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:
564 U-Boot stores all clock information in Hz
565 internally. For binary compatibility with older Linux
566 kernels (which expect the clocks passed in the
567 bd_info data to be in MHz) the environment variable
568 "clocks_in_mhz" can be defined so that U-Boot
569 converts clock data to MHZ before passing it to the
571 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
572 "clocks_in_mhz=1" is automatically included in the
575 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
577 When transferring memsize parameter to Linux, some versions
578 expect it to be in bytes, others in MB.
579 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
583 New kernel versions are expecting firmware settings to be
584 passed using flattened device trees (based on open firmware
588 * New libfdt-based support
589 * Adds the "fdt" command
590 * The bootm command automatically updates the fdt
592 OF_TBCLK - The timebase frequency.
593 OF_STDOUT_PATH - The path to the console device
595 boards with QUICC Engines require OF_QE to set UCC MAC
598 CONFIG_OF_BOARD_SETUP
600 Board code has addition modification that it wants to make
601 to the flat device tree before handing it off to the kernel
603 CONFIG_OF_SYSTEM_SETUP
605 Other code has addition modification that it wants to make
606 to the flat device tree before handing it off to the kernel.
607 This causes ft_system_setup() to be called before booting
612 U-Boot can detect if an IDE device is present or not.
613 If not, and this new config option is activated, U-Boot
614 removes the ATA node from the DTS before booting Linux,
615 so the Linux IDE driver does not probe the device and
616 crash. This is needed for buggy hardware (uc101) where
617 no pull down resistor is connected to the signal IDE5V_DD7.
619 CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
621 This setting is mandatory for all boards that have only one
622 machine type and must be used to specify the machine type
623 number as it appears in the ARM machine registry
624 (see http://www.arm.linux.org.uk/developer/machines/).
625 Only boards that have multiple machine types supported
626 in a single configuration file and the machine type is
627 runtime discoverable, do not have to use this setting.
629 - vxWorks boot parameters:
631 bootvx constructs a valid bootline using the following
632 environments variables: bootdev, bootfile, ipaddr, netmask,
633 serverip, gatewayip, hostname, othbootargs.
634 It loads the vxWorks image pointed bootfile.
636 Note: If a "bootargs" environment is defined, it will overwride
637 the defaults discussed just above.
639 - Cache Configuration:
640 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
642 - Cache Configuration for ARM:
643 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
645 CONFIG_SYS_PL310_BASE - Physical base address of PL310
646 controller register space
651 Define this if you want support for Amba PrimeCell PL010 UARTs.
655 Define this if you want support for Amba PrimeCell PL011 UARTs.
659 If you have Amba PrimeCell PL011 UARTs, set this variable to
660 the clock speed of the UARTs.
664 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
665 define this to a list of base addresses for each (supported)
666 port. See e.g. include/configs/versatile.h
668 CONFIG_SERIAL_HW_FLOW_CONTROL
670 Define this variable to enable hw flow control in serial driver.
671 Current user of this option is drivers/serial/nsl16550.c driver
674 CONFIG_BAUDRATE - in bps
675 Select one of the baudrates listed in
676 CONFIG_SYS_BAUDRATE_TABLE, see below.
680 Only needed when CONFIG_BOOTDELAY is enabled;
681 define a command string that is automatically executed
682 when no character is read on the console interface
683 within "Boot Delay" after reset.
685 CONFIG_RAMBOOT and CONFIG_NFSBOOT
686 The value of these goes into the environment as
687 "ramboot" and "nfsboot" respectively, and can be used
688 as a convenience, when switching between booting from
691 - Serial Download Echo Mode:
693 If defined to 1, all characters received during a
694 serial download (using the "loads" command) are
695 echoed back. This might be needed by some terminal
696 emulations (like "cu"), but may as well just take
697 time on others. This setting #define's the initial
698 value of the "loads_echo" environment variable.
700 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
702 Select one of the baudrates listed in
703 CONFIG_SYS_BAUDRATE_TABLE, see below.
705 - Removal of commands
706 If no commands are needed to boot, you can disable
707 CONFIG_CMDLINE to remove them. In this case, the command line
708 will not be available, and when U-Boot wants to execute the
709 boot command (on start-up) it will call board_run_command()
710 instead. This can reduce image size significantly for very
711 simple boot procedures.
713 - Regular expression support:
715 If this variable is defined, U-Boot is linked against
716 the SLRE (Super Light Regular Expression) library,
717 which adds regex support to some commands, as for
718 example "env grep" and "setexpr".
722 If this variable is defined, U-Boot will use a device tree
723 to configure its devices, instead of relying on statically
724 compiled #defines in the board file. This option is
725 experimental and only available on a few boards. The device
726 tree is available in the global data as gd->fdt_blob.
728 U-Boot needs to get its device tree from somewhere. This can
729 be done using one of the three options below:
732 If this variable is defined, U-Boot will embed a device tree
733 binary in its image. This device tree file should be in the
734 board directory and called <soc>-<board>.dts. The binary file
735 is then picked up in board_init_f() and made available through
736 the global data structure as gd->fdt_blob.
739 If this variable is defined, U-Boot will build a device tree
740 binary. It will be called u-boot.dtb. Architecture-specific
741 code will locate it at run-time. Generally this works by:
743 cat u-boot.bin u-boot.dtb >image.bin
745 and in fact, U-Boot does this for you, creating a file called
746 u-boot-dtb.bin which is useful in the common case. You can
747 still use the individual files if you need something more
751 If this variable is defined, U-Boot will use the device tree
752 provided by the board at runtime instead of embedding one with
753 the image. Only boards defining board_fdt_blob_setup() support
754 this option (see include/fdtdec.h file).
758 If this variable is defined, it enables watchdog
759 support for the SoC. There must be support in the SoC
760 specific code for a watchdog. For the 8xx
761 CPUs, the SIU Watchdog feature is enabled in the SYPCR
762 register. When supported for a specific SoC is
763 available, then no further board specific code should
767 When using a watchdog circuitry external to the used
768 SoC, then define this variable and provide board
769 specific code for the "hw_watchdog_reset" function.
773 When CONFIG_CMD_DATE is selected, the type of the RTC
774 has to be selected, too. Define exactly one of the
777 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
778 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
779 CONFIG_RTC_MC146818 - use MC146818 RTC
780 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
781 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
782 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
783 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
784 CONFIG_RTC_DS164x - use Dallas DS164x RTC
785 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
786 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
787 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
788 CONFIG_SYS_RV3029_TCR - enable trickle charger on
791 Note that if the RTC uses I2C, then the I2C interface
792 must also be configured. See I2C Support, below.
795 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
797 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
798 chip-ngpio pairs that tell the PCA953X driver the number of
799 pins supported by a particular chip.
801 Note that if the GPIO device uses I2C, then the I2C interface
802 must also be configured. See I2C Support, below.
805 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
806 accesses and can checksum them or write a list of them out
807 to memory. See the 'iotrace' command for details. This is
808 useful for testing device drivers since it can confirm that
809 the driver behaves the same way before and after a code
810 change. Currently this is supported on sandbox and arm. To
811 add support for your architecture, add '#include <iotrace.h>'
812 to the bottom of arch/<arch>/include/asm/io.h and test.
814 Example output from the 'iotrace stats' command is below.
815 Note that if the trace buffer is exhausted, the checksum will
816 still continue to operate.
819 Start: 10000000 (buffer start address)
820 Size: 00010000 (buffer size)
821 Offset: 00000120 (current buffer offset)
822 Output: 10000120 (start + offset)
823 Count: 00000018 (number of trace records)
824 CRC32: 9526fb66 (CRC32 of all trace records)
828 When CONFIG_TIMESTAMP is selected, the timestamp
829 (date and time) of an image is printed by image
830 commands like bootm or iminfo. This option is
831 automatically enabled when you select CONFIG_CMD_DATE .
833 - Partition Labels (disklabels) Supported:
834 Zero or more of the following:
835 CONFIG_MAC_PARTITION Apple's MacOS partition table.
836 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
837 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
838 bootloader. Note 2TB partition limit; see
840 CONFIG_SCSI) you must configure support for at
841 least one non-MTD partition type as well.
844 CONFIG_IDE_RESET_ROUTINE - this is defined in several
845 board configurations files but used nowhere!
847 CONFIG_IDE_RESET - is this is defined, IDE Reset will
848 be performed by calling the function
849 ide_set_reset(int reset)
850 which has to be defined in a board specific file
855 Set this to enable ATAPI support.
860 Set this to enable support for disks larger than 137GB
861 Also look at CONFIG_SYS_64BIT_LBA.
862 Whithout these , LBA48 support uses 32bit variables and will 'only'
863 support disks up to 2.1TB.
865 CONFIG_SYS_64BIT_LBA:
866 When enabled, makes the IDE subsystem use 64bit sector addresses.
870 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
871 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
872 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
873 maximum numbers of LUNs, SCSI ID's and target
876 The environment variable 'scsidevs' is set to the number of
877 SCSI devices found during the last scan.
879 - NETWORK Support (PCI):
881 Support for Intel 8254x/8257x gigabit chips.
884 Utility code for direct access to the SPI bus on Intel 8257x.
885 This does not do anything useful unless you set at least one
886 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
888 CONFIG_E1000_SPI_GENERIC
889 Allow generic access to the SPI bus on the Intel 8257x, for
890 example with the "sspi" command.
893 Support for Intel 82557/82559/82559ER chips.
894 Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
895 write routine for first time initialisation.
898 Support for Digital 2114x chips.
899 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
900 modem chip initialisation (KS8761/QS6611).
903 Support for National dp83815 chips.
906 Support for National dp8382[01] gigabit chips.
908 - NETWORK Support (other):
910 CONFIG_DRIVER_AT91EMAC
911 Support for AT91RM9200 EMAC.
914 Define this to use reduced MII inteface
916 CONFIG_DRIVER_AT91EMAC_QUIET
917 If this defined, the driver is quiet.
918 The driver doen't show link status messages.
921 Support for the Calxeda XGMAC device
924 Support for SMSC's LAN91C96 chips.
926 CONFIG_LAN91C96_USE_32_BIT
927 Define this to enable 32 bit addressing
930 Support for SMSC's LAN91C111 chip
933 Define this to hold the physical address
934 of the device (I/O space)
936 CONFIG_SMC_USE_32_BIT
937 Define this if data bus is 32 bits
939 CONFIG_SMC_USE_IOFUNCS
940 Define this to use i/o functions instead of macros
941 (some hardware wont work with macros)
943 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
944 Define this if you have more then 3 PHYs.
947 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
949 CONFIG_FTGMAC100_EGIGA
950 Define this to use GE link update with gigabit PHY.
951 Define this if FTGMAC100 is connected to gigabit PHY.
952 If your system has 10/100 PHY only, it might not occur
953 wrong behavior. Because PHY usually return timeout or
954 useless data when polling gigabit status and gigabit
955 control registers. This behavior won't affect the
956 correctnessof 10/100 link speed update.
959 Support for Renesas on-chip Ethernet controller
961 CONFIG_SH_ETHER_USE_PORT
962 Define the number of ports to be used
964 CONFIG_SH_ETHER_PHY_ADDR
965 Define the ETH PHY's address
967 CONFIG_SH_ETHER_CACHE_WRITEBACK
968 If this option is set, the driver enables cache flush.
974 CONFIG_TPM_TIS_INFINEON
975 Support for Infineon i2c bus TPM devices. Only one device
976 per system is supported at this time.
978 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
979 Define the burst count bytes upper limit
982 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
984 CONFIG_TPM_ST33ZP24_I2C
985 Support for STMicroelectronics ST33ZP24 I2C devices.
986 Requires TPM_ST33ZP24 and I2C.
988 CONFIG_TPM_ST33ZP24_SPI
989 Support for STMicroelectronics ST33ZP24 SPI devices.
990 Requires TPM_ST33ZP24 and SPI.
993 Support for Atmel TWI TPM device. Requires I2C support.
996 Support for generic parallel port TPM devices. Only one device
997 per system is supported at this time.
999 CONFIG_TPM_TIS_BASE_ADDRESS
1000 Base address where the generic TPM device is mapped
1001 to. Contemporary x86 systems usually map it at
1005 Define this to enable the TPM support library which provides
1006 functional interfaces to some TPM commands.
1007 Requires support for a TPM device.
1009 CONFIG_TPM_AUTH_SESSIONS
1010 Define this to enable authorized functions in the TPM library.
1011 Requires CONFIG_TPM and CONFIG_SHA1.
1014 At the moment only the UHCI host controller is
1015 supported (PIP405, MIP405); define
1016 CONFIG_USB_UHCI to enable it.
1017 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1018 and define CONFIG_USB_STORAGE to enable the USB
1021 Supported are USB Keyboards and USB Floppy drives
1024 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1025 txfilltuning field in the EHCI controller on reset.
1027 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1028 HW module registers.
