1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see http://lists.denx.de/pipermail/u-boot and
55 http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
58 Where to get source code:
59 =========================
61 The U-Boot source code is maintained in the Git repository at
62 git://www.denx.de/git/u-boot.git ; you can browse it online at
63 http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
65 The "snapshot" links on this page allow you to download tarballs of
66 any version you might be interested in. Official releases are also
67 available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
70 Pre-built (and tested) images are available from
71 ftp://ftp.denx.de/pub/u-boot/images/
77 - start from 8xxrom sources
78 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
80 - make it easier to add custom boards
81 - make it possible to add other [PowerPC] CPUs
82 - extend functions, especially:
83 * Provide extended interface to Linux boot loader
86 * ATA disk / SCSI ... boot
87 - create ARMBoot project (http://sourceforge.net/projects/armboot)
88 - add other CPU families (starting with ARM)
89 - create U-Boot project (http://sourceforge.net/projects/u-boot)
90 - current project page: see http://www.denx.de/wiki/U-Boot
96 The "official" name of this project is "Das U-Boot". The spelling
97 "U-Boot" shall be used in all written text (documentation, comments
98 in source files etc.). Example:
100 This is the README file for the U-Boot project.
102 File names etc. shall be based on the string "u-boot". Examples:
104 include/asm-ppc/u-boot.h
106 #include <asm/u-boot.h>
108 Variable names, preprocessor constants etc. shall be either based on
109 the string "u_boot" or on "U_BOOT". Example:
111 U_BOOT_VERSION u_boot_logo
112 IH_OS_U_BOOT u_boot_hush_start
118 Starting with the release in October 2008, the names of the releases
119 were changed from numerical release numbers without deeper meaning
120 into a time stamp based numbering. Regular releases are identified by
121 names consisting of the calendar year and month of the release date.
122 Additional fields (if present) indicate release candidates or bug fix
123 releases in "stable" maintenance trees.
126 U-Boot v2009.11 - Release November 2009
127 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
128 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
134 /arch Architecture specific files
135 /arc Files generic to ARC architecture
136 /arm Files generic to ARM architecture
137 /m68k Files generic to m68k architecture
138 /microblaze Files generic to microblaze architecture
139 /mips Files generic to MIPS architecture
140 /nds32 Files generic to NDS32 architecture
141 /nios2 Files generic to Altera NIOS2 architecture
142 /openrisc Files generic to OpenRISC architecture
143 /powerpc Files generic to PowerPC architecture
144 /riscv Files generic to RISC-V architecture
145 /sandbox Files generic to HW-independent "sandbox"
146 /sh Files generic to SH architecture
147 /x86 Files generic to x86 architecture
148 /api Machine/arch independent API for external apps
149 /board Board dependent files
150 /cmd U-Boot commands functions
151 /common Misc architecture independent functions
152 /configs Board default configuration files
153 /disk Code for disk drive partition handling
154 /doc Documentation (don't expect too much)
155 /drivers Commonly used device drivers
156 /dts Contains Makefile for building internal U-Boot fdt.
157 /examples Example code for standalone applications, etc.
158 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
159 /include Header Files
160 /lib Library routines generic to all architectures
161 /Licenses Various license files
163 /post Power On Self Test
164 /scripts Various build scripts and Makefiles
165 /test Various unit test files
166 /tools Tools to build S-Record or U-Boot images, etc.
168 Software Configuration:
169 =======================
171 Configuration is usually done using C preprocessor defines; the
172 rationale behind that is to avoid dead code whenever possible.
174 There are two classes of configuration variables:
176 * Configuration _OPTIONS_:
177 These are selectable by the user and have names beginning with
180 * Configuration _SETTINGS_:
181 These depend on the hardware etc. and should not be meddled with if
182 you don't know what you're doing; they have names beginning with
185 Previously, all configuration was done by hand, which involved creating
186 symbolic links and editing configuration files manually. More recently,
187 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
188 allowing you to use the "make menuconfig" command to configure your
192 Selection of Processor Architecture and Board Type:
193 ---------------------------------------------------
195 For all supported boards there are ready-to-use default
196 configurations available; just type "make <board_name>_defconfig".
198 Example: For a TQM823L module type:
201 make TQM823L_defconfig
203 Note: If you're looking for the default configuration file for a board
204 you're sure used to be there but is now missing, check the file
205 doc/README.scrapyard for a list of no longer supported boards.
210 U-Boot can be built natively to run on a Linux host using the 'sandbox'
211 board. This allows feature development which is not board- or architecture-
212 specific to be undertaken on a native platform. The sandbox is also used to
213 run some of U-Boot's tests.
215 See doc/arch/index.rst for more details.
218 Board Initialisation Flow:
219 --------------------------
221 This is the intended start-up flow for boards. This should apply for both
222 SPL and U-Boot proper (i.e. they both follow the same rules).
224 Note: "SPL" stands for "Secondary Program Loader," which is explained in
225 more detail later in this file.
227 At present, SPL mostly uses a separate code path, but the function names
228 and roles of each function are the same. Some boards or architectures
229 may not conform to this. At least most ARM boards which use
230 CONFIG_SPL_FRAMEWORK conform to this.
232 Execution typically starts with an architecture-specific (and possibly
233 CPU-specific) start.S file, such as:
235 - arch/arm/cpu/armv7/start.S
236 - arch/powerpc/cpu/mpc83xx/start.S
237 - arch/mips/cpu/start.S
239 and so on. From there, three functions are called; the purpose and
240 limitations of each of these functions are described below.
243 - purpose: essential init to permit execution to reach board_init_f()
244 - no global_data or BSS
245 - there is no stack (ARMv7 may have one but it will soon be removed)
246 - must not set up SDRAM or use console
247 - must only do the bare minimum to allow execution to continue to
249 - this is almost never needed
250 - return normally from this function
253 - purpose: set up the machine ready for running board_init_r():
254 i.e. SDRAM and serial UART
255 - global_data is available
257 - BSS is not available, so you cannot use global/static variables,
258 only stack variables and global_data
260 Non-SPL-specific notes:
261 - dram_init() is called to set up DRAM. If already done in SPL this
265 - you can override the entire board_init_f() function with your own
267 - preloader_console_init() can be called here in extremis
268 - should set up SDRAM, and anything needed to make the UART work
269 - these is no need to clear BSS, it will be done by crt0.S
270 - for specific scenarios on certain architectures an early BSS *can*
271 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
272 of BSS prior to entering board_init_f()) but doing so is discouraged.
273 Instead it is strongly recommended to architect any code changes
274 or additions such to not depend on the availability of BSS during
275 board_init_f() as indicated in other sections of this README to
276 maintain compatibility and consistency across the entire code base.
277 - must return normally from this function (don't call board_init_r()
280 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
281 this point the stack and global_data are relocated to below
282 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
286 - purpose: main execution, common code
287 - global_data is available
289 - BSS is available, all static/global variables can be used
290 - execution eventually continues to main_loop()
292 Non-SPL-specific notes:
293 - U-Boot is relocated to the top of memory and is now running from
297 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
298 CONFIG_SPL_STACK_R_ADDR points into SDRAM
299 - preloader_console_init() can be called here - typically this is
300 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
301 spl_board_init() function containing this call
302 - loads U-Boot or (in falcon mode) Linux
306 Configuration Options:
307 ----------------------
309 Configuration depends on the combination of board and CPU type; all
310 such information is kept in a configuration file
311 "include/configs/<board_name>.h".
313 Example: For a TQM823L module, all configuration settings are in
314 "include/configs/TQM823L.h".
317 Many of the options are named exactly as the corresponding Linux
318 kernel configuration options. The intention is to make it easier to
319 build a config tool - later.
321 - ARM Platform Bus Type(CCI):
322 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
323 provides full cache coherency between two clusters of multi-core
324 CPUs and I/O coherency for devices and I/O masters
326 CONFIG_SYS_FSL_HAS_CCI400
328 Defined For SoC that has cache coherent interconnect
331 CONFIG_SYS_FSL_HAS_CCN504
333 Defined for SoC that has cache coherent interconnect CCN-504
335 The following options need to be configured:
337 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
339 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
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
496 CONFIG_SYS_FSL_DDR_BE
497 Defines the DDR controller register space as Big Endian
499 CONFIG_SYS_FSL_DDR_LE
500 Defines the DDR controller register space as Little Endian
502 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
503 Physical address from the view of DDR controllers. It is the
504 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
505 it could be different for ARM SoCs.
507 CONFIG_SYS_FSL_DDR_INTLV_256B
508 DDR controller interleaving on 256-byte. This is a special
509 interleaving mode, handled by Dickens for Freescale layerscape
512 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
513 Number of controllers used as main memory.
515 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
516 Number of controllers used for other than main memory.
518 CONFIG_SYS_FSL_HAS_DP_DDR
519 Defines the SoC has DP-DDR used for DPAA.
521 CONFIG_SYS_FSL_SEC_BE
522 Defines the SEC controller register space as Big Endian
524 CONFIG_SYS_FSL_SEC_LE
525 Defines the SEC controller register space as Little Endian
528 CONFIG_SYS_INIT_SP_OFFSET
530 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
531 pointer. This is needed for the temporary stack before
534 CONFIG_XWAY_SWAP_BYTES
536 Enable compilation of tools/xway-swap-bytes needed for Lantiq
537 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
538 be swapped if a flash programmer is used.
541 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
543 Select high exception vectors of the ARM core, e.g., do not
544 clear the V bit of the c1 register of CP15.
547 Generic timer clock source frequency.
549 COUNTER_FREQUENCY_REAL
550 Generic timer clock source frequency if the real clock is
551 different from COUNTER_FREQUENCY, and can only be determined
555 CONFIG_TEGRA_SUPPORT_NON_SECURE
557 Support executing U-Boot in non-secure (NS) mode. Certain
558 impossible actions will be skipped if the CPU is in NS mode,
559 such as ARM architectural timer initialization.
561 - Linux Kernel Interface:
562 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
564 When transferring memsize parameter to Linux, some versions
565 expect it to be in bytes, others in MB.
566 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
570 New kernel versions are expecting firmware settings to be
571 passed using flattened device trees (based on open firmware
575 * New libfdt-based support
576 * Adds the "fdt" command
577 * The bootm command automatically updates the fdt
579 OF_TBCLK - The timebase frequency.
580 OF_STDOUT_PATH - The path to the console device
582 boards with QUICC Engines require OF_QE to set UCC MAC
585 CONFIG_OF_BOARD_SETUP
587 Board code has addition modification that it wants to make
588 to the flat device tree before handing it off to the kernel
590 CONFIG_OF_SYSTEM_SETUP
592 Other code has addition modification that it wants to make
593 to the flat device tree before handing it off to the kernel.
594 This causes ft_system_setup() to be called before booting
599 U-Boot can detect if an IDE device is present or not.
600 If not, and this new config option is activated, U-Boot
601 removes the ATA node from the DTS before booting Linux,
602 so the Linux IDE driver does not probe the device and
603 crash. This is needed for buggy hardware (uc101) where
604 no pull down resistor is connected to the signal IDE5V_DD7.
606 CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
608 This setting is mandatory for all boards that have only one
609 machine type and must be used to specify the machine type
610 number as it appears in the ARM machine registry
611 (see http://www.arm.linux.org.uk/developer/machines/).
612 Only boards that have multiple machine types supported
613 in a single configuration file and the machine type is
614 runtime discoverable, do not have to use this setting.
616 - vxWorks boot parameters:
618 bootvx constructs a valid bootline using the following
619 environments variables: bootdev, bootfile, ipaddr, netmask,
620 serverip, gatewayip, hostname, othbootargs.
621 It loads the vxWorks image pointed bootfile.
623 Note: If a "bootargs" environment is defined, it will overwride
624 the defaults discussed just above.
626 - Cache Configuration:
627 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
629 - Cache Configuration for ARM:
630 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
632 CONFIG_SYS_PL310_BASE - Physical base address of PL310
633 controller register space
638 Define this if you want support for Amba PrimeCell PL010 UARTs.
642 Define this if you want support for Amba PrimeCell PL011 UARTs.
646 If you have Amba PrimeCell PL011 UARTs, set this variable to
647 the clock speed of the UARTs.
651 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
652 define this to a list of base addresses for each (supported)
653 port. See e.g. include/configs/versatile.h
655 CONFIG_SERIAL_HW_FLOW_CONTROL
657 Define this variable to enable hw flow control in serial driver.
658 Current user of this option is drivers/serial/nsl16550.c driver
662 Only needed when CONFIG_BOOTDELAY is enabled;
663 define a command string that is automatically executed
664 when no character is read on the console interface
665 within "Boot Delay" after reset.
667 CONFIG_RAMBOOT and CONFIG_NFSBOOT
668 The value of these goes into the environment as
669 "ramboot" and "nfsboot" respectively, and can be used
670 as a convenience, when switching between booting from
673 - Serial Download Echo Mode:
675 If defined to 1, all characters received during a
676 serial download (using the "loads" command) are
677 echoed back. This might be needed by some terminal
678 emulations (like "cu"), but may as well just take
679 time on others. This setting #define's the initial
680 value of the "loads_echo" environment variable.
682 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
684 Select one of the baudrates listed in
685 CONFIG_SYS_BAUDRATE_TABLE, see below.
687 - Removal of commands
688 If no commands are needed to boot, you can disable
689 CONFIG_CMDLINE to remove them. In this case, the command line
690 will not be available, and when U-Boot wants to execute the
691 boot command (on start-up) it will call board_run_command()
692 instead. This can reduce image size significantly for very
693 simple boot procedures.
695 - Regular expression support:
697 If this variable is defined, U-Boot is linked against
698 the SLRE (Super Light Regular Expression) library,
699 which adds regex support to some commands, as for
700 example "env grep" and "setexpr".
704 If this variable is defined, U-Boot will use a device tree
705 to configure its devices, instead of relying on statically
706 compiled #defines in the board file. This option is
707 experimental and only available on a few boards. The device
708 tree is available in the global data as gd->fdt_blob.
710 U-Boot needs to get its device tree from somewhere. This can
711 be done using one of the three options below:
714 If this variable is defined, U-Boot will embed a device tree
715 binary in its image. This device tree file should be in the
716 board directory and called <soc>-<board>.dts. The binary file
717 is then picked up in board_init_f() and made available through
718 the global data structure as gd->fdt_blob.
721 If this variable is defined, U-Boot will build a device tree
722 binary. It will be called u-boot.dtb. Architecture-specific
723 code will locate it at run-time. Generally this works by:
725 cat u-boot.bin u-boot.dtb >image.bin
727 and in fact, U-Boot does this for you, creating a file called
728 u-boot-dtb.bin which is useful in the common case. You can
729 still use the individual files if you need something more
733 If this variable is defined, U-Boot will use the device tree
734 provided by the board at runtime instead of embedding one with
735 the image. Only boards defining board_fdt_blob_setup() support
736 this option (see include/fdtdec.h file).
740 If this variable is defined, it enables watchdog
741 support for the SoC. There must be support in the SoC
742 specific code for a watchdog. For the 8xx
743 CPUs, the SIU Watchdog feature is enabled in the SYPCR
744 register. When supported for a specific SoC is
745 available, then no further board specific code should
749 When using a watchdog circuitry external to the used
750 SoC, then define this variable and provide board
751 specific code for the "hw_watchdog_reset" function.
755 When CONFIG_CMD_DATE is selected, the type of the RTC
756 has to be selected, too. Define exactly one of the
759 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
760 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
761 CONFIG_RTC_MC146818 - use MC146818 RTC
762 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
763 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
764 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
765 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
766 CONFIG_RTC_DS164x - use Dallas DS164x RTC
767 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
768 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
769 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
770 CONFIG_SYS_RV3029_TCR - enable trickle charger on
773 Note that if the RTC uses I2C, then the I2C interface
774 must also be configured. See I2C Support, below.
777 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
779 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
780 chip-ngpio pairs that tell the PCA953X driver the number of
781 pins supported by a particular chip.
783 Note that if the GPIO device uses I2C, then the I2C interface
784 must also be configured. See I2C Support, below.
787 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
788 accesses and can checksum them or write a list of them out
789 to memory. See the 'iotrace' command for details. This is
790 useful for testing device drivers since it can confirm that
791 the driver behaves the same way before and after a code
792 change. Currently this is supported on sandbox and arm. To
793 add support for your architecture, add '#include <iotrace.h>'
794 to the bottom of arch/<arch>/include/asm/io.h and test.
796 Example output from the 'iotrace stats' command is below.
797 Note that if the trace buffer is exhausted, the checksum will
798 still continue to operate.
