device addresses
1933 #undef CONFIG_I2C_MULTI_BUS
1934 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1936 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1938 #define CONFIG_I2C_MULTI_BUS
1939 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1941 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1943 CONFIG_SYS_SPD_BUS_NUM
1945 If defined, then this indicates the I2C bus number for DDR SPD.
1946 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1948 CONFIG_SYS_RTC_BUS_NUM
1950 If defined, then this indicates the I2C bus number for the RTC.
1951 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1953 CONFIG_SOFT_I2C_READ_REPEATED_START
1955 defining this will force the i2c_read() function in
1956 the soft_i2c driver to perform an I2C repeated start
1957 between writing the address pointer and reading the
1958 data. If this define is omitted the default behaviour
1959 of doing a stop-start sequence will be used. Most I2C
1960 devices can use either method, but some require one or
1963 - SPI Support: CONFIG_SPI
1965 Enables SPI driver (so far only tested with
1966 SPI EEPROM, also an instance works with Crystal A/D and
1967 D/As on the SACSng board)
1971 Enables a software (bit-bang) SPI driver rather than
1972 using hardware support. This is a general purpose
1973 driver that only requires three general I/O port pins
1974 (two outputs, one input) to function. If this is
1975 defined, the board configuration must define several
1976 SPI configuration items (port pins to use, etc). For
1977 an example, see include/configs/sacsng.h.
1981 Enables a hardware SPI driver for general-purpose reads
1982 and writes. As with CONFIG_SOFT_SPI, the board configuration
1983 must define a list of chip-select function pointers.
1984 Currently supported on some MPC8xxx processors. For an
1985 example, see include/configs/mpc8349emds.h.
1987 CONFIG_SYS_SPI_MXC_WAIT
1988 Timeout for waiting until spi transfer completed.
1989 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1991 - FPGA Support: CONFIG_FPGA
1993 Enables FPGA subsystem.
1995 CONFIG_FPGA_<vendor>
1997 Enables support for specific chip vendors.
2000 CONFIG_FPGA_<family>
2002 Enables support for FPGA family.
2003 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2007 Specify the number of FPGA devices to support.
2009 CONFIG_SYS_FPGA_PROG_FEEDBACK
2011 Enable printing of hash marks during FPGA configuration.
2013 CONFIG_SYS_FPGA_CHECK_BUSY
2015 Enable checks on FPGA configuration interface busy
2016 status by the configuration function. This option
2017 will require a board or device specific function to
2022 If defined, a function that provides delays in the FPGA
2023 configuration driver.
2025 CONFIG_SYS_FPGA_CHECK_CTRLC
2026 Allow Control-C to interrupt FPGA configuration
2028 CONFIG_SYS_FPGA_CHECK_ERROR
2030 Check for configuration errors during FPGA bitfile
2031 loading. For example, abort during Virtex II
2032 configuration if the INIT_B line goes low (which
2033 indicated a CRC error).
2035 CONFIG_SYS_FPGA_WAIT_INIT
2037 Maximum time to wait for the INIT_B line to de-assert
2038 after PROB_B has been de-asserted during a Virtex II
2039 FPGA configuration sequence. The default time is 500
2042 CONFIG_SYS_FPGA_WAIT_BUSY
2044 Maximum time to wait for BUSY to de-assert during
2045 Virtex II FPGA configuration. The default is 5 ms.
2047 CONFIG_SYS_FPGA_WAIT_CONFIG
2049 Time to wait after FPGA configuration. The default is
2052 - Configuration Management:
2055 Some SoCs need special image types (e.g. U-Boot binary
2056 with a special header) as build targets. By defining
2057 CONFIG_BUILD_TARGET in the SoC / board header, this
2058 special image will be automatically built upon calling
2063 If defined, this string will be added to the U-Boot
2064 version information (U_BOOT_VERSION)
2066 - Vendor Parameter Protection:
2068 U-Boot considers the values of the environment
2069 variables "serial#" (Board Serial Number) and
2070 "ethaddr" (Ethernet Address) to be parameters that
2071 are set once by the board vendor / manufacturer, and
2072 protects these variables from casual modification by
2073 the user. Once set, these variables are read-only,
2074 and write or delete attempts are rejected. You can
2075 change this behaviour:
2077 If CONFIG_ENV_OVERWRITE is #defined in your config
2078 file, the write protection for vendor parameters is
2079 completely disabled. Anybody can change or delete
2082 Alternatively, if you define _both_ an ethaddr in the
2083 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2084 Ethernet address is installed in the environment,
2085 which can be changed exactly ONCE by the user. [The
2086 serial# is unaffected by this, i. e. it remains
2089 The same can be accomplished in a more flexible way
2090 for any variable by configuring the type of access
2091 to allow for those variables in the ".flags" variable
2092 or define CONFIG_ENV_FLAGS_LIST_STATIC.
2097 Define this variable to enable the reservation of
2098 "protected RAM", i. e. RAM which is not overwritten
2099 by U-Boot. Define CONFIG_PRAM to hold the number of
2100 kB you want to reserve for pRAM. You can overwrite
2101 this default value by defining an environment
2102 variable "pram" to the number of kB you want to
2103 reserve. Note that the board info structure will
2104 still show the full amount of RAM. If pRAM is
2105 reserved, a new environment variable "mem" will
2106 automatically be defined to hold the amount of
2107 remaining RAM in a form that can be passed as boot
2108 argument to Linux, for instance like that:
2110 setenv bootargs ... mem=\${mem}
2113 This way you can tell Linux not to use this memory,
2114 either, which results in a memory region that will
2115 not be affected by reboots.
2117 *WARNING* If your board configuration uses automatic
2118 detection of the RAM size, you must make sure that
2119 this memory test is non-destructive. So far, the
2120 following board configurations are known to be
2123 IVMS8, IVML24, SPD8xx,
2124 HERMES, IP860, RPXlite, LWMON,
2127 - Access to physical memory region (> 4GB)
2128 Some basic support is provided for operations on memory not
2129 normally accessible to U-Boot - e.g. some architectures
2130 support access to more than 4GB of memory on 32-bit
2131 machines using physical address extension or similar.
2132 Define CONFIG_PHYSMEM to access this basic support, which
2133 currently only supports clearing the memory.
2136 CONFIG_NET_RETRY_COUNT
2138 This variable defines the number of retries for
2139 network operations like ARP, RARP, TFTP, or BOOTP
2140 before giving up the operation. If not defined, a
2141 default value of 5 is used.
2145 Timeout waiting for an ARP reply in milliseconds.
2149 Timeout in milliseconds used in NFS protocol.
2150 If you encounter "ERROR: Cannot umount" in nfs command,
2151 try longer timeout such as
2152 #define CONFIG_NFS_TIMEOUT 10000UL
2154 - Command Interpreter:
2155 CONFIG_SYS_PROMPT_HUSH_PS2
2157 This defines the secondary prompt string, which is
2158 printed when the command interpreter needs more input
2159 to complete a command. Usually "> ".
2163 In the current implementation, the local variables
2164 space and global environment variables space are
2165 separated. Local variables are those you define by
2166 simply typing `name=value'. To access a local
2167 variable later on, you have write `$name' or
2168 `${name}'; to execute the contents of a variable
2169 directly type `$name' at the command prompt.
2171 Global environment variables are those you use
2172 setenv/printenv to work with. To run a command stored
2173 in such a variable, you need to use the run command,
2174 and you must not use the '$' sign to access them.
2176 To store commands and special characters in a
2177 variable, please use double quotation marks
2178 surrounding the whole text of the variable, instead
2179 of the backslashes before semicolons and special
2182 - Command Line Editing and History:
2183 CONFIG_CMDLINE_PS_SUPPORT
2185 Enable support for changing the command prompt string
2186 at run-time. Only static string is supported so far.
2187 The string is obtained from environment variables PS1
2190 - Default Environment:
2191 CONFIG_EXTRA_ENV_SETTINGS
2193 Define this to contain any number of null terminated
2194 strings (variable = value pairs) that will be part of
2195 the default environment compiled into the boot image.
2197 For example, place something like this in your
2198 board's config file:
2200 #define CONFIG_EXTRA_ENV_SETTINGS \
2204 Warning: This method is based on knowledge about the
2205 internal format how the environment is stored by the
2206 U-Boot code. This is NOT an official, exported
2207 interface! Although it is unlikely that this format
2208 will change soon, there is no guarantee either.
2209 You better know what you are doing here.
2211 Note: overly (ab)use of the default environment is
2212 discouraged. Make sure to check other ways to preset
2213 the environment like the "source" command or the
2216 CONFIG_DELAY_ENVIRONMENT
2218 Normally the environment is loaded when the board is
2219 initialised so that it is available to U-Boot. This inhibits
2220 that so that the environment is not available until
2221 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2222 this is instead controlled by the value of
2223 /config/load-environment.
2225 - Serial Flash support
2226 Usage requires an initial 'sf probe' to define the serial
2227 flash parameters, followed by read/write/erase/update
2230 The following defaults may be provided by the platform
2231 to handle the common case when only a single serial
2232 flash is present on the system.
2234 CONFIG_SF_DEFAULT_BUS Bus identifier
2235 CONFIG_SF_DEFAULT_CS Chip-select
2236 CONFIG_SF_DEFAULT_MODE (see include/spi.h)
2237 CONFIG_SF_DEFAULT_SPEED in Hz
2240 - TFTP Fixed UDP Port:
2243 If this is defined, the environment variable tftpsrcp
2244 is used to supply the TFTP UDP source port value.
2245 If tftpsrcp isn't defined, the normal pseudo-random port
2246 number generator is used.
2248 Also, the environment variable tftpdstp is used to supply
2249 the TFTP UDP destination port value. If tftpdstp isn't
2250 defined, the normal port 69 is used.
2252 The purpose for tftpsrcp is to allow a TFTP server to
2253 blindly start the TFTP transfer using the pre-configured
2254 target IP address and UDP port. This has the effect of
2255 "punching through" the (Windows XP) firewall, allowing
2256 the remainder of the TFTP transfer to proceed normally.
2257 A better solution is to properly configure the firewall,
2258 but sometimes that is not allowed.
2260 - Show boot progress:
2261 CONFIG_SHOW_BOOT_PROGRESS
2263 Defining this option allows to add some board-
2264 specific code (calling a user-provided function
2265 "show_boot_progress(int)") that enables you to show
2266 the system's boot progress on some display (for
2267 example, some LED's) on your board. At the moment,
2268 the following checkpoints are implemented:
2271 Legacy uImage format:
2274 1 common/cmd_bootm.c before attempting to boot an image
2275 -1 common/cmd_bootm.c Image header has bad magic number
2276 2 common/cmd_bootm.c Image header has correct magic number
2277 -2 common/cmd_bootm.c Image header has bad checksum
2278 3 common/cmd_bootm.c Image header has correct checksum
2279 -3 common/cmd_bootm.c Image data has bad checksum
2280 4 common/cmd_bootm.c Image data has correct checksum
2281 -4 common/cmd_bootm.c Image is for unsupported architecture
2282 5 common/cmd_bootm.c Architecture check OK
2283 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi)
2284 6 common/cmd_bootm.c Image Type check OK
2285 -6 common/cmd_bootm.c gunzip uncompression error
2286 -7 common/cmd_bootm.c Unimplemented compression type
2287 7 common/cmd_bootm.c Uncompression OK
2288 8 common/cmd_bootm.c No uncompress/copy overwrite error
2289 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
2291 9 common/image.c Start initial ramdisk verification
2292 -10 common/image.c Ramdisk header has bad magic number
2293 -11 common/image.c Ramdisk header has bad checksum
2294 10 common/image.c Ramdisk header is OK
2295 -12 common/image.c Ramdisk data has bad checksum
2296 11 common/image.c Ramdisk data has correct checksum
2297 12 common/image.c Ramdisk verification complete, start loading
2298 -13 common/image.c Wrong Image Type (not PPC Linux ramdisk)
2299 13 common/image.c Start multifile image verification
2300 14 common/image.c No initial ramdisk, no multifile, continue.