1031 Define the below if you wish to use the USB console.
1032 Once firmware is rebuilt from a serial console issue the
1033 command "setenv stdin usbtty; setenv stdout usbtty" and
1034 attach your USB cable. The Unix command "dmesg" should print
1035 it has found a new device. The environment variable usbtty
1036 can be set to gserial or cdc_acm to enable your device to
1037 appear to a USB host as a Linux gserial device or a
1038 Common Device Class Abstract Control Model serial device.
1039 If you select usbtty = gserial you should be able to enumerate
1041 # modprobe usbserial vendor=0xVendorID product=0xProductID
1042 else if using cdc_acm, simply setting the environment
1043 variable usbtty to be cdc_acm should suffice. The following
1044 might be defined in YourBoardName.h
1047 Define this to build a UDC device
1050 Define this to have a tty type of device available to
1051 talk to the UDC device
1054 Define this to enable the high speed support for usb
1055 device and usbtty. If this feature is enabled, a routine
1056 int is_usbd_high_speed(void)
1057 also needs to be defined by the driver to dynamically poll
1058 whether the enumeration has succeded at high speed or full
1061 CONFIG_SYS_CONSOLE_IS_IN_ENV
1062 Define this if you want stdin, stdout &/or stderr to
1065 If you have a USB-IF assigned VendorID then you may wish to
1066 define your own vendor specific values either in BoardName.h
1067 or directly in usbd_vendor_info.h. If you don't define
1068 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1069 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1070 should pretend to be a Linux device to it's target host.
1072 CONFIG_USBD_MANUFACTURER
1073 Define this string as the name of your company for
1074 - CONFIG_USBD_MANUFACTURER "my company"
1076 CONFIG_USBD_PRODUCT_NAME
1077 Define this string as the name of your product
1078 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1080 CONFIG_USBD_VENDORID
1081 Define this as your assigned Vendor ID from the USB
1082 Implementors Forum. This *must* be a genuine Vendor ID
1083 to avoid polluting the USB namespace.
1084 - CONFIG_USBD_VENDORID 0xFFFF
1086 CONFIG_USBD_PRODUCTID
1087 Define this as the unique Product ID
1089 - CONFIG_USBD_PRODUCTID 0xFFFF
1091 - ULPI Layer Support:
1092 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1093 the generic ULPI layer. The generic layer accesses the ULPI PHY
1094 via the platform viewport, so you need both the genric layer and
1095 the viewport enabled. Currently only Chipidea/ARC based
1096 viewport is supported.
1097 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1098 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1099 If your ULPI phy needs a different reference clock than the
1100 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1101 the appropriate value in Hz.
1104 The MMC controller on the Intel PXA is supported. To
1105 enable this define CONFIG_MMC. The MMC can be
1106 accessed from the boot prompt by mapping the device
1107 to physical memory similar to flash. Command line is
1108 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1109 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1112 Support for Renesas on-chip MMCIF controller
1114 CONFIG_SH_MMCIF_ADDR
1115 Define the base address of MMCIF registers
1118 Define the clock frequency for MMCIF
1120 - USB Device Firmware Update (DFU) class support:
1122 This enables the USB portion of the DFU USB class
1125 This enables support for exposing NAND devices via DFU.
1128 This enables support for exposing RAM via DFU.
1129 Note: DFU spec refer to non-volatile memory usage, but
1130 allow usages beyond the scope of spec - here RAM usage,
1131 one that would help mostly the developer.
1133 CONFIG_SYS_DFU_DATA_BUF_SIZE
1134 Dfu transfer uses a buffer before writing data to the
1135 raw storage device. Make the size (in bytes) of this buffer
1136 configurable. The size of this buffer is also configurable
1137 through the "dfu_bufsiz" environment variable.
1139 CONFIG_SYS_DFU_MAX_FILE_SIZE
1140 When updating files rather than the raw storage device,
1141 we use a static buffer to copy the file into and then write
1142 the buffer once we've been given the whole file. Define
1143 this to the maximum filesize (in bytes) for the buffer.
1144 Default is 4 MiB if undefined.
1146 DFU_DEFAULT_POLL_TIMEOUT
1147 Poll timeout [ms], is the timeout a device can send to the
1148 host. The host must wait for this timeout before sending
1149 a subsequent DFU_GET_STATUS request to the device.
1151 DFU_MANIFEST_POLL_TIMEOUT
1152 Poll timeout [ms], which the device sends to the host when
1153 entering dfuMANIFEST state. Host waits this timeout, before
1154 sending again an USB request to the device.
1156 - Journaling Flash filesystem support:
1158 Define these for a default partition on a NAND device
1160 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1161 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1162 Define these for a default partition on a NOR device
1165 See Kconfig help for available keyboard drivers.
1169 Define this to enable a custom keyboard support.
1170 This simply calls drv_keyboard_init() which must be
1171 defined in your board-specific files. This option is deprecated
1172 and is only used by novena. For new boards, use driver model
1177 Enable the Freescale DIU video driver. Reference boards for
1178 SOCs that have a DIU should define this macro to enable DIU
1179 support, and should also define these other macros:
1184 CONFIG_VIDEO_SW_CURSOR
1185 CONFIG_VGA_AS_SINGLE_DEVICE
1187 CONFIG_VIDEO_BMP_LOGO
1189 The DIU driver will look for the 'video-mode' environment
1190 variable, and if defined, enable the DIU as a console during
1191 boot. See the documentation file doc/README.video for a
1192 description of this variable.
1194 - LCD Support: CONFIG_LCD
1196 Define this to enable LCD support (for output to LCD
1197 display); also select one of the supported displays
1198 by defining one of these:
1202 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1204 CONFIG_NEC_NL6448AC33:
1206 NEC NL6448AC33-18. Active, color, single scan.
1208 CONFIG_NEC_NL6448BC20
1210 NEC NL6448BC20-08. 6.5", 640x480.
1211 Active, color, single scan.
1213 CONFIG_NEC_NL6448BC33_54
1215 NEC NL6448BC33-54. 10.4", 640x480.
1216 Active, color, single scan.
1220 Sharp 320x240. Active, color, single scan.
1221 It isn't 16x9, and I am not sure what it is.
1223 CONFIG_SHARP_LQ64D341
1225 Sharp LQ64D341 display, 640x480.
1226 Active, color, single scan.
1230 HLD1045 display, 640x480.
1231 Active, color, single scan.
1235 Optrex CBL50840-2 NF-FW 99 22 M5
1237 Hitachi LMG6912RPFC-00T
1241 320x240. Black & white.
1243 CONFIG_LCD_ALIGNMENT
1245 Normally the LCD is page-aligned (typically 4KB). If this is
1246 defined then the LCD will be aligned to this value instead.
1247 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1248 here, since it is cheaper to change data cache settings on
1249 a per-section basis.
1254 Sometimes, for example if the display is mounted in portrait
1255 mode or even if it's mounted landscape but rotated by 180degree,
1256 we need to rotate our content of the display relative to the
1257 framebuffer, so that user can read the messages which are
1259 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1260 initialized with a given rotation from "vl_rot" out of
1261 "vidinfo_t" which is provided by the board specific code.
1262 The value for vl_rot is coded as following (matching to
1263 fbcon=rotate:<n> linux-kernel commandline):
1264 0 = no rotation respectively 0 degree
1265 1 = 90 degree rotation
1266 2 = 180 degree rotation
1267 3 = 270 degree rotation
1269 If CONFIG_LCD_ROTATION is not defined, the console will be
1270 initialized with 0degree rotation.
1274 Support drawing of RLE8-compressed bitmaps on the LCD.
1278 Enables an 'i2c edid' command which can read EDID
1279 information over I2C from an attached LCD display.
1281 - Splash Screen Support: CONFIG_SPLASH_SCREEN
1283 If this option is set, the environment is checked for
1284 a variable "splashimage". If found, the usual display
1285 of logo, copyright and system information on the LCD
1286 is suppressed and the BMP image at the address
1287 specified in "splashimage" is loaded instead. The
1288 console is redirected to the "nulldev", too. This
1289 allows for a "silent" boot where a splash screen is
1290 loaded very quickly after power-on.
1292 CONFIG_SPLASHIMAGE_GUARD
1294 If this option is set, then U-Boot will prevent the environment
1295 variable "splashimage" from being set to a problematic address
1296 (see doc/README.displaying-bmps).
1297 This option is useful for targets where, due to alignment
1298 restrictions, an improperly aligned BMP image will cause a data
1299 abort. If you think you will not have problems with unaligned
1300 accesses (for example because your toolchain prevents them)
1301 there is no need to set this option.
1303 CONFIG_SPLASH_SCREEN_ALIGN
1305 If this option is set the splash image can be freely positioned
1306 on the screen. Environment variable "splashpos" specifies the
1307 position as "x,y". If a positive number is given it is used as
1308 number of pixel from left/top. If a negative number is given it
1309 is used as number of pixel from right/bottom. You can also
1310 specify 'm' for centering the image.
1313 setenv splashpos m,m
1314 => image at center of screen
1316 setenv splashpos 30,20
1317 => image at x = 30 and y = 20
1319 setenv splashpos -10,m
1320 => vertically centered image
1321 at x = dspWidth - bmpWidth - 9
1323 - Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1325 If this option is set, additionally to standard BMP
1326 images, gzipped BMP images can be displayed via the
1327 splashscreen support or the bmp command.
1329 - Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1331 If this option is set, 8-bit RLE compressed BMP images
1332 can be displayed via the splashscreen support or the
1335 - Compression support:
1338 Enabled by default to support gzip compressed images.
1342 If this option is set, support for bzip2 compressed
1343 images is included. If not, only uncompressed and gzip
1344 compressed images are supported.
1346 NOTE: the bzip2 algorithm requires a lot of RAM, so
1347 the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1351 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1353 The clock frequency of the MII bus
1355 CONFIG_PHY_RESET_DELAY
1357 Some PHY like Intel LXT971A need extra delay after
1358 reset before any MII register access is possible.
1359 For such PHY, set this option to the usec delay
1360 required. (minimum 300usec for LXT971A)
1362 CONFIG_PHY_CMD_DELAY (ppc4xx)
1364 Some PHY like Intel LXT971A need extra delay after
1365 command issued before MII status register can be read
1370 Define a default value for the IP address to use for
1371 the default Ethernet interface, in case this is not
1372 determined through e.g. bootp.
1373 (Environment variable "ipaddr")
1375 - Server IP address:
1378 Defines a default value for the IP address of a TFTP
1379 server to contact when using the "tftboot" command.
1380 (Environment variable "serverip")
1382 CONFIG_KEEP_SERVERADDR
1384 Keeps the server's MAC address, in the env 'serveraddr'
1385 for passing to bootargs (like Linux's netconsole option)
1387 - Gateway IP address:
1390 Defines a default value for the IP address of the
1391 default router where packets to other networks are
1393 (Environment variable "gatewayip")
1398 Defines a default value for the subnet mask (or
1399 routing prefix) which is used to determine if an IP
1400 address belongs to the local subnet or needs to be
1401 forwarded through a router.
1402 (Environment variable "netmask")
1404 - BOOTP Recovery Mode:
1405 CONFIG_BOOTP_RANDOM_DELAY
1407 If you have many targets in a network that try to
1408 boot using BOOTP, you may want to avoid that all
1409 systems send out BOOTP requests at precisely the same
1410 moment (which would happen for instance at recovery
1411 from a power failure, when all systems will try to
1412 boot, thus flooding the BOOTP server. Defining
1413 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1414 inserted before sending out BOOTP requests. The
1415 following delays are inserted then:
1417 1st BOOTP request: delay 0 ... 1 sec
1418 2nd BOOTP request: delay 0 ... 2 sec
1419 3rd BOOTP request: delay 0 ... 4 sec
1421 BOOTP requests: delay 0 ... 8 sec
1423 CONFIG_BOOTP_ID_CACHE_SIZE
1425 BOOTP packets are uniquely identified using a 32-bit ID. The
1426 server will copy the ID from client requests to responses and
1427 U-Boot will use this to determine if it is the destination of
1428 an incoming response. Some servers will check that addresses
1429 aren't in use before handing them out (usually using an ARP
1430 ping) and therefore take up to a few hundred milliseconds to
1431 respond. Network congestion may also influence the time it
1432 takes for a response to make it back to the client. If that
1433 time is too long, U-Boot will retransmit requests. In order
1434 to allow earlier responses to still be accepted after these
1435 retransmissions, U-Boot's BOOTP client keeps a small cache of
1436 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1437 cache. The default is to keep IDs for up to four outstanding
1438 requests. Increasing this will allow U-Boot to accept offers
1439 from a BOOTP client in networks with unusually high latency.
1441 - DHCP Advanced Options:
1442 You can fine tune the DHCP functionality by defining
1443 CONFIG_BOOTP_* symbols:
1445 CONFIG_BOOTP_NISDOMAIN
1446 CONFIG_BOOTP_BOOTFILESIZE
1447 CONFIG_BOOTP_SEND_HOSTNAME
1448 CONFIG_BOOTP_NTPSERVER
1449 CONFIG_BOOTP_TIMEOFFSET
1450 CONFIG_BOOTP_VENDOREX
1451 CONFIG_BOOTP_MAY_FAIL
1453 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1454 environment variable, not the BOOTP server.
1456 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1457 after the configured retry count, the call will fail
1458 instead of starting over. This can be used to fail over
1459 to Link-local IP address configuration if the DHCP server
1462 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1463 to do a dynamic update of a DNS server. To do this, they
1464 need the hostname of the DHCP requester.
1465 If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1466 of the "hostname" environment variable is passed as
1467 option 12 to the DHCP server.
1469 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1471 A 32bit value in microseconds for a delay between
1472 receiving a "DHCP Offer" and sending the "DHCP Request".