801 Start: 10000000 (buffer start address)
802 Size: 00010000 (buffer size)
803 Offset: 00000120 (current buffer offset)
804 Output: 10000120 (start + offset)
805 Count: 00000018 (number of trace records)
806 CRC32: 9526fb66 (CRC32 of all trace records)
810 When CONFIG_TIMESTAMP is selected, the timestamp
811 (date and time) of an image is printed by image
812 commands like bootm or iminfo. This option is
813 automatically enabled when you select CONFIG_CMD_DATE .
815 - Partition Labels (disklabels) Supported:
816 Zero or more of the following:
817 CONFIG_MAC_PARTITION Apple's MacOS partition table.
818 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
819 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
820 bootloader. Note 2TB partition limit; see
822 CONFIG_SCSI) you must configure support for at
823 least one non-MTD partition type as well.
826 CONFIG_IDE_RESET_ROUTINE - this is defined in several
827 board configurations files but used nowhere!
829 CONFIG_IDE_RESET - is this is defined, IDE Reset will
830 be performed by calling the function
831 ide_set_reset(int reset)
832 which has to be defined in a board specific file
837 Set this to enable ATAPI support.
842 Set this to enable support for disks larger than 137GB
843 Also look at CONFIG_SYS_64BIT_LBA.
844 Whithout these , LBA48 support uses 32bit variables and will 'only'
845 support disks up to 2.1TB.
847 CONFIG_SYS_64BIT_LBA:
848 When enabled, makes the IDE subsystem use 64bit sector addresses.
852 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
853 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
854 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
855 maximum numbers of LUNs, SCSI ID's and target
858 The environment variable 'scsidevs' is set to the number of
859 SCSI devices found during the last scan.
861 - NETWORK Support (PCI):
863 Support for Intel 8254x/8257x gigabit chips.
866 Utility code for direct access to the SPI bus on Intel 8257x.
867 This does not do anything useful unless you set at least one
868 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
870 CONFIG_E1000_SPI_GENERIC
871 Allow generic access to the SPI bus on the Intel 8257x, for
872 example with the "sspi" command.
875 Support for National dp83815 chips.
878 Support for National dp8382[01] gigabit chips.
880 - NETWORK Support (other):
882 CONFIG_DRIVER_AT91EMAC
883 Support for AT91RM9200 EMAC.
886 Define this to use reduced MII inteface
888 CONFIG_DRIVER_AT91EMAC_QUIET
889 If this defined, the driver is quiet.
890 The driver doen't show link status messages.
893 Support for the Calxeda XGMAC device
896 Support for SMSC's LAN91C96 chips.
898 CONFIG_LAN91C96_USE_32_BIT
899 Define this to enable 32 bit addressing
902 Support for SMSC's LAN91C111 chip
905 Define this to hold the physical address
906 of the device (I/O space)
908 CONFIG_SMC_USE_32_BIT
909 Define this if data bus is 32 bits
911 CONFIG_SMC_USE_IOFUNCS
912 Define this to use i/o functions instead of macros
913 (some hardware wont work with macros)
915 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
916 Define this if you have more then 3 PHYs.
919 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
921 CONFIG_FTGMAC100_EGIGA
922 Define this to use GE link update with gigabit PHY.
923 Define this if FTGMAC100 is connected to gigabit PHY.
924 If your system has 10/100 PHY only, it might not occur
925 wrong behavior. Because PHY usually return timeout or
926 useless data when polling gigabit status and gigabit
927 control registers. This behavior won't affect the
928 correctnessof 10/100 link speed update.
931 Support for Renesas on-chip Ethernet controller
933 CONFIG_SH_ETHER_USE_PORT
934 Define the number of ports to be used
936 CONFIG_SH_ETHER_PHY_ADDR
937 Define the ETH PHY's address
939 CONFIG_SH_ETHER_CACHE_WRITEBACK
940 If this option is set, the driver enables cache flush.
946 CONFIG_TPM_TIS_INFINEON
947 Support for Infineon i2c bus TPM devices. Only one device
948 per system is supported at this time.
950 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
951 Define the burst count bytes upper limit
954 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
956 CONFIG_TPM_ST33ZP24_I2C
957 Support for STMicroelectronics ST33ZP24 I2C devices.
958 Requires TPM_ST33ZP24 and I2C.
960 CONFIG_TPM_ST33ZP24_SPI
961 Support for STMicroelectronics ST33ZP24 SPI devices.
962 Requires TPM_ST33ZP24 and SPI.
965 Support for Atmel TWI TPM device. Requires I2C support.
968 Support for generic parallel port TPM devices. Only one device
969 per system is supported at this time.
971 CONFIG_TPM_TIS_BASE_ADDRESS
972 Base address where the generic TPM device is mapped
973 to. Contemporary x86 systems usually map it at
977 Define this to enable the TPM support library which provides
978 functional interfaces to some TPM commands.
979 Requires support for a TPM device.
981 CONFIG_TPM_AUTH_SESSIONS
982 Define this to enable authorized functions in the TPM library.
983 Requires CONFIG_TPM and CONFIG_SHA1.
986 At the moment only the UHCI host controller is
987 supported (PIP405, MIP405); define
988 CONFIG_USB_UHCI to enable it.
989 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
990 and define CONFIG_USB_STORAGE to enable the USB
993 Supported are USB Keyboards and USB Floppy drives
996 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
997 txfilltuning field in the EHCI controller on reset.
999 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1000 HW module registers.
1003 Define the below if you wish to use the USB console.
1004 Once firmware is rebuilt from a serial console issue the
1005 command "setenv stdin usbtty; setenv stdout usbtty" and
1006 attach your USB cable. The Unix command "dmesg" should print
1007 it has found a new device. The environment variable usbtty
1008 can be set to gserial or cdc_acm to enable your device to
1009 appear to a USB host as a Linux gserial device or a
1010 Common Device Class Abstract Control Model serial device.
1011 If you select usbtty = gserial you should be able to enumerate
1013 # modprobe usbserial vendor=0xVendorID product=0xProductID
1014 else if using cdc_acm, simply setting the environment
1015 variable usbtty to be cdc_acm should suffice. The following
1016 might be defined in YourBoardName.h
1019 Define this to build a UDC device
1022 Define this to have a tty type of device available to
1023 talk to the UDC device
1026 Define this to enable the high speed support for usb
1027 device and usbtty. If this feature is enabled, a routine
1028 int is_usbd_high_speed(void)
1029 also needs to be defined by the driver to dynamically poll
1030 whether the enumeration has succeded at high speed or full
1033 CONFIG_SYS_CONSOLE_IS_IN_ENV
1034 Define this if you want stdin, stdout &/or stderr to
1037 If you have a USB-IF assigned VendorID then you may wish to
1038 define your own vendor specific values either in BoardName.h
1039 or directly in usbd_vendor_info.h. If you don't define
1040 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1041 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1042 should pretend to be a Linux device to it's target host.
1044 CONFIG_USBD_MANUFACTURER
1045 Define this string as the name of your company for
1046 - CONFIG_USBD_MANUFACTURER "my company"
1048 CONFIG_USBD_PRODUCT_NAME
1049 Define this string as the name of your product
1050 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1052 CONFIG_USBD_VENDORID
1053 Define this as your assigned Vendor ID from the USB
1054 Implementors Forum. This *must* be a genuine Vendor ID
1055 to avoid polluting the USB namespace.
1056 - CONFIG_USBD_VENDORID 0xFFFF
1058 CONFIG_USBD_PRODUCTID
1059 Define this as the unique Product ID
1061 - CONFIG_USBD_PRODUCTID 0xFFFF
1063 - ULPI Layer Support:
1064 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1065 the generic ULPI layer. The generic layer accesses the ULPI PHY
1066 via the platform viewport, so you need both the genric layer and
1067 the viewport enabled. Currently only Chipidea/ARC based
1068 viewport is supported.
1069 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1070 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1071 If your ULPI phy needs a different reference clock than the
1072 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1073 the appropriate value in Hz.
1076 The MMC controller on the Intel PXA is supported. To
1077 enable this define CONFIG_MMC. The MMC can be
1078 accessed from the boot prompt by mapping the device
1079 to physical memory similar to flash. Command line is
1080 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1081 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1084 Support for Renesas on-chip MMCIF controller
1086 CONFIG_SH_MMCIF_ADDR
1087 Define the base address of MMCIF registers
1090 Define the clock frequency for MMCIF
1092 - USB Device Firmware Update (DFU) class support:
1094 This enables the USB portion of the DFU USB class
1097 This enables support for exposing NAND devices via DFU.
1100 This enables support for exposing RAM via DFU.
1101 Note: DFU spec refer to non-volatile memory usage, but
1102 allow usages beyond the scope of spec - here RAM usage,
1103 one that would help mostly the developer.
1105 CONFIG_SYS_DFU_DATA_BUF_SIZE
1106 Dfu transfer uses a buffer before writing data to the
1107 raw storage device. Make the size (in bytes) of this buffer
1108 configurable. The size of this buffer is also configurable
1109 through the "dfu_bufsiz" environment variable.
1111 CONFIG_SYS_DFU_MAX_FILE_SIZE
1112 When updating files rather than the raw storage device,
1113 we use a static buffer to copy the file into and then write
1114 the buffer once we've been given the whole file. Define
1115 this to the maximum filesize (in bytes) for the buffer.
1116 Default is 4 MiB if undefined.
1118 DFU_DEFAULT_POLL_TIMEOUT
1119 Poll timeout [ms], is the timeout a device can send to the
1120 host. The host must wait for this timeout before sending
1121 a subsequent DFU_GET_STATUS request to the device.
1123 DFU_MANIFEST_POLL_TIMEOUT
1124 Poll timeout [ms], which the device sends to the host when
1125 entering dfuMANIFEST state. Host waits this timeout, before
1126 sending again an USB request to the device.
1128 - Journaling Flash filesystem support:
1130 Define these for a default partition on a NAND device
1132 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1133 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1134 Define these for a default partition on a NOR device
1137 See Kconfig help for available keyboard drivers.
1141 Define this to enable a custom keyboard support.
1142 This simply calls drv_keyboard_init() which must be
1143 defined in your board-specific files. This option is deprecated
1144 and is only used by novena. For new boards, use driver model
1149 Enable the Freescale DIU video driver. Reference boards for
1150 SOCs that have a DIU should define this macro to enable DIU
1151 support, and should also define these other macros:
1156 CONFIG_VIDEO_SW_CURSOR
1157 CONFIG_VGA_AS_SINGLE_DEVICE
1159 CONFIG_VIDEO_BMP_LOGO
1161 The DIU driver will look for the 'video-mode' environment
1162 variable, and if defined, enable the DIU as a console during
1163 boot. See the documentation file doc/README.video for a
1164 description of this variable.
1166 - LCD Support: CONFIG_LCD
1168 Define this to enable LCD support (for output to LCD
1169 display); also select one of the supported displays
1170 by defining one of these:
1174 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1176 CONFIG_NEC_NL6448AC33:
1178 NEC NL6448AC33-18. Active, color, single scan.
1180 CONFIG_NEC_NL6448BC20
1182 NEC NL6448BC20-08. 6.5", 640x480.
1183 Active, color, single scan.
1185 CONFIG_NEC_NL6448BC33_54
1187 NEC NL6448BC33-54. 10.4", 640x480.
1188 Active, color, single scan.
1192 Sharp 320x240. Active, color, single scan.
1193 It isn't 16x9, and I am not sure what it is.
1195 CONFIG_SHARP_LQ64D341
1197 Sharp LQ64D341 display, 640x480.
1198 Active, color, single scan.
1202 HLD1045 display, 640x480.
1203 Active, color, single scan.
1207 Optrex CBL50840-2 NF-FW 99 22 M5
1209 Hitachi LMG6912RPFC-00T
1213 320x240. Black & white.
1215 CONFIG_LCD_ALIGNMENT
1217 Normally the LCD is page-aligned (typically 4KB). If this is
1218 defined then the LCD will be aligned to this value instead.
1219 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1220 here, since it is cheaper to change data cache settings on
1221 a per-section basis.
1226 Sometimes, for example if the display is mounted in portrait
1227 mode or even if it's mounted landscape but rotated by 180degree,
1228 we need to rotate our content of the display relative to the
1229 framebuffer, so that user can read the messages which are
1231 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1232 initialized with a given rotation from "vl_rot" out of
1233 "vidinfo_t" which is provided by the board specific code.
1234 The value for vl_rot is coded as following (matching to
1235 fbcon=rotate:<n> linux-kernel commandline):
1236 0 = no rotation respectively 0 degree
1237 1 = 90 degree rotation
1238 2 = 180 degree rotation
1239 3 = 270 degree rotation
1241 If CONFIG_LCD_ROTATION is not defined, the console will be
1242 initialized with 0degree rotation.
1246 Support drawing of RLE8-compressed bitmaps on the LCD.
1250 Enables an 'i2c edid' command which can read EDID
1251 information over I2C from an attached LCD display.
1253 - Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1255 If this option is set, additionally to standard BMP
1256 images, gzipped BMP images can be displayed via the
1257 splashscreen support or the bmp command.
1259 - Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1261 If this option is set, 8-bit RLE compressed BMP images
1262 can be displayed via the splashscreen support or the
1266 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1268 The clock frequency of the MII bus
1270 CONFIG_PHY_RESET_DELAY
1272 Some PHY like Intel LXT971A need extra delay after
1273 reset before any MII register access is possible.
1274 For such PHY, set this option to the usec delay
1275 required. (minimum 300usec for LXT971A)
1277 CONFIG_PHY_CMD_DELAY (ppc4xx)
1279 Some PHY like Intel LXT971A need extra delay after
1280 command issued before MII status register can be read
1285 Define a default value for the IP address to use for
1286 the default Ethernet interface, in case this is not
1287 determined through e.g. bootp.
1288 (Environment variable "ipaddr")
1290 - Server IP address:
1293 Defines a default value for the IP address of a TFTP
1294 server to contact when using the "tftboot" command.
1295 (Environment variable "serverip")
1297 CONFIG_KEEP_SERVERADDR
1299 Keeps the server's MAC address, in the env 'serveraddr'
1300 for passing to bootargs (like Linux's netconsole option)
1302 - Gateway IP address:
1305 Defines a default value for the IP address of the
1306 default router where packets to other networks are
1308 (Environment variable "gatewayip")
1313 Defines a default value for the subnet mask (or
1314 routing prefix) which is used to determine if an IP
1315 address belongs to the local subnet or needs to be
1316 forwarded through a router.
1317 (Environment variable "netmask")
1319 - BOOTP Recovery Mode:
1320 CONFIG_BOOTP_RANDOM_DELAY
1322 If you have many targets in a network that try to
1323 boot using BOOTP, you may want to avoid that all
1324 systems send out BOOTP requests at precisely the same
1325 moment (which would happen for instance at recovery
1326 from a power failure, when all systems will try to
1327 boot, thus flooding the BOOTP server. Defining
1328 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1329 inserted before sending out BOOTP requests. The
1330 following delays are inserted then:
1332 1st BOOTP request: delay 0 ... 1 sec
1333 2nd BOOTP request: delay 0 ... 2 sec
1334 3rd BOOTP request: delay 0 ... 4 sec
1336 BOOTP requests: delay 0 ... 8 sec
1338 CONFIG_BOOTP_ID_CACHE_SIZE
1340 BOOTP packets are uniquely identified using a 32-bit ID. The
1341 server will copy the ID from client requests to responses and
1342 U-Boot will use this to determine if it is the destination of
1343 an incoming response. Some servers will check that addresses
1344 aren't in use before handing them out (usually using an ARP
1345 ping) and therefore take up to a few hundred milliseconds to
1346 respond. Network congestion may also influence the time it
1347 takes for a response to make it back to the client. If that
1348 time is too long, U-Boot will retransmit requests. In order
1349 to allow earlier responses to still be accepted after these
1350 retransmissions, U-Boot's BOOTP client keeps a small cache of
1351 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1352 cache. The default is to keep IDs for up to four outstanding
1353 requests. Increasing this will allow U-Boot to accept offers
1354 from a BOOTP client in networks with unusually high latency.
1356 - DHCP Advanced Options:
1357 You can fine tune the DHCP functionality by defining
1358 CONFIG_BOOTP_* symbols:
1360 CONFIG_BOOTP_NISDOMAIN
1361 CONFIG_BOOTP_BOOTFILESIZE
1362 CONFIG_BOOTP_NTPSERVER
1363 CONFIG_BOOTP_TIMEOFFSET
1364 CONFIG_BOOTP_VENDOREX
1365 CONFIG_BOOTP_MAY_FAIL
1367 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1368 environment variable, not the BOOTP server.