2302 15 arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2304 -30 arch/powerpc/lib/board.c Fatal error, hang the system
2305 -31 post/post.c POST test failed, detected by post_output_backlog()
2306 -32 post/post.c POST test failed, detected by post_run_single()
2308 34 common/cmd_doc.c before loading a Image from a DOC device
2309 -35 common/cmd_doc.c Bad usage of "doc" command
2310 35 common/cmd_doc.c correct usage of "doc" command
2311 -36 common/cmd_doc.c No boot device
2312 36 common/cmd_doc.c correct boot device
2313 -37 common/cmd_doc.c Unknown Chip ID on boot device
2314 37 common/cmd_doc.c correct chip ID found, device available
2315 -38 common/cmd_doc.c Read Error on boot device
2316 38 common/cmd_doc.c reading Image header from DOC device OK
2317 -39 common/cmd_doc.c Image header has bad magic number
2318 39 common/cmd_doc.c Image header has correct magic number
2319 -40 common/cmd_doc.c Error reading Image from DOC device
2320 40 common/cmd_doc.c Image header has correct magic number
2321 41 common/cmd_ide.c before loading a Image from a IDE device
2322 -42 common/cmd_ide.c Bad usage of "ide" command
2323 42 common/cmd_ide.c correct usage of "ide" command
2324 -43 common/cmd_ide.c No boot device
2325 43 common/cmd_ide.c boot device found
2326 -44 common/cmd_ide.c Device not available
2327 44 common/cmd_ide.c Device available
2328 -45 common/cmd_ide.c wrong partition selected
2329 45 common/cmd_ide.c partition selected
2330 -46 common/cmd_ide.c Unknown partition table
2331 46 common/cmd_ide.c valid partition table found
2332 -47 common/cmd_ide.c Invalid partition type
2333 47 common/cmd_ide.c correct partition type
2334 -48 common/cmd_ide.c Error reading Image Header on boot device
2335 48 common/cmd_ide.c reading Image Header from IDE device OK
2336 -49 common/cmd_ide.c Image header has bad magic number
2337 49 common/cmd_ide.c Image header has correct magic number
2338 -50 common/cmd_ide.c Image header has bad checksum
2339 50 common/cmd_ide.c Image header has correct checksum
2340 -51 common/cmd_ide.c Error reading Image from IDE device
2341 51 common/cmd_ide.c reading Image from IDE device OK
2342 52 common/cmd_nand.c before loading a Image from a NAND device
2343 -53 common/cmd_nand.c Bad usage of "nand" command
2344 53 common/cmd_nand.c correct usage of "nand" command
2345 -54 common/cmd_nand.c No boot device
2346 54 common/cmd_nand.c boot device found
2347 -55 common/cmd_nand.c Unknown Chip ID on boot device
2348 55 common/cmd_nand.c correct chip ID found, device available
2349 -56 common/cmd_nand.c Error reading Image Header on boot device
2350 56 common/cmd_nand.c reading Image Header from NAND device OK
2351 -57 common/cmd_nand.c Image header has bad magic number
2352 57 common/cmd_nand.c Image header has correct magic number
2353 -58 common/cmd_nand.c Error reading Image from NAND device
2354 58 common/cmd_nand.c reading Image from NAND device OK
2356 -60 common/env_common.c Environment has a bad CRC, using default
2358 64 net/eth.c starting with Ethernet configuration.
2359 -64 net/eth.c no Ethernet found.
2360 65 net/eth.c Ethernet found.
2362 -80 common/cmd_net.c usage wrong
2363 80 common/cmd_net.c before calling net_loop()
2364 -81 common/cmd_net.c some error in net_loop() occurred
2365 81 common/cmd_net.c net_loop() back without error
2366 -82 common/cmd_net.c size == 0 (File with size 0 loaded)
2367 82 common/cmd_net.c trying automatic boot
2368 83 common/cmd_net.c running "source" command
2369 -83 common/cmd_net.c some error in automatic boot or "source" command
2370 84 common/cmd_net.c end without errors
2375 100 common/cmd_bootm.c Kernel FIT Image has correct format
2376 -100 common/cmd_bootm.c Kernel FIT Image has incorrect format
2377 101 common/cmd_bootm.c No Kernel subimage unit name, using configuration
2378 -101 common/cmd_bootm.c Can't get configuration for kernel subimage
2379 102 common/cmd_bootm.c Kernel unit name specified
2380 -103 common/cmd_bootm.c Can't get kernel subimage node offset
2381 103 common/cmd_bootm.c Found configuration node
2382 104 common/cmd_bootm.c Got kernel subimage node offset
2383 -104 common/cmd_bootm.c Kernel subimage hash verification failed
2384 105 common/cmd_bootm.c Kernel subimage hash verification OK
2385 -105 common/cmd_bootm.c Kernel subimage is for unsupported architecture
2386 106 common/cmd_bootm.c Architecture check OK
2387 -106 common/cmd_bootm.c Kernel subimage has wrong type
2388 107 common/cmd_bootm.c Kernel subimage type OK
2389 -107 common/cmd_bootm.c Can't get kernel subimage data/size
2390 108 common/cmd_bootm.c Got kernel subimage data/size
2391 -108 common/cmd_bootm.c Wrong image type (not legacy, FIT)
2392 -109 common/cmd_bootm.c Can't get kernel subimage type
2393 -110 common/cmd_bootm.c Can't get kernel subimage comp
2394 -111 common/cmd_bootm.c Can't get kernel subimage os
2395 -112 common/cmd_bootm.c Can't get kernel subimage load address
2396 -113 common/cmd_bootm.c Image uncompress/copy overwrite error
2398 120 common/image.c Start initial ramdisk verification
2399 -120 common/image.c Ramdisk FIT image has incorrect format
2400 121 common/image.c Ramdisk FIT image has correct format
2401 122 common/image.c No ramdisk subimage unit name, using configuration
2402 -122 common/image.c Can't get configuration for ramdisk subimage
2403 123 common/image.c Ramdisk unit name specified
2404 -124 common/image.c Can't get ramdisk subimage node offset
2405 125 common/image.c Got ramdisk subimage node offset
2406 -125 common/image.c Ramdisk subimage hash verification failed
2407 126 common/image.c Ramdisk subimage hash verification OK
2408 -126 common/image.c Ramdisk subimage for unsupported architecture
2409 127 common/image.c Architecture check OK
2410 -127 common/image.c Can't get ramdisk subimage data/size
2411 128 common/image.c Got ramdisk subimage data/size
2412 129 common/image.c Can't get ramdisk load address
2413 -129 common/image.c Got ramdisk load address
2415 -130 common/cmd_doc.c Incorrect FIT image format
2416 131 common/cmd_doc.c FIT image format OK
2418 -140 common/cmd_ide.c Incorrect FIT image format
2419 141 common/cmd_ide.c FIT image format OK
2421 -150 common/cmd_nand.c Incorrect FIT image format
2422 151 common/cmd_nand.c FIT image format OK
2424 - legacy image format:
2425 CONFIG_IMAGE_FORMAT_LEGACY
2426 enables the legacy image format support in U-Boot.
2429 enabled if CONFIG_FIT_SIGNATURE is not defined.
2431 CONFIG_DISABLE_IMAGE_LEGACY
2432 disable the legacy image format
2434 This define is introduced, as the legacy image format is
2435 enabled per default for backward compatibility.
2437 - Standalone program support:
2438 CONFIG_STANDALONE_LOAD_ADDR
2440 This option defines a board specific value for the
2441 address where standalone program gets loaded, thus
2442 overwriting the architecture dependent default
2445 - Frame Buffer Address:
2448 Define CONFIG_FB_ADDR if you want to use specific
2449 address for frame buffer. This is typically the case
2450 when using a graphics controller has separate video
2451 memory. U-Boot will then place the frame buffer at
2452 the given address instead of dynamically reserving it
2453 in system RAM by calling lcd_setmem(), which grabs
2454 the memory for the frame buffer depending on the
2455 configured panel size.
2457 Please see board_init_f function.
2459 - Automatic software updates via TFTP server
2461 CONFIG_UPDATE_TFTP_CNT_MAX
2462 CONFIG_UPDATE_TFTP_MSEC_MAX
2464 These options enable and control the auto-update feature;
2465 for a more detailed description refer to doc/README.update.
2467 - MTD Support (mtdparts command, UBI support)
2470 Adds the MTD device infrastructure from the Linux kernel.
2471 Needed for mtdparts command support.
2473 CONFIG_MTD_PARTITIONS
2475 Adds the MTD partitioning infrastructure from the Linux
2476 kernel. Needed for UBI support.
2479 CONFIG_MTD_UBI_WL_THRESHOLD
2480 This parameter defines the maximum difference between the highest
2481 erase counter value and the lowest erase counter value of eraseblocks
2482 of UBI devices. When this threshold is exceeded, UBI starts performing
2483 wear leveling by means of moving data from eraseblock with low erase
2484 counter to eraseblocks with high erase counter.
2486 The default value should be OK for SLC NAND flashes, NOR flashes and
2487 other flashes which have eraseblock life-cycle 100000 or more.
2488 However, in case of MLC NAND flashes which typically have eraseblock
2489 life-cycle less than 10000, the threshold should be lessened (e.g.,
2490 to 128 or 256, although it does not have to be power of 2).
2494 CONFIG_MTD_UBI_BEB_LIMIT
2495 This option specifies the maximum bad physical eraseblocks UBI
2496 expects on the MTD device (per 1024 eraseblocks). If the
2497 underlying flash does not admit of bad eraseblocks (e.g. NOR
2498 flash), this value is ignored.
2500 NAND datasheets often specify the minimum and maximum NVM
2501 (Number of Valid Blocks) for the flashes' endurance lifetime.
2502 The maximum expected bad eraseblocks per 1024 eraseblocks
2503 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2504 which gives 20 for most NANDs (MaxNVB is basically the total
2505 count of eraseblocks on the chip).
2507 To put it differently, if this value is 20, UBI will try to
2508 reserve about 1.9% of physical eraseblocks for bad blocks
2509 handling. And that will be 1.9% of eraseblocks on the entire
2510 NAND chip, not just the MTD partition UBI attaches. This means
2511 that if you have, say, a NAND flash chip admits maximum 40 bad
2512 eraseblocks, and it is split on two MTD partitions of the same
2513 size, UBI will reserve 40 eraseblocks when attaching a
2518 CONFIG_MTD_UBI_FASTMAP
2519 Fastmap is a mechanism which allows attaching an UBI device
2520 in nearly constant time. Instead of scanning the whole MTD device it
2521 only has to locate a checkpoint (called fastmap) on the device.
2522 The on-flash fastmap contains all information needed to attach
2523 the device. Using fastmap makes only sense on large devices where
2524 attaching by scanning takes long. UBI will not automatically install
2525 a fastmap on old images, but you can set the UBI parameter
2526 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2527 that fastmap-enabled images are still usable with UBI implementations
2528 without fastmap support. On typical flash devices the whole fastmap
2529 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2531 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2532 Set this parameter to enable fastmap automatically on images
2536 CONFIG_MTD_UBI_FM_DEBUG
2537 Enable UBI fastmap debug
2542 Enable building of SPL globally.
2545 LDSCRIPT for linking the SPL binary.
2547 CONFIG_SPL_MAX_FOOTPRINT
2548 Maximum size in memory allocated to the SPL, BSS included.
2549 When defined, the linker checks that the actual memory
2550 used by SPL from _start to __bss_end does not exceed it.
2551 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2552 must not be both defined at the same time.
2555 Maximum size of the SPL image (text, data, rodata, and
2556 linker lists sections), BSS excluded.
2557 When defined, the linker checks that the actual size does
2560 CONFIG_SPL_TEXT_BASE
2561 TEXT_BASE for linking the SPL binary.
2563 CONFIG_SPL_RELOC_TEXT_BASE
2564 Address to relocate to. If unspecified, this is equal to
2565 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2567 CONFIG_SPL_BSS_START_ADDR
2568 Link address for the BSS within the SPL binary.
2570 CONFIG_SPL_BSS_MAX_SIZE
2571 Maximum size in memory allocated to the SPL BSS.
2572 When defined, the linker checks that the actual memory used
2573 by SPL from __bss_start to __bss_end does not exceed it.
2574 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2575 must not be both defined at the same time.
2578 Adress of the start of the stack SPL will use
2580 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2581 When defined, SPL will panic() if the image it has
2582 loaded does not have a signature.
2583 Defining this is useful when code which loads images
2584 in SPL cannot guarantee that absolutely all read errors
2586 An example is the LPC32XX MLC NAND driver, which will
2587 consider that a completely unreadable NAND block is bad,
2588 and thus should be skipped silently.
2590 CONFIG_SPL_RELOC_STACK
2591 Adress of the start of the stack SPL will use after
2592 relocation. If unspecified, this is equal to
2595 CONFIG_SYS_SPL_MALLOC_START
2596 Starting address of the malloc pool used in SPL.
2597 When this option is set the full malloc is used in SPL and
2598 it is set up by spl_init() and before that, the simple malloc()
2599 can be used if CONFIG_SYS_MALLOC_F is defined.
2601 CONFIG_SYS_SPL_MALLOC_SIZE
2602 The size of the malloc pool used in SPL.
2605 Enable booting directly to an OS from SPL.
2606 See also: doc/README.falcon
2608 CONFIG_SPL_DISPLAY_PRINT
2609 For ARM, enable an optional function to print more information
2610 about the running system.
2612 CONFIG_SPL_INIT_MINIMAL
2613 Arch init code should be built for a very small image
2615 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2616 Partition on the MMC to load U-Boot from when the MMC is being
2619 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2620 Sector to load kernel uImage from when MMC is being
2621 used in raw mode (for Falcon mode)
2623 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2624 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2625 Sector and number of sectors to load kernel argument
2626 parameters from when MMC is being used in raw mode
2629 CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
2630 Partition on the MMC to load U-Boot from when the MMC is being
2633 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2634 Filename to read to load U-Boot when reading from filesystem
2636 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2637 Filename to read to load kernel uImage when reading
2638 from filesystem (for Falcon mode)
2640 CONFIG_SPL_FS_LOAD_ARGS_NAME
2641 Filename to read to load kernel argument parameters
2642 when reading from filesystem (for Falcon mode)
2644 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2645 Set this for NAND SPL on PPC mpc83xx targets, so that
2646 start.S waits for the rest of the SPL to load before
2647 continuing (the hardware starts execution after just
2648 loading the first page rather than the full 4K).