1473 This fixes a problem with certain DHCP servers that don't
1474 respond 100% of the time to a "DHCP request". E.g. On an
1475 AT91RM9200 processor running at 180MHz, this delay needed
1476 to be *at least* 15,000 usec before a Windows Server 2003
1477 DHCP server would reply 100% of the time. I recommend at
1478 least 50,000 usec to be safe. The alternative is to hope
1479 that one of the retries will be successful but note that
1480 the DHCP timeout and retry process takes a longer than
1483 - Link-local IP address negotiation:
1484 Negotiate with other link-local clients on the local network
1485 for an address that doesn't require explicit configuration.
1486 This is especially useful if a DHCP server cannot be guaranteed
1487 to exist in all environments that the device must operate.
1489 See doc/README.link-local for more information.
1491 - MAC address from environment variables
1493 FDT_SEQ_MACADDR_FROM_ENV
1495 Fix-up device tree with MAC addresses fetched sequentially from
1496 environment variables. This config work on assumption that
1497 non-usable ethernet node of device-tree are either not present
1498 or their status has been marked as "disabled".
1501 CONFIG_CDP_DEVICE_ID
1503 The device id used in CDP trigger frames.
1505 CONFIG_CDP_DEVICE_ID_PREFIX
1507 A two character string which is prefixed to the MAC address
1512 A printf format string which contains the ascii name of
1513 the port. Normally is set to "eth%d" which sets
1514 eth0 for the first Ethernet, eth1 for the second etc.
1516 CONFIG_CDP_CAPABILITIES
1518 A 32bit integer which indicates the device capabilities;
1519 0x00000010 for a normal host which does not forwards.
1523 An ascii string containing the version of the software.
1527 An ascii string containing the name of the platform.
1531 A 32bit integer sent on the trigger.
1533 CONFIG_CDP_POWER_CONSUMPTION
1535 A 16bit integer containing the power consumption of the
1536 device in .1 of milliwatts.
1538 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1540 A byte containing the id of the VLAN.
1542 - Status LED: CONFIG_LED_STATUS
1544 Several configurations allow to display the current
1545 status using a LED. For instance, the LED will blink
1546 fast while running U-Boot code, stop blinking as
1547 soon as a reply to a BOOTP request was received, and
1548 start blinking slow once the Linux kernel is running
1549 (supported by a status LED driver in the Linux
1550 kernel). Defining CONFIG_LED_STATUS enables this
1555 CONFIG_LED_STATUS_GPIO
1556 The status LED can be connected to a GPIO pin.
1557 In such cases, the gpio_led driver can be used as a
1558 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1559 to include the gpio_led driver in the U-Boot binary.
1561 CONFIG_GPIO_LED_INVERTED_TABLE
1562 Some GPIO connected LEDs may have inverted polarity in which
1563 case the GPIO high value corresponds to LED off state and
1564 GPIO low value corresponds to LED on state.
1565 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1566 with a list of GPIO LEDs that have inverted polarity.
1568 - I2C Support: CONFIG_SYS_I2C
1570 This enable the NEW i2c subsystem, and will allow you to use
1571 i2c commands at the u-boot command line (as long as you set
1572 CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
1573 based realtime clock chips or other i2c devices. See
1574 common/cmd_i2c.c for a description of the command line
1577 ported i2c driver to the new framework:
1578 - drivers/i2c/soft_i2c.c:
1579 - activate first bus with CONFIG_SYS_I2C_SOFT define
1580 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1581 for defining speed and slave address
1582 - activate second bus with I2C_SOFT_DECLARATIONS2 define
1583 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1584 for defining speed and slave address
1585 - activate third bus with I2C_SOFT_DECLARATIONS3 define
1586 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1587 for defining speed and slave address
1588 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1589 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1590 for defining speed and slave address
1592 - drivers/i2c/fsl_i2c.c:
1593 - activate i2c driver with CONFIG_SYS_I2C_FSL
1594 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1595 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1596 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1598 - If your board supports a second fsl i2c bus, define
1599 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1600 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1601 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1604 - drivers/i2c/tegra_i2c.c:
1605 - activate this driver with CONFIG_SYS_I2C_TEGRA
1606 - This driver adds 4 i2c buses with a fix speed from
1607 100000 and the slave addr 0!
1609 - drivers/i2c/ppc4xx_i2c.c
1610 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1611 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1612 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1614 - drivers/i2c/i2c_mxc.c
1615 - activate this driver with CONFIG_SYS_I2C_MXC
1616 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1617 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1618 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1619 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1620 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1621 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1622 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1623 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1624 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1625 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1626 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1627 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1628 If those defines are not set, default value is 100000
1629 for speed, and 0 for slave.
1631 - drivers/i2c/rcar_i2c.c:
1632 - activate this driver with CONFIG_SYS_I2C_RCAR
1633 - This driver adds 4 i2c buses
1635 - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
1636 - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
1637 - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
1638 - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
1639 - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
1640 - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
1641 - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
1642 - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
1643 - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
1645 - drivers/i2c/sh_i2c.c:
1646 - activate this driver with CONFIG_SYS_I2C_SH
1647 - This driver adds from 2 to 5 i2c buses
1649 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1650 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1651 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1652 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1653 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1654 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1655 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1656 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1657 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1658 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1659 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1661 - drivers/i2c/omap24xx_i2c.c
1662 - activate this driver with CONFIG_SYS_I2C_OMAP24XX
1663 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
1664 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
1665 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
1666 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
1667 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
1668 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
1669 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
1670 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
1671 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
1672 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
1674 - drivers/i2c/s3c24x0_i2c.c:
1675 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1676 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1677 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1678 with a fix speed from 100000 and the slave addr 0!
1680 - drivers/i2c/ihs_i2c.c
1681 - activate this driver with CONFIG_SYS_I2C_IHS
1682 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1683 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1684 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1685 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1686 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1687 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1688 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1689 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1690 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1691 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1692 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1693 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1694 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1695 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1696 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1697 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1698 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1699 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1700 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1701 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1702 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1706 CONFIG_SYS_NUM_I2C_BUSES
1707 Hold the number of i2c buses you want to use.
1709 CONFIG_SYS_I2C_DIRECT_BUS
1710 define this, if you don't use i2c muxes on your hardware.
1711 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1714 CONFIG_SYS_I2C_MAX_HOPS
1715 define how many muxes are maximal consecutively connected
1716 on one i2c bus. If you not use i2c muxes, omit this
1719 CONFIG_SYS_I2C_BUSES
1720 hold a list of buses you want to use, only used if
1721 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1722 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1723 CONFIG_SYS_NUM_I2C_BUSES = 9:
1725 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1726 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1727 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1728 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1729 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1730 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1731 {1, {I2C_NULL_HOP}}, \
1732 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1733 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1737 bus 0 on adapter 0 without a mux
1738 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1739 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1740 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1741 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1742 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1743 bus 6 on adapter 1 without a mux
1744 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1745 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1747 If you do not have i2c muxes on your board, omit this define.
1749 - Legacy I2C Support:
1750 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1751 then the following macros need to be defined (examples are
1752 from include/configs/lwmon.h):
1756 (Optional). Any commands necessary to enable the I2C
1757 controller or configure ports.
1759 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1763 The code necessary to make the I2C data line active
1764 (driven). If the data line is open collector, this
1767 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1771 The code necessary to make the I2C data line tri-stated
1772 (inactive). If the data line is open collector, this
1775 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1779 Code that returns true if the I2C data line is high,
1782 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1786 If <bit> is true, sets the I2C data line high. If it
1787 is false, it clears it (low).
1789 eg: #define I2C_SDA(bit) \
1790 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1791 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1795 If <bit> is true, sets the I2C clock line high. If it
1796 is false, it clears it (low).
1798 eg: #define I2C_SCL(bit) \
1799 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1800 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1804 This delay is invoked four times per clock cycle so this
1805 controls the rate of data transfer. The data rate thus
1806 is 1 / (I2C_DELAY * 4). Often defined to be something
1809 #define I2C_DELAY udelay(2)
1811 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1813 If your arch supports the generic GPIO framework (asm/gpio.h),
1814 then you may alternatively define the two GPIOs that are to be
1815 used as SCL / SDA. Any of the previous I2C_xxx macros will
1816 have GPIO-based defaults assigned to them as appropriate.
1818 You should define these to the GPIO value as given directly to
1819 the generic GPIO functions.
1821 CONFIG_SYS_I2C_INIT_BOARD
1823 When a board is reset during an i2c bus transfer
1824 chips might think that the current transfer is still
1825 in progress. On some boards it is possible to access
1826 the i2c SCLK line directly, either by using the
1827 processor pin as a GPIO or by having a second pin
1828 connected to the bus. If this option is defined a
1829 custom i2c_init_board() routine in boards/xxx/board.c
1830 is run early in the boot sequence.
1832 CONFIG_I2C_MULTI_BUS
1834 This option allows the use of multiple I2C buses, each of which
1835 must have a controller. At any point in time, only one bus is
1836 active. To switch to a different bus, use the 'i2c dev' command.
1837 Note that bus numbering is zero-based.
1839 CONFIG_SYS_I2C_NOPROBES
1841 This option specifies a list of I2C devices that will be skipped
1842 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1843 is set, specify a list of bus-device pairs. Otherwise, specify
1844 a 1D array of device addresses
1847 #undef CONFIG_I2C_MULTI_BUS
1848 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1850 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1852 #define CONFIG_I2C_MULTI_BUS
1853 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1855 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1857 CONFIG_SYS_SPD_BUS_NUM
1859 If defined, then this indicates the I2C bus number for DDR SPD.
1860 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1862 CONFIG_SYS_RTC_BUS_NUM
1864 If defined, then this indicates the I2C bus number for the RTC.
1865 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1867 CONFIG_SOFT_I2C_READ_REPEATED_START
1869 defining this will force the i2c_read() function in
1870 the soft_i2c driver to perform an I2C repeated start
1871 between writing the address pointer and reading the
1872 data. If this define is omitted the default behaviour
1873 of doing a stop-start sequence will be used. Most I2C
1874 devices can use either method, but some require one or
1877 - SPI Support: CONFIG_SPI
1879 Enables SPI driver (so far only tested with
1880 SPI EEPROM, also an instance works with Crystal A/D and
1881 D/As on the SACSng board)
1885 Enables a software (bit-bang) SPI driver rather than
1886 using hardware support. This is a general purpose
1887 driver that only requires three general I/O port pins
1888 (two outputs, one input) to function. If this is
1889 defined, the board configuration must define several
1890 SPI configuration items (port pins to use, etc). For
1891 an example, see include/configs/sacsng.h.
1893 CONFIG_SYS_SPI_MXC_WAIT
1894 Timeout for waiting until spi transfer completed.
1895 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1897 - FPGA Support: CONFIG_FPGA
1899 Enables FPGA subsystem.
1901 CONFIG_FPGA_<vendor>
1903 Enables support for specific chip vendors.
1906 CONFIG_FPGA_<family>
1908 Enables support for FPGA family.
1909 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1913 Specify the number of FPGA devices to support.
1915 CONFIG_SYS_FPGA_PROG_FEEDBACK
1917 Enable printing of hash marks during FPGA configuration.
1919 CONFIG_SYS_FPGA_CHECK_BUSY
1921 Enable checks on FPGA configuration interface busy
1922 status by the configuration function. This option
1923 will require a board or device specific function to
1928 If defined, a function that provides delays in the FPGA
1929 configuration driver.
1931 CONFIG_SYS_FPGA_CHECK_CTRLC
1932 Allow Control-C to interrupt FPGA configuration
1934 CONFIG_SYS_FPGA_CHECK_ERROR
1936 Check for configuration errors during FPGA bitfile
1937 loading. For example, abort during Virtex II
1938 configuration if the INIT_B line goes low (which
1939 indicated a CRC error).
1941 CONFIG_SYS_FPGA_WAIT_INIT
1943 Maximum time to wait for the INIT_B line to de-assert
1944 after PROB_B has been de-asserted during a Virtex II
1945 FPGA configuration sequence. The default time is 500
1948 CONFIG_SYS_FPGA_WAIT_BUSY
1950 Maximum time to wait for BUSY to de-assert during
1951 Virtex II FPGA configuration. The default is 5 ms.
1953 CONFIG_SYS_FPGA_WAIT_CONFIG
1955 Time to wait after FPGA configuration. The default is
1958 - Configuration Management:
1962 If defined, this string will be added to the U-Boot
1963 version information (U_BOOT_VERSION)
1965 - Vendor Parameter Protection:
1967 U-Boot considers the values of the environment
1968 variables "serial#" (Board Serial Number) and
1969 "ethaddr" (Ethernet Address) to be parameters that
1970 are set once by the board vendor / manufacturer, and
1971 protects these variables from casual modification by
1972 the user. Once set, these variables are read-only,
1973 and write or delete attempts are rejected. You can
1974 change this behaviour:
1976 If CONFIG_ENV_OVERWRITE is #defined in your config
1977 file, the write protection for vendor parameters is
1978 completely disabled. Anybody can change or delete
1981 Alternatively, if you define _both_ an ethaddr in the
1982 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1983 Ethernet address is installed in the environment,
1984 which can be changed exactly ONCE by the user. [The
1985 serial# is unaffected by this, i. e. it remains
1988 The same can be accomplished in a more flexible way
1989 for any variable by configuring the type of access
1990 to allow for those variables in the ".flags" variable
1991 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1996 Define this variable to enable the reservation of
1997 "protected RAM", i. e. RAM which is not overwritten
1998 by U-Boot. Define CONFIG_PRAM to hold the number of
1999 kB you want to reserve for pRAM. You can overwrite
2000 this default value by defining an environment
2001 variable "pram" to the number of kB you want to
2002 reserve. Note that the board info structure will
2003 still show the full amount of RAM. If pRAM is
2004 reserved, a new environment variable "mem" will
2005 automatically be defined to hold the amount of
2006 remaining RAM in a form that can be passed as boot
2007 argument to Linux, for instance like that:
2009 setenv bootargs ... mem=\${mem}
2012 This way you can tell Linux not to use this memory,
2013 either, which results in a memory region that will
2014 not be affected by reboots.