1370 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1371 after the configured retry count, the call will fail
1372 instead of starting over. This can be used to fail over
1373 to Link-local IP address configuration if the DHCP server
1376 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1378 A 32bit value in microseconds for a delay between
1379 receiving a "DHCP Offer" and sending the "DHCP Request".
1380 This fixes a problem with certain DHCP servers that don't
1381 respond 100% of the time to a "DHCP request". E.g. On an
1382 AT91RM9200 processor running at 180MHz, this delay needed
1383 to be *at least* 15,000 usec before a Windows Server 2003
1384 DHCP server would reply 100% of the time. I recommend at
1385 least 50,000 usec to be safe. The alternative is to hope
1386 that one of the retries will be successful but note that
1387 the DHCP timeout and retry process takes a longer than
1390 - Link-local IP address negotiation:
1391 Negotiate with other link-local clients on the local network
1392 for an address that doesn't require explicit configuration.
1393 This is especially useful if a DHCP server cannot be guaranteed
1394 to exist in all environments that the device must operate.
1396 See doc/README.link-local for more information.
1398 - MAC address from environment variables
1400 FDT_SEQ_MACADDR_FROM_ENV
1402 Fix-up device tree with MAC addresses fetched sequentially from
1403 environment variables. This config work on assumption that
1404 non-usable ethernet node of device-tree are either not present
1405 or their status has been marked as "disabled".
1408 CONFIG_CDP_DEVICE_ID
1410 The device id used in CDP trigger frames.
1412 CONFIG_CDP_DEVICE_ID_PREFIX
1414 A two character string which is prefixed to the MAC address
1419 A printf format string which contains the ascii name of
1420 the port. Normally is set to "eth%d" which sets
1421 eth0 for the first Ethernet, eth1 for the second etc.
1423 CONFIG_CDP_CAPABILITIES
1425 A 32bit integer which indicates the device capabilities;
1426 0x00000010 for a normal host which does not forwards.
1430 An ascii string containing the version of the software.
1434 An ascii string containing the name of the platform.
1438 A 32bit integer sent on the trigger.
1440 CONFIG_CDP_POWER_CONSUMPTION
1442 A 16bit integer containing the power consumption of the
1443 device in .1 of milliwatts.
1445 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1447 A byte containing the id of the VLAN.
1449 - Status LED: CONFIG_LED_STATUS
1451 Several configurations allow to display the current
1452 status using a LED. For instance, the LED will blink
1453 fast while running U-Boot code, stop blinking as
1454 soon as a reply to a BOOTP request was received, and
1455 start blinking slow once the Linux kernel is running
1456 (supported by a status LED driver in the Linux
1457 kernel). Defining CONFIG_LED_STATUS enables this
1462 CONFIG_LED_STATUS_GPIO
1463 The status LED can be connected to a GPIO pin.
1464 In such cases, the gpio_led driver can be used as a
1465 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1466 to include the gpio_led driver in the U-Boot binary.
1468 CONFIG_GPIO_LED_INVERTED_TABLE
1469 Some GPIO connected LEDs may have inverted polarity in which
1470 case the GPIO high value corresponds to LED off state and
1471 GPIO low value corresponds to LED on state.
1472 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1473 with a list of GPIO LEDs that have inverted polarity.
1475 - I2C Support: CONFIG_SYS_I2C
1477 This enable the NEW i2c subsystem, and will allow you to use
1478 i2c commands at the u-boot command line (as long as you set
1479 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1480 for defining speed and slave address
1481 - activate second bus with I2C_SOFT_DECLARATIONS2 define
1482 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1483 for defining speed and slave address
1484 - activate third bus with I2C_SOFT_DECLARATIONS3 define
1485 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1486 for defining speed and slave address
1487 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1488 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1489 for defining speed and slave address
1491 - drivers/i2c/fsl_i2c.c:
1492 - activate i2c driver with CONFIG_SYS_I2C_FSL
1493 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1494 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1495 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1497 - If your board supports a second fsl i2c bus, define
1498 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1499 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1500 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1503 - drivers/i2c/tegra_i2c.c:
1504 - activate this driver with CONFIG_SYS_I2C_TEGRA
1505 - This driver adds 4 i2c buses with a fix speed from
1506 100000 and the slave addr 0!
1508 - drivers/i2c/ppc4xx_i2c.c
1509 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1510 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1511 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1513 - drivers/i2c/i2c_mxc.c
1514 - activate this driver with CONFIG_SYS_I2C_MXC
1515 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1516 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1517 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1518 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1519 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1520 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1521 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1522 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1523 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1524 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1525 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1526 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1527 If those defines are not set, default value is 100000
1528 for speed, and 0 for slave.
1530 - drivers/i2c/rcar_i2c.c:
1531 - activate this driver with CONFIG_SYS_I2C_RCAR
1532 - This driver adds 4 i2c buses
1534 - drivers/i2c/sh_i2c.c:
1535 - activate this driver with CONFIG_SYS_I2C_SH
1536 - This driver adds from 2 to 5 i2c buses
1538 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1539 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1540 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1541 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1542 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1543 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1544 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1545 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1546 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1547 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1548 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1550 - drivers/i2c/omap24xx_i2c.c
1551 - activate this driver with CONFIG_SYS_I2C_OMAP24XX
1552 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
1553 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
1554 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
1555 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
1556 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
1557 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
1558 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
1559 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
1560 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
1561 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
1563 - drivers/i2c/s3c24x0_i2c.c:
1564 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1565 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1566 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1567 with a fix speed from 100000 and the slave addr 0!
1569 - drivers/i2c/ihs_i2c.c
1570 - activate this driver with CONFIG_SYS_I2C_IHS
1571 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1572 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1573 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1574 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1575 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1576 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1577 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1578 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1579 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1580 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1581 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1582 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1583 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1584 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1585 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1586 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1587 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1588 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1589 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1590 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1591 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1595 CONFIG_SYS_NUM_I2C_BUSES
1596 Hold the number of i2c buses you want to use.
1598 CONFIG_SYS_I2C_DIRECT_BUS
1599 define this, if you don't use i2c muxes on your hardware.
1600 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1603 CONFIG_SYS_I2C_MAX_HOPS
1604 define how many muxes are maximal consecutively connected
1605 on one i2c bus. If you not use i2c muxes, omit this
1608 CONFIG_SYS_I2C_BUSES
1609 hold a list of buses you want to use, only used if
1610 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1611 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1612 CONFIG_SYS_NUM_I2C_BUSES = 9:
1614 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1615 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1616 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1617 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1618 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1619 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1620 {1, {I2C_NULL_HOP}}, \
1621 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1622 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1626 bus 0 on adapter 0 without a mux
1627 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1628 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1629 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1630 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1631 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1632 bus 6 on adapter 1 without a mux
1633 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1634 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1636 If you do not have i2c muxes on your board, omit this define.
1638 - Legacy I2C Support:
1639 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1640 then the following macros need to be defined (examples are
1641 from include/configs/lwmon.h):
1645 (Optional). Any commands necessary to enable the I2C
1646 controller or configure ports.
1648 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1652 The code necessary to make the I2C data line active
1653 (driven). If the data line is open collector, this
1656 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1660 The code necessary to make the I2C data line tri-stated
1661 (inactive). If the data line is open collector, this
1664 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1668 Code that returns true if the I2C data line is high,
1671 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1675 If <bit> is true, sets the I2C data line high. If it
1676 is false, it clears it (low).
1678 eg: #define I2C_SDA(bit) \
1679 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1680 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1684 If <bit> is true, sets the I2C clock line high. If it
1685 is false, it clears it (low).
1687 eg: #define I2C_SCL(bit) \
1688 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1689 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1693 This delay is invoked four times per clock cycle so this
1694 controls the rate of data transfer. The data rate thus
1695 is 1 / (I2C_DELAY * 4). Often defined to be something
1698 #define I2C_DELAY udelay(2)
1700 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1702 If your arch supports the generic GPIO framework (asm/gpio.h),
1703 then you may alternatively define the two GPIOs that are to be
1704 used as SCL / SDA. Any of the previous I2C_xxx macros will
1705 have GPIO-based defaults assigned to them as appropriate.
1707 You should define these to the GPIO value as given directly to
1708 the generic GPIO functions.
1710 CONFIG_SYS_I2C_INIT_BOARD
1712 When a board is reset during an i2c bus transfer
1713 chips might think that the current transfer is still
1714 in progress. On some boards it is possible to access
1715 the i2c SCLK line directly, either by using the
1716 processor pin as a GPIO or by having a second pin
1717 connected to the bus. If this option is defined a
1718 custom i2c_init_board() routine in boards/xxx/board.c
1719 is run early in the boot sequence.
1721 CONFIG_I2C_MULTI_BUS
1723 This option allows the use of multiple I2C buses, each of which
1724 must have a controller. At any point in time, only one bus is
1725 active. To switch to a different bus, use the 'i2c dev' command.
1726 Note that bus numbering is zero-based.
1728 CONFIG_SYS_I2C_NOPROBES
1730 This option specifies a list of I2C devices that will be skipped
1731 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1732 is set, specify a list of bus-device pairs. Otherwise, specify
1733 a 1D array of device addresses
1736 #undef CONFIG_I2C_MULTI_BUS
1737 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1739 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1741 #define CONFIG_I2C_MULTI_BUS
1742 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1744 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1746 CONFIG_SYS_SPD_BUS_NUM
1748 If defined, then this indicates the I2C bus number for DDR SPD.
1749 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1751 CONFIG_SYS_RTC_BUS_NUM
1753 If defined, then this indicates the I2C bus number for the RTC.
1754 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1756 CONFIG_SOFT_I2C_READ_REPEATED_START
1758 defining this will force the i2c_read() function in
1759 the soft_i2c driver to perform an I2C repeated start
1760 between writing the address pointer and reading the
1761 data. If this define is omitted the default behaviour
1762 of doing a stop-start sequence will be used. Most I2C
1763 devices can use either method, but some require one or
1766 - SPI Support: CONFIG_SPI
1768 Enables SPI driver (so far only tested with
1769 SPI EEPROM, also an instance works with Crystal A/D and
1770 D/As on the SACSng board)
1774 Enables a software (bit-bang) SPI driver rather than
1775 using hardware support. This is a general purpose
1776 driver that only requires three general I/O port pins
1777 (two outputs, one input) to function. If this is
1778 defined, the board configuration must define several
1779 SPI configuration items (port pins to use, etc). For
1780 an example, see include/configs/sacsng.h.
1782 CONFIG_SYS_SPI_MXC_WAIT
1783 Timeout for waiting until spi transfer completed.
1784 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1786 - FPGA Support: CONFIG_FPGA
1788 Enables FPGA subsystem.
1790 CONFIG_FPGA_<vendor>
1792 Enables support for specific chip vendors.
1795 CONFIG_FPGA_<family>
1797 Enables support for FPGA family.
1798 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1802 Specify the number of FPGA devices to support.
1804 CONFIG_SYS_FPGA_PROG_FEEDBACK
1806 Enable printing of hash marks during FPGA configuration.
1808 CONFIG_SYS_FPGA_CHECK_BUSY
1810 Enable checks on FPGA configuration interface busy
1811 status by the configuration function. This option
1812 will require a board or device specific function to
1817 If defined, a function that provides delays in the FPGA
1818 configuration driver.
1820 CONFIG_SYS_FPGA_CHECK_CTRLC
1821 Allow Control-C to interrupt FPGA configuration
1823 CONFIG_SYS_FPGA_CHECK_ERROR
1825 Check for configuration errors during FPGA bitfile
1826 loading. For example, abort during Virtex II
1827 configuration if the INIT_B line goes low (which
1828 indicated a CRC error).
1830 CONFIG_SYS_FPGA_WAIT_INIT
1832 Maximum time to wait for the INIT_B line to de-assert
1833 after PROB_B has been de-asserted during a Virtex II
1834 FPGA configuration sequence. The default time is 500
1837 CONFIG_SYS_FPGA_WAIT_BUSY
1839 Maximum time to wait for BUSY to de-assert during
1840 Virtex II FPGA configuration. The default is 5 ms.
1842 CONFIG_SYS_FPGA_WAIT_CONFIG
1844 Time to wait after FPGA configuration. The default is
1847 - Configuration Management:
1851 If defined, this string will be added to the U-Boot
1852 version information (U_BOOT_VERSION)
1854 - Vendor Parameter Protection:
1856 U-Boot considers the values of the environment
1857 variables "serial#" (Board Serial Number) and
1858 "ethaddr" (Ethernet Address) to be parameters that
1859 are set once by the board vendor / manufacturer, and
1860 protects these variables from casual modification by
1861 the user. Once set, these variables are read-only,
1862 and write or delete attempts are rejected. You can
1863 change this behaviour:
1865 If CONFIG_ENV_OVERWRITE is #defined in your config
1866 file, the write protection for vendor parameters is
1867 completely disabled. Anybody can change or delete
1870 Alternatively, if you define _both_ an ethaddr in the
1871 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1872 Ethernet address is installed in the environment,
1873 which can be changed exactly ONCE by the user. [The
1874 serial# is unaffected by this, i. e. it remains
1877 The same can be accomplished in a more flexible way
1878 for any variable by configuring the type of access
1879 to allow for those variables in the ".flags" variable
1880 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1885 Define this variable to enable the reservation of
1886 "protected RAM", i. e. RAM which is not overwritten
1887 by U-Boot. Define CONFIG_PRAM to hold the number of
1888 kB you want to reserve for pRAM. You can overwrite
1889 this default value by defining an environment
1890 variable "pram" to the number of kB you want to
1891 reserve. Note that the board info structure will
1892 still show the full amount of RAM. If pRAM is
1893 reserved, a new environment variable "mem" will
1894 automatically be defined to hold the amount of
1895 remaining RAM in a form that can be passed as boot
1896 argument to Linux, for instance like that:
1898 setenv bootargs ... mem=\${mem}
1901 This way you can tell Linux not to use this memory,
1902 either, which results in a memory region that will
1903 not be affected by reboots.
1905 *WARNING* If your board configuration uses automatic
1906 detection of the RAM size, you must make sure that
1907 this memory test is non-destructive. So far, the
1908 following board configurations are known to be
1911 IVMS8, IVML24, SPD8xx,
1912 HERMES, IP860, RPXlite, LWMON,
1915 - Access to physical memory region (> 4GB)
1916 Some basic support is provided for operations on memory not
1917 normally accessible to U-Boot - e.g. some architectures
1918 support access to more than 4GB of memory on 32-bit
1919 machines using physical address extension or similar.
1920 Define CONFIG_PHYSMEM to access this basic support, which
1921 currently only supports clearing the memory.
1924 CONFIG_NET_RETRY_COUNT
1926 This variable defines the number of retries for
1927 network operations like ARP, RARP, TFTP, or BOOTP
1928 before giving up the operation. If not defined, a
1929 default value of 5 is used.
1933 Timeout waiting for an ARP reply in milliseconds.
1937 Timeout in milliseconds used in NFS protocol.
1938 If you encounter "ERROR: Cannot umount" in nfs command,
1939 try longer timeout such as
1940 #define CONFIG_NFS_TIMEOUT 10000UL
1942 - Command Interpreter:
1943 CONFIG_SYS_PROMPT_HUSH_PS2
1945 This defines the secondary prompt string, which is
1946 printed when the command interpreter needs more input
1947 to complete a command. Usually "> ".
1951 In the current implementation, the local variables
1952 space and global environment variables space are
1953 separated. Local variables are those you define by
1954 simply typing `name=value'. To access a local
1955 variable later on, you have write `$name' or
1956 `${name}'; to execute the contents of a variable
1957 directly type `$name' at the command prompt.
1959 Global environment variables are those you use
1960 setenv/printenv to work with. To run a command stored
1961 in such a variable, you need to use the run command,
1962 and you must not use the '$' sign to access them.
1964 To store commands and special characters in a
1965 variable, please use double quotation marks
1966 surrounding the whole text of the variable, instead
1967 of the backslashes before semicolons and special
1970 - Command Line Editing and History:
1971 CONFIG_CMDLINE_PS_SUPPORT
1973 Enable support for changing the command prompt string
1974 at run-time. Only static string is supported so far.
1975 The string is obtained from environment variables PS1
1978 - Default Environment:
1979 CONFIG_EXTRA_ENV_SETTINGS
1981 Define this to contain any number of null terminated
1982 strings (variable = value pairs) that will be part of
1983 the default environment compiled into the boot image.
1985 For example, place something like this in your
1986 board's config file:
1988 #define CONFIG_EXTRA_ENV_SETTINGS \
1992 Warning: This method is based on knowledge about the
1993 internal format how the environment is stored by the
1994 U-Boot code. This is NOT an official, exported
1995 interface! Although it is unlikely that this format
1996 will change soon, there is no guarantee either.