2650 CONFIG_SPL_SKIP_RELOCATE
2651 Avoid SPL relocation
2653 CONFIG_SPL_NAND_BASE
2654 Include nand_base.c in the SPL. Requires
2655 CONFIG_SPL_NAND_DRIVERS.
2657 CONFIG_SPL_NAND_DRIVERS
2658 SPL uses normal NAND drivers, not minimal drivers.
2661 Include standard software ECC in the SPL
2663 CONFIG_SPL_NAND_SIMPLE
2664 Support for NAND boot using simple NAND drivers that
2665 expose the cmd_ctrl() interface.
2668 Support for a lightweight UBI (fastmap) scanner and
2671 CONFIG_SPL_NAND_RAW_ONLY
2672 Support to boot only raw u-boot.bin images. Use this only
2673 if you need to save space.
2675 CONFIG_SPL_COMMON_INIT_DDR
2676 Set for common ddr init with serial presence detect in
2679 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2680 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2681 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2682 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2683 CONFIG_SYS_NAND_ECCBYTES
2684 Defines the size and behavior of the NAND that SPL uses
2687 CONFIG_SPL_NAND_BOOT
2688 Add support NAND boot
2690 CONFIG_SYS_NAND_U_BOOT_OFFS
2691 Location in NAND to read U-Boot from
2693 CONFIG_SYS_NAND_U_BOOT_DST
2694 Location in memory to load U-Boot to
2696 CONFIG_SYS_NAND_U_BOOT_SIZE
2697 Size of image to load
2699 CONFIG_SYS_NAND_U_BOOT_START
2700 Entry point in loaded image to jump to
2702 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2703 Define this if you need to first read the OOB and then the
2704 data. This is used, for example, on davinci platforms.
2706 CONFIG_SPL_RAM_DEVICE
2707 Support for running image already present in ram, in SPL binary
2710 Image offset to which the SPL should be padded before appending
2711 the SPL payload. By default, this is defined as
2712 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2713 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2714 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2717 Final target image containing SPL and payload. Some SPLs
2718 use an arch-specific makefile fragment instead, for
2719 example if more than one image needs to be produced.
2721 CONFIG_FIT_SPL_PRINT
2722 Printing information about a FIT image adds quite a bit of
2723 code to SPL. So this is normally disabled in SPL. Use this
2724 option to re-enable it. This will affect the output of the
2725 bootm command when booting a FIT image.
2729 Enable building of TPL globally.
2732 Image offset to which the TPL should be padded before appending
2733 the TPL payload. By default, this is defined as
2734 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2735 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2736 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2738 - Interrupt support (PPC):
2740 There are common interrupt_init() and timer_interrupt()
2741 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2742 for CPU specific initialization. interrupt_init_cpu()
2743 should set decrementer_count to appropriate value. If
2744 CPU resets decrementer automatically after interrupt
2745 (ppc4xx) it should set decrementer_count to zero.
2746 timer_interrupt() calls timer_interrupt_cpu() for CPU
2747 specific handling. If board has watchdog / status_led
2748 / other_activity_monitor it works automatically from
2749 general timer_interrupt().
2752 Board initialization settings:
2753 ------------------------------
2755 During Initialization u-boot calls a number of board specific functions
2756 to allow the preparation of board specific prerequisites, e.g. pin setup
2757 before drivers are initialized. To enable these callbacks the
2758 following configuration macros have to be defined. Currently this is
2759 architecture specific, so please check arch/your_architecture/lib/board.c
2760 typically in board_init_f() and board_init_r().
2762 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2763 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2764 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2765 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2767 Configuration Settings:
2768 -----------------------
2770 - CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2771 Optionally it can be defined to support 64-bit memory commands.
2773 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2774 undefine this when you're short of memory.
2776 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2777 width of the commands listed in the 'help' command output.
2779 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2780 prompt for user input.
2782 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2784 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2786 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2788 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2789 the application (usually a Linux kernel) when it is
2792 - CONFIG_SYS_BAUDRATE_TABLE:
2793 List of legal baudrate settings for this board.
2795 - CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2796 Begin and End addresses of the area used by the
2799 - CONFIG_SYS_MEMTEST_SCRATCH:
2800 Scratch address used by the alternate memory test
2801 You only need to set this if address zero isn't writeable
2803 - CONFIG_SYS_MEM_RESERVE_SECURE
2804 Only implemented for ARMv8 for now.
2805 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2806 is substracted from total RAM and won't be reported to OS.
2807 This memory can be used as secure memory. A variable
2808 gd->arch.secure_ram is used to track the location. In systems
2809 the RAM base is not zero, or RAM is divided into banks,
2810 this variable needs to be recalcuated to get the address.
2812 - CONFIG_SYS_MEM_TOP_HIDE:
2813 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2814 this specified memory area will get subtracted from the top
2815 (end) of RAM and won't get "touched" at all by U-Boot. By
2816 fixing up gd->ram_size the Linux kernel should gets passed
2817 the now "corrected" memory size and won't touch it either.
2818 This should work for arch/ppc and arch/powerpc. Only Linux
2819 board ports in arch/powerpc with bootwrapper support that
2820 recalculate the memory size from the SDRAM controller setup
2821 will have to get fixed in Linux additionally.
2823 This option can be used as a workaround for the 440EPx/GRx
2824 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2827 WARNING: Please make sure that this value is a multiple of
2828 the Linux page size (normally 4k). If this is not the case,
2829 then the end address of the Linux memory will be located at a
2830 non page size aligned address and this could cause major
2833 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2834 Enable temporary baudrate change while serial download
2836 - CONFIG_SYS_SDRAM_BASE:
2837 Physical start address of SDRAM. _Must_ be 0 here.
2839 - CONFIG_SYS_FLASH_BASE:
2840 Physical start address of Flash memory.
2842 - CONFIG_SYS_MONITOR_BASE:
2843 Physical start address of boot monitor code (set by
2844 make config files to be same as the text base address
2845 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2846 CONFIG_SYS_FLASH_BASE when booting from flash.
2848 - CONFIG_SYS_MONITOR_LEN:
2849 Size of memory reserved for monitor code, used to
2850 determine _at_compile_time_ (!) if the environment is
2851 embedded within the U-Boot image, or in a separate
2854 - CONFIG_SYS_MALLOC_LEN:
2855 Size of DRAM reserved for malloc() use.
2857 - CONFIG_SYS_MALLOC_F_LEN
2858 Size of the malloc() pool for use before relocation. If
2859 this is defined, then a very simple malloc() implementation
2860 will become available before relocation. The address is just
2861 below the global data, and the stack is moved down to make
2864 This feature allocates regions with increasing addresses
2865 within the region. calloc() is supported, but realloc()
2866 is not available. free() is supported but does nothing.
2867 The memory will be freed (or in fact just forgotten) when
2868 U-Boot relocates itself.
2870 - CONFIG_SYS_MALLOC_SIMPLE
2871 Provides a simple and small malloc() and calloc() for those
2872 boards which do not use the full malloc in SPL (which is
2873 enabled with CONFIG_SYS_SPL_MALLOC_START).
2875 - CONFIG_SYS_NONCACHED_MEMORY:
2876 Size of non-cached memory area. This area of memory will be
2877 typically located right below the malloc() area and mapped
2878 uncached in the MMU. This is useful for drivers that would
2879 otherwise require a lot of explicit cache maintenance. For
2880 some drivers it's also impossible to properly maintain the
2881 cache. For example if the regions that need to be flushed
2882 are not a multiple of the cache-line size, *and* padding
2883 cannot be allocated between the regions to align them (i.e.
2884 if the HW requires a contiguous array of regions, and the
2885 size of each region is not cache-aligned), then a flush of
2886 one region may result in overwriting data that hardware has
2887 written to another region in the same cache-line. This can
2888 happen for example in network drivers where descriptors for
2889 buffers are typically smaller than the CPU cache-line (e.g.
2890 16 bytes vs. 32 or 64 bytes).
2892 Non-cached memory is only supported on 32-bit ARM at present.
2894 - CONFIG_SYS_BOOTM_LEN:
2895 Normally compressed uImages are limited to an
2896 uncompressed size of 8 MBytes. If this is not enough,
2897 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2898 to adjust this setting to your needs.
2900 - CONFIG_SYS_BOOTMAPSZ:
2901 Maximum size of memory mapped by the startup code of
2902 the Linux kernel; all data that must be processed by
2903 the Linux kernel (bd_info, boot arguments, FDT blob if
2904 used) must be put below this limit, unless "bootm_low"
2905 environment variable is defined and non-zero. In such case
2906 all data for the Linux kernel must be between "bootm_low"
2907 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2908 variable "bootm_mapsize" will override the value of
2909 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2910 then the value in "bootm_size" will be used instead.
2912 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2913 Enable initrd_high functionality. If defined then the
2914 initrd_high feature is enabled and the bootm ramdisk subcommand
2917 - CONFIG_SYS_BOOT_GET_CMDLINE:
2918 Enables allocating and saving kernel cmdline in space between
2919 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2921 - CONFIG_SYS_BOOT_GET_KBD:
2922 Enables allocating and saving a kernel copy of the bd_info in
2923 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2925 - CONFIG_SYS_MAX_FLASH_BANKS:
2926 Max number of Flash memory banks
2928 - CONFIG_SYS_MAX_FLASH_SECT:
2929 Max number of sectors on a Flash chip
2931 - CONFIG_SYS_FLASH_ERASE_TOUT:
2932 Timeout for Flash erase operations (in ms)
2934 - CONFIG_SYS_FLASH_WRITE_TOUT:
2935 Timeout for Flash write operations (in ms)
2937 - CONFIG_SYS_FLASH_LOCK_TOUT
2938 Timeout for Flash set sector lock bit operation (in ms)
2940 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2941 Timeout for Flash clear lock bits operation (in ms)
2943 - CONFIG_SYS_FLASH_PROTECTION
2944 If defined, hardware flash sectors protection is used
2945 instead of U-Boot software protection.
2947 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2949 Enable TFTP transfers directly to flash memory;
2950 without this option such a download has to be
2951 performed in two steps: (1) download to RAM, and (2)
2952 copy from RAM to flash.
2954 The two-step approach is usually more reliable, since
2955 you can check if the download worked before you erase
2956 the flash, but in some situations (when system RAM is
2957 too limited to allow for a temporary copy of the
2958 downloaded image) this option may be very useful.
2960 - CONFIG_SYS_FLASH_CFI:
2961 Define if the flash driver uses extra elements in the
2962 common flash structure for storing flash geometry.
2964 - CONFIG_FLASH_CFI_DRIVER
2965 This option also enables the building of the cfi_flash driver
2966 in the drivers directory
2968 - CONFIG_FLASH_CFI_MTD
2969 This option enables the building of the cfi_mtd driver
2970 in the drivers directory. The driver exports CFI flash
2973 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2974 Use buffered writes to flash.
2976 - CONFIG_FLASH_SPANSION_S29WS_N
2977 s29ws-n MirrorBit flash has non-standard addresses for buffered
2980 - CONFIG_SYS_FLASH_QUIET_TEST
2981 If this option is defined, the common CFI flash doesn't
2982 print it's warning upon not recognized FLASH banks. This
2983 is useful, if some of the configured banks are only
2984 optionally available.
2986 - CONFIG_FLASH_SHOW_PROGRESS
2987 If defined (must be an integer), print out countdown
2988 digits and dots. Recommended value: 45 (9..1) for 80
2989 column displays, 15 (3..1) for 40 column displays.
2991 - CONFIG_FLASH_VERIFY
2992 If defined, the content of the flash (destination) is compared
2993 against the source after the write operation. An error message
2994 will be printed when the contents are not identical.
2995 Please note that this option is useless in nearly all cases,
2996 since such flash programming errors usually are detected earlier
2997 while unprotecting/erasing/programming. Please only enable
2998 this option if you really know what you are doing.
3000 - CONFIG_SYS_RX_ETH_BUFFER:
3001 Defines the number of Ethernet receive buffers. On some
3002 Ethernet controllers it is recommended to set this value
3003 to 8 or even higher (EEPRO100 or 405 EMAC), since all
3004 buffers can be full shortly after enabling the interface
3005 on high Ethernet traffic.
3006 Defaults to 4 if not defined.
3008 - CONFIG_ENV_MAX_ENTRIES
3010 Maximum number of entries in the hash table that is used
3011 internally to store the environment settings. The default
3012 setting is supposed to be generous and should work in most
3013 cases. This setting can be used to tune behaviour; see
3014 lib/hashtable.c for details.