2016 *WARNING* If your board configuration uses automatic
2017 detection of the RAM size, you must make sure that
2018 this memory test is non-destructive. So far, the
2019 following board configurations are known to be
2022 IVMS8, IVML24, SPD8xx,
2023 HERMES, IP860, RPXlite, LWMON,
2026 - Access to physical memory region (> 4GB)
2027 Some basic support is provided for operations on memory not
2028 normally accessible to U-Boot - e.g. some architectures
2029 support access to more than 4GB of memory on 32-bit
2030 machines using physical address extension or similar.
2031 Define CONFIG_PHYSMEM to access this basic support, which
2032 currently only supports clearing the memory.
2035 CONFIG_NET_RETRY_COUNT
2037 This variable defines the number of retries for
2038 network operations like ARP, RARP, TFTP, or BOOTP
2039 before giving up the operation. If not defined, a
2040 default value of 5 is used.
2044 Timeout waiting for an ARP reply in milliseconds.
2048 Timeout in milliseconds used in NFS protocol.
2049 If you encounter "ERROR: Cannot umount" in nfs command,
2050 try longer timeout such as
2051 #define CONFIG_NFS_TIMEOUT 10000UL
2053 - Command Interpreter:
2054 CONFIG_SYS_PROMPT_HUSH_PS2
2056 This defines the secondary prompt string, which is
2057 printed when the command interpreter needs more input
2058 to complete a command. Usually "> ".
2062 In the current implementation, the local variables
2063 space and global environment variables space are
2064 separated. Local variables are those you define by
2065 simply typing `name=value'. To access a local
2066 variable later on, you have write `$name' or
2067 `${name}'; to execute the contents of a variable
2068 directly type `$name' at the command prompt.
2070 Global environment variables are those you use
2071 setenv/printenv to work with. To run a command stored
2072 in such a variable, you need to use the run command,
2073 and you must not use the '$' sign to access them.
2075 To store commands and special characters in a
2076 variable, please use double quotation marks
2077 surrounding the whole text of the variable, instead
2078 of the backslashes before semicolons and special
2081 - Command Line Editing and History:
2082 CONFIG_CMDLINE_PS_SUPPORT
2084 Enable support for changing the command prompt string
2085 at run-time. Only static string is supported so far.
2086 The string is obtained from environment variables PS1
2089 - Default Environment:
2090 CONFIG_EXTRA_ENV_SETTINGS
2092 Define this to contain any number of null terminated
2093 strings (variable = value pairs) that will be part of
2094 the default environment compiled into the boot image.
2096 For example, place something like this in your
2097 board's config file:
2099 #define CONFIG_EXTRA_ENV_SETTINGS \
2103 Warning: This method is based on knowledge about the
2104 internal format how the environment is stored by the
2105 U-Boot code. This is NOT an official, exported
2106 interface! Although it is unlikely that this format
2107 will change soon, there is no guarantee either.
2108 You better know what you are doing here.
2110 Note: overly (ab)use of the default environment is
2111 discouraged. Make sure to check other ways to preset
2112 the environment like the "source" command or the
2115 CONFIG_DELAY_ENVIRONMENT
2117 Normally the environment is loaded when the board is
2118 initialised so that it is available to U-Boot. This inhibits
2119 that so that the environment is not available until
2120 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2121 this is instead controlled by the value of
2122 /config/load-environment.
2124 - TFTP Fixed UDP Port:
2127 If this is defined, the environment variable tftpsrcp
2128 is used to supply the TFTP UDP source port value.
2129 If tftpsrcp isn't defined, the normal pseudo-random port
2130 number generator is used.
2132 Also, the environment variable tftpdstp is used to supply
2133 the TFTP UDP destination port value. If tftpdstp isn't
2134 defined, the normal port 69 is used.
2136 The purpose for tftpsrcp is to allow a TFTP server to
2137 blindly start the TFTP transfer using the pre-configured
2138 target IP address and UDP port. This has the effect of
2139 "punching through" the (Windows XP) firewall, allowing
2140 the remainder of the TFTP transfer to proceed normally.
2141 A better solution is to properly configure the firewall,
2142 but sometimes that is not allowed.
2144 CONFIG_STANDALONE_LOAD_ADDR
2146 This option defines a board specific value for the
2147 address where standalone program gets loaded, thus
2148 overwriting the architecture dependent default
2151 - Frame Buffer Address:
2154 Define CONFIG_FB_ADDR if you want to use specific
2155 address for frame buffer. This is typically the case
2156 when using a graphics controller has separate video
2157 memory. U-Boot will then place the frame buffer at
2158 the given address instead of dynamically reserving it
2159 in system RAM by calling lcd_setmem(), which grabs
2160 the memory for the frame buffer depending on the
2161 configured panel size.
2163 Please see board_init_f function.
2165 - Automatic software updates via TFTP server
2167 CONFIG_UPDATE_TFTP_CNT_MAX
2168 CONFIG_UPDATE_TFTP_MSEC_MAX
2170 These options enable and control the auto-update feature;
2171 for a more detailed description refer to doc/README.update.
2173 - MTD Support (mtdparts command, UBI support)
2174 CONFIG_MTD_UBI_WL_THRESHOLD
2175 This parameter defines the maximum difference between the highest
2176 erase counter value and the lowest erase counter value of eraseblocks
2177 of UBI devices. When this threshold is exceeded, UBI starts performing
2178 wear leveling by means of moving data from eraseblock with low erase
2179 counter to eraseblocks with high erase counter.
2181 The default value should be OK for SLC NAND flashes, NOR flashes and
2182 other flashes which have eraseblock life-cycle 100000 or more.
2183 However, in case of MLC NAND flashes which typically have eraseblock
2184 life-cycle less than 10000, the threshold should be lessened (e.g.,
2185 to 128 or 256, although it does not have to be power of 2).
2189 CONFIG_MTD_UBI_BEB_LIMIT
2190 This option specifies the maximum bad physical eraseblocks UBI
2191 expects on the MTD device (per 1024 eraseblocks). If the
2192 underlying flash does not admit of bad eraseblocks (e.g. NOR
2193 flash), this value is ignored.
2195 NAND datasheets often specify the minimum and maximum NVM
2196 (Number of Valid Blocks) for the flashes' endurance lifetime.
2197 The maximum expected bad eraseblocks per 1024 eraseblocks
2198 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2199 which gives 20 for most NANDs (MaxNVB is basically the total
2200 count of eraseblocks on the chip).
2202 To put it differently, if this value is 20, UBI will try to
2203 reserve about 1.9% of physical eraseblocks for bad blocks
2204 handling. And that will be 1.9% of eraseblocks on the entire
2205 NAND chip, not just the MTD partition UBI attaches. This means
2206 that if you have, say, a NAND flash chip admits maximum 40 bad
2207 eraseblocks, and it is split on two MTD partitions of the same
2208 size, UBI will reserve 40 eraseblocks when attaching a
2213 CONFIG_MTD_UBI_FASTMAP
2214 Fastmap is a mechanism which allows attaching an UBI device
2215 in nearly constant time. Instead of scanning the whole MTD device it
2216 only has to locate a checkpoint (called fastmap) on the device.
2217 The on-flash fastmap contains all information needed to attach
2218 the device. Using fastmap makes only sense on large devices where
2219 attaching by scanning takes long. UBI will not automatically install
2220 a fastmap on old images, but you can set the UBI parameter
2221 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2222 that fastmap-enabled images are still usable with UBI implementations
2223 without fastmap support. On typical flash devices the whole fastmap
2224 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2226 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2227 Set this parameter to enable fastmap automatically on images
2231 CONFIG_MTD_UBI_FM_DEBUG
2232 Enable UBI fastmap debug
2237 Enable building of SPL globally.
2240 LDSCRIPT for linking the SPL binary.
2242 CONFIG_SPL_MAX_FOOTPRINT
2243 Maximum size in memory allocated to the SPL, BSS included.
2244 When defined, the linker checks that the actual memory
2245 used by SPL from _start to __bss_end does not exceed it.
2246 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2247 must not be both defined at the same time.
2250 Maximum size of the SPL image (text, data, rodata, and
2251 linker lists sections), BSS excluded.
2252 When defined, the linker checks that the actual size does
2255 CONFIG_SPL_RELOC_TEXT_BASE
2256 Address to relocate to. If unspecified, this is equal to
2257 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2259 CONFIG_SPL_BSS_START_ADDR
2260 Link address for the BSS within the SPL binary.
2262 CONFIG_SPL_BSS_MAX_SIZE
2263 Maximum size in memory allocated to the SPL BSS.
2264 When defined, the linker checks that the actual memory used
2265 by SPL from __bss_start to __bss_end does not exceed it.
2266 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2267 must not be both defined at the same time.
2270 Adress of the start of the stack SPL will use
2272 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2273 When defined, SPL will panic() if the image it has
2274 loaded does not have a signature.
2275 Defining this is useful when code which loads images
2276 in SPL cannot guarantee that absolutely all read errors
2278 An example is the LPC32XX MLC NAND driver, which will
2279 consider that a completely unreadable NAND block is bad,
2280 and thus should be skipped silently.
2282 CONFIG_SPL_RELOC_STACK
2283 Adress of the start of the stack SPL will use after
2284 relocation. If unspecified, this is equal to
2287 CONFIG_SYS_SPL_MALLOC_START
2288 Starting address of the malloc pool used in SPL.
2289 When this option is set the full malloc is used in SPL and
2290 it is set up by spl_init() and before that, the simple malloc()
2291 can be used if CONFIG_SYS_MALLOC_F is defined.
2293 CONFIG_SYS_SPL_MALLOC_SIZE
2294 The size of the malloc pool used in SPL.
2297 Enable booting directly to an OS from SPL.
2298 See also: doc/README.falcon
2300 CONFIG_SPL_DISPLAY_PRINT
2301 For ARM, enable an optional function to print more information
2302 about the running system.
2304 CONFIG_SPL_INIT_MINIMAL
2305 Arch init code should be built for a very small image
2307 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2308 Partition on the MMC to load U-Boot from when the MMC is being
2311 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2312 Sector to load kernel uImage from when MMC is being
2313 used in raw mode (for Falcon mode)
2315 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2316 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2317 Sector and number of sectors to load kernel argument
2318 parameters from when MMC is being used in raw mode
2321 CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
2322 Partition on the MMC to load U-Boot from when the MMC is being
2325 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2326 Filename to read to load U-Boot when reading from filesystem
2328 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2329 Filename to read to load kernel uImage when reading
2330 from filesystem (for Falcon mode)
2332 CONFIG_SPL_FS_LOAD_ARGS_NAME
2333 Filename to read to load kernel argument parameters
2334 when reading from filesystem (for Falcon mode)
2336 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2337 Set this for NAND SPL on PPC mpc83xx targets, so that
2338 start.S waits for the rest of the SPL to load before
2339 continuing (the hardware starts execution after just
2340 loading the first page rather than the full 4K).
2342 CONFIG_SPL_SKIP_RELOCATE
2343 Avoid SPL relocation
2345 CONFIG_SPL_NAND_BASE
2346 Include nand_base.c in the SPL. Requires
2347 CONFIG_SPL_NAND_DRIVERS.
2349 CONFIG_SPL_NAND_DRIVERS
2350 SPL uses normal NAND drivers, not minimal drivers.
2352 CONFIG_SPL_NAND_IDENT
2353 SPL uses the chip ID list to identify the NAND flash.
2354 Requires CONFIG_SPL_NAND_BASE.
2357 Include standard software ECC in the SPL
2359 CONFIG_SPL_NAND_SIMPLE
2360 Support for NAND boot using simple NAND drivers that
2361 expose the cmd_ctrl() interface.
2364 Support for a lightweight UBI (fastmap) scanner and
2367 CONFIG_SPL_NAND_RAW_ONLY
2368 Support to boot only raw u-boot.bin images. Use this only
2369 if you need to save space.
2371 CONFIG_SPL_COMMON_INIT_DDR
2372 Set for common ddr init with serial presence detect in
2375 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2376 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2377 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2378 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2379 CONFIG_SYS_NAND_ECCBYTES
2380 Defines the size and behavior of the NAND that SPL uses
2383 CONFIG_SYS_NAND_U_BOOT_OFFS
2384 Location in NAND to read U-Boot from
2386 CONFIG_SYS_NAND_U_BOOT_DST
2387 Location in memory to load U-Boot to
2389 CONFIG_SYS_NAND_U_BOOT_SIZE
2390 Size of image to load
2392 CONFIG_SYS_NAND_U_BOOT_START
2393 Entry point in loaded image to jump to
2395 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2396 Define this if you need to first read the OOB and then the
2397 data. This is used, for example, on davinci platforms.