1997 You better know what you are doing here.
1999 Note: overly (ab)use of the default environment is
2000 discouraged. Make sure to check other ways to preset
2001 the environment like the "source" command or the
2004 CONFIG_DELAY_ENVIRONMENT
2006 Normally the environment is loaded when the board is
2007 initialised so that it is available to U-Boot. This inhibits
2008 that so that the environment is not available until
2009 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2010 this is instead controlled by the value of
2011 /config/load-environment.
2013 - TFTP Fixed UDP Port:
2016 If this is defined, the environment variable tftpsrcp
2017 is used to supply the TFTP UDP source port value.
2018 If tftpsrcp isn't defined, the normal pseudo-random port
2019 number generator is used.
2021 Also, the environment variable tftpdstp is used to supply
2022 the TFTP UDP destination port value. If tftpdstp isn't
2023 defined, the normal port 69 is used.
2025 The purpose for tftpsrcp is to allow a TFTP server to
2026 blindly start the TFTP transfer using the pre-configured
2027 target IP address and UDP port. This has the effect of
2028 "punching through" the (Windows XP) firewall, allowing
2029 the remainder of the TFTP transfer to proceed normally.
2030 A better solution is to properly configure the firewall,
2031 but sometimes that is not allowed.
2033 CONFIG_STANDALONE_LOAD_ADDR
2035 This option defines a board specific value for the
2036 address where standalone program gets loaded, thus
2037 overwriting the architecture dependent default
2040 - Frame Buffer Address:
2043 Define CONFIG_FB_ADDR if you want to use specific
2044 address for frame buffer. This is typically the case
2045 when using a graphics controller has separate video
2046 memory. U-Boot will then place the frame buffer at
2047 the given address instead of dynamically reserving it
2048 in system RAM by calling lcd_setmem(), which grabs
2049 the memory for the frame buffer depending on the
2050 configured panel size.
2052 Please see board_init_f function.
2054 - Automatic software updates via TFTP server
2056 CONFIG_UPDATE_TFTP_CNT_MAX
2057 CONFIG_UPDATE_TFTP_MSEC_MAX
2059 These options enable and control the auto-update feature;
2060 for a more detailed description refer to doc/README.update.
2062 - MTD Support (mtdparts command, UBI support)
2063 CONFIG_MTD_UBI_WL_THRESHOLD
2064 This parameter defines the maximum difference between the highest
2065 erase counter value and the lowest erase counter value of eraseblocks
2066 of UBI devices. When this threshold is exceeded, UBI starts performing
2067 wear leveling by means of moving data from eraseblock with low erase
2068 counter to eraseblocks with high erase counter.
2070 The default value should be OK for SLC NAND flashes, NOR flashes and
2071 other flashes which have eraseblock life-cycle 100000 or more.
2072 However, in case of MLC NAND flashes which typically have eraseblock
2073 life-cycle less than 10000, the threshold should be lessened (e.g.,
2074 to 128 or 256, although it does not have to be power of 2).
2078 CONFIG_MTD_UBI_BEB_LIMIT
2079 This option specifies the maximum bad physical eraseblocks UBI
2080 expects on the MTD device (per 1024 eraseblocks). If the
2081 underlying flash does not admit of bad eraseblocks (e.g. NOR
2082 flash), this value is ignored.
2084 NAND datasheets often specify the minimum and maximum NVM
2085 (Number of Valid Blocks) for the flashes' endurance lifetime.
2086 The maximum expected bad eraseblocks per 1024 eraseblocks
2087 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2088 which gives 20 for most NANDs (MaxNVB is basically the total
2089 count of eraseblocks on the chip).
2091 To put it differently, if this value is 20, UBI will try to
2092 reserve about 1.9% of physical eraseblocks for bad blocks
2093 handling. And that will be 1.9% of eraseblocks on the entire
2094 NAND chip, not just the MTD partition UBI attaches. This means
2095 that if you have, say, a NAND flash chip admits maximum 40 bad
2096 eraseblocks, and it is split on two MTD partitions of the same
2097 size, UBI will reserve 40 eraseblocks when attaching a
2102 CONFIG_MTD_UBI_FASTMAP
2103 Fastmap is a mechanism which allows attaching an UBI device
2104 in nearly constant time. Instead of scanning the whole MTD device it
2105 only has to locate a checkpoint (called fastmap) on the device.
2106 The on-flash fastmap contains all information needed to attach
2107 the device. Using fastmap makes only sense on large devices where
2108 attaching by scanning takes long. UBI will not automatically install
2109 a fastmap on old images, but you can set the UBI parameter
2110 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2111 that fastmap-enabled images are still usable with UBI implementations
2112 without fastmap support. On typical flash devices the whole fastmap
2113 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2115 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2116 Set this parameter to enable fastmap automatically on images
2120 CONFIG_MTD_UBI_FM_DEBUG
2121 Enable UBI fastmap debug
2126 Enable building of SPL globally.
2129 LDSCRIPT for linking the SPL binary.
2131 CONFIG_SPL_MAX_FOOTPRINT
2132 Maximum size in memory allocated to the SPL, BSS included.
2133 When defined, the linker checks that the actual memory
2134 used by SPL from _start to __bss_end does not exceed it.
2135 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2136 must not be both defined at the same time.
2139 Maximum size of the SPL image (text, data, rodata, and
2140 linker lists sections), BSS excluded.
2141 When defined, the linker checks that the actual size does
2144 CONFIG_SPL_RELOC_TEXT_BASE
2145 Address to relocate to. If unspecified, this is equal to
2146 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2148 CONFIG_SPL_BSS_START_ADDR
2149 Link address for the BSS within the SPL binary.
2151 CONFIG_SPL_BSS_MAX_SIZE
2152 Maximum size in memory allocated to the SPL BSS.
2153 When defined, the linker checks that the actual memory used
2154 by SPL from __bss_start to __bss_end does not exceed it.
2155 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2156 must not be both defined at the same time.
2159 Adress of the start of the stack SPL will use
2161 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2162 When defined, SPL will panic() if the image it has
2163 loaded does not have a signature.
2164 Defining this is useful when code which loads images
2165 in SPL cannot guarantee that absolutely all read errors
2167 An example is the LPC32XX MLC NAND driver, which will
2168 consider that a completely unreadable NAND block is bad,
2169 and thus should be skipped silently.
2171 CONFIG_SPL_RELOC_STACK
2172 Adress of the start of the stack SPL will use after
2173 relocation. If unspecified, this is equal to
2176 CONFIG_SYS_SPL_MALLOC_START
2177 Starting address of the malloc pool used in SPL.
2178 When this option is set the full malloc is used in SPL and
2179 it is set up by spl_init() and before that, the simple malloc()
2180 can be used if CONFIG_SYS_MALLOC_F is defined.
2182 CONFIG_SYS_SPL_MALLOC_SIZE
2183 The size of the malloc pool used in SPL.
2186 Enable booting directly to an OS from SPL.
2187 See also: doc/README.falcon
2189 CONFIG_SPL_DISPLAY_PRINT
2190 For ARM, enable an optional function to print more information
2191 about the running system.
2193 CONFIG_SPL_INIT_MINIMAL
2194 Arch init code should be built for a very small image
2196 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2197 Partition on the MMC to load U-Boot from when the MMC is being
2200 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2201 Sector to load kernel uImage from when MMC is being
2202 used in raw mode (for Falcon mode)
2204 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2205 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2206 Sector and number of sectors to load kernel argument
2207 parameters from when MMC is being used in raw mode
2210 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2211 Filename to read to load U-Boot when reading from filesystem
2213 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2214 Filename to read to load kernel uImage when reading
2215 from filesystem (for Falcon mode)
2217 CONFIG_SPL_FS_LOAD_ARGS_NAME
2218 Filename to read to load kernel argument parameters
2219 when reading from filesystem (for Falcon mode)
2221 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2222 Set this for NAND SPL on PPC mpc83xx targets, so that
2223 start.S waits for the rest of the SPL to load before
2224 continuing (the hardware starts execution after just
2225 loading the first page rather than the full 4K).
2227 CONFIG_SPL_SKIP_RELOCATE
2228 Avoid SPL relocation
2230 CONFIG_SPL_NAND_IDENT
2231 SPL uses the chip ID list to identify the NAND flash.
2232 Requires CONFIG_SPL_NAND_BASE.
2235 Support for a lightweight UBI (fastmap) scanner and
2238 CONFIG_SPL_NAND_RAW_ONLY
2239 Support to boot only raw u-boot.bin images. Use this only
2240 if you need to save space.
2242 CONFIG_SPL_COMMON_INIT_DDR
2243 Set for common ddr init with serial presence detect in
2246 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2247 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2248 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2249 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2250 CONFIG_SYS_NAND_ECCBYTES
2251 Defines the size and behavior of the NAND that SPL uses
2254 CONFIG_SYS_NAND_U_BOOT_OFFS
2255 Location in NAND to read U-Boot from
2257 CONFIG_SYS_NAND_U_BOOT_DST
2258 Location in memory to load U-Boot to
2260 CONFIG_SYS_NAND_U_BOOT_SIZE
2261 Size of image to load
2263 CONFIG_SYS_NAND_U_BOOT_START
2264 Entry point in loaded image to jump to
2266 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2267 Define this if you need to first read the OOB and then the
2268 data. This is used, for example, on davinci platforms.
2270 CONFIG_SPL_RAM_DEVICE
2271 Support for running image already present in ram, in SPL binary
2274 Image offset to which the SPL should be padded before appending
2275 the SPL payload. By default, this is defined as
2276 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2277 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2278 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2281 Final target image containing SPL and payload. Some SPLs
2282 use an arch-specific makefile fragment instead, for
2283 example if more than one image needs to be produced.
2285 CONFIG_SPL_FIT_PRINT
2286 Printing information about a FIT image adds quite a bit of
2287 code to SPL. So this is normally disabled in SPL. Use this
2288 option to re-enable it. This will affect the output of the
2289 bootm command when booting a FIT image.
2293 Enable building of TPL globally.
2296 Image offset to which the TPL should be padded before appending
2297 the TPL payload. By default, this is defined as
2298 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2299 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2300 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2302 - Interrupt support (PPC):
2304 There are common interrupt_init() and timer_interrupt()
2305 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2306 for CPU specific initialization. interrupt_init_cpu()
2307 should set decrementer_count to appropriate value. If
2308 CPU resets decrementer automatically after interrupt
2309 (ppc4xx) it should set decrementer_count to zero.
2310 timer_interrupt() calls timer_interrupt_cpu() for CPU
2311 specific handling. If board has watchdog / status_led
2312 / other_activity_monitor it works automatically from
2313 general timer_interrupt().
2316 Board initialization settings:
2317 ------------------------------
2319 During Initialization u-boot calls a number of board specific functions
2320 to allow the preparation of board specific prerequisites, e.g. pin setup
2321 before drivers are initialized. To enable these callbacks the
2322 following configuration macros have to be defined. Currently this is
2323 architecture specific, so please check arch/your_architecture/lib/board.c
2324 typically in board_init_f() and board_init_r().
2326 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2327 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2328 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2329 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2331 Configuration Settings:
2332 -----------------------
2334 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2335 Optionally it can be defined to support 64-bit memory commands.
2337 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2338 undefine this when you're short of memory.
2340 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2341 width of the commands listed in the 'help' command output.
2343 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2344 prompt for user input.
2346 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2348 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2350 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2352 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2353 the application (usually a Linux kernel) when it is
2356 - CONFIG_SYS_BAUDRATE_TABLE:
2357 List of legal baudrate settings for this board.
2359 - CONFIG_SYS_MEM_RESERVE_SECURE
2360 Only implemented for ARMv8 for now.
2361 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2362 is substracted from total RAM and won't be reported to OS.
2363 This memory can be used as secure memory. A variable
2364 gd->arch.secure_ram is used to track the location. In systems
2365 the RAM base is not zero, or RAM is divided into banks,
2366 this variable needs to be recalcuated to get the address.
2368 - CONFIG_SYS_MEM_TOP_HIDE:
2369 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2370 this specified memory area will get subtracted from the top
2371 (end) of RAM and won't get "touched" at all by U-Boot. By
2372 fixing up gd->ram_size the Linux kernel should gets passed
2373 the now "corrected" memory size and won't touch it either.
2374 This should work for arch/ppc and arch/powerpc. Only Linux
2375 board ports in arch/powerpc with bootwrapper support that
2376 recalculate the memory size from the SDRAM controller setup
2377 will have to get fixed in Linux additionally.
2379 This option can be used as a workaround for the 440EPx/GRx
2380 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2383 WARNING: Please make sure that this value is a multiple of
2384 the Linux page size (normally 4k). If this is not the case,
2385 then the end address of the Linux memory will be located at a
2386 non page size aligned address and this could cause major
2389 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2390 Enable temporary baudrate change while serial download
2392 - CONFIG_SYS_SDRAM_BASE:
2393 Physical start address of SDRAM. _Must_ be 0 here.
2395 - CONFIG_SYS_FLASH_BASE:
2396 Physical start address of Flash memory.
2398 - CONFIG_SYS_MONITOR_BASE:
2399 Physical start address of boot monitor code (set by
2400 make config files to be same as the text base address
2401 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2402 CONFIG_SYS_FLASH_BASE when booting from flash.
2404 - CONFIG_SYS_MONITOR_LEN:
2405 Size of memory reserved for monitor code, used to
2406 determine _at_compile_time_ (!) if the environment is
2407 embedded within the U-Boot image, or in a separate
2410 - CONFIG_SYS_MALLOC_LEN:
2411 Size of DRAM reserved for malloc() use.
2413 - CONFIG_SYS_MALLOC_F_LEN
2414 Size of the malloc() pool for use before relocation. If
2415 this is defined, then a very simple malloc() implementation
2416 will become available before relocation. The address is just
2417 below the global data, and the stack is moved down to make
2420 This feature allocates regions with increasing addresses
2421 within the region. calloc() is supported, but realloc()
2422 is not available. free() is supported but does nothing.
2423 The memory will be freed (or in fact just forgotten) when
2424 U-Boot relocates itself.
2426 - CONFIG_SYS_MALLOC_SIMPLE
2427 Provides a simple and small malloc() and calloc() for those
2428 boards which do not use the full malloc in SPL (which is
2429 enabled with CONFIG_SYS_SPL_MALLOC_START).
2431 - CONFIG_SYS_NONCACHED_MEMORY:
2432 Size of non-cached memory area. This area of memory will be
2433 typically located right below the malloc() area and mapped
2434 uncached in the MMU. This is useful for drivers that would
2435 otherwise require a lot of explicit cache maintenance. For
2436 some drivers it's also impossible to properly maintain the
2437 cache. For example if the regions that need to be flushed
2438 are not a multiple of the cache-line size, *and* padding
2439 cannot be allocated between the regions to align them (i.e.
2440 if the HW requires a contiguous array of regions, and the
2441 size of each region is not cache-aligned), then a flush of
2442 one region may result in overwriting data that hardware has
2443 written to another region in the same cache-line. This can
2444 happen for example in network drivers where descriptors for
2445 buffers are typically smaller than the CPU cache-line (e.g.
2446 16 bytes vs. 32 or 64 bytes).
2448 Non-cached memory is only supported on 32-bit ARM at present.
2450 - CONFIG_SYS_BOOTM_LEN:
2451 Normally compressed uImages are limited to an
2452 uncompressed size of 8 MBytes. If this is not enough,
2453 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2454 to adjust this setting to your needs.
2456 - CONFIG_SYS_BOOTMAPSZ:
2457 Maximum size of memory mapped by the startup code of
2458 the Linux kernel; all data that must be processed by
2459 the Linux kernel (bd_info, boot arguments, FDT blob if
2460 used) must be put below this limit, unless "bootm_low"
2461 environment variable is defined and non-zero. In such case
2462 all data for the Linux kernel must be between "bootm_low"
2463 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2464 variable "bootm_mapsize" will override the value of
2465 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2466 then the value in "bootm_size" will be used instead.
2468 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2469 Enable initrd_high functionality. If defined then the
2470 initrd_high feature is enabled and the bootm ramdisk subcommand
2473 - CONFIG_SYS_BOOT_GET_CMDLINE:
2474 Enables allocating and saving kernel cmdline in space between
2475 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2477 - CONFIG_SYS_BOOT_GET_KBD:
2478 Enables allocating and saving a kernel copy of the bd_info in
2479 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2481 - CONFIG_SYS_MAX_FLASH_BANKS:
2482 Max number of Flash memory banks
2484 - CONFIG_SYS_MAX_FLASH_SECT:
2485 Max number of sectors on a Flash chip
2487 - CONFIG_SYS_FLASH_ERASE_TOUT:
2488 Timeout for Flash erase operations (in ms)
2490 - CONFIG_SYS_FLASH_WRITE_TOUT:
2491 Timeout for Flash write operations (in ms)
2493 - CONFIG_SYS_FLASH_LOCK_TOUT
2494 Timeout for Flash set sector lock bit operation (in ms)
2496 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2497 Timeout for Flash clear lock bits operation (in ms)
2499 - CONFIG_SYS_FLASH_PROTECTION
2500 If defined, hardware flash sectors protection is used
2501 instead of U-Boot software protection.