3016 - CONFIG_ENV_FLAGS_LIST_DEFAULT
3017 - CONFIG_ENV_FLAGS_LIST_STATIC
3018 Enable validation of the values given to environment variables when
3019 calling env set. Variables can be restricted to only decimal,
3020 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
3021 the variables can also be restricted to IP address or MAC address.
3023 The format of the list is:
3024 type_attribute = [s|d|x|b|i|m]
3025 access_attribute = [a|r|o|c]
3026 attributes = type_attribute[access_attribute]
3027 entry = variable_name[:attributes]
3030 The type attributes are:
3031 s - String (default)
3034 b - Boolean ([1yYtT|0nNfF])
3038 The access attributes are:
3044 - CONFIG_ENV_FLAGS_LIST_DEFAULT
3045 Define this to a list (string) to define the ".flags"
3046 environment variable in the default or embedded environment.
3048 - CONFIG_ENV_FLAGS_LIST_STATIC
3049 Define this to a list (string) to define validation that
3050 should be done if an entry is not found in the ".flags"
3051 environment variable. To override a setting in the static
3052 list, simply add an entry for the same variable name to the
3055 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3056 regular expression. This allows multiple variables to define the same
3057 flags without explicitly listing them for each variable.
3059 - CONFIG_ENV_ACCESS_IGNORE_FORCE
3060 If defined, don't allow the -f switch to env set override variable
3064 If stdint.h is available with your toolchain you can define this
3065 option to enable it. You can provide option 'USE_STDINT=1' when
3066 building U-Boot to enable this.
3068 The following definitions that deal with the placement and management
3069 of environment data (variable area); in general, we support the
3070 following configurations:
3072 - CONFIG_BUILD_ENVCRC:
3074 Builds up envcrc with the target environment so that external utils
3075 may easily extract it and embed it in final U-Boot images.
3077 BE CAREFUL! The first access to the environment happens quite early
3078 in U-Boot initialization (when we try to get the setting of for the
3079 console baudrate). You *MUST* have mapped your NVRAM area then, or
3082 Please note that even with NVRAM we still use a copy of the
3083 environment in RAM: we could work on NVRAM directly, but we want to
3084 keep settings there always unmodified except somebody uses "saveenv"
3085 to save the current settings.
3087 BE CAREFUL! For some special cases, the local device can not use
3088 "saveenv" command. For example, the local device will get the
3089 environment stored in a remote NOR flash by SRIO or PCIE link,
3090 but it can not erase, write this NOR flash by SRIO or PCIE interface.
3092 - CONFIG_NAND_ENV_DST
3094 Defines address in RAM to which the nand_spl code should copy the
3095 environment. If redundant environment is used, it will be copied to
3096 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3098 Please note that the environment is read-only until the monitor
3099 has been relocated to RAM and a RAM copy of the environment has been
3100 created; also, when using EEPROM you will have to use env_get_f()
3101 until then to read environment variables.
3103 The environment is protected by a CRC32 checksum. Before the monitor
3104 is relocated into RAM, as a result of a bad CRC you will be working
3105 with the compiled-in default environment - *silently*!!! [This is
3106 necessary, because the first environment variable we need is the
3107 "baudrate" setting for the console - if we have a bad CRC, we don't
3108 have any device yet where we could complain.]
3110 Note: once the monitor has been relocated, then it will complain if
3111 the default environment is used; a new CRC is computed as soon as you
3112 use the "saveenv" command to store a valid environment.
3114 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3115 Echo the inverted Ethernet link state to the fault LED.
3117 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3118 also needs to be defined.
3120 - CONFIG_SYS_FAULT_MII_ADDR:
3121 MII address of the PHY to check for the Ethernet link state.
3123 - CONFIG_NS16550_MIN_FUNCTIONS:
3124 Define this if you desire to only have use of the NS16550_init
3125 and NS16550_putc functions for the serial driver located at
3126 drivers/serial/ns16550.c. This option is useful for saving
3127 space for already greatly restricted images, including but not
3128 limited to NAND_SPL configurations.
3130 - CONFIG_DISPLAY_BOARDINFO
3131 Display information about the board that U-Boot is running on
3132 when U-Boot starts up. The board function checkboard() is called
3135 - CONFIG_DISPLAY_BOARDINFO_LATE
3136 Similar to the previous option, but display this information
3137 later, once stdio is running and output goes to the LCD, if
3140 - CONFIG_BOARD_SIZE_LIMIT:
3141 Maximum size of the U-Boot image. When defined, the
3142 build system checks that the actual size does not
3145 Low Level (hardware related) configuration options:
3146 ---------------------------------------------------
3148 - CONFIG_SYS_CACHELINE_SIZE:
3149 Cache Line Size of the CPU.
3151 - CONFIG_SYS_CCSRBAR_DEFAULT:
3152 Default (power-on reset) physical address of CCSR on Freescale
3155 - CONFIG_SYS_CCSRBAR:
3156 Virtual address of CCSR. On a 32-bit build, this is typically
3157 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3159 - CONFIG_SYS_CCSRBAR_PHYS:
3160 Physical address of CCSR. CCSR can be relocated to a new
3161 physical address, if desired. In this case, this macro should
3162 be set to that address. Otherwise, it should be set to the
3163 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
3164 is typically relocated on 36-bit builds. It is recommended
3165 that this macro be defined via the _HIGH and _LOW macros:
3167 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3168 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3170 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3171 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
3172 either 0 (32-bit build) or 0xF (36-bit build). This macro is
3173 used in assembly code, so it must not contain typecasts or
3174 integer size suffixes (e.g. "ULL").
3176 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
3177 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
3178 used in assembly code, so it must not contain typecasts or
3179 integer size suffixes (e.g. "ULL").
3181 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3182 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3183 forced to a value that ensures that CCSR is not relocated.
3185 - Floppy Disk Support:
3186 CONFIG_SYS_FDC_DRIVE_NUMBER
3188 the default drive number (default value 0)
3190 CONFIG_SYS_ISA_IO_STRIDE
3192 defines the spacing between FDC chipset registers
3195 CONFIG_SYS_ISA_IO_OFFSET
3197 defines the offset of register from address. It
3198 depends on which part of the data bus is connected to
3199 the FDC chipset. (default value 0)
3201 If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3202 CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3205 if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3206 fdc_hw_init() is called at the beginning of the FDC
3207 setup. fdc_hw_init() must be provided by the board
3208 source code. It is used to make hardware-dependent
3212 Most IDE controllers were designed to be connected with PCI
3213 interface. Only few of them were designed for AHB interface.
3214 When software is doing ATA command and data transfer to
3215 IDE devices through IDE-AHB controller, some additional
3216 registers accessing to these kind of IDE-AHB controller
3219 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
3220 DO NOT CHANGE unless you know exactly what you're
3221 doing! (11-4) [MPC8xx systems only]
3223 - CONFIG_SYS_INIT_RAM_ADDR:
3225 Start address of memory area that can be used for
3226 initial data and stack; please note that this must be
3227 writable memory that is working WITHOUT special
3228 initialization, i. e. you CANNOT use normal RAM which
3229 will become available only after programming the
3230 memory controller and running certain initialization
3233 U-Boot uses the following memory types:
3234 - MPC8xx: IMMR (internal memory of the CPU)
3236 - CONFIG_SYS_GBL_DATA_OFFSET:
3238 Offset of the initial data structure in the memory
3239 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3240 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3241 data is located at the end of the available space
3242 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3243 GENERATED_GBL_DATA_SIZE), and the initial stack is just
3244 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3245 CONFIG_SYS_GBL_DATA_OFFSET) downward.
3248 On the MPC824X (or other systems that use the data
3249 cache for initial memory) the address chosen for
3250 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3251 point to an otherwise UNUSED address space between
3252 the top of RAM and the start of the PCI space.
3254 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
3256 - CONFIG_SYS_OR_TIMING_SDRAM:
3259 - CONFIG_SYS_MAMR_PTA:
3260 periodic timer for refresh
3262 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3263 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3264 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3265 CONFIG_SYS_BR1_PRELIM:
3266 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3268 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3269 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3270 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3271 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3273 - CONFIG_PCI_ENUM_ONLY
3274 Only scan through and get the devices on the buses.
3275 Don't do any setup work, presumably because someone or
3276 something has already done it, and we don't need to do it
3277 a second time. Useful for platforms that are pre-booted
3278 by coreboot or similar.
3280 - CONFIG_PCI_INDIRECT_BRIDGE:
3281 Enable support for indirect PCI bridges.
3284 Chip has SRIO or not
3287 Board has SRIO 1 port available
3290 Board has SRIO 2 port available
3292 - CONFIG_SRIO_PCIE_BOOT_MASTER
3293 Board can support master function for Boot from SRIO and PCIE
3295 - CONFIG_SYS_SRIOn_MEM_VIRT:
3296 Virtual Address of SRIO port 'n' memory region
3298 - CONFIG_SYS_SRIOn_MEM_PHYS:
3299 Physical Address of SRIO port 'n' memory region
3301 - CONFIG_SYS_SRIOn_MEM_SIZE:
3302 Size of SRIO port 'n' memory region
3304 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
3305 Defined to tell the NAND controller that the NAND chip is using
3307 Not all NAND drivers use this symbol.
3308 Example of drivers that use it:
3309 - drivers/mtd/nand/ndfc.c
3310 - drivers/mtd/nand/mxc_nand.c
3312 - CONFIG_SYS_NDFC_EBC0_CFG
3313 Sets the EBC0_CFG register for the NDFC. If not defined
3314 a default value will be used.
3317 Get DDR timing information from an I2C EEPROM. Common
3318 with pluggable memory modules such as SODIMMs
3321 I2C address of the SPD EEPROM
3323 - CONFIG_SYS_SPD_BUS_NUM
3324 If SPD EEPROM is on an I2C bus other than the first
3325 one, specify here. Note that the value must resolve
3326 to something your driver can deal with.
3328 - CONFIG_SYS_DDR_RAW_TIMING
3329 Get DDR timing information from other than SPD. Common with
3330 soldered DDR chips onboard without SPD. DDR raw timing
3331 parameters are extracted from datasheet and hard-coded into
3332 header files or board specific files.
3334 - CONFIG_FSL_DDR_INTERACTIVE
3335 Enable interactive DDR debugging. See doc/README.fsl-ddr.
3337 - CONFIG_FSL_DDR_SYNC_REFRESH
3338 Enable sync of refresh for multiple controllers.
3340 - CONFIG_FSL_DDR_BIST
3341 Enable built-in memory test for Freescale DDR controllers.
3343 - CONFIG_SYS_83XX_DDR_USES_CS0
3344 Only for 83xx systems. If specified, then DDR should
3345 be configured using CS0 and CS1 instead of CS2 and CS3.
3348 Enable RMII mode for all FECs.
3349 Note that this is a global option, we can't
3350 have one FEC in standard MII mode and another in RMII mode.
3352 - CONFIG_CRC32_VERIFY
3353 Add a verify option to the crc32 command.
3356 => crc32 -v <address> <count> <crc32>
3358 Where address/count indicate a memory area
3359 and crc32 is the correct crc32 which the
3363 Add the "loopw" memory command. This only takes effect if
3364 the memory commands are activated globally (CONFIG_CMD_MEMORY).
3367 Add the "mdc" and "mwc" memory commands. These are cyclic
3372 This command will print 4 bytes (10,11,12,13) each 500 ms.
3374 => mwc.l 100 12345678 10
3375 This command will write 12345678 to address 100 all 10 ms.
3377 This only takes effect if the memory commands are activated
3378 globally (CONFIG_CMD_MEMORY).
3380 - CONFIG_SKIP_LOWLEVEL_INIT
3381 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
3382 low level initializations (like setting up the memory
3383 controller) are omitted and/or U-Boot does not
3384 relocate itself into RAM.
3386 Normally this variable MUST NOT be defined. The only
3387 exception is when U-Boot is loaded (to RAM) by some
3388 other boot loader or by a debugger which performs
3389 these initializations itself.
3391 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
3392 [ARM926EJ-S only] This allows just the call to lowlevel_init()
3393 to be skipped. The normal CP15 init (such as enabling the
3394 instruction cache) is still performed.
3397 Modifies the behaviour of start.S when compiling a loader
3398 that is executed before the actual U-Boot. E.g. when
3399 compiling a NAND SPL.
3402 Modifies the behaviour of start.S when compiling a loader
3403 that is executed after the SPL and before the actual U-Boot.
3404 It is loaded by the SPL.
3406 - CONFIG_SYS_MPC85XX_NO_RESETVEC
3407 Only for 85xx systems. If this variable is specified, the section
3408 .resetvec is not kept and the section .bootpg is placed in the
3409 previous 4k of the .text section.
3411 - CONFIG_ARCH_MAP_SYSMEM
3412 Generally U-Boot (and in particular the md command) uses
3413 effective address. It is therefore not necessary to regard
3414 U-Boot address as virtual addresses that need to be translated
3415 to physical addresses. However, sandbox requires this, since
3416 it maintains its own little RAM buffer which contains all
3417 addressable memory. This option causes some memory accesses
3418 to be mapped through map_sysmem() / unmap_sysmem().