2399 CONFIG_SPL_RAM_DEVICE
2400 Support for running image already present in ram, in SPL binary
2403 Image offset to which the SPL should be padded before appending
2404 the SPL payload. By default, this is defined as
2405 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2406 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2407 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2410 Final target image containing SPL and payload. Some SPLs
2411 use an arch-specific makefile fragment instead, for
2412 example if more than one image needs to be produced.
2414 CONFIG_SPL_FIT_PRINT
2415 Printing information about a FIT image adds quite a bit of
2416 code to SPL. So this is normally disabled in SPL. Use this
2417 option to re-enable it. This will affect the output of the
2418 bootm command when booting a FIT image.
2422 Enable building of TPL globally.
2425 Image offset to which the TPL should be padded before appending
2426 the TPL payload. By default, this is defined as
2427 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2428 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2429 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2431 - Interrupt support (PPC):
2433 There are common interrupt_init() and timer_interrupt()
2434 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2435 for CPU specific initialization. interrupt_init_cpu()
2436 should set decrementer_count to appropriate value. If
2437 CPU resets decrementer automatically after interrupt
2438 (ppc4xx) it should set decrementer_count to zero.
2439 timer_interrupt() calls timer_interrupt_cpu() for CPU
2440 specific handling. If board has watchdog / status_led
2441 / other_activity_monitor it works automatically from
2442 general timer_interrupt().
2445 Board initialization settings:
2446 ------------------------------
2448 During Initialization u-boot calls a number of board specific functions
2449 to allow the preparation of board specific prerequisites, e.g. pin setup
2450 before drivers are initialized. To enable these callbacks the
2451 following configuration macros have to be defined. Currently this is
2452 architecture specific, so please check arch/your_architecture/lib/board.c
2453 typically in board_init_f() and board_init_r().
2455 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2456 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2457 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2458 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2460 Configuration Settings:
2461 -----------------------
2463 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2464 Optionally it can be defined to support 64-bit memory commands.
2466 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2467 undefine this when you're short of memory.
2469 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2470 width of the commands listed in the 'help' command output.
2472 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2473 prompt for user input.
2475 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2477 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2479 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2481 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2482 the application (usually a Linux kernel) when it is
2485 - CONFIG_SYS_BAUDRATE_TABLE:
2486 List of legal baudrate settings for this board.
2488 - CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2489 Begin and End addresses of the area used by the
2492 - CONFIG_SYS_MEMTEST_SCRATCH:
2493 Scratch address used by the alternate memory test
2494 You only need to set this if address zero isn't writeable
2496 - CONFIG_SYS_MEM_RESERVE_SECURE
2497 Only implemented for ARMv8 for now.
2498 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2499 is substracted from total RAM and won't be reported to OS.
2500 This memory can be used as secure memory. A variable
2501 gd->arch.secure_ram is used to track the location. In systems
2502 the RAM base is not zero, or RAM is divided into banks,
2503 this variable needs to be recalcuated to get the address.
2505 - CONFIG_SYS_MEM_TOP_HIDE:
2506 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2507 this specified memory area will get subtracted from the top
2508 (end) of RAM and won't get "touched" at all by U-Boot. By
2509 fixing up gd->ram_size the Linux kernel should gets passed
2510 the now "corrected" memory size and won't touch it either.
2511 This should work for arch/ppc and arch/powerpc. Only Linux
2512 board ports in arch/powerpc with bootwrapper support that
2513 recalculate the memory size from the SDRAM controller setup
2514 will have to get fixed in Linux additionally.
2516 This option can be used as a workaround for the 440EPx/GRx
2517 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2520 WARNING: Please make sure that this value is a multiple of
2521 the Linux page size (normally 4k). If this is not the case,
2522 then the end address of the Linux memory will be located at a
2523 non page size aligned address and this could cause major
2526 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2527 Enable temporary baudrate change while serial download
2529 - CONFIG_SYS_SDRAM_BASE:
2530 Physical start address of SDRAM. _Must_ be 0 here.
2532 - CONFIG_SYS_FLASH_BASE:
2533 Physical start address of Flash memory.
2535 - CONFIG_SYS_MONITOR_BASE:
2536 Physical start address of boot monitor code (set by
2537 make config files to be same as the text base address
2538 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2539 CONFIG_SYS_FLASH_BASE when booting from flash.
2541 - CONFIG_SYS_MONITOR_LEN:
2542 Size of memory reserved for monitor code, used to
2543 determine _at_compile_time_ (!) if the environment is
2544 embedded within the U-Boot image, or in a separate
2547 - CONFIG_SYS_MALLOC_LEN:
2548 Size of DRAM reserved for malloc() use.
2550 - CONFIG_SYS_MALLOC_F_LEN
2551 Size of the malloc() pool for use before relocation. If
2552 this is defined, then a very simple malloc() implementation
2553 will become available before relocation. The address is just
2554 below the global data, and the stack is moved down to make
2557 This feature allocates regions with increasing addresses
2558 within the region. calloc() is supported, but realloc()
2559 is not available. free() is supported but does nothing.
2560 The memory will be freed (or in fact just forgotten) when
2561 U-Boot relocates itself.
2563 - CONFIG_SYS_MALLOC_SIMPLE
2564 Provides a simple and small malloc() and calloc() for those
2565 boards which do not use the full malloc in SPL (which is
2566 enabled with CONFIG_SYS_SPL_MALLOC_START).
2568 - CONFIG_SYS_NONCACHED_MEMORY:
2569 Size of non-cached memory area. This area of memory will be
2570 typically located right below the malloc() area and mapped
2571 uncached in the MMU. This is useful for drivers that would
2572 otherwise require a lot of explicit cache maintenance. For
2573 some drivers it's also impossible to properly maintain the
2574 cache. For example if the regions that need to be flushed
2575 are not a multiple of the cache-line size, *and* padding
2576 cannot be allocated between the regions to align them (i.e.
2577 if the HW requires a contiguous array of regions, and the
2578 size of each region is not cache-aligned), then a flush of
2579 one region may result in overwriting data that hardware has
2580 written to another region in the same cache-line. This can
2581 happen for example in network drivers where descriptors for
2582 buffers are typically smaller than the CPU cache-line (e.g.
2583 16 bytes vs. 32 or 64 bytes).
2585 Non-cached memory is only supported on 32-bit ARM at present.
2587 - CONFIG_SYS_BOOTM_LEN:
2588 Normally compressed uImages are limited to an
2589 uncompressed size of 8 MBytes. If this is not enough,
2590 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2591 to adjust this setting to your needs.
2593 - CONFIG_SYS_BOOTMAPSZ:
2594 Maximum size of memory mapped by the startup code of
2595 the Linux kernel; all data that must be processed by
2596 the Linux kernel (bd_info, boot arguments, FDT blob if
2597 used) must be put below this limit, unless "bootm_low"
2598 environment variable is defined and non-zero. In such case
2599 all data for the Linux kernel must be between "bootm_low"
2600 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2601 variable "bootm_mapsize" will override the value of
2602 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2603 then the value in "bootm_size" will be used instead.
2605 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2606 Enable initrd_high functionality. If defined then the
2607 initrd_high feature is enabled and the bootm ramdisk subcommand
2610 - CONFIG_SYS_BOOT_GET_CMDLINE:
2611 Enables allocating and saving kernel cmdline in space between
2612 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2614 - CONFIG_SYS_BOOT_GET_KBD:
2615 Enables allocating and saving a kernel copy of the bd_info in
2616 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2618 - CONFIG_SYS_MAX_FLASH_BANKS:
2619 Max number of Flash memory banks
2621 - CONFIG_SYS_MAX_FLASH_SECT:
2622 Max number of sectors on a Flash chip
2624 - CONFIG_SYS_FLASH_ERASE_TOUT:
2625 Timeout for Flash erase operations (in ms)
2627 - CONFIG_SYS_FLASH_WRITE_TOUT:
2628 Timeout for Flash write operations (in ms)
2630 - CONFIG_SYS_FLASH_LOCK_TOUT
2631 Timeout for Flash set sector lock bit operation (in ms)
2633 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2634 Timeout for Flash clear lock bits operation (in ms)
2636 - CONFIG_SYS_FLASH_PROTECTION
2637 If defined, hardware flash sectors protection is used
2638 instead of U-Boot software protection.
2640 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2642 Enable TFTP transfers directly to flash memory;
2643 without this option such a download has to be
2644 performed in two steps: (1) download to RAM, and (2)
2645 copy from RAM to flash.
2647 The two-step approach is usually more reliable, since
2648 you can check if the download worked before you erase
2649 the flash, but in some situations (when system RAM is
2650 too limited to allow for a temporary copy of the
2651 downloaded image) this option may be very useful.
2653 - CONFIG_SYS_FLASH_CFI:
2654 Define if the flash driver uses extra elements in the
2655 common flash structure for storing flash geometry.
2657 - CONFIG_FLASH_CFI_DRIVER
2658 This option also enables the building of the cfi_flash driver
2659 in the drivers directory
2661 - CONFIG_FLASH_CFI_MTD
2662 This option enables the building of the cfi_mtd driver
2663 in the drivers directory. The driver exports CFI flash
2666 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2667 Use buffered writes to flash.
2669 - CONFIG_FLASH_SPANSION_S29WS_N
2670 s29ws-n MirrorBit flash has non-standard addresses for buffered
2673 - CONFIG_SYS_FLASH_QUIET_TEST
2674 If this option is defined, the common CFI flash doesn't
2675 print it's warning upon not recognized FLASH banks. This
2676 is useful, if some of the configured banks are only
2677 optionally available.
2679 - CONFIG_FLASH_SHOW_PROGRESS
2680 If defined (must be an integer), print out countdown
2681 digits and dots. Recommended value: 45 (9..1) for 80
2682 column displays, 15 (3..1) for 40 column displays.
2684 - CONFIG_FLASH_VERIFY
2685 If defined, the content of the flash (destination) is compared
2686 against the source after the write operation. An error message
2687 will be printed when the contents are not identical.
2688 Please note that this option is useless in nearly all cases,
2689 since such flash programming errors usually are detected earlier
2690 while unprotecting/erasing/programming. Please only enable
2691 this option if you really know what you are doing.
2693 - CONFIG_SYS_RX_ETH_BUFFER:
2694 Defines the number of Ethernet receive buffers. On some
2695 Ethernet controllers it is recommended to set this value
2696 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2697 buffers can be full shortly after enabling the interface
2698 on high Ethernet traffic.
2699 Defaults to 4 if not defined.
2701 - CONFIG_ENV_MAX_ENTRIES
2703 Maximum number of entries in the hash table that is used
2704 internally to store the environment settings. The default
2705 setting is supposed to be generous and should work in most
2706 cases. This setting can be used to tune behaviour; see
2707 lib/hashtable.c for details.
2709 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2710 - CONFIG_ENV_FLAGS_LIST_STATIC
2711 Enable validation of the values given to environment variables when
2712 calling env set. Variables can be restricted to only decimal,
2713 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2714 the variables can also be restricted to IP address or MAC address.
2716 The format of the list is:
2717 type_attribute = [s|d|x|b|i|m]
2718 access_attribute = [a|r|o|c]
2719 attributes = type_attribute[access_attribute]
2720 entry = variable_name[:attributes]
2723 The type attributes are:
2724 s - String (default)
2727 b - Boolean ([1yYtT|0nNfF])
2731 The access attributes are:
2737 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2738 Define this to a list (string) to define the ".flags"
2739 environment variable in the default or embedded environment.
2741 - CONFIG_ENV_FLAGS_LIST_STATIC
2742 Define this to a list (string) to define validation that
2743 should be done if an entry is not found in the ".flags"
2744 environment variable. To override a setting in the static
2745 list, simply add an entry for the same variable name to the
2748 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2749 regular expression. This allows multiple variables to define the same
2750 flags without explicitly listing them for each variable.
2752 - CONFIG_ENV_ACCESS_IGNORE_FORCE
2753 If defined, don't allow the -f switch to env set override variable
2756 The following definitions that deal with the placement and management
2757 of environment data (variable area); in general, we support the
2758 following configurations:
2760 - CONFIG_BUILD_ENVCRC:
2762 Builds up envcrc with the target environment so that external utils
2763 may easily extract it and embed it in final U-Boot images.
2765 BE CAREFUL! The first access to the environment happens quite early
2766 in U-Boot initialization (when we try to get the setting of for the
2767 console baudrate). You *MUST* have mapped your NVRAM area then, or
2770 Please note that even with NVRAM we still use a copy of the
2771 environment in RAM: we could work on NVRAM directly, but we want to
2772 keep settings there always unmodified except somebody uses "saveenv"
2773 to save the current settings.
2775 BE CAREFUL! For some special cases, the local device can not use
2776 "saveenv" command. For example, the local device will get the
2777 environment stored in a remote NOR flash by SRIO or PCIE link,
2778 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2780 - CONFIG_NAND_ENV_DST
2782 Defines address in RAM to which the nand_spl code should copy the
2783 environment. If redundant environment is used, it will be copied to
2784 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2786 Please note that the environment is read-only until the monitor
2787 has been relocated to RAM and a RAM copy of the environment has been
2788 created; also, when using EEPROM you will have to use env_get_f()
2789 until then to read environment variables.