2503 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2505 Enable TFTP transfers directly to flash memory;
2506 without this option such a download has to be
2507 performed in two steps: (1) download to RAM, and (2)
2508 copy from RAM to flash.
2510 The two-step approach is usually more reliable, since
2511 you can check if the download worked before you erase
2512 the flash, but in some situations (when system RAM is
2513 too limited to allow for a temporary copy of the
2514 downloaded image) this option may be very useful.
2516 - CONFIG_SYS_FLASH_CFI:
2517 Define if the flash driver uses extra elements in the
2518 common flash structure for storing flash geometry.
2520 - CONFIG_FLASH_CFI_DRIVER
2521 This option also enables the building of the cfi_flash driver
2522 in the drivers directory
2524 - CONFIG_FLASH_CFI_MTD
2525 This option enables the building of the cfi_mtd driver
2526 in the drivers directory. The driver exports CFI flash
2529 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2530 Use buffered writes to flash.
2532 - CONFIG_FLASH_SPANSION_S29WS_N
2533 s29ws-n MirrorBit flash has non-standard addresses for buffered
2536 - CONFIG_SYS_FLASH_QUIET_TEST
2537 If this option is defined, the common CFI flash doesn't
2538 print it's warning upon not recognized FLASH banks. This
2539 is useful, if some of the configured banks are only
2540 optionally available.
2542 - CONFIG_FLASH_SHOW_PROGRESS
2543 If defined (must be an integer), print out countdown
2544 digits and dots. Recommended value: 45 (9..1) for 80
2545 column displays, 15 (3..1) for 40 column displays.
2547 - CONFIG_FLASH_VERIFY
2548 If defined, the content of the flash (destination) is compared
2549 against the source after the write operation. An error message
2550 will be printed when the contents are not identical.
2551 Please note that this option is useless in nearly all cases,
2552 since such flash programming errors usually are detected earlier
2553 while unprotecting/erasing/programming. Please only enable
2554 this option if you really know what you are doing.
2556 - CONFIG_SYS_RX_ETH_BUFFER:
2557 Defines the number of Ethernet receive buffers. On some
2558 Ethernet controllers it is recommended to set this value
2559 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2560 buffers can be full shortly after enabling the interface
2561 on high Ethernet traffic.
2562 Defaults to 4 if not defined.
2564 - CONFIG_ENV_MAX_ENTRIES
2566 Maximum number of entries in the hash table that is used
2567 internally to store the environment settings. The default
2568 setting is supposed to be generous and should work in most
2569 cases. This setting can be used to tune behaviour; see
2570 lib/hashtable.c for details.
2572 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2573 - CONFIG_ENV_FLAGS_LIST_STATIC
2574 Enable validation of the values given to environment variables when
2575 calling env set. Variables can be restricted to only decimal,
2576 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2577 the variables can also be restricted to IP address or MAC address.
2579 The format of the list is:
2580 type_attribute = [s|d|x|b|i|m]
2581 access_attribute = [a|r|o|c]
2582 attributes = type_attribute[access_attribute]
2583 entry = variable_name[:attributes]
2586 The type attributes are:
2587 s - String (default)
2590 b - Boolean ([1yYtT|0nNfF])
2594 The access attributes are:
2600 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2601 Define this to a list (string) to define the ".flags"
2602 environment variable in the default or embedded environment.
2604 - CONFIG_ENV_FLAGS_LIST_STATIC
2605 Define this to a list (string) to define validation that
2606 should be done if an entry is not found in the ".flags"
2607 environment variable. To override a setting in the static
2608 list, simply add an entry for the same variable name to the
2611 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2612 regular expression. This allows multiple variables to define the same
2613 flags without explicitly listing them for each variable.
2615 The following definitions that deal with the placement and management
2616 of environment data (variable area); in general, we support the
2617 following configurations:
2619 - CONFIG_BUILD_ENVCRC:
2621 Builds up envcrc with the target environment so that external utils
2622 may easily extract it and embed it in final U-Boot images.
2624 BE CAREFUL! The first access to the environment happens quite early
2625 in U-Boot initialization (when we try to get the setting of for the
2626 console baudrate). You *MUST* have mapped your NVRAM area then, or
2629 Please note that even with NVRAM we still use a copy of the
2630 environment in RAM: we could work on NVRAM directly, but we want to
2631 keep settings there always unmodified except somebody uses "saveenv"
2632 to save the current settings.
2634 BE CAREFUL! For some special cases, the local device can not use
2635 "saveenv" command. For example, the local device will get the
2636 environment stored in a remote NOR flash by SRIO or PCIE link,
2637 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2639 - CONFIG_NAND_ENV_DST
2641 Defines address in RAM to which the nand_spl code should copy the
2642 environment. If redundant environment is used, it will be copied to
2643 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2645 Please note that the environment is read-only until the monitor
2646 has been relocated to RAM and a RAM copy of the environment has been
2647 created; also, when using EEPROM you will have to use env_get_f()
2648 until then to read environment variables.
2650 The environment is protected by a CRC32 checksum. Before the monitor
2651 is relocated into RAM, as a result of a bad CRC you will be working
2652 with the compiled-in default environment - *silently*!!! [This is
2653 necessary, because the first environment variable we need is the
2654 "baudrate" setting for the console - if we have a bad CRC, we don't
2655 have any device yet where we could complain.]
2657 Note: once the monitor has been relocated, then it will complain if
2658 the default environment is used; a new CRC is computed as soon as you
2659 use the "saveenv" command to store a valid environment.
2661 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2662 Echo the inverted Ethernet link state to the fault LED.
2664 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2665 also needs to be defined.
2667 - CONFIG_SYS_FAULT_MII_ADDR:
2668 MII address of the PHY to check for the Ethernet link state.
2670 - CONFIG_NS16550_MIN_FUNCTIONS:
2671 Define this if you desire to only have use of the NS16550_init
2672 and NS16550_putc functions for the serial driver located at
2673 drivers/serial/ns16550.c. This option is useful for saving
2674 space for already greatly restricted images, including but not
2675 limited to NAND_SPL configurations.
2677 - CONFIG_DISPLAY_BOARDINFO
2678 Display information about the board that U-Boot is running on
2679 when U-Boot starts up. The board function checkboard() is called
2682 - CONFIG_DISPLAY_BOARDINFO_LATE
2683 Similar to the previous option, but display this information
2684 later, once stdio is running and output goes to the LCD, if
2687 - CONFIG_BOARD_SIZE_LIMIT:
2688 Maximum size of the U-Boot image. When defined, the
2689 build system checks that the actual size does not
2692 Low Level (hardware related) configuration options:
2693 ---------------------------------------------------
2695 - CONFIG_SYS_CACHELINE_SIZE:
2696 Cache Line Size of the CPU.
2698 - CONFIG_SYS_CCSRBAR_DEFAULT:
2699 Default (power-on reset) physical address of CCSR on Freescale
2702 - CONFIG_SYS_CCSRBAR:
2703 Virtual address of CCSR. On a 32-bit build, this is typically
2704 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2706 - CONFIG_SYS_CCSRBAR_PHYS:
2707 Physical address of CCSR. CCSR can be relocated to a new
2708 physical address, if desired. In this case, this macro should
2709 be set to that address. Otherwise, it should be set to the
2710 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2711 is typically relocated on 36-bit builds. It is recommended
2712 that this macro be defined via the _HIGH and _LOW macros:
2714 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2715 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2717 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2718 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2719 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2720 used in assembly code, so it must not contain typecasts or
2721 integer size suffixes (e.g. "ULL").
2723 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2724 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2725 used in assembly code, so it must not contain typecasts or
2726 integer size suffixes (e.g. "ULL").
2728 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2729 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2730 forced to a value that ensures that CCSR is not relocated.
2733 Most IDE controllers were designed to be connected with PCI
2734 interface. Only few of them were designed for AHB interface.
2735 When software is doing ATA command and data transfer to
2736 IDE devices through IDE-AHB controller, some additional
2737 registers accessing to these kind of IDE-AHB controller
2740 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2741 DO NOT CHANGE unless you know exactly what you're
2742 doing! (11-4) [MPC8xx systems only]
2744 - CONFIG_SYS_INIT_RAM_ADDR:
2746 Start address of memory area that can be used for
2747 initial data and stack; please note that this must be
2748 writable memory that is working WITHOUT special
2749 initialization, i. e. you CANNOT use normal RAM which
2750 will become available only after programming the
2751 memory controller and running certain initialization
2754 U-Boot uses the following memory types:
2755 - MPC8xx: IMMR (internal memory of the CPU)
2757 - CONFIG_SYS_GBL_DATA_OFFSET:
2759 Offset of the initial data structure in the memory
2760 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2761 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2762 data is located at the end of the available space
2763 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2764 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2765 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2766 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2769 On the MPC824X (or other systems that use the data
2770 cache for initial memory) the address chosen for
2771 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2772 point to an otherwise UNUSED address space between
2773 the top of RAM and the start of the PCI space.
2775 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2777 - CONFIG_SYS_OR_TIMING_SDRAM:
2780 - CONFIG_SYS_MAMR_PTA:
2781 periodic timer for refresh
2783 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2784 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2785 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2786 CONFIG_SYS_BR1_PRELIM:
2787 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2789 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2790 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2791 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2792 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2794 - CONFIG_PCI_ENUM_ONLY
2795 Only scan through and get the devices on the buses.
2796 Don't do any setup work, presumably because someone or
2797 something has already done it, and we don't need to do it
2798 a second time. Useful for platforms that are pre-booted
2799 by coreboot or similar.
2801 - CONFIG_PCI_INDIRECT_BRIDGE:
2802 Enable support for indirect PCI bridges.
2805 Chip has SRIO or not
2808 Board has SRIO 1 port available
2811 Board has SRIO 2 port available
2813 - CONFIG_SRIO_PCIE_BOOT_MASTER
2814 Board can support master function for Boot from SRIO and PCIE
2816 - CONFIG_SYS_SRIOn_MEM_VIRT:
2817 Virtual Address of SRIO port 'n' memory region
2819 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2820 Physical Address of SRIO port 'n' memory region
2822 - CONFIG_SYS_SRIOn_MEM_SIZE:
2823 Size of SRIO port 'n' memory region
2825 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2826 Defined to tell the NAND controller that the NAND chip is using
2828 Not all NAND drivers use this symbol.
2829 Example of drivers that use it:
2830 - drivers/mtd/nand/raw/ndfc.c
2831 - drivers/mtd/nand/raw/mxc_nand.c
2833 - CONFIG_SYS_NDFC_EBC0_CFG
2834 Sets the EBC0_CFG register for the NDFC. If not defined
2835 a default value will be used.
2838 Get DDR timing information from an I2C EEPROM. Common
2839 with pluggable memory modules such as SODIMMs
2842 I2C address of the SPD EEPROM
2844 - CONFIG_SYS_SPD_BUS_NUM
2845 If SPD EEPROM is on an I2C bus other than the first
2846 one, specify here. Note that the value must resolve
2847 to something your driver can deal with.
2849 - CONFIG_SYS_DDR_RAW_TIMING
2850 Get DDR timing information from other than SPD. Common with
2851 soldered DDR chips onboard without SPD. DDR raw timing
2852 parameters are extracted from datasheet and hard-coded into
2853 header files or board specific files.
2855 - CONFIG_FSL_DDR_INTERACTIVE
2856 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2858 - CONFIG_FSL_DDR_SYNC_REFRESH
2859 Enable sync of refresh for multiple controllers.
2861 - CONFIG_FSL_DDR_BIST
2862 Enable built-in memory test for Freescale DDR controllers.
2864 - CONFIG_SYS_83XX_DDR_USES_CS0
2865 Only for 83xx systems. If specified, then DDR should
2866 be configured using CS0 and CS1 instead of CS2 and CS3.
2869 Enable RMII mode for all FECs.
2870 Note that this is a global option, we can't
2871 have one FEC in standard MII mode and another in RMII mode.
2873 - CONFIG_CRC32_VERIFY
2874 Add a verify option to the crc32 command.
2877 => crc32 -v <address> <count> <crc32>
2879 Where address/count indicate a memory area
2880 and crc32 is the correct crc32 which the
2884 Add the "loopw" memory command. This only takes effect if
2885 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2887 - CONFIG_CMD_MX_CYCLIC
2888 Add the "mdc" and "mwc" memory commands. These are cyclic
2893 This command will print 4 bytes (10,11,12,13) each 500 ms.
2895 => mwc.l 100 12345678 10
2896 This command will write 12345678 to address 100 all 10 ms.
2898 This only takes effect if the memory commands are activated
2899 globally (CONFIG_CMD_MEMORY).
2901 - CONFIG_SKIP_LOWLEVEL_INIT
2902 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
2903 low level initializations (like setting up the memory
2904 controller) are omitted and/or U-Boot does not
2905 relocate itself into RAM.
2907 Normally this variable MUST NOT be defined. The only
2908 exception is when U-Boot is loaded (to RAM) by some
2909 other boot loader or by a debugger which performs
2910 these initializations itself.
2912 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
2913 [ARM926EJ-S only] This allows just the call to lowlevel_init()
2914 to be skipped. The normal CP15 init (such as enabling the
2915 instruction cache) is still performed.
2918 Set when the currently-running compilation is for an artifact
2919 that will end up in the SPL (as opposed to the TPL or U-Boot
2920 proper). Code that needs stage-specific behavior should check
2924 Set when the currently-running compilation is for an artifact
2925 that will end up in the TPL (as opposed to the SPL or U-Boot
2926 proper). Code that needs stage-specific behavior should check
2929 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2930 Only for 85xx systems. If this variable is specified, the section
2931 .resetvec is not kept and the section .bootpg is placed in the
2932 previous 4k of the .text section.
2934 - CONFIG_ARCH_MAP_SYSMEM
2935 Generally U-Boot (and in particular the md command) uses
2936 effective address. It is therefore not necessary to regard
2937 U-Boot address as virtual addresses that need to be translated
2938 to physical addresses. However, sandbox requires this, since
2939 it maintains its own little RAM buffer which contains all
2940 addressable memory. This option causes some memory accesses
2941 to be mapped through map_sysmem() / unmap_sysmem().
2943 - CONFIG_X86_RESET_VECTOR
2944 If defined, the x86 reset vector code is included. This is not
2945 needed when U-Boot is running from Coreboot.
2947 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2948 Option to disable subpage write in NAND driver
2949 driver that uses this:
2950 drivers/mtd/nand/raw/davinci_nand.c
2952 Freescale QE/FMAN Firmware Support:
2953 -----------------------------------
2955 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2956 loading of "firmware", which is encoded in the QE firmware binary format.
2957 This firmware often needs to be loaded during U-Boot booting, so macros
2958 are used to identify the storage device (NOR flash, SPI, etc) and the address
2961 - CONFIG_SYS_FMAN_FW_ADDR
2962 The address in the storage device where the FMAN microcode is located. The
2963 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2966 - CONFIG_SYS_QE_FW_ADDR
2967 The address in the storage device where the QE microcode is located. The
2968 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2971 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2972 The maximum possible size of the firmware. The firmware binary format
2973 has a field that specifies the actual size of the firmware, but it
2974 might not be possible to read any part of the firmware unless some
2975 local storage is allocated to hold the entire firmware first.
2977 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2978 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2979 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2980 virtual address in NOR flash.
2982 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2983 Specifies that QE/FMAN firmware is located in NAND flash.
2984 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2986 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2987 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2988 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2990 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2991 Specifies that QE/FMAN firmware is located in the remote (master)
2992 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2993 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2994 window->master inbound window->master LAW->the ucode address in
2995 master's memory space.
2997 Freescale Layerscape Management Complex Firmware Support:
2998 ---------------------------------------------------------
2999 The Freescale Layerscape Management Complex (MC) supports the loading of
3001 This firmware often needs to be loaded during U-Boot booting, so macros
3002 are used to identify the storage device (NOR flash, SPI, etc) and the address
3005 - CONFIG_FSL_MC_ENET
3006 Enable the MC driver for Layerscape SoCs.
3008 Freescale Layerscape Debug Server Support:
3009 -------------------------------------------
3010 The Freescale Layerscape Debug Server Support supports the loading of
3011 "Debug Server firmware" and triggering SP boot-rom.