3420 - CONFIG_X86_RESET_VECTOR
3421 If defined, the x86 reset vector code is included. This is not
3422 needed when U-Boot is running from Coreboot.
3424 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
3425 Option to disable subpage write in NAND driver
3426 driver that uses this:
3427 drivers/mtd/nand/davinci_nand.c
3429 Freescale QE/FMAN Firmware Support:
3430 -----------------------------------
3432 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3433 loading of "firmware", which is encoded in the QE firmware binary format.
3434 This firmware often needs to be loaded during U-Boot booting, so macros
3435 are used to identify the storage device (NOR flash, SPI, etc) and the address
3438 - CONFIG_SYS_FMAN_FW_ADDR
3439 The address in the storage device where the FMAN microcode is located. The
3440 meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3443 - CONFIG_SYS_QE_FW_ADDR
3444 The address in the storage device where the QE microcode is located. The
3445 meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3448 - CONFIG_SYS_QE_FMAN_FW_LENGTH
3449 The maximum possible size of the firmware. The firmware binary format
3450 has a field that specifies the actual size of the firmware, but it
3451 might not be possible to read any part of the firmware unless some
3452 local storage is allocated to hold the entire firmware first.
3454 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
3455 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3456 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
3457 virtual address in NOR flash.
3459 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
3460 Specifies that QE/FMAN firmware is located in NAND flash.
3461 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3463 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
3464 Specifies that QE/FMAN firmware is located on the primary SD/MMC
3465 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3467 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3468 Specifies that QE/FMAN firmware is located in the remote (master)
3469 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3470 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3471 window->master inbound window->master LAW->the ucode address in
3472 master's memory space.
3474 Freescale Layerscape Management Complex Firmware Support:
3475 ---------------------------------------------------------
3476 The Freescale Layerscape Management Complex (MC) supports the loading of
3478 This firmware often needs to be loaded during U-Boot booting, so macros
3479 are used to identify the storage device (NOR flash, SPI, etc) and the address
3482 - CONFIG_FSL_MC_ENET
3483 Enable the MC driver for Layerscape SoCs.
3485 Freescale Layerscape Debug Server Support:
3486 -------------------------------------------
3487 The Freescale Layerscape Debug Server Support supports the loading of
3488 "Debug Server firmware" and triggering SP boot-rom.
3489 This firmware often needs to be loaded during U-Boot booting.
3491 - CONFIG_SYS_MC_RSV_MEM_ALIGN
3492 Define alignment of reserved memory MC requires
3497 In order to achieve reproducible builds, timestamps used in the U-Boot build
3498 process have to be set to a fixed value.
3500 This is done using the SOURCE_DATE_EPOCH environment variable.
3501 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
3502 option for U-Boot or an environment variable in U-Boot.
3504 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
3506 Building the Software:
3507 ======================
3509 Building U-Boot has been tested in several native build environments
3510 and in many different cross environments. Of course we cannot support
3511 all possibly existing versions of cross development tools in all
3512 (potentially obsolete) versions. In case of tool chain problems we
3513 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3514 which is extensively used to build and test U-Boot.
3516 If you are not using a native environment, it is assumed that you
3517 have GNU cross compiling tools available in your path. In this case,
3518 you must set the environment variable CROSS_COMPILE in your shell.
3519 Note that no changes to the Makefile or any other source files are
3520 necessary. For example using the ELDK on a 4xx CPU, please enter:
3522 $ CROSS_COMPILE=ppc_4xx-
3523 $ export CROSS_COMPILE
3525 Note: If you wish to generate Windows versions of the utilities in
3526 the tools directory you can use the MinGW toolchain
3527 (http://www.mingw.org). Set your HOST tools to the MinGW
3528 toolchain and execute 'make tools'. For example:
3530 $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3532 Binaries such as tools/mkimage.exe will be created which can
3533 be executed on computers running Windows.
3535 U-Boot is intended to be simple to build. After installing the
3536 sources you must configure U-Boot for one specific board type. This
3541 where "NAME_defconfig" is the name of one of the existing configu-
3542 rations; see boards.cfg for supported names.
3544 Note: for some board special configuration names may exist; check if
3545 additional information is available from the board vendor; for
3546 instance, the TQM823L systems are available without (standard)
3547 or with LCD support. You can select such additional "features"
3548 when choosing the configuration, i. e.
3550 make TQM823L_defconfig
3551 - will configure for a plain TQM823L, i. e. no LCD support
3553 make TQM823L_LCD_defconfig
3554 - will configure for a TQM823L with U-Boot console on LCD
3559 Finally, type "make all", and you should get some working U-Boot
3560 images ready for download to / installation on your system:
3562 - "u-boot.bin" is a raw binary image
3563 - "u-boot" is an image in ELF binary format
3564 - "u-boot.srec" is in Motorola S-Record format
3566 By default the build is performed locally and the objects are saved
3567 in the source directory. One of the two methods can be used to change
3568 this behavior and build U-Boot to some external directory:
3570 1. Add O= to the make command line invocations:
3572 make O=/tmp/build distclean
3573 make O=/tmp/build NAME_defconfig
3574 make O=/tmp/build all
3576 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3578 export KBUILD_OUTPUT=/tmp/build
3583 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3586 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3587 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3588 For example to treat all compiler warnings as errors:
3590 make KCFLAGS=-Werror
3592 Please be aware that the Makefiles assume you are using GNU make, so
3593 for instance on NetBSD you might need to use "gmake" instead of
3597 If the system board that you have is not listed, then you will need
3598 to port U-Boot to your hardware platform. To do this, follow these
3601 1. Create a new directory to hold your board specific code. Add any
3602 files you need. In your board directory, you will need at least
3603 the "Makefile" and a "<board>.c".
3604 2. Create a new configuration file "include/configs/<board>.h" for
3606 3. If you're porting U-Boot to a new CPU, then also create a new
3607 directory to hold your CPU specific code. Add any files you need.
3608 4. Run "make <board>_defconfig" with your new name.
3609 5. Type "make", and you should get a working "u-boot.srec" file
3610 to be installed on your target system.
3611 6. Debug and solve any problems that might arise.
3612 [Of course, this last step is much harder than it sounds.]
3615 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3616 ==============================================================
3618 If you have modified U-Boot sources (for instance added a new board
3619 or support for new devices, a new CPU, etc.) you are expected to
3620 provide feedback to the other developers. The feedback normally takes
3621 the form of a "patch", i. e. a context diff against a certain (latest
3622 official or latest in the git repository) version of U-Boot sources.
3624 But before you submit such a patch, please verify that your modifi-
3625 cation did not break existing code. At least make sure that *ALL* of
3626 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3627 just run the buildman script (tools/buildman/buildman), which will
3628 configure and build U-Boot for ALL supported system. Be warned, this
3629 will take a while. Please see the buildman README, or run 'buildman -H'
3633 See also "U-Boot Porting Guide" below.
3636 Monitor Commands - Overview:
3637 ============================
3639 go - start application at address 'addr'
3640 run - run commands in an environment variable
3641 bootm - boot application image from memory
3642 bootp - boot image via network using BootP/TFTP protocol
3643 bootz - boot zImage from memory
3644 tftpboot- boot image via network using TFTP protocol
3645 and env variables "ipaddr" and "serverip"
3646 (and eventually "gatewayip")
3647 tftpput - upload a file via network using TFTP protocol
3648 rarpboot- boot image via network using RARP/TFTP protocol
3649 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3650 loads - load S-Record file over serial line
3651 loadb - load binary file over serial line (kermit mode)
3653 mm - memory modify (auto-incrementing)
3654 nm - memory modify (constant address)
3655 mw - memory write (fill)
3657 cmp - memory compare
3658 crc32 - checksum calculation
3659 i2c - I2C sub-system
3660 sspi - SPI utility commands
3661 base - print or set address offset
3662 printenv- print environment variables
3663 setenv - set environment variables
3664 saveenv - save environment variables to persistent storage
3665 protect - enable or disable FLASH write protection
3666 erase - erase FLASH memory
3667 flinfo - print FLASH memory information
3668 nand - NAND memory operations (see doc/README.nand)
3669 bdinfo - print Board Info structure
3670 iminfo - print header information for application image
3671 coninfo - print console devices and informations
3672 ide - IDE sub-system
3673 loop - infinite loop on address range
3674 loopw - infinite write loop on address range
3675 mtest - simple RAM test
3676 icache - enable or disable instruction cache
3677 dcache - enable or disable data cache
3678 reset - Perform RESET of the CPU
3679 echo - echo args to console
3680 version - print monitor version
3681 help - print online help
3682 ? - alias for 'help'
3685 Monitor Commands - Detailed Description:
3686 ========================================
3690 For now: just type "help <command>".
3693 Environment Variables:
3694 ======================
3696 U-Boot supports user configuration using Environment Variables which
3697 can be made persistent by saving to Flash memory.
3699 Environment Variables are set using "setenv", printed using
3700 "printenv", and saved to Flash using "saveenv". Using "setenv"
3701 without a value can be used to delete a variable from the
3702 environment. As long as you don't save the environment you are
3703 working with an in-memory copy. In case the Flash area containing the
3704 environment is erased by accident, a default environment is provided.
3706 Some configuration options can be set using Environment Variables.
3708 List of environment variables (most likely not complete):
3710 baudrate - see CONFIG_BAUDRATE
3712 bootdelay - see CONFIG_BOOTDELAY
3714 bootcmd - see CONFIG_BOOTCOMMAND
3716 bootargs - Boot arguments when booting an RTOS image
3718 bootfile - Name of the image to load with TFTP
3720 bootm_low - Memory range available for image processing in the bootm
3721 command can be restricted. This variable is given as
3722 a hexadecimal number and defines lowest address allowed
3723 for use by the bootm command. See also "bootm_size"
3724 environment variable. Address defined by "bootm_low" is
3725 also the base of the initial memory mapping for the Linux
3726 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3729 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3730 This variable is given as a hexadecimal number and it
3731 defines the size of the memory region starting at base
3732 address bootm_low that is accessible by the Linux kernel
3733 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3734 as the default value if it is defined, and bootm_size is
3737 bootm_size - Memory range available for image processing in the bootm
3738 command can be restricted. This variable is given as
3739 a hexadecimal number and defines the size of the region
3740 allowed for use by the bootm command. See also "bootm_low"
3741 environment variable.
3743 updatefile - Location of the software update file on a TFTP server, used
3744 by the automatic software update feature. Please refer to
3745 documentation in doc/README.update for more details.
3747 autoload - if set to "no" (any string beginning with 'n'),
3748 "bootp" will just load perform a lookup of the
3749 configuration from the BOOTP server, but not try to
3750 load any image using TFTP
3752 autostart - if set to "yes", an image loaded using the "bootp",
3753 "rarpboot", "tftpboot" or "diskboot" commands will
3754 be automatically started (by internally calling
3757 If set to "no", a standalone image passed to the
3758 "bootm" command will be copied to the load address
3759 (and eventually uncompressed), but NOT be started.
3760 This can be used to load and uncompress arbitrary
3763 fdt_high - if set this restricts the maximum address that the
3764 flattened device tree will be copied into upon boot.
3765 For example, if you have a system with 1 GB memory
3766 at physical address 0x10000000, while Linux kernel
3767 only recognizes the first 704 MB as low memory, you
3768 may need to set fdt_high as 0x3C000000 to have the
3769 device tree blob be copied to the maximum address
3770 of the 704 MB low memory, so that Linux kernel can
3771 access it during the boot procedure.
3773 If this is set to the special value 0xFFFFFFFF then
3774 the fdt will not be copied at all on boot. For this
3775 to work it must reside in writable memory, have
3776 sufficient padding on the end of it for u-boot to
3777 add the information it needs into it, and the memory
3778 must be accessible by the kernel.
3780 fdtcontroladdr- if set this is the address of the control flattened
3781 device tree used by U-Boot when CONFIG_OF_CONTROL is
3784 i2cfast - (PPC405GP|PPC405EP only)
3785 if set to 'y' configures Linux I2C driver for fast
3786 mode (400kHZ). This environment variable is used in
3787 initialization code. So, for changes to be effective
3788 it must be saved and board must be reset.
3790 initrd_high - restrict positioning of initrd images:
3791 If this variable is not set, initrd images will be
3792 copied to the highest possible address in RAM; this
3793 is usually what you want since it allows for
3794 maximum initrd size. If for some reason you want to
3795 make sure that the initrd image is loaded below the
3796 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3797 variable to a value of "no" or "off" or "0".
3798 Alternatively, you can set it to a maximum upper
3799 address to use (U-Boot will still check that it
3800 does not overwrite the U-Boot stack and data).