2791 The environment is protected by a CRC32 checksum. Before the monitor
2792 is relocated into RAM, as a result of a bad CRC you will be working
2793 with the compiled-in default environment - *silently*!!! [This is
2794 necessary, because the first environment variable we need is the
2795 "baudrate" setting for the console - if we have a bad CRC, we don't
2796 have any device yet where we could complain.]
2798 Note: once the monitor has been relocated, then it will complain if
2799 the default environment is used; a new CRC is computed as soon as you
2800 use the "saveenv" command to store a valid environment.
2802 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2803 Echo the inverted Ethernet link state to the fault LED.
2805 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2806 also needs to be defined.
2808 - CONFIG_SYS_FAULT_MII_ADDR:
2809 MII address of the PHY to check for the Ethernet link state.
2811 - CONFIG_NS16550_MIN_FUNCTIONS:
2812 Define this if you desire to only have use of the NS16550_init
2813 and NS16550_putc functions for the serial driver located at
2814 drivers/serial/ns16550.c. This option is useful for saving
2815 space for already greatly restricted images, including but not
2816 limited to NAND_SPL configurations.
2818 - CONFIG_DISPLAY_BOARDINFO
2819 Display information about the board that U-Boot is running on
2820 when U-Boot starts up. The board function checkboard() is called
2823 - CONFIG_DISPLAY_BOARDINFO_LATE
2824 Similar to the previous option, but display this information
2825 later, once stdio is running and output goes to the LCD, if
2828 - CONFIG_BOARD_SIZE_LIMIT:
2829 Maximum size of the U-Boot image. When defined, the
2830 build system checks that the actual size does not
2833 Low Level (hardware related) configuration options:
2834 ---------------------------------------------------
2836 - CONFIG_SYS_CACHELINE_SIZE:
2837 Cache Line Size of the CPU.
2839 - CONFIG_SYS_CCSRBAR_DEFAULT:
2840 Default (power-on reset) physical address of CCSR on Freescale
2843 - CONFIG_SYS_CCSRBAR:
2844 Virtual address of CCSR. On a 32-bit build, this is typically
2845 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2847 - CONFIG_SYS_CCSRBAR_PHYS:
2848 Physical address of CCSR. CCSR can be relocated to a new
2849 physical address, if desired. In this case, this macro should
2850 be set to that address. Otherwise, it should be set to the
2851 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2852 is typically relocated on 36-bit builds. It is recommended
2853 that this macro be defined via the _HIGH and _LOW macros:
2855 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2856 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2858 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2859 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2860 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2861 used in assembly code, so it must not contain typecasts or
2862 integer size suffixes (e.g. "ULL").
2864 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2865 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2866 used in assembly code, so it must not contain typecasts or
2867 integer size suffixes (e.g. "ULL").
2869 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2870 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2871 forced to a value that ensures that CCSR is not relocated.
2874 Most IDE controllers were designed to be connected with PCI
2875 interface. Only few of them were designed for AHB interface.
2876 When software is doing ATA command and data transfer to
2877 IDE devices through IDE-AHB controller, some additional
2878 registers accessing to these kind of IDE-AHB controller
2881 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2882 DO NOT CHANGE unless you know exactly what you're
2883 doing! (11-4) [MPC8xx systems only]
2885 - CONFIG_SYS_INIT_RAM_ADDR:
2887 Start address of memory area that can be used for
2888 initial data and stack; please note that this must be
2889 writable memory that is working WITHOUT special
2890 initialization, i. e. you CANNOT use normal RAM which
2891 will become available only after programming the
2892 memory controller and running certain initialization
2895 U-Boot uses the following memory types:
2896 - MPC8xx: IMMR (internal memory of the CPU)
2898 - CONFIG_SYS_GBL_DATA_OFFSET:
2900 Offset of the initial data structure in the memory
2901 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2902 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2903 data is located at the end of the available space
2904 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2905 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2906 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2907 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2910 On the MPC824X (or other systems that use the data
2911 cache for initial memory) the address chosen for
2912 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2913 point to an otherwise UNUSED address space between
2914 the top of RAM and the start of the PCI space.
2916 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2918 - CONFIG_SYS_OR_TIMING_SDRAM:
2921 - CONFIG_SYS_MAMR_PTA:
2922 periodic timer for refresh
2924 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2925 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2926 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2927 CONFIG_SYS_BR1_PRELIM:
2928 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2930 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2931 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2932 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2933 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2935 - CONFIG_PCI_ENUM_ONLY
2936 Only scan through and get the devices on the buses.
2937 Don't do any setup work, presumably because someone or
2938 something has already done it, and we don't need to do it
2939 a second time. Useful for platforms that are pre-booted
2940 by coreboot or similar.
2942 - CONFIG_PCI_INDIRECT_BRIDGE:
2943 Enable support for indirect PCI bridges.
2946 Chip has SRIO or not
2949 Board has SRIO 1 port available
2952 Board has SRIO 2 port available
2954 - CONFIG_SRIO_PCIE_BOOT_MASTER
2955 Board can support master function for Boot from SRIO and PCIE
2957 - CONFIG_SYS_SRIOn_MEM_VIRT:
2958 Virtual Address of SRIO port 'n' memory region
2960 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2961 Physical Address of SRIO port 'n' memory region
2963 - CONFIG_SYS_SRIOn_MEM_SIZE:
2964 Size of SRIO port 'n' memory region
2966 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2967 Defined to tell the NAND controller that the NAND chip is using
2969 Not all NAND drivers use this symbol.
2970 Example of drivers that use it:
2971 - drivers/mtd/nand/raw/ndfc.c
2972 - drivers/mtd/nand/raw/mxc_nand.c
2974 - CONFIG_SYS_NDFC_EBC0_CFG
2975 Sets the EBC0_CFG register for the NDFC. If not defined
2976 a default value will be used.
2979 Get DDR timing information from an I2C EEPROM. Common
2980 with pluggable memory modules such as SODIMMs
2983 I2C address of the SPD EEPROM
2985 - CONFIG_SYS_SPD_BUS_NUM
2986 If SPD EEPROM is on an I2C bus other than the first
2987 one, specify here. Note that the value must resolve
2988 to something your driver can deal with.
2990 - CONFIG_SYS_DDR_RAW_TIMING
2991 Get DDR timing information from other than SPD. Common with
2992 soldered DDR chips onboard without SPD. DDR raw timing
2993 parameters are extracted from datasheet and hard-coded into
2994 header files or board specific files.
2996 - CONFIG_FSL_DDR_INTERACTIVE
2997 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2999 - CONFIG_FSL_DDR_SYNC_REFRESH
3000 Enable sync of refresh for multiple controllers.
3002 - CONFIG_FSL_DDR_BIST
3003 Enable built-in memory test for Freescale DDR controllers.
3005 - CONFIG_SYS_83XX_DDR_USES_CS0
3006 Only for 83xx systems. If specified, then DDR should
3007 be configured using CS0 and CS1 instead of CS2 and CS3.
3010 Enable RMII mode for all FECs.
3011 Note that this is a global option, we can't
3012 have one FEC in standard MII mode and another in RMII mode.
3014 - CONFIG_CRC32_VERIFY
3015 Add a verify option to the crc32 command.
3018 => crc32 -v <address> <count> <crc32>
3020 Where address/count indicate a memory area
3021 and crc32 is the correct crc32 which the
3025 Add the "loopw" memory command. This only takes effect if
3026 the memory commands are activated globally (CONFIG_CMD_MEMORY).
3028 - CONFIG_CMD_MX_CYCLIC
3029 Add the "mdc" and "mwc" memory commands. These are cyclic
3034 This command will print 4 bytes (10,11,12,13) each 500 ms.
3036 => mwc.l 100 12345678 10
3037 This command will write 12345678 to address 100 all 10 ms.
3039 This only takes effect if the memory commands are activated
3040 globally (CONFIG_CMD_MEMORY).
3042 - CONFIG_SKIP_LOWLEVEL_INIT
3043 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
3044 low level initializations (like setting up the memory
3045 controller) are omitted and/or U-Boot does not
3046 relocate itself into RAM.
3048 Normally this variable MUST NOT be defined. The only
3049 exception is when U-Boot is loaded (to RAM) by some
3050 other boot loader or by a debugger which performs
3051 these initializations itself.
3053 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
3054 [ARM926EJ-S only] This allows just the call to lowlevel_init()
3055 to be skipped. The normal CP15 init (such as enabling the
3056 instruction cache) is still performed.
3059 Set when the currently-running compilation is for an artifact
3060 that will end up in the SPL (as opposed to the TPL or U-Boot
3061 proper). Code that needs stage-specific behavior should check
3065 Set when the currently-running compilation is for an artifact
3066 that will end up in the TPL (as opposed to the SPL or U-Boot
3067 proper). Code that needs stage-specific behavior should check
3070 - CONFIG_SYS_MPC85XX_NO_RESETVEC
3071 Only for 85xx systems. If this variable is specified, the section
3072 .resetvec is not kept and the section .bootpg is placed in the
3073 previous 4k of the .text section.
3075 - CONFIG_ARCH_MAP_SYSMEM
3076 Generally U-Boot (and in particular the md command) uses
3077 effective address. It is therefore not necessary to regard
3078 U-Boot address as virtual addresses that need to be translated
3079 to physical addresses. However, sandbox requires this, since
3080 it maintains its own little RAM buffer which contains all
3081 addressable memory. This option causes some memory accesses
3082 to be mapped through map_sysmem() / unmap_sysmem().
3084 - CONFIG_X86_RESET_VECTOR
3085 If defined, the x86 reset vector code is included. This is not
3086 needed when U-Boot is running from Coreboot.
3088 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
3089 Option to disable subpage write in NAND driver
3090 driver that uses this:
3091 drivers/mtd/nand/raw/davinci_nand.c
3093 Freescale QE/FMAN Firmware Support:
3094 -----------------------------------
3096 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3097 loading of "firmware", which is encoded in the QE firmware binary format.
3098 This firmware often needs to be loaded during U-Boot booting, so macros
3099 are used to identify the storage device (NOR flash, SPI, etc) and the address
3102 - CONFIG_SYS_FMAN_FW_ADDR
3103 The address in the storage device where the FMAN microcode is located. The
3104 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
3107 - CONFIG_SYS_QE_FW_ADDR
3108 The address in the storage device where the QE microcode is located. The
3109 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
3112 - CONFIG_SYS_QE_FMAN_FW_LENGTH
3113 The maximum possible size of the firmware. The firmware binary format
3114 has a field that specifies the actual size of the firmware, but it
3115 might not be possible to read any part of the firmware unless some
3116 local storage is allocated to hold the entire firmware first.
3118 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
3119 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3120 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
3121 virtual address in NOR flash.
3123 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
3124 Specifies that QE/FMAN firmware is located in NAND flash.
3125 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3127 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
3128 Specifies that QE/FMAN firmware is located on the primary SD/MMC
3129 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3131 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3132 Specifies that QE/FMAN firmware is located in the remote (master)
3133 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3134 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3135 window->master inbound window->master LAW->the ucode address in
3136 master's memory space.
3138 Freescale Layerscape Management Complex Firmware Support:
3139 ---------------------------------------------------------
3140 The Freescale Layerscape Management Complex (MC) supports the loading of
3142 This firmware often needs to be loaded during U-Boot booting, so macros
3143 are used to identify the storage device (NOR flash, SPI, etc) and the address
3146 - CONFIG_FSL_MC_ENET
3147 Enable the MC driver for Layerscape SoCs.
3149 Freescale Layerscape Debug Server Support:
3150 -------------------------------------------
3151 The Freescale Layerscape Debug Server Support supports the loading of
3152 "Debug Server firmware" and triggering SP boot-rom.
3153 This firmware often needs to be loaded during U-Boot booting.
3155 - CONFIG_SYS_MC_RSV_MEM_ALIGN
3156 Define alignment of reserved memory MC requires
3161 In order to achieve reproducible builds, timestamps used in the U-Boot build
3162 process have to be set to a fixed value.
3164 This is done using the SOURCE_DATE_EPOCH environment variable.
3165 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
3166 option for U-Boot or an environment variable in U-Boot.
3168 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
3170 Building the Software:
3171 ======================
3173 Building U-Boot has been tested in several native build environments
3174 and in many different cross environments. Of course we cannot support
3175 all possibly existing versions of cross development tools in all
3176 (potentially obsolete) versions. In case of tool chain problems we
3177 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3178 which is extensively used to build and test U-Boot.
3180 If you are not using a native environment, it is assumed that you
3181 have GNU cross compiling tools available in your path. In this case,
3182 you must set the environment variable CROSS_COMPILE in your shell.
3183 Note that no changes to the Makefile or any other source files are
3184 necessary. For example using the ELDK on a 4xx CPU, please enter:
3186 $ CROSS_COMPILE=ppc_4xx-
3187 $ export CROSS_COMPILE
3189 Note: If you wish to generate Windows versions of the utilities in
3190 the tools directory you can use the MinGW toolchain
3191 (http://www.mingw.org). Set your HOST tools to the MinGW
3192 toolchain and execute 'make tools'. For example:
3194 $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3196 Binaries such as tools/mkimage.exe will be created which can
3197 be executed on computers running Windows.