3012 This firmware often needs to be loaded during U-Boot booting.
3014 - CONFIG_SYS_MC_RSV_MEM_ALIGN
3015 Define alignment of reserved memory MC requires
3020 In order to achieve reproducible builds, timestamps used in the U-Boot build
3021 process have to be set to a fixed value.
3023 This is done using the SOURCE_DATE_EPOCH environment variable.
3024 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
3025 option for U-Boot or an environment variable in U-Boot.
3027 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
3029 Building the Software:
3030 ======================
3032 Building U-Boot has been tested in several native build environments
3033 and in many different cross environments. Of course we cannot support
3034 all possibly existing versions of cross development tools in all
3035 (potentially obsolete) versions. In case of tool chain problems we
3036 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3037 which is extensively used to build and test U-Boot.
3039 If you are not using a native environment, it is assumed that you
3040 have GNU cross compiling tools available in your path. In this case,
3041 you must set the environment variable CROSS_COMPILE in your shell.
3042 Note that no changes to the Makefile or any other source files are
3043 necessary. For example using the ELDK on a 4xx CPU, please enter:
3045 $ CROSS_COMPILE=ppc_4xx-
3046 $ export CROSS_COMPILE
3048 U-Boot is intended to be simple to build. After installing the
3049 sources you must configure U-Boot for one specific board type. This
3054 where "NAME_defconfig" is the name of one of the existing configu-
3055 rations; see configs/*_defconfig for supported names.
3057 Note: for some boards special configuration names may exist; check if
3058 additional information is available from the board vendor; for
3059 instance, the TQM823L systems are available without (standard)
3060 or with LCD support. You can select such additional "features"
3061 when choosing the configuration, i. e.
3063 make TQM823L_defconfig
3064 - will configure for a plain TQM823L, i. e. no LCD support
3066 make TQM823L_LCD_defconfig
3067 - will configure for a TQM823L with U-Boot console on LCD
3072 Finally, type "make all", and you should get some working U-Boot
3073 images ready for download to / installation on your system:
3075 - "u-boot.bin" is a raw binary image
3076 - "u-boot" is an image in ELF binary format
3077 - "u-boot.srec" is in Motorola S-Record format
3079 By default the build is performed locally and the objects are saved
3080 in the source directory. One of the two methods can be used to change
3081 this behavior and build U-Boot to some external directory:
3083 1. Add O= to the make command line invocations:
3085 make O=/tmp/build distclean
3086 make O=/tmp/build NAME_defconfig
3087 make O=/tmp/build all
3089 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3091 export KBUILD_OUTPUT=/tmp/build
3096 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3099 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3100 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3101 For example to treat all compiler warnings as errors:
3103 make KCFLAGS=-Werror
3105 Please be aware that the Makefiles assume you are using GNU make, so
3106 for instance on NetBSD you might need to use "gmake" instead of
3110 If the system board that you have is not listed, then you will need
3111 to port U-Boot to your hardware platform. To do this, follow these
3114 1. Create a new directory to hold your board specific code. Add any
3115 files you need. In your board directory, you will need at least
3116 the "Makefile" and a "<board>.c".
3117 2. Create a new configuration file "include/configs/<board>.h" for
3119 3. If you're porting U-Boot to a new CPU, then also create a new
3120 directory to hold your CPU specific code. Add any files you need.
3121 4. Run "make <board>_defconfig" with your new name.
3122 5. Type "make", and you should get a working "u-boot.srec" file
3123 to be installed on your target system.
3124 6. Debug and solve any problems that might arise.
3125 [Of course, this last step is much harder than it sounds.]
3128 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3129 ==============================================================
3131 If you have modified U-Boot sources (for instance added a new board
3132 or support for new devices, a new CPU, etc.) you are expected to
3133 provide feedback to the other developers. The feedback normally takes
3134 the form of a "patch", i.e. a context diff against a certain (latest
3135 official or latest in the git repository) version of U-Boot sources.
3137 But before you submit such a patch, please verify that your modifi-
3138 cation did not break existing code. At least make sure that *ALL* of
3139 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3140 just run the buildman script (tools/buildman/buildman), which will
3141 configure and build U-Boot for ALL supported system. Be warned, this
3142 will take a while. Please see the buildman README, or run 'buildman -H'
3146 See also "U-Boot Porting Guide" below.
3149 Monitor Commands - Overview:
3150 ============================
3152 go - start application at address 'addr'
3153 run - run commands in an environment variable
3154 bootm - boot application image from memory
3155 bootp - boot image via network using BootP/TFTP protocol
3156 bootz - boot zImage from memory
3157 tftpboot- boot image via network using TFTP protocol
3158 and env variables "ipaddr" and "serverip"
3159 (and eventually "gatewayip")
3160 tftpput - upload a file via network using TFTP protocol
3161 rarpboot- boot image via network using RARP/TFTP protocol
3162 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3163 loads - load S-Record file over serial line
3164 loadb - load binary file over serial line (kermit mode)
3166 mm - memory modify (auto-incrementing)
3167 nm - memory modify (constant address)
3168 mw - memory write (fill)
3171 cmp - memory compare
3172 crc32 - checksum calculation
3173 i2c - I2C sub-system
3174 sspi - SPI utility commands
3175 base - print or set address offset
3176 printenv- print environment variables
3177 setenv - set environment variables
3178 saveenv - save environment variables to persistent storage
3179 protect - enable or disable FLASH write protection
3180 erase - erase FLASH memory
3181 flinfo - print FLASH memory information
3182 nand - NAND memory operations (see doc/README.nand)
3183 bdinfo - print Board Info structure
3184 iminfo - print header information for application image
3185 coninfo - print console devices and informations
3186 ide - IDE sub-system
3187 loop - infinite loop on address range
3188 loopw - infinite write loop on address range
3189 mtest - simple RAM test
3190 icache - enable or disable instruction cache
3191 dcache - enable or disable data cache
3192 reset - Perform RESET of the CPU
3193 echo - echo args to console
3194 version - print monitor version
3195 help - print online help
3196 ? - alias for 'help'
3199 Monitor Commands - Detailed Description:
3200 ========================================
3204 For now: just type "help <command>".
3207 Environment Variables:
3208 ======================
3210 U-Boot supports user configuration using Environment Variables which
3211 can be made persistent by saving to Flash memory.
3213 Environment Variables are set using "setenv", printed using
3214 "printenv", and saved to Flash using "saveenv". Using "setenv"
3215 without a value can be used to delete a variable from the
3216 environment. As long as you don't save the environment you are
3217 working with an in-memory copy. In case the Flash area containing the
3218 environment is erased by accident, a default environment is provided.
3220 Some configuration options can be set using Environment Variables.
3222 List of environment variables (most likely not complete):
3224 baudrate - see CONFIG_BAUDRATE
3226 bootdelay - see CONFIG_BOOTDELAY
3228 bootcmd - see CONFIG_BOOTCOMMAND
3230 bootargs - Boot arguments when booting an RTOS image
3232 bootfile - Name of the image to load with TFTP
3234 bootm_low - Memory range available for image processing in the bootm
3235 command can be restricted. This variable is given as
3236 a hexadecimal number and defines lowest address allowed
3237 for use by the bootm command. See also "bootm_size"
3238 environment variable. Address defined by "bootm_low" is
3239 also the base of the initial memory mapping for the Linux
3240 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3243 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3244 This variable is given as a hexadecimal number and it
3245 defines the size of the memory region starting at base
3246 address bootm_low that is accessible by the Linux kernel
3247 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3248 as the default value if it is defined, and bootm_size is
3251 bootm_size - Memory range available for image processing in the bootm
3252 command can be restricted. This variable is given as
3253 a hexadecimal number and defines the size of the region
3254 allowed for use by the bootm command. See also "bootm_low"
3255 environment variable.
3257 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3259 updatefile - Location of the software update file on a TFTP server, used
3260 by the automatic software update feature. Please refer to
3261 documentation in doc/README.update for more details.
3263 autoload - if set to "no" (any string beginning with 'n'),
3264 "bootp" will just load perform a lookup of the
3265 configuration from the BOOTP server, but not try to
3266 load any image using TFTP
3268 autostart - if set to "yes", an image loaded using the "bootp",
3269 "rarpboot", "tftpboot" or "diskboot" commands will
3270 be automatically started (by internally calling
3273 If set to "no", a standalone image passed to the
3274 "bootm" command will be copied to the load address
3275 (and eventually uncompressed), but NOT be started.
3276 This can be used to load and uncompress arbitrary
3279 fdt_high - if set this restricts the maximum address that the
3280 flattened device tree will be copied into upon boot.
3281 For example, if you have a system with 1 GB memory
3282 at physical address 0x10000000, while Linux kernel
3283 only recognizes the first 704 MB as low memory, you
3284 may need to set fdt_high as 0x3C000000 to have the
3285 device tree blob be copied to the maximum address
3286 of the 704 MB low memory, so that Linux kernel can
3287 access it during the boot procedure.
3289 If this is set to the special value 0xFFFFFFFF then
3290 the fdt will not be copied at all on boot. For this
3291 to work it must reside in writable memory, have
3292 sufficient padding on the end of it for u-boot to
3293 add the information it needs into it, and the memory
3294 must be accessible by the kernel.
3296 fdtcontroladdr- if set this is the address of the control flattened
3297 device tree used by U-Boot when CONFIG_OF_CONTROL is
3300 i2cfast - (PPC405GP|PPC405EP only)
3301 if set to 'y' configures Linux I2C driver for fast
3302 mode (400kHZ). This environment variable is used in
3303 initialization code. So, for changes to be effective
3304 it must be saved and board must be reset.
3306 initrd_high - restrict positioning of initrd images:
3307 If this variable is not set, initrd images will be
3308 copied to the highest possible address in RAM; this
3309 is usually what you want since it allows for
3310 maximum initrd size. If for some reason you want to
3311 make sure that the initrd image is loaded below the
3312 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3313 variable to a value of "no" or "off" or "0".
3314 Alternatively, you can set it to a maximum upper
3315 address to use (U-Boot will still check that it
3316 does not overwrite the U-Boot stack and data).
3318 For instance, when you have a system with 16 MB
3319 RAM, and want to reserve 4 MB from use by Linux,
3320 you can do this by adding "mem=12M" to the value of
3321 the "bootargs" variable. However, now you must make
3322 sure that the initrd image is placed in the first
3323 12 MB as well - this can be done with
3325 setenv initrd_high 00c00000
3327 If you set initrd_high to 0xFFFFFFFF, this is an
3328 indication to U-Boot that all addresses are legal
3329 for the Linux kernel, including addresses in flash
3330 memory. In this case U-Boot will NOT COPY the
3331 ramdisk at all. This may be useful to reduce the
3332 boot time on your system, but requires that this
3333 feature is supported by your Linux kernel.
3335 ipaddr - IP address; needed for tftpboot command
3337 loadaddr - Default load address for commands like "bootp",
3338 "rarpboot", "tftpboot", "loadb" or "diskboot"
3340 loads_echo - see CONFIG_LOADS_ECHO
3342 serverip - TFTP server IP address; needed for tftpboot command
3344 bootretry - see CONFIG_BOOT_RETRY_TIME
3346 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3348 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3350 ethprime - controls which interface is used first.
3352 ethact - controls which interface is currently active.
3353 For example you can do the following
3355 => setenv ethact FEC
3356 => ping 192.168.0.1 # traffic sent on FEC
3357 => setenv ethact SCC
3358 => ping 10.0.0.1 # traffic sent on SCC
3360 ethrotate - When set to "no" U-Boot does not go through all
3361 available network interfaces.
3362 It just stays at the currently selected interface.
3364 netretry - When set to "no" each network operation will
3365 either succeed or fail without retrying.
3366 When set to "once" the network operation will
3367 fail when all the available network interfaces
3368 are tried once without success.
3369 Useful on scripts which control the retry operation
3372 npe_ucode - set load address for the NPE microcode
3374 silent_linux - If set then Linux will be told to boot silently, by
3375 changing the console to be empty. If "yes" it will be
3376 made silent. If "no" it will not be made silent. If
3377 unset, then it will be made silent if the U-Boot console
3380 tftpsrcp - If this is set, the value is used for TFTP's
3383 tftpdstp - If this is set, the value is used for TFTP's UDP
3384 destination port instead of the Well Know Port 69.
3386 tftpblocksize - Block size to use for TFTP transfers; if not set,
3387 we use the TFTP server's default block size
3389 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3390 seconds, minimum value is 1000 = 1 second). Defines
3391 when a packet is considered to be lost so it has to
3392 be retransmitted. The default is 5000 = 5 seconds.
3393 Lowering this value may make downloads succeed
3394 faster in networks with high packet loss rates or
3395 with unreliable TFTP servers.
3397 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3398 unit, minimum value = 0). Defines how many timeouts
3399 can happen during a single file transfer before that
3400 transfer is aborted. The default is 10, and 0 means
3401 'no timeouts allowed'. Increasing this value may help
3402 downloads succeed with high packet loss rates, or with
3403 unreliable TFTP servers or client hardware.
3405 tftpwindowsize - if this is set, the value is used for TFTP's
3406 window size as described by RFC 7440.
3407 This means the count of blocks we can receive before
3408 sending ack to server.
3410 vlan - When set to a value < 4095 the traffic over
3411 Ethernet is encapsulated/received over 802.1q
3414 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3415 Unsigned value, in milliseconds. If not set, the period will
3416 be either the default (28000), or a value based on
3417 CONFIG_NET_RETRY_COUNT, if defined. This value has
3418 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3420 memmatches - Number of matches found by the last 'ms' command, in hex
3422 memaddr - Address of the last match found by the 'ms' command, in hex,
3425 mempos - Index position of the last match found by the 'ms' command,
3426 in units of the size (.b, .w, .l) of the search
3429 The following image location variables contain the location of images
3430 used in booting. The "Image" column gives the role of the image and is
3431 not an environment variable name. The other columns are environment
3432 variable names. "File Name" gives the name of the file on a TFTP
3433 server, "RAM Address" gives the location in RAM the image will be
3434 loaded to, and "Flash Location" gives the image's address in NOR
3435 flash or offset in NAND flash.
3437 *Note* - these variables don't have to be defined for all boards, some
3438 boards currently use other variables for these purposes, and some
3439 boards use these variables for other purposes.
3441 Image File Name RAM Address Flash Location
3442 ----- --------- ----------- --------------
3443 u-boot u-boot u-boot_addr_r u-boot_addr
3444 Linux kernel bootfile kernel_addr_r kernel_addr
3445 device tree blob fdtfile fdt_addr_r fdt_addr
3446 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3448 The following environment variables may be used and automatically
3449 updated by the network boot commands ("bootp" and "rarpboot"),
3450 depending the information provided by your boot server:
3452 bootfile - see above
3453 dnsip - IP address of your Domain Name Server
3454 dnsip2 - IP address of your secondary Domain Name Server
3455 gatewayip - IP address of the Gateway (Router) to use
3456 hostname - Target hostname
3458 netmask - Subnet Mask
3459 rootpath - Pathname of the root filesystem on the NFS server
3460 serverip - see above
3463 There are two special Environment Variables:
3465 serial# - contains hardware identification information such
3466 as type string and/or serial number
3467 ethaddr - Ethernet address
3469 These variables can be set only once (usually during manufacturing of
3470 the board). U-Boot refuses to delete or overwrite these variables
3471 once they have been set once.
3474 Further special Environment Variables:
3476 ver - Contains the U-Boot version string as printed
3477 with the "version" command. This variable is
3478 readonly (see CONFIG_VERSION_VARIABLE).
3481 Please note that changes to some configuration parameters may take
3482 only effect after the next boot (yes, that's just like Windoze :-).
3485 Callback functions for environment variables:
3486 ---------------------------------------------
3488 For some environment variables, the behavior of u-boot needs to change
3489 when their values are changed. This functionality allows functions to
3490 be associated with arbitrary variables. On creation, overwrite, or
3491 deletion, the callback will provide the opportunity for some side
3492 effect to happen or for the change to be rejected.
3494 The callbacks are named and associated with a function using the
3495 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3497 These callbacks are associated with variables in one of two ways. The
3498 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3499 in the board configuration to a string that defines a list of
3500 associations. The list must be in the following format:
3502 entry = variable_name[:callback_name]
3505 If the callback name is not specified, then the callback is deleted.
3506 Spaces are also allowed anywhere in the list.
3508 Callbacks can also be associated by defining the ".callbacks" variable
3509 with the same list format above. Any association in ".callbacks" will
3510 override any association in the static list. You can define
3511 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3512 ".callbacks" environment variable in the default or embedded environment.