3802 For instance, when you have a system with 16 MB
3803 RAM, and want to reserve 4 MB from use by Linux,
3804 you can do this by adding "mem=12M" to the value of
3805 the "bootargs" variable. However, now you must make
3806 sure that the initrd image is placed in the first
3807 12 MB as well - this can be done with
3809 setenv initrd_high 00c00000
3811 If you set initrd_high to 0xFFFFFFFF, this is an
3812 indication to U-Boot that all addresses are legal
3813 for the Linux kernel, including addresses in flash
3814 memory. In this case U-Boot will NOT COPY the
3815 ramdisk at all. This may be useful to reduce the
3816 boot time on your system, but requires that this
3817 feature is supported by your Linux kernel.
3819 ipaddr - IP address; needed for tftpboot command
3821 loadaddr - Default load address for commands like "bootp",
3822 "rarpboot", "tftpboot", "loadb" or "diskboot"
3824 loads_echo - see CONFIG_LOADS_ECHO
3826 serverip - TFTP server IP address; needed for tftpboot command
3828 bootretry - see CONFIG_BOOT_RETRY_TIME
3830 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3832 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3834 ethprime - controls which interface is used first.
3836 ethact - controls which interface is currently active.
3837 For example you can do the following
3839 => setenv ethact FEC
3840 => ping 192.168.0.1 # traffic sent on FEC
3841 => setenv ethact SCC
3842 => ping 10.0.0.1 # traffic sent on SCC
3844 ethrotate - When set to "no" U-Boot does not go through all
3845 available network interfaces.
3846 It just stays at the currently selected interface.
3848 netretry - When set to "no" each network operation will
3849 either succeed or fail without retrying.
3850 When set to "once" the network operation will
3851 fail when all the available network interfaces
3852 are tried once without success.
3853 Useful on scripts which control the retry operation
3856 npe_ucode - set load address for the NPE microcode
3858 silent_linux - If set then Linux will be told to boot silently, by
3859 changing the console to be empty. If "yes" it will be
3860 made silent. If "no" it will not be made silent. If
3861 unset, then it will be made silent if the U-Boot console
3864 tftpsrcp - If this is set, the value is used for TFTP's
3867 tftpdstp - If this is set, the value is used for TFTP's UDP
3868 destination port instead of the Well Know Port 69.
3870 tftpblocksize - Block size to use for TFTP transfers; if not set,
3871 we use the TFTP server's default block size
3873 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3874 seconds, minimum value is 1000 = 1 second). Defines
3875 when a packet is considered to be lost so it has to
3876 be retransmitted. The default is 5000 = 5 seconds.
3877 Lowering this value may make downloads succeed
3878 faster in networks with high packet loss rates or
3879 with unreliable TFTP servers.
3881 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3882 unit, minimum value = 0). Defines how many timeouts
3883 can happen during a single file transfer before that
3884 transfer is aborted. The default is 10, and 0 means
3885 'no timeouts allowed'. Increasing this value may help
3886 downloads succeed with high packet loss rates, or with
3887 unreliable TFTP servers or client hardware.
3889 vlan - When set to a value < 4095 the traffic over
3890 Ethernet is encapsulated/received over 802.1q
3893 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3894 Unsigned value, in milliseconds. If not set, the period will
3895 be either the default (28000), or a value based on
3896 CONFIG_NET_RETRY_COUNT, if defined. This value has
3897 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3899 The following image location variables contain the location of images
3900 used in booting. The "Image" column gives the role of the image and is
3901 not an environment variable name. The other columns are environment
3902 variable names. "File Name" gives the name of the file on a TFTP
3903 server, "RAM Address" gives the location in RAM the image will be
3904 loaded to, and "Flash Location" gives the image's address in NOR
3905 flash or offset in NAND flash.
3907 *Note* - these variables don't have to be defined for all boards, some
3908 boards currently use other variables for these purposes, and some
3909 boards use these variables for other purposes.
3911 Image File Name RAM Address Flash Location
3912 ----- --------- ----------- --------------
3913 u-boot u-boot u-boot_addr_r u-boot_addr
3914 Linux kernel bootfile kernel_addr_r kernel_addr
3915 device tree blob fdtfile fdt_addr_r fdt_addr
3916 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3918 The following environment variables may be used and automatically
3919 updated by the network boot commands ("bootp" and "rarpboot"),
3920 depending the information provided by your boot server:
3922 bootfile - see above
3923 dnsip - IP address of your Domain Name Server
3924 dnsip2 - IP address of your secondary Domain Name Server
3925 gatewayip - IP address of the Gateway (Router) to use
3926 hostname - Target hostname
3928 netmask - Subnet Mask
3929 rootpath - Pathname of the root filesystem on the NFS server
3930 serverip - see above
3933 There are two special Environment Variables:
3935 serial# - contains hardware identification information such
3936 as type string and/or serial number
3937 ethaddr - Ethernet address
3939 These variables can be set only once (usually during manufacturing of
3940 the board). U-Boot refuses to delete or overwrite these variables
3941 once they have been set once.
3944 Further special Environment Variables:
3946 ver - Contains the U-Boot version string as printed
3947 with the "version" command. This variable is
3948 readonly (see CONFIG_VERSION_VARIABLE).
3951 Please note that changes to some configuration parameters may take
3952 only effect after the next boot (yes, that's just like Windoze :-).
3955 Callback functions for environment variables:
3956 ---------------------------------------------
3958 For some environment variables, the behavior of u-boot needs to change
3959 when their values are changed. This functionality allows functions to
3960 be associated with arbitrary variables. On creation, overwrite, or
3961 deletion, the callback will provide the opportunity for some side
3962 effect to happen or for the change to be rejected.
3964 The callbacks are named and associated with a function using the
3965 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3967 These callbacks are associated with variables in one of two ways. The
3968 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3969 in the board configuration to a string that defines a list of
3970 associations. The list must be in the following format:
3972 entry = variable_name[:callback_name]
3975 If the callback name is not specified, then the callback is deleted.
3976 Spaces are also allowed anywhere in the list.
3978 Callbacks can also be associated by defining the ".callbacks" variable
3979 with the same list format above. Any association in ".callbacks" will
3980 override any association in the static list. You can define
3981 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3982 ".callbacks" environment variable in the default or embedded environment.
3984 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3985 regular expression. This allows multiple variables to be connected to
3986 the same callback without explicitly listing them all out.
3989 Command Line Parsing:
3990 =====================
3992 There are two different command line parsers available with U-Boot:
3993 the old "simple" one, and the much more powerful "hush" shell:
3995 Old, simple command line parser:
3996 --------------------------------
3998 - supports environment variables (through setenv / saveenv commands)
3999 - several commands on one line, separated by ';'
4000 - variable substitution using "... ${name} ..." syntax
4001 - special characters ('$', ';') can be escaped by prefixing with '\',
4003 setenv bootcmd bootm \${address}
4004 - You can also escape text by enclosing in single apostrophes, for example:
4005 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4010 - similar to Bourne shell, with control structures like
4011 if...then...else...fi, for...do...done; while...do...done,
4012 until...do...done, ...
4013 - supports environment ("global") variables (through setenv / saveenv
4014 commands) and local shell variables (through standard shell syntax
4015 "name=value"); only environment variables can be used with "run"
4021 (1) If a command line (or an environment variable executed by a "run"
4022 command) contains several commands separated by semicolon, and
4023 one of these commands fails, then the remaining commands will be
4026 (2) If you execute several variables with one call to run (i. e.
4027 calling run with a list of variables as arguments), any failing
4028 command will cause "run" to terminate, i. e. the remaining
4029 variables are not executed.
4031 Note for Redundant Ethernet Interfaces:
4032 =======================================
4034 Some boards come with redundant Ethernet interfaces; U-Boot supports
4035 such configurations and is capable of automatic selection of a
4036 "working" interface when needed. MAC assignment works as follows:
4038 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4039 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4040 "eth1addr" (=>eth1), "eth2addr", ...
4042 If the network interface stores some valid MAC address (for instance
4043 in SROM), this is used as default address if there is NO correspon-
4044 ding setting in the environment; if the corresponding environment
4045 variable is set, this overrides the settings in the card; that means:
4047 o If the SROM has a valid MAC address, and there is no address in the
4048 environment, the SROM's address is used.
4050 o If there is no valid address in the SROM, and a definition in the
4051 environment exists, then the value from the environment variable is
4054 o If both the SROM and the environment contain a MAC address, and
4055 both addresses are the same, this MAC address is used.
4057 o If both the SROM and the environment contain a MAC address, and the
4058 addresses differ, the value from the environment is used and a
4061 o If neither SROM nor the environment contain a MAC address, an error
4062 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
4063 a random, locally-assigned MAC is used.
4065 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4066 will be programmed into hardware as part of the initialization process. This
4067 may be skipped by setting the appropriate 'ethmacskip' environment variable.
4068 The naming convention is as follows:
4069 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4074 U-Boot is capable of booting (and performing other auxiliary operations on)
4075 images in two formats:
4077 New uImage format (FIT)
4078 -----------------------
4080 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4081 to Flattened Device Tree). It allows the use of images with multiple
4082 components (several kernels, ramdisks, etc.), with contents protected by
4083 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4089 Old image format is based on binary files which can be basically anything,
4090 preceded by a special header; see the definitions in include/image.h for
4091 details; basically, the header defines the following image properties:
4093 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4094 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4095 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4096 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4098 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
4099 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4100 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4101 * Compression Type (uncompressed, gzip, bzip2)
4107 The header is marked by a special Magic Number, and both the header
4108 and the data portions of the image are secured against corruption by
4115 Although U-Boot should support any OS or standalone application
4116 easily, the main focus has always been on Linux during the design of
4119 U-Boot includes many features that so far have been part of some
4120 special "boot loader" code within the Linux kernel. Also, any
4121 "initrd" images to be used are no longer part of one big Linux image;
4122 instead, kernel and "initrd" are separate images. This implementation
4123 serves several purposes:
4125 - the same features can be used for other OS or standalone
4126 applications (for instance: using compressed images to reduce the
4127 Flash memory footprint)
4129 - it becomes much easier to port new Linux kernel versions because
4130 lots of low-level, hardware dependent stuff are done by U-Boot
4132 - the same Linux kernel image can now be used with different "initrd"
4133 images; of course this also means that different kernel images can
4134 be run with the same "initrd". This makes testing easier (you don't
4135 have to build a new "zImage.initrd" Linux image when you just
4136 change a file in your "initrd"). Also, a field-upgrade of the
4137 software is easier now.
4143 Porting Linux to U-Boot based systems:
4144 ---------------------------------------
4146 U-Boot cannot save you from doing all the necessary modifications to
4147 configure the Linux device drivers for use with your target hardware
4148 (no, we don't intend to provide a full virtual machine interface to
4151 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4153 Just make sure your machine specific header file (for instance
4154 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4155 Information structure as we define in include/asm-<arch>/u-boot.h,
4156 and make sure that your definition of IMAP_ADDR uses the same value
4157 as your U-Boot configuration in CONFIG_SYS_IMMR.
4159 Note that U-Boot now has a driver model, a unified model for drivers.
4160 If you are adding a new driver, plumb it into driver model. If there
4161 is no uclass available, you are encouraged to create one. See
4165 Configuring the Linux kernel:
4166 -----------------------------
4168 No specific requirements for U-Boot. Make sure you have some root
4169 device (initial ramdisk, NFS) for your target system.
4172 Building a Linux Image:
4173 -----------------------
4175 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4176 not used. If you use recent kernel source, a new build target
4177 "uImage" will exist which automatically builds an image usable by
4178 U-Boot. Most older kernels also have support for a "pImage" target,
4179 which was introduced for our predecessor project PPCBoot and uses a
4180 100% compatible format.
4184 make TQM850L_defconfig
4189 The "uImage" build target uses a special tool (in 'tools/mkimage') to
4190 encapsulate a compressed Linux kernel image with header information,
4191 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4193 * build a standard "vmlinux" kernel image (in ELF binary format):
4195 * convert the kernel into a raw binary image:
4197 ${CROSS_COMPILE}-objcopy -O binary \
4198 -R .note -R .comment \
4199 -S vmlinux linux.bin
4201 * compress the binary image:
4205 * package compressed binary image for U-Boot:
4207 mkimage -A ppc -O linux -T kernel -C gzip \
4208 -a 0 -e 0 -n "Linux Kernel Image" \
4209 -d linux.bin.gz uImage
4212 The "mkimage" tool can also be used to create ramdisk images for use
4213 with U-Boot, either separated from the Linux kernel image, or
4214 combined into one file. "mkimage" encapsulates the images with a 64
4215 byte header containing information about target architecture,
4216 operating system, image type, compression method, entry points, time
4217 stamp, CRC32 checksums, etc.
4219 "mkimage" can be called in two ways: to verify existing images and
4220 print the header information, or to build new images.