3199 U-Boot is intended to be simple to build. After installing the
3200 sources you must configure U-Boot for one specific board type. This
3205 where "NAME_defconfig" is the name of one of the existing configu-
3206 rations; see boards.cfg for supported names.
3208 Note: for some board special configuration names may exist; check if
3209 additional information is available from the board vendor; for
3210 instance, the TQM823L systems are available without (standard)
3211 or with LCD support. You can select such additional "features"
3212 when choosing the configuration, i. e.
3214 make TQM823L_defconfig
3215 - will configure for a plain TQM823L, i. e. no LCD support
3217 make TQM823L_LCD_defconfig
3218 - will configure for a TQM823L with U-Boot console on LCD
3223 Finally, type "make all", and you should get some working U-Boot
3224 images ready for download to / installation on your system:
3226 - "u-boot.bin" is a raw binary image
3227 - "u-boot" is an image in ELF binary format
3228 - "u-boot.srec" is in Motorola S-Record format
3230 By default the build is performed locally and the objects are saved
3231 in the source directory. One of the two methods can be used to change
3232 this behavior and build U-Boot to some external directory:
3234 1. Add O= to the make command line invocations:
3236 make O=/tmp/build distclean
3237 make O=/tmp/build NAME_defconfig
3238 make O=/tmp/build all
3240 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3242 export KBUILD_OUTPUT=/tmp/build
3247 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3250 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3251 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3252 For example to treat all compiler warnings as errors:
3254 make KCFLAGS=-Werror
3256 Please be aware that the Makefiles assume you are using GNU make, so
3257 for instance on NetBSD you might need to use "gmake" instead of
3261 If the system board that you have is not listed, then you will need
3262 to port U-Boot to your hardware platform. To do this, follow these
3265 1. Create a new directory to hold your board specific code. Add any
3266 files you need. In your board directory, you will need at least
3267 the "Makefile" and a "<board>.c".
3268 2. Create a new configuration file "include/configs/<board>.h" for
3270 3. If you're porting U-Boot to a new CPU, then also create a new
3271 directory to hold your CPU specific code. Add any files you need.
3272 4. Run "make <board>_defconfig" with your new name.
3273 5. Type "make", and you should get a working "u-boot.srec" file
3274 to be installed on your target system.
3275 6. Debug and solve any problems that might arise.
3276 [Of course, this last step is much harder than it sounds.]
3279 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3280 ==============================================================
3282 If you have modified U-Boot sources (for instance added a new board
3283 or support for new devices, a new CPU, etc.) you are expected to
3284 provide feedback to the other developers. The feedback normally takes
3285 the form of a "patch", i.e. a context diff against a certain (latest
3286 official or latest in the git repository) version of U-Boot sources.
3288 But before you submit such a patch, please verify that your modifi-
3289 cation did not break existing code. At least make sure that *ALL* of
3290 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3291 just run the buildman script (tools/buildman/buildman), which will
3292 configure and build U-Boot for ALL supported system. Be warned, this
3293 will take a while. Please see the buildman README, or run 'buildman -H'
3297 See also "U-Boot Porting Guide" below.
3300 Monitor Commands - Overview:
3301 ============================
3303 go - start application at address 'addr'
3304 run - run commands in an environment variable
3305 bootm - boot application image from memory
3306 bootp - boot image via network using BootP/TFTP protocol
3307 bootz - boot zImage from memory
3308 tftpboot- boot image via network using TFTP protocol
3309 and env variables "ipaddr" and "serverip"
3310 (and eventually "gatewayip")
3311 tftpput - upload a file via network using TFTP protocol
3312 rarpboot- boot image via network using RARP/TFTP protocol
3313 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3314 loads - load S-Record file over serial line
3315 loadb - load binary file over serial line (kermit mode)
3317 mm - memory modify (auto-incrementing)
3318 nm - memory modify (constant address)
3319 mw - memory write (fill)
3321 cmp - memory compare
3322 crc32 - checksum calculation
3323 i2c - I2C sub-system
3324 sspi - SPI utility commands
3325 base - print or set address offset
3326 printenv- print environment variables
3327 setenv - set environment variables
3328 saveenv - save environment variables to persistent storage
3329 protect - enable or disable FLASH write protection
3330 erase - erase FLASH memory
3331 flinfo - print FLASH memory information
3332 nand - NAND memory operations (see doc/README.nand)
3333 bdinfo - print Board Info structure
3334 iminfo - print header information for application image
3335 coninfo - print console devices and informations
3336 ide - IDE sub-system
3337 loop - infinite loop on address range
3338 loopw - infinite write loop on address range
3339 mtest - simple RAM test
3340 icache - enable or disable instruction cache
3341 dcache - enable or disable data cache
3342 reset - Perform RESET of the CPU
3343 echo - echo args to console
3344 version - print monitor version
3345 help - print online help
3346 ? - alias for 'help'
3349 Monitor Commands - Detailed Description:
3350 ========================================
3354 For now: just type "help <command>".
3357 Environment Variables:
3358 ======================
3360 U-Boot supports user configuration using Environment Variables which
3361 can be made persistent by saving to Flash memory.
3363 Environment Variables are set using "setenv", printed using
3364 "printenv", and saved to Flash using "saveenv". Using "setenv"
3365 without a value can be used to delete a variable from the
3366 environment. As long as you don't save the environment you are
3367 working with an in-memory copy. In case the Flash area containing the
3368 environment is erased by accident, a default environment is provided.
3370 Some configuration options can be set using Environment Variables.
3372 List of environment variables (most likely not complete):
3374 baudrate - see CONFIG_BAUDRATE
3376 bootdelay - see CONFIG_BOOTDELAY
3378 bootcmd - see CONFIG_BOOTCOMMAND
3380 bootargs - Boot arguments when booting an RTOS image
3382 bootfile - Name of the image to load with TFTP
3384 bootm_low - Memory range available for image processing in the bootm
3385 command can be restricted. This variable is given as
3386 a hexadecimal number and defines lowest address allowed
3387 for use by the bootm command. See also "bootm_size"
3388 environment variable. Address defined by "bootm_low" is
3389 also the base of the initial memory mapping for the Linux
3390 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3393 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3394 This variable is given as a hexadecimal number and it
3395 defines the size of the memory region starting at base
3396 address bootm_low that is accessible by the Linux kernel
3397 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3398 as the default value if it is defined, and bootm_size is
3401 bootm_size - Memory range available for image processing in the bootm
3402 command can be restricted. This variable is given as
3403 a hexadecimal number and defines the size of the region
3404 allowed for use by the bootm command. See also "bootm_low"
3405 environment variable.
3407 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3409 updatefile - Location of the software update file on a TFTP server, used
3410 by the automatic software update feature. Please refer to
3411 documentation in doc/README.update for more details.
3413 autoload - if set to "no" (any string beginning with 'n'),
3414 "bootp" will just load perform a lookup of the
3415 configuration from the BOOTP server, but not try to
3416 load any image using TFTP
3418 autostart - if set to "yes", an image loaded using the "bootp",
3419 "rarpboot", "tftpboot" or "diskboot" commands will
3420 be automatically started (by internally calling
3423 If set to "no", a standalone image passed to the
3424 "bootm" command will be copied to the load address
3425 (and eventually uncompressed), but NOT be started.
3426 This can be used to load and uncompress arbitrary
3429 fdt_high - if set this restricts the maximum address that the
3430 flattened device tree will be copied into upon boot.
3431 For example, if you have a system with 1 GB memory
3432 at physical address 0x10000000, while Linux kernel
3433 only recognizes the first 704 MB as low memory, you
3434 may need to set fdt_high as 0x3C000000 to have the
3435 device tree blob be copied to the maximum address
3436 of the 704 MB low memory, so that Linux kernel can
3437 access it during the boot procedure.
3439 If this is set to the special value 0xFFFFFFFF then
3440 the fdt will not be copied at all on boot. For this
3441 to work it must reside in writable memory, have
3442 sufficient padding on the end of it for u-boot to
3443 add the information it needs into it, and the memory
3444 must be accessible by the kernel.
3446 fdtcontroladdr- if set this is the address of the control flattened
3447 device tree used by U-Boot when CONFIG_OF_CONTROL is
3450 i2cfast - (PPC405GP|PPC405EP only)
3451 if set to 'y' configures Linux I2C driver for fast
3452 mode (400kHZ). This environment variable is used in
3453 initialization code. So, for changes to be effective
3454 it must be saved and board must be reset.
3456 initrd_high - restrict positioning of initrd images:
3457 If this variable is not set, initrd images will be
3458 copied to the highest possible address in RAM; this
3459 is usually what you want since it allows for
3460 maximum initrd size. If for some reason you want to
3461 make sure that the initrd image is loaded below the
3462 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3463 variable to a value of "no" or "off" or "0".
3464 Alternatively, you can set it to a maximum upper
3465 address to use (U-Boot will still check that it
3466 does not overwrite the U-Boot stack and data).
3468 For instance, when you have a system with 16 MB
3469 RAM, and want to reserve 4 MB from use by Linux,
3470 you can do this by adding "mem=12M" to the value of
3471 the "bootargs" variable. However, now you must make
3472 sure that the initrd image is placed in the first
3473 12 MB as well - this can be done with
3475 setenv initrd_high 00c00000
3477 If you set initrd_high to 0xFFFFFFFF, this is an
3478 indication to U-Boot that all addresses are legal
3479 for the Linux kernel, including addresses in flash
3480 memory. In this case U-Boot will NOT COPY the
3481 ramdisk at all. This may be useful to reduce the
3482 boot time on your system, but requires that this
3483 feature is supported by your Linux kernel.
3485 ipaddr - IP address; needed for tftpboot command
3487 loadaddr - Default load address for commands like "bootp",
3488 "rarpboot", "tftpboot", "loadb" or "diskboot"
3490 loads_echo - see CONFIG_LOADS_ECHO
3492 serverip - TFTP server IP address; needed for tftpboot command
3494 bootretry - see CONFIG_BOOT_RETRY_TIME
3496 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3498 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3500 ethprime - controls which interface is used first.
3502 ethact - controls which interface is currently active.
3503 For example you can do the following
3505 => setenv ethact FEC
3506 => ping 192.168.0.1 # traffic sent on FEC
3507 => setenv ethact SCC
3508 => ping 10.0.0.1 # traffic sent on SCC
3510 ethrotate - When set to "no" U-Boot does not go through all
3511 available network interfaces.
3512 It just stays at the currently selected interface.
3514 netretry - When set to "no" each network operation will
3515 either succeed or fail without retrying.
3516 When set to "once" the network operation will
3517 fail when all the available network interfaces
3518 are tried once without success.
3519 Useful on scripts which control the retry operation
3522 npe_ucode - set load address for the NPE microcode
3524 silent_linux - If set then Linux will be told to boot silently, by
3525 changing the console to be empty. If "yes" it will be
3526 made silent. If "no" it will not be made silent. If
3527 unset, then it will be made silent if the U-Boot console
3530 tftpsrcp - If this is set, the value is used for TFTP's
3533 tftpdstp - If this is set, the value is used for TFTP's UDP
3534 destination port instead of the Well Know Port 69.
3536 tftpblocksize - Block size to use for TFTP transfers; if not set,
3537 we use the TFTP server's default block size
3539 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3540 seconds, minimum value is 1000 = 1 second). Defines
3541 when a packet is considered to be lost so it has to
3542 be retransmitted. The default is 5000 = 5 seconds.
3543 Lowering this value may make downloads succeed
3544 faster in networks with high packet loss rates or
3545 with unreliable TFTP servers.
3547 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3548 unit, minimum value = 0). Defines how many timeouts
3549 can happen during a single file transfer before that
3550 transfer is aborted. The default is 10, and 0 means
3551 'no timeouts allowed'. Increasing this value may help
3552 downloads succeed with high packet loss rates, or with
3553 unreliable TFTP servers or client hardware.
3555 vlan - When set to a value < 4095 the traffic over
3556 Ethernet is encapsulated/received over 802.1q
3559 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3560 Unsigned value, in milliseconds. If not set, the period will
3561 be either the default (28000), or a value based on
3562 CONFIG_NET_RETRY_COUNT, if defined. This value has
3563 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3565 The following image location variables contain the location of images
3566 used in booting. The "Image" column gives the role of the image and is
3567 not an environment variable name. The other columns are environment
3568 variable names. "File Name" gives the name of the file on a TFTP
3569 server, "RAM Address" gives the location in RAM the image will be
3570 loaded to, and "Flash Location" gives the image's address in NOR
3571 flash or offset in NAND flash.
3573 *Note* - these variables don't have to be defined for all boards, some
3574 boards currently use other variables for these purposes, and some
3575 boards use these variables for other purposes.