3514 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3515 regular expression. This allows multiple variables to be connected to
3516 the same callback without explicitly listing them all out.
3518 The signature of the callback functions is:
3520 int callback(const char *name, const char *value, enum env_op op, int flags)
3522 * name - changed environment variable
3523 * value - new value of the environment variable
3524 * op - operation (create, overwrite, or delete)
3525 * flags - attributes of the environment variable change, see flags H_* in
3528 The return value is 0 if the variable change is accepted and 1 otherwise.
3530 Command Line Parsing:
3531 =====================
3533 There are two different command line parsers available with U-Boot:
3534 the old "simple" one, and the much more powerful "hush" shell:
3536 Old, simple command line parser:
3537 --------------------------------
3539 - supports environment variables (through setenv / saveenv commands)
3540 - several commands on one line, separated by ';'
3541 - variable substitution using "... ${name} ..." syntax
3542 - special characters ('$', ';') can be escaped by prefixing with '\',
3544 setenv bootcmd bootm \${address}
3545 - You can also escape text by enclosing in single apostrophes, for example:
3546 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3551 - similar to Bourne shell, with control structures like
3552 if...then...else...fi, for...do...done; while...do...done,
3553 until...do...done, ...
3554 - supports environment ("global") variables (through setenv / saveenv
3555 commands) and local shell variables (through standard shell syntax
3556 "name=value"); only environment variables can be used with "run"
3562 (1) If a command line (or an environment variable executed by a "run"
3563 command) contains several commands separated by semicolon, and
3564 one of these commands fails, then the remaining commands will be
3567 (2) If you execute several variables with one call to run (i. e.
3568 calling run with a list of variables as arguments), any failing
3569 command will cause "run" to terminate, i. e. the remaining
3570 variables are not executed.
3572 Note for Redundant Ethernet Interfaces:
3573 =======================================
3575 Some boards come with redundant Ethernet interfaces; U-Boot supports
3576 such configurations and is capable of automatic selection of a
3577 "working" interface when needed. MAC assignment works as follows:
3579 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3580 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3581 "eth1addr" (=>eth1), "eth2addr", ...
3583 If the network interface stores some valid MAC address (for instance
3584 in SROM), this is used as default address if there is NO correspon-
3585 ding setting in the environment; if the corresponding environment
3586 variable is set, this overrides the settings in the card; that means:
3588 o If the SROM has a valid MAC address, and there is no address in the
3589 environment, the SROM's address is used.
3591 o If there is no valid address in the SROM, and a definition in the
3592 environment exists, then the value from the environment variable is
3595 o If both the SROM and the environment contain a MAC address, and
3596 both addresses are the same, this MAC address is used.
3598 o If both the SROM and the environment contain a MAC address, and the
3599 addresses differ, the value from the environment is used and a
3602 o If neither SROM nor the environment contain a MAC address, an error
3603 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3604 a random, locally-assigned MAC is used.
3606 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3607 will be programmed into hardware as part of the initialization process. This
3608 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3609 The naming convention is as follows:
3610 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3615 U-Boot is capable of booting (and performing other auxiliary operations on)
3616 images in two formats:
3618 New uImage format (FIT)
3619 -----------------------
3621 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3622 to Flattened Device Tree). It allows the use of images with multiple
3623 components (several kernels, ramdisks, etc.), with contents protected by
3624 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3630 Old image format is based on binary files which can be basically anything,
3631 preceded by a special header; see the definitions in include/image.h for
3632 details; basically, the header defines the following image properties:
3634 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3635 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3636 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3637 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3639 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3640 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3641 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3642 * Compression Type (uncompressed, gzip, bzip2)
3648 The header is marked by a special Magic Number, and both the header
3649 and the data portions of the image are secured against corruption by
3656 Although U-Boot should support any OS or standalone application
3657 easily, the main focus has always been on Linux during the design of
3660 U-Boot includes many features that so far have been part of some
3661 special "boot loader" code within the Linux kernel. Also, any
3662 "initrd" images to be used are no longer part of one big Linux image;
3663 instead, kernel and "initrd" are separate images. This implementation
3664 serves several purposes:
3666 - the same features can be used for other OS or standalone
3667 applications (for instance: using compressed images to reduce the
3668 Flash memory footprint)
3670 - it becomes much easier to port new Linux kernel versions because
3671 lots of low-level, hardware dependent stuff are done by U-Boot
3673 - the same Linux kernel image can now be used with different "initrd"
3674 images; of course this also means that different kernel images can
3675 be run with the same "initrd". This makes testing easier (you don't
3676 have to build a new "zImage.initrd" Linux image when you just
3677 change a file in your "initrd"). Also, a field-upgrade of the
3678 software is easier now.
3684 Porting Linux to U-Boot based systems:
3685 ---------------------------------------
3687 U-Boot cannot save you from doing all the necessary modifications to
3688 configure the Linux device drivers for use with your target hardware
3689 (no, we don't intend to provide a full virtual machine interface to
3692 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3694 Just make sure your machine specific header file (for instance
3695 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3696 Information structure as we define in include/asm-<arch>/u-boot.h,
3697 and make sure that your definition of IMAP_ADDR uses the same value
3698 as your U-Boot configuration in CONFIG_SYS_IMMR.
3700 Note that U-Boot now has a driver model, a unified model for drivers.
3701 If you are adding a new driver, plumb it into driver model. If there
3702 is no uclass available, you are encouraged to create one. See
3706 Configuring the Linux kernel:
3707 -----------------------------
3709 No specific requirements for U-Boot. Make sure you have some root
3710 device (initial ramdisk, NFS) for your target system.
3713 Building a Linux Image:
3714 -----------------------
3716 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3717 not used. If you use recent kernel source, a new build target
3718 "uImage" will exist which automatically builds an image usable by
3719 U-Boot. Most older kernels also have support for a "pImage" target,
3720 which was introduced for our predecessor project PPCBoot and uses a
3721 100% compatible format.
3725 make TQM850L_defconfig
3730 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3731 encapsulate a compressed Linux kernel image with header information,
3732 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3734 * build a standard "vmlinux" kernel image (in ELF binary format):
3736 * convert the kernel into a raw binary image:
3738 ${CROSS_COMPILE}-objcopy -O binary \
3739 -R .note -R .comment \
3740 -S vmlinux linux.bin
3742 * compress the binary image:
3746 * package compressed binary image for U-Boot:
3748 mkimage -A ppc -O linux -T kernel -C gzip \
3749 -a 0 -e 0 -n "Linux Kernel Image" \
3750 -d linux.bin.gz uImage
3753 The "mkimage" tool can also be used to create ramdisk images for use
3754 with U-Boot, either separated from the Linux kernel image, or
3755 combined into one file. "mkimage" encapsulates the images with a 64
3756 byte header containing information about target architecture,
3757 operating system, image type, compression method, entry points, time
3758 stamp, CRC32 checksums, etc.
3760 "mkimage" can be called in two ways: to verify existing images and
3761 print the header information, or to build new images.
3763 In the first form (with "-l" option) mkimage lists the information
3764 contained in the header of an existing U-Boot image; this includes
3765 checksum verification:
3767 tools/mkimage -l image
3768 -l ==> list image header information
3770 The second form (with "-d" option) is used to build a U-Boot image
3771 from a "data file" which is used as image payload:
3773 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3774 -n name -d data_file image
3775 -A ==> set architecture to 'arch'
3776 -O ==> set operating system to 'os'
3777 -T ==> set image type to 'type'
3778 -C ==> set compression type 'comp'
3779 -a ==> set load address to 'addr' (hex)
3780 -e ==> set entry point to 'ep' (hex)
3781 -n ==> set image name to 'name'
3782 -d ==> use image data from 'datafile'
3784 Right now, all Linux kernels for PowerPC systems use the same load
3785 address (0x00000000), but the entry point address depends on the
3788 - 2.2.x kernels have the entry point at 0x0000000C,
3789 - 2.3.x and later kernels have the entry point at 0x00000000.
3791 So a typical call to build a U-Boot image would read:
3793 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3794 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3795 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3796 > examples/uImage.TQM850L
3797 Image Name: 2.4.4 kernel for TQM850L
3798 Created: Wed Jul 19 02:34:59 2000
3799 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3800 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3801 Load Address: 0x00000000
3802 Entry Point: 0x00000000
3804 To verify the contents of the image (or check for corruption):
3806 -> tools/mkimage -l examples/uImage.TQM850L
3807 Image Name: 2.4.4 kernel for TQM850L
3808 Created: Wed Jul 19 02:34:59 2000
3809 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3810 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3811 Load Address: 0x00000000
3812 Entry Point: 0x00000000
3814 NOTE: for embedded systems where boot time is critical you can trade
3815 speed for memory and install an UNCOMPRESSED image instead: this
3816 needs more space in Flash, but boots much faster since it does not
3817 need to be uncompressed:
3819 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3820 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3821 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3822 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3823 > examples/uImage.TQM850L-uncompressed
3824 Image Name: 2.4.4 kernel for TQM850L
3825 Created: Wed Jul 19 02:34:59 2000
3826 Image Type: PowerPC Linux Kernel Image (uncompressed)
3827 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3828 Load Address: 0x00000000
3829 Entry Point: 0x00000000
3832 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3833 when your kernel is intended to use an initial ramdisk:
3835 -> tools/mkimage -n 'Simple Ramdisk Image' \
3836 > -A ppc -O linux -T ramdisk -C gzip \
3837 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3838 Image Name: Simple Ramdisk Image
3839 Created: Wed Jan 12 14:01:50 2000
3840 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3841 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3842 Load Address: 0x00000000
3843 Entry Point: 0x00000000
3845 The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
3846 option performs the converse operation of the mkimage's second form (the "-d"
3847 option). Given an image built by mkimage, the dumpimage extracts a "data file"
3850 tools/dumpimage -i image -T type -p position data_file
3851 -i ==> extract from the 'image' a specific 'data_file'
3852 -T ==> set image type to 'type'
3853 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
3856 Installing a Linux Image:
3857 -------------------------
3859 To downloading a U-Boot image over the serial (console) interface,
3860 you must convert the image to S-Record format:
3862 objcopy -I binary -O srec examples/image examples/image.srec
3864 The 'objcopy' does not understand the information in the U-Boot
3865 image header, so the resulting S-Record file will be relative to
3866 address 0x00000000. To load it to a given address, you need to
3867 specify the target address as 'offset' parameter with the 'loads'
3870 Example: install the image to address 0x40100000 (which on the
3871 TQM8xxL is in the first Flash bank):
3873 => erase 40100000 401FFFFF
3879 ## Ready for S-Record download ...
3880 ~>examples/image.srec
3881 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3883 15989 15990 15991 15992
3884 [file transfer complete]
3886 ## Start Addr = 0x00000000
3889 You can check the success of the download using the 'iminfo' command;
3890 this includes a checksum verification so you can be sure no data
3891 corruption happened:
3895 ## Checking Image at 40100000 ...
3896 Image Name: 2.2.13 for initrd on TQM850L
3897 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3898 Data Size: 335725 Bytes = 327 kB = 0 MB
3899 Load Address: 00000000
3900 Entry Point: 0000000c
3901 Verifying Checksum ... OK
3907 The "bootm" command is used to boot an application that is stored in
3908 memory (RAM or Flash). In case of a Linux kernel image, the contents
3909 of the "bootargs" environment variable is passed to the kernel as
3910 parameters. You can check and modify this variable using the
3911 "printenv" and "setenv" commands:
3914 => printenv bootargs
3915 bootargs=root=/dev/ram
3917 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3919 => printenv bootargs
3920 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3923 ## Booting Linux kernel at 40020000 ...
3924 Image Name: 2.2.13 for NFS on TQM850L
3925 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3926 Data Size: 381681 Bytes = 372 kB = 0 MB
3927 Load Address: 00000000
3928 Entry Point: 0000000c
3929 Verifying Checksum ... OK
3930 Uncompressing Kernel Image ... OK
3931 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
3932 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3933 time_init: decrementer frequency = 187500000/60
3934 Calibrating delay loop... 49.77 BogoMIPS
3935 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3938 If you want to boot a Linux kernel with initial RAM disk, you pass
3939 the memory addresses of both the kernel and the initrd image (PPBCOOT
3940 format!) to the "bootm" command:
3942 => imi 40100000 40200000
3944 ## Checking Image at 40100000 ...
3945 Image Name: 2.2.13 for initrd on TQM850L
3946 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3947 Data Size: 335725 Bytes = 327 kB = 0 MB
3948 Load Address: 00000000
3949 Entry Point: 0000000c
3950 Verifying Checksum ... OK
3952 ## Checking Image at 40200000 ...
3953 Image Name: Simple Ramdisk Image
3954 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3955 Data Size: 566530 Bytes = 553 kB = 0 MB
3956 Load Address: 00000000
3957 Entry Point: 00000000
3958 Verifying Checksum ... OK
3960 => bootm 40100000 40200000
3961 ## Booting Linux kernel at 40100000 ...
3962 Image Name: 2.2.13 for initrd on TQM850L
3963 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3964 Data Size: 335725 Bytes = 327 kB = 0 MB
3965 Load Address: 00000000
3966 Entry Point: 0000000c
3967 Verifying Checksum ... OK
3968 Uncompressing Kernel Image ... OK
3969 ## Loading RAMDisk Image at 40200000 ...
3970 Image Name: Simple Ramdisk Image
3971 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3972 Data Size: 566530 Bytes = 553 kB = 0 MB
3973 Load Address: 00000000
3974 Entry Point: 00000000
3975 Verifying Checksum ... OK
3976 Loading Ramdisk ... OK
3977 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
3978 Boot arguments: root=/dev/ram
3979 time_init: decrementer frequency = 187500000/60
3980 Calibrating delay loop... 49.77 BogoMIPS
3982 RAMDISK: Compressed image found at block 0
3983 VFS: Mounted root (ext2 filesystem).
3987 Boot Linux and pass a flat device tree:
3990 First, U-Boot must be compiled with the appropriate defines. See the section
3991 titled "Linux Kernel Interface" above for a more in depth explanation. The
3992 following is an example of how to start a kernel and pass an updated
3998 oft=oftrees/mpc8540ads.dtb
3999 => tftp $oftaddr $oft
4000 Speed: 1000, full duplex
4002 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4003 Filename 'oftrees/mpc8540ads.dtb'.
4004 Load address: 0x300000
4007 Bytes transferred = 4106 (100a hex)
4008 => tftp $loadaddr $bootfile
4009 Speed: 1000, full duplex
4011 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4013 Load address: 0x200000
4014 Loading:############
4016 Bytes transferred = 1029407 (fb51f hex)
4021 => bootm $loadaddr - $oftaddr
4022 ## Booting image at 00200000 ...
4023 Image Name: Linux-2.6.17-dirty
4024 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4025 Data Size: 1029343 Bytes = 1005.2 kB
4026 Load Address: 00000000
4027 Entry Point: 00000000
4028 Verifying Checksum ... OK
4029 Uncompressing Kernel Image ... OK
4030 Booting using flat device tree at 0x300000
4031 Using MPC85xx ADS machine description
4032 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4036 More About U-Boot Image Types:
4037 ------------------------------
4039 U-Boot supports the following image types:
4041 "Standalone Programs" are directly runnable in the environment
4042 provided by U-Boot; it is expected that (if they behave
4043 well) you can continue to work in U-Boot after return from
4044 the Standalone Program.
4045 "OS Kernel Images" are usually images of some Embedded OS which
4046 will take over control completely. Usually these programs
4047 will install their own set of exception handlers, device
4048 drivers, set up the MMU, etc. - this means, that you cannot
4049 expect to re-enter U-Boot except by resetting the CPU.
4050 "RAMDisk Images" are more or less just data blocks, and their
4051 parameters (address, size) are passed to an OS kernel that is
4053 "Multi-File Images" contain several images, typically an OS
4054 (Linux) kernel image and one or more data images like
4055 RAMDisks. This construct is useful for instance when you want
4056 to boot over the network using BOOTP etc., where the boot
4057 server provides just a single image file, but you want to get
4058 for instance an OS kernel and a RAMDisk image.
4060 "Multi-File Images" start with a list of image sizes, each
4061 image size (in bytes) specified by an "uint32_t" in network
4062 byte order. This list is terminated by an "(uint32_t)0".
4063 Immediately after the terminating 0 follow the images, one by
4064 one, all aligned on "uint32_t" boundaries (size rounded up to
4065 a multiple of 4 bytes).
4067 "Firmware Images" are binary images containing firmware (like
4068 U-Boot or FPGA images) which usually will be programmed to
4071 "Script files" are command sequences that will be executed by
4072 U-Boot's command interpreter; this feature is especially
4073 useful when you configure U-Boot to use a real shell (hush)
4074 as command interpreter.