4222 In the first form (with "-l" option) mkimage lists the information
4223 contained in the header of an existing U-Boot image; this includes
4224 checksum verification:
4226 tools/mkimage -l image
4227 -l ==> list image header information
4229 The second form (with "-d" option) is used to build a U-Boot image
4230 from a "data file" which is used as image payload:
4232 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4233 -n name -d data_file image
4234 -A ==> set architecture to 'arch'
4235 -O ==> set operating system to 'os'
4236 -T ==> set image type to 'type'
4237 -C ==> set compression type 'comp'
4238 -a ==> set load address to 'addr' (hex)
4239 -e ==> set entry point to 'ep' (hex)
4240 -n ==> set image name to 'name'
4241 -d ==> use image data from 'datafile'
4243 Right now, all Linux kernels for PowerPC systems use the same load
4244 address (0x00000000), but the entry point address depends on the
4247 - 2.2.x kernels have the entry point at 0x0000000C,
4248 - 2.3.x and later kernels have the entry point at 0x00000000.
4250 So a typical call to build a U-Boot image would read:
4252 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4253 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4254 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4255 > examples/uImage.TQM850L
4256 Image Name: 2.4.4 kernel for TQM850L
4257 Created: Wed Jul 19 02:34:59 2000
4258 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4259 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
4260 Load Address: 0x00000000
4261 Entry Point: 0x00000000
4263 To verify the contents of the image (or check for corruption):
4265 -> tools/mkimage -l examples/uImage.TQM850L
4266 Image Name: 2.4.4 kernel for TQM850L
4267 Created: Wed Jul 19 02:34:59 2000
4268 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4269 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
4270 Load Address: 0x00000000
4271 Entry Point: 0x00000000
4273 NOTE: for embedded systems where boot time is critical you can trade
4274 speed for memory and install an UNCOMPRESSED image instead: this
4275 needs more space in Flash, but boots much faster since it does not
4276 need to be uncompressed:
4278 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4279 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4280 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4281 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4282 > examples/uImage.TQM850L-uncompressed
4283 Image Name: 2.4.4 kernel for TQM850L
4284 Created: Wed Jul 19 02:34:59 2000
4285 Image Type: PowerPC Linux Kernel Image (uncompressed)
4286 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
4287 Load Address: 0x00000000
4288 Entry Point: 0x00000000
4291 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4292 when your kernel is intended to use an initial ramdisk:
4294 -> tools/mkimage -n 'Simple Ramdisk Image' \
4295 > -A ppc -O linux -T ramdisk -C gzip \
4296 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4297 Image Name: Simple Ramdisk Image
4298 Created: Wed Jan 12 14:01:50 2000
4299 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4300 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
4301 Load Address: 0x00000000
4302 Entry Point: 0x00000000
4304 The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
4305 option performs the converse operation of the mkimage's second form (the "-d"
4306 option). Given an image built by mkimage, the dumpimage extracts a "data file"
4309 tools/dumpimage -i image -T type -p position data_file
4310 -i ==> extract from the 'image' a specific 'data_file'
4311 -T ==> set image type to 'type'
4312 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
4315 Installing a Linux Image:
4316 -------------------------
4318 To downloading a U-Boot image over the serial (console) interface,
4319 you must convert the image to S-Record format:
4321 objcopy -I binary -O srec examples/image examples/image.srec
4323 The 'objcopy' does not understand the information in the U-Boot
4324 image header, so the resulting S-Record file will be relative to
4325 address 0x00000000. To load it to a given address, you need to
4326 specify the target address as 'offset' parameter with the 'loads'
4329 Example: install the image to address 0x40100000 (which on the
4330 TQM8xxL is in the first Flash bank):
4332 => erase 40100000 401FFFFF
4338 ## Ready for S-Record download ...
4339 ~>examples/image.srec
4340 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4342 15989 15990 15991 15992
4343 [file transfer complete]
4345 ## Start Addr = 0x00000000
4348 You can check the success of the download using the 'iminfo' command;
4349 this includes a checksum verification so you can be sure no data
4350 corruption happened:
4354 ## Checking Image at 40100000 ...
4355 Image Name: 2.2.13 for initrd on TQM850L
4356 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4357 Data Size: 335725 Bytes = 327 kB = 0 MB
4358 Load Address: 00000000
4359 Entry Point: 0000000c
4360 Verifying Checksum ... OK
4366 The "bootm" command is used to boot an application that is stored in
4367 memory (RAM or Flash). In case of a Linux kernel image, the contents
4368 of the "bootargs" environment variable is passed to the kernel as
4369 parameters. You can check and modify this variable using the
4370 "printenv" and "setenv" commands:
4373 => printenv bootargs
4374 bootargs=root=/dev/ram
4376 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4378 => printenv bootargs
4379 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4382 ## Booting Linux kernel at 40020000 ...
4383 Image Name: 2.2.13 for NFS on TQM850L
4384 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4385 Data Size: 381681 Bytes = 372 kB = 0 MB
4386 Load Address: 00000000
4387 Entry Point: 0000000c
4388 Verifying Checksum ... OK
4389 Uncompressing Kernel Image ... OK
4390 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
4391 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4392 time_init: decrementer frequency = 187500000/60
4393 Calibrating delay loop... 49.77 BogoMIPS
4394 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4397 If you want to boot a Linux kernel with initial RAM disk, you pass
4398 the memory addresses of both the kernel and the initrd image (PPBCOOT
4399 format!) to the "bootm" command:
4401 => imi 40100000 40200000
4403 ## Checking Image at 40100000 ...
4404 Image Name: 2.2.13 for initrd on TQM850L
4405 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4406 Data Size: 335725 Bytes = 327 kB = 0 MB
4407 Load Address: 00000000
4408 Entry Point: 0000000c
4409 Verifying Checksum ... OK
4411 ## Checking Image at 40200000 ...
4412 Image Name: Simple Ramdisk Image
4413 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4414 Data Size: 566530 Bytes = 553 kB = 0 MB
4415 Load Address: 00000000
4416 Entry Point: 00000000
4417 Verifying Checksum ... OK
4419 => bootm 40100000 40200000
4420 ## Booting Linux kernel at 40100000 ...
4421 Image Name: 2.2.13 for initrd on TQM850L
4422 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4423 Data Size: 335725 Bytes = 327 kB = 0 MB
4424 Load Address: 00000000
4425 Entry Point: 0000000c
4426 Verifying Checksum ... OK
4427 Uncompressing Kernel Image ... OK
4428 ## Loading RAMDisk Image at 40200000 ...
4429 Image Name: Simple Ramdisk Image
4430 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4431 Data Size: 566530 Bytes = 553 kB = 0 MB
4432 Load Address: 00000000
4433 Entry Point: 00000000
4434 Verifying Checksum ... OK
4435 Loading Ramdisk ... OK
4436 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
4437 Boot arguments: root=/dev/ram
4438 time_init: decrementer frequency = 187500000/60
4439 Calibrating delay loop... 49.77 BogoMIPS
4441 RAMDISK: Compressed image found at block 0
4442 VFS: Mounted root (ext2 filesystem).
4446 Boot Linux and pass a flat device tree:
4449 First, U-Boot must be compiled with the appropriate defines. See the section
4450 titled "Linux Kernel Interface" above for a more in depth explanation. The
4451 following is an example of how to start a kernel and pass an updated
4457 oft=oftrees/mpc8540ads.dtb
4458 => tftp $oftaddr $oft
4459 Speed: 1000, full duplex
4461 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4462 Filename 'oftrees/mpc8540ads.dtb'.
4463 Load address: 0x300000
4466 Bytes transferred = 4106 (100a hex)
4467 => tftp $loadaddr $bootfile
4468 Speed: 1000, full duplex
4470 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4472 Load address: 0x200000
4473 Loading:############
4475 Bytes transferred = 1029407 (fb51f hex)
4480 => bootm $loadaddr - $oftaddr
4481 ## Booting image at 00200000 ...
4482 Image Name: Linux-2.6.17-dirty
4483 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4484 Data Size: 1029343 Bytes = 1005.2 kB
4485 Load Address: 00000000
4486 Entry Point: 00000000
4487 Verifying Checksum ... OK
4488 Uncompressing Kernel Image ... OK
4489 Booting using flat device tree at 0x300000
4490 Using MPC85xx ADS machine description
4491 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4495 More About U-Boot Image Types:
4496 ------------------------------
4498 U-Boot supports the following image types:
4500 "Standalone Programs" are directly runnable in the environment
4501 provided by U-Boot; it is expected that (if they behave
4502 well) you can continue to work in U-Boot after return from
4503 the Standalone Program.
4504 "OS Kernel Images" are usually images of some Embedded OS which
4505 will take over control completely. Usually these programs
4506 will install their own set of exception handlers, device
4507 drivers, set up the MMU, etc. - this means, that you cannot
4508 expect to re-enter U-Boot except by resetting the CPU.
4509 "RAMDisk Images" are more or less just data blocks, and their
4510 parameters (address, size) are passed to an OS kernel that is
4512 "Multi-File Images" contain several images, typically an OS
4513 (Linux) kernel image and one or more data images like
4514 RAMDisks. This construct is useful for instance when you want
4515 to boot over the network using BOOTP etc., where the boot
4516 server provides just a single image file, but you want to get
4517 for instance an OS kernel and a RAMDisk image.
4519 "Multi-File Images" start with a list of image sizes, each
4520 image size (in bytes) specified by an "uint32_t" in network
4521 byte order. This list is terminated by an "(uint32_t)0".
4522 Immediately after the terminating 0 follow the images, one by
4523 one, all aligned on "uint32_t" boundaries (size rounded up to
4524 a multiple of 4 bytes).
4526 "Firmware Images" are binary images containing firmware (like
4527 U-Boot or FPGA images) which usually will be programmed to
4530 "Script files" are command sequences that will be executed by
4531 U-Boot's command interpreter; this feature is especially
4532 useful when you configure U-Boot to use a real shell (hush)
4533 as command interpreter.
4535 Booting the Linux zImage:
4536 -------------------------
4538 On some platforms, it's possible to boot Linux zImage. This is done
4539 using the "bootz" command. The syntax of "bootz" command is the same
4540 as the syntax of "bootm" command.
4542 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
4543 kernel with raw initrd images. The syntax is slightly different, the
4544 address of the initrd must be augmented by it's size, in the following
4545 format: "<initrd addres>:<initrd size>".
4551 One of the features of U-Boot is that you can dynamically load and
4552 run "standalone" applications, which can use some resources of
4553 U-Boot like console I/O functions or interrupt services.
4555 Two simple examples are included with the sources:
4560 'examples/hello_world.c' contains a small "Hello World" Demo
4561 application; it is automatically compiled when you build U-Boot.
4562 It's configured to run at address 0x00040004, so you can play with it
4566 ## Ready for S-Record download ...
4567 ~>examples/hello_world.srec
4568 1 2 3 4 5 6 7 8 9 10 11 ...
4569 [file transfer complete]
4571 ## Start Addr = 0x00040004
4573 => go 40004 Hello World! This is a test.
4574 ## Starting application at 0x00040004 ...
4585 Hit any key to exit ...
4587 ## Application terminated, rc = 0x0
4589 Another example, which demonstrates how to register a CPM interrupt
4590 handler with the U-Boot code, can be found in 'examples/timer.c'.
4591 Here, a CPM timer is set up to generate an interrupt every second.
4592 The interrupt service routine is trivial, just printing a '.'
4593 character, but this is just a demo program. The application can be
4594 controlled by the following keys:
4596 ? - print current values og the CPM Timer registers
4597 b - enable interrupts and start timer
4598 e - stop timer and disable interrupts
4599 q - quit application
4602 ## Ready for S-Record download ...
4603 ~>examples/timer.srec
4604 1 2 3 4 5 6 7 8 9 10 11 ...
4605 [file transfer complete]
4607 ## Start Addr = 0x00040004
4610 ## Starting application at 0x00040004 ...
4613 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4616 [q, b, e, ?] Set interval 1000000 us
4619 [q, b, e, ?] ........
4620 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4623 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4626 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4629 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4631 [q, b, e, ?] ...Stopping timer
4633 [q, b, e, ?] ## Application terminated, rc = 0x0
4639 Over time, many people have reported problems when trying to use the
4640 "minicom" terminal emulation program for serial download. I (wd)
4641 consider minicom to be broken, and recommend not to use it. Under
4642 Unix, I recommend to use C-Kermit for general purpose use (and
4643 especially for kermit binary protocol download ("loadb" command), and
4644 use "cu" for S-Record download ("loads" command). See
4645 http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4646 for help with kermit.
4649 Nevertheless, if you absolutely want to use it try adding this
4650 configuration to your "File transfer protocols" section:
4652 Name Program Name U/D FullScr IO-Red. Multi
4653 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4654 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4660 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4661 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4663 Building requires a cross environment; it is known to work on
4664 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4665 need gmake since the Makefiles are not compatible with BSD make).
4666 Note that the cross-powerpc package does not install include files;
4667 attempting to build U-Boot will fail because <machine/ansi.h> is
4668 missing. This file has to be installed and patched manually:
4670 # cd /usr/pkg/cross/powerpc-netbsd/include
4672 # ln -s powerpc machine
4673 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4674 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4676 Native builds *don't* work due to incompatibilities between native
4677 and U-Boot include files.