4076 Booting the Linux zImage:
4077 -------------------------
4079 On some platforms, it's possible to boot Linux zImage. This is done
4080 using the "bootz" command. The syntax of "bootz" command is the same
4081 as the syntax of "bootm" command.
4083 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
4084 kernel with raw initrd images. The syntax is slightly different, the
4085 address of the initrd must be augmented by it's size, in the following
4086 format: "<initrd addres>:<initrd size>".
4092 One of the features of U-Boot is that you can dynamically load and
4093 run "standalone" applications, which can use some resources of
4094 U-Boot like console I/O functions or interrupt services.
4096 Two simple examples are included with the sources:
4101 'examples/hello_world.c' contains a small "Hello World" Demo
4102 application; it is automatically compiled when you build U-Boot.
4103 It's configured to run at address 0x00040004, so you can play with it
4107 ## Ready for S-Record download ...
4108 ~>examples/hello_world.srec
4109 1 2 3 4 5 6 7 8 9 10 11 ...
4110 [file transfer complete]
4112 ## Start Addr = 0x00040004
4114 => go 40004 Hello World! This is a test.
4115 ## Starting application at 0x00040004 ...
4126 Hit any key to exit ...
4128 ## Application terminated, rc = 0x0
4130 Another example, which demonstrates how to register a CPM interrupt
4131 handler with the U-Boot code, can be found in 'examples/timer.c'.
4132 Here, a CPM timer is set up to generate an interrupt every second.
4133 The interrupt service routine is trivial, just printing a '.'
4134 character, but this is just a demo program. The application can be
4135 controlled by the following keys:
4137 ? - print current values og the CPM Timer registers
4138 b - enable interrupts and start timer
4139 e - stop timer and disable interrupts
4140 q - quit application
4143 ## Ready for S-Record download ...
4144 ~>examples/timer.srec
4145 1 2 3 4 5 6 7 8 9 10 11 ...
4146 [file transfer complete]
4148 ## Start Addr = 0x00040004
4151 ## Starting application at 0x00040004 ...
4154 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4157 [q, b, e, ?] Set interval 1000000 us
4160 [q, b, e, ?] ........
4161 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4164 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4167 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4170 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4172 [q, b, e, ?] ...Stopping timer
4174 [q, b, e, ?] ## Application terminated, rc = 0x0
4180 Over time, many people have reported problems when trying to use the
4181 "minicom" terminal emulation program for serial download. I (wd)
4182 consider minicom to be broken, and recommend not to use it. Under
4183 Unix, I recommend to use C-Kermit for general purpose use (and
4184 especially for kermit binary protocol download ("loadb" command), and
4185 use "cu" for S-Record download ("loads" command). See
4186 http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4187 for help with kermit.
4190 Nevertheless, if you absolutely want to use it try adding this
4191 configuration to your "File transfer protocols" section:
4193 Name Program Name U/D FullScr IO-Red. Multi
4194 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4195 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4201 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4202 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4204 Building requires a cross environment; it is known to work on
4205 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4206 need gmake since the Makefiles are not compatible with BSD make).
4207 Note that the cross-powerpc package does not install include files;
4208 attempting to build U-Boot will fail because <machine/ansi.h> is
4209 missing. This file has to be installed and patched manually:
4211 # cd /usr/pkg/cross/powerpc-netbsd/include
4213 # ln -s powerpc machine
4214 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4215 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4217 Native builds *don't* work due to incompatibilities between native
4218 and U-Boot include files.
4220 Booting assumes that (the first part of) the image booted is a
4221 stage-2 loader which in turn loads and then invokes the kernel
4222 proper. Loader sources will eventually appear in the NetBSD source
4223 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4224 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4227 Implementation Internals:
4228 =========================
4230 The following is not intended to be a complete description of every
4231 implementation detail. However, it should help to understand the
4232 inner workings of U-Boot and make it easier to port it to custom
4236 Initial Stack, Global Data:
4237 ---------------------------
4239 The implementation of U-Boot is complicated by the fact that U-Boot
4240 starts running out of ROM (flash memory), usually without access to
4241 system RAM (because the memory controller is not initialized yet).
4242 This means that we don't have writable Data or BSS segments, and BSS
4243 is not initialized as zero. To be able to get a C environment working
4244 at all, we have to allocate at least a minimal stack. Implementation
4245 options for this are defined and restricted by the CPU used: Some CPU
4246 models provide on-chip memory (like the IMMR area on MPC8xx and
4247 MPC826x processors), on others (parts of) the data cache can be
4248 locked as (mis-) used as memory, etc.
4250 Chris Hallinan posted a good summary of these issues to the
4251 U-Boot mailing list:
4253 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4254 From: "Chris Hallinan" <clh@net1plus.com>
4255 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4258 Correct me if I'm wrong, folks, but the way I understand it
4259 is this: Using DCACHE as initial RAM for Stack, etc, does not
4260 require any physical RAM backing up the cache. The cleverness
4261 is that the cache is being used as a temporary supply of
4262 necessary storage before the SDRAM controller is setup. It's
4263 beyond the scope of this list to explain the details, but you
4264 can see how this works by studying the cache architecture and
4265 operation in the architecture and processor-specific manuals.
4267 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4268 is another option for the system designer to use as an
4269 initial stack/RAM area prior to SDRAM being available. Either
4270 option should work for you. Using CS 4 should be fine if your
4271 board designers haven't used it for something that would
4272 cause you grief during the initial boot! It is frequently not
4275 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4276 with your processor/board/system design. The default value
4277 you will find in any recent u-boot distribution in
4278 walnut.h should work for you. I'd set it to a value larger
4279 than your SDRAM module. If you have a 64MB SDRAM module, set
4280 it above 400_0000. Just make sure your board has no resources
4281 that are supposed to respond to that address! That code in
4282 start.S has been around a while and should work as is when
4283 you get the config right.
4288 It is essential to remember this, since it has some impact on the C
4289 code for the initialization procedures:
4291 * Initialized global data (data segment) is read-only. Do not attempt
4294 * Do not use any uninitialized global data (or implicitly initialized
4295 as zero data - BSS segment) at all - this is undefined, initiali-
4296 zation is performed later (when relocating to RAM).
4298 * Stack space is very limited. Avoid big data buffers or things like
4301 Having only the stack as writable memory limits means we cannot use
4302 normal global data to share information between the code. But it
4303 turned out that the implementation of U-Boot can be greatly
4304 simplified by making a global data structure (gd_t) available to all
4305 functions. We could pass a pointer to this data as argument to _all_
4306 functions, but this would bloat the code. Instead we use a feature of
4307 the GCC compiler (Global Register Variables) to share the data: we
4308 place a pointer (gd) to the global data into a register which we
4309 reserve for this purpose.
4311 When choosing a register for such a purpose we are restricted by the
4312 relevant (E)ABI specifications for the current architecture, and by
4313 GCC's implementation.
4315 For PowerPC, the following registers have specific use:
4317 R2: reserved for system use
4318 R3-R4: parameter passing and return values
4319 R5-R10: parameter passing
4320 R13: small data area pointer
4324 (U-Boot also uses R12 as internal GOT pointer. r12
4325 is a volatile register so r12 needs to be reset when
4326 going back and forth between asm and C)
4328 ==> U-Boot will use R2 to hold a pointer to the global data
4330 Note: on PPC, we could use a static initializer (since the
4331 address of the global data structure is known at compile time),
4332 but it turned out that reserving a register results in somewhat
4333 smaller code - although the code savings are not that big (on
4334 average for all boards 752 bytes for the whole U-Boot image,
4335 624 text + 127 data).
4337 On ARM, the following registers are used:
4339 R0: function argument word/integer result
4340 R1-R3: function argument word
4341 R9: platform specific
4342 R10: stack limit (used only if stack checking is enabled)
4343 R11: argument (frame) pointer
4344 R12: temporary workspace
4347 R15: program counter
4349 ==> U-Boot will use R9 to hold a pointer to the global data
4351 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4353 On Nios II, the ABI is documented here:
4354 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4356 ==> U-Boot will use gp to hold a pointer to the global data
4358 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4359 to access small data sections, so gp is free.
4361 On NDS32, the following registers are used:
4363 R0-R1: argument/return
4365 R15: temporary register for assembler
4366 R16: trampoline register
4367 R28: frame pointer (FP)
4368 R29: global pointer (GP)
4369 R30: link register (LP)
4370 R31: stack pointer (SP)
4371 PC: program counter (PC)
4373 ==> U-Boot will use R10 to hold a pointer to the global data
4375 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4376 or current versions of GCC may "optimize" the code too much.
4378 On RISC-V, the following registers are used:
4380 x0: hard-wired zero (zero)
4381 x1: return address (ra)
4382 x2: stack pointer (sp)
4383 x3: global pointer (gp)
4384 x4: thread pointer (tp)
4385 x5: link register (t0)
4386 x8: frame pointer (fp)
4387 x10-x11: arguments/return values (a0-1)
4388 x12-x17: arguments (a2-7)
4389 x28-31: temporaries (t3-6)
4390 pc: program counter (pc)
4392 ==> U-Boot will use gp to hold a pointer to the global data
4397 U-Boot runs in system state and uses physical addresses, i.e. the
4398 MMU is not used either for address mapping nor for memory protection.
4400 The available memory is mapped to fixed addresses using the memory
4401 controller. In this process, a contiguous block is formed for each
4402 memory type (Flash, SDRAM, SRAM), even when it consists of several
4403 physical memory banks.
4405 U-Boot is installed in the first 128 kB of the first Flash bank (on
4406 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4407 booting and sizing and initializing DRAM, the code relocates itself
4408 to the upper end of DRAM. Immediately below the U-Boot code some
4409 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4410 configuration setting]. Below that, a structure with global Board
4411 Info data is placed, followed by the stack (growing downward).
4413 Additionally, some exception handler code is copied to the low 8 kB
4414 of DRAM (0x00000000 ... 0x00001FFF).
4416 So a typical memory configuration with 16 MB of DRAM could look like
4419 0x0000 0000 Exception Vector code
4422 0x0000 2000 Free for Application Use
4428 0x00FB FF20 Monitor Stack (Growing downward)
4429 0x00FB FFAC Board Info Data and permanent copy of global data
4430 0x00FC 0000 Malloc Arena
4433 0x00FE 0000 RAM Copy of Monitor Code
4434 ... eventually: LCD or video framebuffer
4435 ... eventually: pRAM (Protected RAM - unchanged by reset)
4436 0x00FF FFFF [End of RAM]
4439 System Initialization:
4440 ----------------------
4442 In the reset configuration, U-Boot starts at the reset entry point
4443 (on most PowerPC systems at address 0x00000100). Because of the reset
4444 configuration for CS0# this is a mirror of the on board Flash memory.
4445 To be able to re-map memory U-Boot then jumps to its link address.
4446 To be able to implement the initialization code in C, a (small!)
4447 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4448 which provide such a feature like), or in a locked part of the data
4449 cache. After that, U-Boot initializes the CPU core, the caches and
4452 Next, all (potentially) available memory banks are mapped using a
4453 preliminary mapping. For example, we put them on 512 MB boundaries
4454 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4455 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4456 programmed for SDRAM access. Using the temporary configuration, a
4457 simple memory test is run that determines the size of the SDRAM
4460 When there is more than one SDRAM bank, and the banks are of
4461 different size, the largest is mapped first. For equal size, the first
4462 bank (CS2#) is mapped first. The first mapping is always for address
4463 0x00000000, with any additional banks following immediately to create
4464 contiguous memory starting from 0.
4466 Then, the monitor installs itself at the upper end of the SDRAM area
4467 and allocates memory for use by malloc() and for the global Board
4468 Info data; also, the exception vector code is copied to the low RAM
4469 pages, and the final stack is set up.
4471 Only after this relocation will you have a "normal" C environment;
4472 until that you are restricted in several ways, mostly because you are
4473 running from ROM, and because the code will have to be relocated to a
4477 U-Boot Porting Guide:
4478 ----------------------
4480 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4484 int main(int argc, char *argv[])
4486 sighandler_t no_more_time;
4488 signal(SIGALRM, no_more_time);
4489 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4491 if (available_money > available_manpower) {
4492 Pay consultant to port U-Boot;
4496 Download latest U-Boot source;
4498 Subscribe to u-boot mailing list;
4501 email("Hi, I am new to U-Boot, how do I get started?");
4504 Read the README file in the top level directory;
4505 Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4506 Read applicable doc/README.*;
4507 Read the source, Luke;
4508 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4511 if (available_money > toLocalCurrency ($2500))
4514 Add a lot of aggravation and time;
4516 if (a similar board exists) { /* hopefully... */
4517 cp -a board/<similar> board/<myboard>
4518 cp include/configs/<similar>.h include/configs/<myboard>.h
4520 Create your own board support subdirectory;
4521 Create your own board include/configs/<myboard>.h file;
4523 Edit new board/<myboard> files
4524 Edit new include/configs/<myboard>.h
4529 Add / modify source code;
4533 email("Hi, I am having problems...");
4535 Send patch file to the U-Boot email list;
4536 if (reasonable critiques)
4537 Incorporate improvements from email list code review;
4539 Defend code as written;
4545 void no_more_time (int sig)
4554 All contributions to U-Boot should conform to the Linux kernel
4555 coding style; see the kernel coding style guide at
4556 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4557 script "scripts/Lindent" in your Linux kernel source directory.
4559 Source files originating from a different project (for example the
4560 MTD subsystem) are generally exempt from these guidelines and are not
4561 reformatted to ease subsequent migration to newer versions of those
4564 Please note that U-Boot is implemented in C (and to some small parts in
4565 Assembler); no C++ is used, so please do not use C++ style comments (//)
4568 Please also stick to the following formatting rules:
4569 - remove any trailing white space
4570 - use TAB characters for indentation and vertical alignment, not spaces
4571 - make sure NOT to use DOS '\r\n' line feeds
4572 - do not add more than 2 consecutive empty lines to source files
4573 - do not add trailing empty lines to source files
4575 Submissions which do not conform to the standards may be returned
4576 with a request to reformat the changes.
4582 Since the number of patches for U-Boot is growing, we need to
4583 establish some rules. Submissions which do not conform to these rules
4584 may be rejected, even when they contain important and valuable stuff.
4586 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4588 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4589 see https://lists.denx.de/listinfo/u-boot
4591 When you send a patch, please include the following information with
4594 * For bug fixes: a description of the bug and how your patch fixes
4595 this bug. Please try to include a way of demonstrating that the
4596 patch actually fixes something.
4598 * For new features: a description of the feature and your
4601 * For major contributions, add a MAINTAINERS file with your
4602 information and associated file and directory references.
4604 * When you add support for a new board, don't forget to add a
4605 maintainer e-mail address to the boards.cfg file, too.
4607 * If your patch adds new configuration options, don't forget to
4608 document these in the README file.
4610 * The patch itself. If you are using git (which is *strongly*
4611 recommended) you can easily generate the patch using the
4612 "git format-patch". If you then use "git send-email" to send it to
4613 the U-Boot mailing list, you will avoid most of the common problems
4614 with some other mail clients.
4616 If you cannot use git, use "diff -purN OLD NEW". If your version of
4617 diff does not support these options, then get the latest version of
4620 The current directory when running this command shall be the parent
4621 directory of the U-Boot source tree (i. e. please make sure that
4622 your patch includes sufficient directory information for the
4625 We prefer patches as plain text. MIME attachments are discouraged,
4626 and compressed attachments must not be used.
4628 * If one logical set of modifications affects or creates several
4629 files, all these changes shall be submitted in a SINGLE patch file.
4631 * Changesets that contain different, unrelated modifications shall be
4632 submitted as SEPARATE patches, one patch per changeset.
4637 * Before sending the patch, run the buildman script on your patched
4638 source tree and make sure that no errors or warnings are reported
4639 for any of the boards.
4641 * Keep your modifications to the necessary minimum: A patch
4642 containing several unrelated changes or arbitrary reformats will be
4643 returned with a request to re-formatting / split it.
4645 * If you modify existing code, make sure that your new code does not
4646 add to the memory footprint of the code ;-) Small is beautiful!
4647 When adding new features, these should compile conditionally only
4648 (using #ifdef), and the resulting code with the new feature
4649 disabled must not need more memory than the old code without your
4652 * Remember that there is a size limit of 100 kB per message on the
4653 u-boot mailing list. Bigger patches will be moderated. If they are
4654 reasonable and not too big, they will be acknowledged. But patches
4655 bigger than the size limit should be avoided.
projects / platform / kernel / u-boot.git / blob