4679 Booting assumes that (the first part of) the image booted is a
4680 stage-2 loader which in turn loads and then invokes the kernel
4681 proper. Loader sources will eventually appear in the NetBSD source
4682 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4683 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4686 Implementation Internals:
4687 =========================
4689 The following is not intended to be a complete description of every
4690 implementation detail. However, it should help to understand the
4691 inner workings of U-Boot and make it easier to port it to custom
4695 Initial Stack, Global Data:
4696 ---------------------------
4698 The implementation of U-Boot is complicated by the fact that U-Boot
4699 starts running out of ROM (flash memory), usually without access to
4700 system RAM (because the memory controller is not initialized yet).
4701 This means that we don't have writable Data or BSS segments, and BSS
4702 is not initialized as zero. To be able to get a C environment working
4703 at all, we have to allocate at least a minimal stack. Implementation
4704 options for this are defined and restricted by the CPU used: Some CPU
4705 models provide on-chip memory (like the IMMR area on MPC8xx and
4706 MPC826x processors), on others (parts of) the data cache can be
4707 locked as (mis-) used as memory, etc.
4709 Chris Hallinan posted a good summary of these issues to the
4710 U-Boot mailing list:
4712 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4713 From: "Chris Hallinan" <clh@net1plus.com>
4714 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4717 Correct me if I'm wrong, folks, but the way I understand it
4718 is this: Using DCACHE as initial RAM for Stack, etc, does not
4719 require any physical RAM backing up the cache. The cleverness
4720 is that the cache is being used as a temporary supply of
4721 necessary storage before the SDRAM controller is setup. It's
4722 beyond the scope of this list to explain the details, but you
4723 can see how this works by studying the cache architecture and
4724 operation in the architecture and processor-specific manuals.
4726 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4727 is another option for the system designer to use as an
4728 initial stack/RAM area prior to SDRAM being available. Either
4729 option should work for you. Using CS 4 should be fine if your
4730 board designers haven't used it for something that would
4731 cause you grief during the initial boot! It is frequently not
4734 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4735 with your processor/board/system design. The default value
4736 you will find in any recent u-boot distribution in
4737 walnut.h should work for you. I'd set it to a value larger
4738 than your SDRAM module. If you have a 64MB SDRAM module, set
4739 it above 400_0000. Just make sure your board has no resources
4740 that are supposed to respond to that address! That code in
4741 start.S has been around a while and should work as is when
4742 you get the config right.
4747 It is essential to remember this, since it has some impact on the C
4748 code for the initialization procedures:
4750 * Initialized global data (data segment) is read-only. Do not attempt
4753 * Do not use any uninitialized global data (or implicitly initialized
4754 as zero data - BSS segment) at all - this is undefined, initiali-
4755 zation is performed later (when relocating to RAM).
4757 * Stack space is very limited. Avoid big data buffers or things like
4760 Having only the stack as writable memory limits means we cannot use
4761 normal global data to share information between the code. But it
4762 turned out that the implementation of U-Boot can be greatly
4763 simplified by making a global data structure (gd_t) available to all
4764 functions. We could pass a pointer to this data as argument to _all_
4765 functions, but this would bloat the code. Instead we use a feature of
4766 the GCC compiler (Global Register Variables) to share the data: we
4767 place a pointer (gd) to the global data into a register which we
4768 reserve for this purpose.
4770 When choosing a register for such a purpose we are restricted by the
4771 relevant (E)ABI specifications for the current architecture, and by
4772 GCC's implementation.
4774 For PowerPC, the following registers have specific use:
4776 R2: reserved for system use
4777 R3-R4: parameter passing and return values
4778 R5-R10: parameter passing
4779 R13: small data area pointer
4783 (U-Boot also uses R12 as internal GOT pointer. r12
4784 is a volatile register so r12 needs to be reset when
4785 going back and forth between asm and C)
4787 ==> U-Boot will use R2 to hold a pointer to the global data
4789 Note: on PPC, we could use a static initializer (since the
4790 address of the global data structure is known at compile time),
4791 but it turned out that reserving a register results in somewhat
4792 smaller code - although the code savings are not that big (on
4793 average for all boards 752 bytes for the whole U-Boot image,
4794 624 text + 127 data).
4796 On ARM, the following registers are used:
4798 R0: function argument word/integer result
4799 R1-R3: function argument word
4800 R9: platform specific
4801 R10: stack limit (used only if stack checking is enabled)
4802 R11: argument (frame) pointer
4803 R12: temporary workspace
4806 R15: program counter
4808 ==> U-Boot will use R9 to hold a pointer to the global data
4810 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4812 On Nios II, the ABI is documented here:
4813 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4815 ==> U-Boot will use gp to hold a pointer to the global data
4817 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4818 to access small data sections, so gp is free.
4820 On NDS32, the following registers are used:
4822 R0-R1: argument/return
4824 R15: temporary register for assembler
4825 R16: trampoline register
4826 R28: frame pointer (FP)
4827 R29: global pointer (GP)
4828 R30: link register (LP)
4829 R31: stack pointer (SP)
4830 PC: program counter (PC)
4832 ==> U-Boot will use R10 to hold a pointer to the global data
4834 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4835 or current versions of GCC may "optimize" the code too much.
4837 On RISC-V, the following registers are used:
4839 x0: hard-wired zero (zero)
4840 x1: return address (ra)
4841 x2: stack pointer (sp)
4842 x3: global pointer (gp)
4843 x4: thread pointer (tp)
4844 x5: link register (t0)
4845 x8: frame pointer (fp)
4846 x10-x11: arguments/return values (a0-1)
4847 x12-x17: arguments (a2-7)
4848 x28-31: temporaries (t3-6)
4849 pc: program counter (pc)
4851 ==> U-Boot will use gp to hold a pointer to the global data
4856 U-Boot runs in system state and uses physical addresses, i.e. the
4857 MMU is not used either for address mapping nor for memory protection.
4859 The available memory is mapped to fixed addresses using the memory
4860 controller. In this process, a contiguous block is formed for each
4861 memory type (Flash, SDRAM, SRAM), even when it consists of several
4862 physical memory banks.
4864 U-Boot is installed in the first 128 kB of the first Flash bank (on
4865 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4866 booting and sizing and initializing DRAM, the code relocates itself
4867 to the upper end of DRAM. Immediately below the U-Boot code some
4868 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4869 configuration setting]. Below that, a structure with global Board
4870 Info data is placed, followed by the stack (growing downward).
4872 Additionally, some exception handler code is copied to the low 8 kB
4873 of DRAM (0x00000000 ... 0x00001FFF).
4875 So a typical memory configuration with 16 MB of DRAM could look like
4878 0x0000 0000 Exception Vector code
4881 0x0000 2000 Free for Application Use
4887 0x00FB FF20 Monitor Stack (Growing downward)
4888 0x00FB FFAC Board Info Data and permanent copy of global data
4889 0x00FC 0000 Malloc Arena
4892 0x00FE 0000 RAM Copy of Monitor Code
4893 ... eventually: LCD or video framebuffer
4894 ... eventually: pRAM (Protected RAM - unchanged by reset)
4895 0x00FF FFFF [End of RAM]
4898 System Initialization:
4899 ----------------------
4901 In the reset configuration, U-Boot starts at the reset entry point
4902 (on most PowerPC systems at address 0x00000100). Because of the reset
4903 configuration for CS0# this is a mirror of the on board Flash memory.
4904 To be able to re-map memory U-Boot then jumps to its link address.
4905 To be able to implement the initialization code in C, a (small!)
4906 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4907 which provide such a feature like), or in a locked part of the data
4908 cache. After that, U-Boot initializes the CPU core, the caches and
4911 Next, all (potentially) available memory banks are mapped using a
4912 preliminary mapping. For example, we put them on 512 MB boundaries
4913 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4914 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4915 programmed for SDRAM access. Using the temporary configuration, a
4916 simple memory test is run that determines the size of the SDRAM
4919 When there is more than one SDRAM bank, and the banks are of
4920 different size, the largest is mapped first. For equal size, the first
4921 bank (CS2#) is mapped first. The first mapping is always for address
4922 0x00000000, with any additional banks following immediately to create
4923 contiguous memory starting from 0.
4925 Then, the monitor installs itself at the upper end of the SDRAM area
4926 and allocates memory for use by malloc() and for the global Board
4927 Info data; also, the exception vector code is copied to the low RAM
4928 pages, and the final stack is set up.
4930 Only after this relocation will you have a "normal" C environment;
4931 until that you are restricted in several ways, mostly because you are
4932 running from ROM, and because the code will have to be relocated to a
4936 U-Boot Porting Guide:
4937 ----------------------
4939 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4943 int main(int argc, char *argv[])
4945 sighandler_t no_more_time;
4947 signal(SIGALRM, no_more_time);
4948 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4950 if (available_money > available_manpower) {
4951 Pay consultant to port U-Boot;
4955 Download latest U-Boot source;
4957 Subscribe to u-boot mailing list;
4960 email("Hi, I am new to U-Boot, how do I get started?");
4963 Read the README file in the top level directory;
4964 Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4965 Read applicable doc/*.README;
4966 Read the source, Luke;
4967 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4970 if (available_money > toLocalCurrency ($2500))
4973 Add a lot of aggravation and time;
4975 if (a similar board exists) { /* hopefully... */
4976 cp -a board/<similar> board/<myboard>
4977 cp include/configs/<similar>.h include/configs/<myboard>.h
4979 Create your own board support subdirectory;
4980 Create your own board include/configs/<myboard>.h file;
4982 Edit new board/<myboard> files
4983 Edit new include/configs/<myboard>.h
4988 Add / modify source code;
4992 email("Hi, I am having problems...");
4994 Send patch file to the U-Boot email list;
4995 if (reasonable critiques)
4996 Incorporate improvements from email list code review;
4998 Defend code as written;
5004 void no_more_time (int sig)
5013 All contributions to U-Boot should conform to the Linux kernel
5014 coding style; see the kernel coding style guide at
5015 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
5016 script "scripts/Lindent" in your Linux kernel source directory.
5018 Source files originating from a different project (for example the
5019 MTD subsystem) are generally exempt from these guidelines and are not
5020 reformatted to ease subsequent migration to newer versions of those
5023 Please note that U-Boot is implemented in C (and to some small parts in
5024 Assembler); no C++ is used, so please do not use C++ style comments (//)
5027 Please also stick to the following formatting rules:
5028 - remove any trailing white space
5029 - use TAB characters for indentation and vertical alignment, not spaces
5030 - make sure NOT to use DOS '\r\n' line feeds
5031 - do not add more than 2 consecutive empty lines to source files
5032 - do not add trailing empty lines to source files
5034 Submissions which do not conform to the standards may be returned
5035 with a request to reformat the changes.
5041 Since the number of patches for U-Boot is growing, we need to
5042 establish some rules. Submissions which do not conform to these rules
5043 may be rejected, even when they contain important and valuable stuff.
5045 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5047 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5048 see https://lists.denx.de/listinfo/u-boot
5050 When you send a patch, please include the following information with
5053 * For bug fixes: a description of the bug and how your patch fixes
5054 this bug. Please try to include a way of demonstrating that the
5055 patch actually fixes something.
5057 * For new features: a description of the feature and your
5060 * A CHANGELOG entry as plaintext (separate from the patch)
5062 * For major contributions, add a MAINTAINERS file with your
5063 information and associated file and directory references.
5065 * When you add support for a new board, don't forget to add a
5066 maintainer e-mail address to the boards.cfg file, too.
5068 * If your patch adds new configuration options, don't forget to
5069 document these in the README file.
5071 * The patch itself. If you are using git (which is *strongly*
5072 recommended) you can easily generate the patch using the
5073 "git format-patch". If you then use "git send-email" to send it to
5074 the U-Boot mailing list, you will avoid most of the common problems
5075 with some other mail clients.
5077 If you cannot use git, use "diff -purN OLD NEW". If your version of
5078 diff does not support these options, then get the latest version of
5081 The current directory when running this command shall be the parent
5082 directory of the U-Boot source tree (i. e. please make sure that
5083 your patch includes sufficient directory information for the
5086 We prefer patches as plain text. MIME attachments are discouraged,
5087 and compressed attachments must not be used.
5089 * If one logical set of modifications affects or creates several
5090 files, all these changes shall be submitted in a SINGLE patch file.
5092 * Changesets that contain different, unrelated modifications shall be
5093 submitted as SEPARATE patches, one patch per changeset.
5098 * Before sending the patch, run the buildman script on your patched
5099 source tree and make sure that no errors or warnings are reported
5100 for any of the boards.
5102 * Keep your modifications to the necessary minimum: A patch
5103 containing several unrelated changes or arbitrary reformats will be
5104 returned with a request to re-formatting / split it.
5106 * If you modify existing code, make sure that your new code does not
5107 add to the memory footprint of the code ;-) Small is beautiful!
5108 When adding new features, these should compile conditionally only
5109 (using #ifdef), and the resulting code with the new feature
5110 disabled must not need more memory than the old code without your
5113 * Remember that there is a size limit of 100 kB per message on the
5114 u-boot mailing list. Bigger patches will be moderated. If they are
5115 reasonable and not too big, they will be acknowledged. But patches
5116 bigger than the size limit should be avoided.