3577 Image File Name RAM Address Flash Location
3578 ----- --------- ----------- --------------
3579 u-boot u-boot u-boot_addr_r u-boot_addr
3580 Linux kernel bootfile kernel_addr_r kernel_addr
3581 device tree blob fdtfile fdt_addr_r fdt_addr
3582 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3584 The following environment variables may be used and automatically
3585 updated by the network boot commands ("bootp" and "rarpboot"),
3586 depending the information provided by your boot server:
3588 bootfile - see above
3589 dnsip - IP address of your Domain Name Server
3590 dnsip2 - IP address of your secondary Domain Name Server
3591 gatewayip - IP address of the Gateway (Router) to use
3592 hostname - Target hostname
3594 netmask - Subnet Mask
3595 rootpath - Pathname of the root filesystem on the NFS server
3596 serverip - see above
3599 There are two special Environment Variables:
3601 serial# - contains hardware identification information such
3602 as type string and/or serial number
3603 ethaddr - Ethernet address
3605 These variables can be set only once (usually during manufacturing of
3606 the board). U-Boot refuses to delete or overwrite these variables
3607 once they have been set once.
3610 Further special Environment Variables:
3612 ver - Contains the U-Boot version string as printed
3613 with the "version" command. This variable is
3614 readonly (see CONFIG_VERSION_VARIABLE).
3617 Please note that changes to some configuration parameters may take
3618 only effect after the next boot (yes, that's just like Windoze :-).
3621 Callback functions for environment variables:
3622 ---------------------------------------------
3624 For some environment variables, the behavior of u-boot needs to change
3625 when their values are changed. This functionality allows functions to
3626 be associated with arbitrary variables. On creation, overwrite, or
3627 deletion, the callback will provide the opportunity for some side
3628 effect to happen or for the change to be rejected.
3630 The callbacks are named and associated with a function using the
3631 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3633 These callbacks are associated with variables in one of two ways. The
3634 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3635 in the board configuration to a string that defines a list of
3636 associations. The list must be in the following format:
3638 entry = variable_name[:callback_name]
3641 If the callback name is not specified, then the callback is deleted.
3642 Spaces are also allowed anywhere in the list.
3644 Callbacks can also be associated by defining the ".callbacks" variable
3645 with the same list format above. Any association in ".callbacks" will
3646 override any association in the static list. You can define
3647 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3648 ".callbacks" environment variable in the default or embedded environment.
3650 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3651 regular expression. This allows multiple variables to be connected to
3652 the same callback without explicitly listing them all out.
3654 The signature of the callback functions is:
3656 int callback(const char *name, const char *value, enum env_op op, int flags)
3658 * name - changed environment variable
3659 * value - new value of the environment variable
3660 * op - operation (create, overwrite, or delete)
3661 * flags - attributes of the environment variable change, see flags H_* in
3664 The return value is 0 if the variable change is accepted and 1 otherwise.
3666 Command Line Parsing:
3667 =====================
3669 There are two different command line parsers available with U-Boot:
3670 the old "simple" one, and the much more powerful "hush" shell:
3672 Old, simple command line parser:
3673 --------------------------------
3675 - supports environment variables (through setenv / saveenv commands)
3676 - several commands on one line, separated by ';'
3677 - variable substitution using "... ${name} ..." syntax
3678 - special characters ('$', ';') can be escaped by prefixing with '\',
3680 setenv bootcmd bootm \${address}
3681 - You can also escape text by enclosing in single apostrophes, for example:
3682 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3687 - similar to Bourne shell, with control structures like
3688 if...then...else...fi, for...do...done; while...do...done,
3689 until...do...done, ...
3690 - supports environment ("global") variables (through setenv / saveenv
3691 commands) and local shell variables (through standard shell syntax
3692 "name=value"); only environment variables can be used with "run"
3698 (1) If a command line (or an environment variable executed by a "run"
3699 command) contains several commands separated by semicolon, and
3700 one of these commands fails, then the remaining commands will be
3703 (2) If you execute several variables with one call to run (i. e.
3704 calling run with a list of variables as arguments), any failing
3705 command will cause "run" to terminate, i. e. the remaining
3706 variables are not executed.
3708 Note for Redundant Ethernet Interfaces:
3709 =======================================
3711 Some boards come with redundant Ethernet interfaces; U-Boot supports
3712 such configurations and is capable of automatic selection of a
3713 "working" interface when needed. MAC assignment works as follows:
3715 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3716 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3717 "eth1addr" (=>eth1), "eth2addr", ...
3719 If the network interface stores some valid MAC address (for instance
3720 in SROM), this is used as default address if there is NO correspon-
3721 ding setting in the environment; if the corresponding environment
3722 variable is set, this overrides the settings in the card; that means:
3724 o If the SROM has a valid MAC address, and there is no address in the
3725 environment, the SROM's address is used.
3727 o If there is no valid address in the SROM, and a definition in the
3728 environment exists, then the value from the environment variable is
3731 o If both the SROM and the environment contain a MAC address, and
3732 both addresses are the same, this MAC address is used.
3734 o If both the SROM and the environment contain a MAC address, and the
3735 addresses differ, the value from the environment is used and a
3738 o If neither SROM nor the environment contain a MAC address, an error
3739 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3740 a random, locally-assigned MAC is used.
3742 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3743 will be programmed into hardware as part of the initialization process. This
3744 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3745 The naming convention is as follows:
3746 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3751 U-Boot is capable of booting (and performing other auxiliary operations on)
3752 images in two formats:
3754 New uImage format (FIT)
3755 -----------------------
3757 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3758 to Flattened Device Tree). It allows the use of images with multiple
3759 components (several kernels, ramdisks, etc.), with contents protected by
3760 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3766 Old image format is based on binary files which can be basically anything,
3767 preceded by a special header; see the definitions in include/image.h for
3768 details; basically, the header defines the following image properties:
3770 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3771 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3772 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3773 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3775 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3776 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3777 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3778 * Compression Type (uncompressed, gzip, bzip2)
3784 The header is marked by a special Magic Number, and both the header
3785 and the data portions of the image are secured against corruption by
3792 Although U-Boot should support any OS or standalone application
3793 easily, the main focus has always been on Linux during the design of
3796 U-Boot includes many features that so far have been part of some
3797 special "boot loader" code within the Linux kernel. Also, any
3798 "initrd" images to be used are no longer part of one big Linux image;
3799 instead, kernel and "initrd" are separate images. This implementation
3800 serves several purposes:
3802 - the same features can be used for other OS or standalone
3803 applications (for instance: using compressed images to reduce the
3804 Flash memory footprint)
3806 - it becomes much easier to port new Linux kernel versions because
3807 lots of low-level, hardware dependent stuff are done by U-Boot
3809 - the same Linux kernel image can now be used with different "initrd"
3810 images; of course this also means that different kernel images can
3811 be run with the same "initrd". This makes testing easier (you don't
3812 have to build a new "zImage.initrd" Linux image when you just
3813 change a file in your "initrd"). Also, a field-upgrade of the
3814 software is easier now.
3820 Porting Linux to U-Boot based systems:
3821 ---------------------------------------
3823 U-Boot cannot save you from doing all the necessary modifications to
3824 configure the Linux device drivers for use with your target hardware
3825 (no, we don't intend to provide a full virtual machine interface to
3828 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3830 Just make sure your machine specific header file (for instance
3831 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3832 Information structure as we define in include/asm-<arch>/u-boot.h,
3833 and make sure that your definition of IMAP_ADDR uses the same value
3834 as your U-Boot configuration in CONFIG_SYS_IMMR.
3836 Note that U-Boot now has a driver model, a unified model for drivers.
3837 If you are adding a new driver, plumb it into driver model. If there
3838 is no uclass available, you are encouraged to create one. See
3842 Configuring the Linux kernel:
3843 -----------------------------
3845 No specific requirements for U-Boot. Make sure you have some root
3846 device (initial ramdisk, NFS) for your target system.
3849 Building a Linux Image:
3850 -----------------------
3852 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3853 not used. If you use recent kernel source, a new build target
3854 "uImage" will exist which automatically builds an image usable by
3855 U-Boot. Most older kernels also have support for a "pImage" target,
3856 which was introduced for our predecessor project PPCBoot and uses a
3857 100% compatible format.
3861 make TQM850L_defconfig
3866 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3867 encapsulate a compressed Linux kernel image with header information,
3868 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3870 * build a standard "vmlinux" kernel image (in ELF binary format):
3872 * convert the kernel into a raw binary image:
3874 ${CROSS_COMPILE}-objcopy -O binary \
3875 -R .note -R .comment \
3876 -S vmlinux linux.bin
3878 * compress the binary image:
3882 * package compressed binary image for U-Boot:
3884 mkimage -A ppc -O linux -T kernel -C gzip \
3885 -a 0 -e 0 -n "Linux Kernel Image" \
3886 -d linux.bin.gz uImage
3889 The "mkimage" tool can also be used to create ramdisk images for use
3890 with U-Boot, either separated from the Linux kernel image, or
3891 combined into one file. "mkimage" encapsulates the images with a 64
3892 byte header containing information about target architecture,
3893 operating system, image type, compression method, entry points, time
3894 stamp, CRC32 checksums, etc.
3896 "mkimage" can be called in two ways: to verify existing images and
3897 print the header information, or to build new images.
3899 In the first form (with "-l" option) mkimage lists the information
3900 contained in the header of an existing U-Boot image; this includes
3901 checksum verification:
3903 tools/mkimage -l image
3904 -l ==> list image header information
3906 The second form (with "-d" option) is used to build a U-Boot image
3907 from a "data file" which is used as image payload:
3909 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3910 -n name -d data_file image
3911 -A ==> set architecture to 'arch'
3912 -O ==> set operating system to 'os'
3913 -T ==> set image type to 'type'
3914 -C ==> set compression type 'comp'
3915 -a ==> set load address to 'addr' (hex)
3916 -e ==> set entry point to 'ep' (hex)
3917 -n ==> set image name to 'name'
3918 -d ==> use image data from 'datafile'
3920 Right now, all Linux kernels for PowerPC systems use the same load
3921 address (0x00000000), but the entry point address depends on the
3924 - 2.2.x kernels have the entry point at 0x0000000C,
3925 - 2.3.x and later kernels have the entry point at 0x00000000.
3927 So a typical call to build a U-Boot image would read:
3929 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3930 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3931 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3932 > examples/uImage.TQM850L
3933 Image Name: 2.4.4 kernel for TQM850L
3934 Created: Wed Jul 19 02:34:59 2000
3935 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3936 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3937 Load Address: 0x00000000
3938 Entry Point: 0x00000000
3940 To verify the contents of the image (or check for corruption):
3942 -> tools/mkimage -l examples/uImage.TQM850L
3943 Image Name: 2.4.4 kernel for TQM850L
3944 Created: Wed Jul 19 02:34:59 2000
3945 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3946 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3947 Load Address: 0x00000000
3948 Entry Point: 0x00000000
3950 NOTE: for embedded systems where boot time is critical you can trade
3951 speed for memory and install an UNCOMPRESSED image instead: this
3952 needs more space in Flash, but boots much faster since it does not
3953 need to be uncompressed:
3955 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3956 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3957 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3958 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3959 > examples/uImage.TQM850L-uncompressed
3960 Image Name: 2.4.4 kernel for TQM850L
3961 Created: Wed Jul 19 02:34:59 2000
3962 Image Type: PowerPC Linux Kernel Image (uncompressed)
3963 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3964 Load Address: 0x00000000
3965 Entry Point: 0x00000000
3968 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3969 when your kernel is intended to use an initial ramdisk:
3971 -> tools/mkimage -n 'Simple Ramdisk Image' \
3972 > -A ppc -O linux -T ramdisk -C gzip \
3973 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3974 Image Name: Simple Ramdisk Image
3975 Created: Wed Jan 12 14:01:50 2000
3976 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3977 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3978 Load Address: 0x00000000
3979 Entry Point: 0x00000000
3981 The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
3982 option performs the converse operation of the mkimage's second form (the "-d"
3983 option). Given an image built by mkimage, the dumpimage extracts a "data file"
3986 tools/dumpimage -i image -T type -p position data_file
3987 -i ==> extract from the 'image' a specific 'data_file'
3988 -T ==> set image type to 'type'
3989 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
3992 Installing a Linux Image:
3993 -------------------------
3995 To downloading a U-Boot image over the serial (console) interface,
3996 you must convert the image to S-Record format:
3998 objcopy -I binary -O srec examples/image examples/image.srec
4000 The 'objcopy' does not understand the information in the U-Boot
4001 image header, so the resulting S-Record file will be relative to
4002 address 0x00000000. To load it to a given address, you need to
4003 specify the target address as 'offset' parameter with the 'loads'
4006 Example: install the image to address 0x40100000 (which on the
4007 TQM8xxL is in the first Flash bank):
4009 => erase 40100000 401FFFFF
4015 ## Ready for S-Record download ...
4016 ~>examples/image.srec
4017 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4019 15989 15990 15991 15992
4020 [file transfer complete]
4022 ## Start Addr = 0x00000000
4025 You can check the success of the download using the 'iminfo' command;
4026 this includes a checksum verification so you can be sure no data
4027 corruption happened:
4031 ## Checking Image at 40100000 ...
4032 Image Name: 2.2.13 for initrd on TQM850L
4033 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4034 Data Size: 335725 Bytes = 327 kB = 0 MB
4035 Load Address: 00000000
4036 Entry Point: 0000000c
4037 Verifying Checksum ... OK
4043 The "bootm" command is used to boot an application that is stored in
4044 memory (RAM or Flash). In case of a Linux kernel image, the contents
4045 of the "bootargs" environment variable is passed to the kernel as
4046 parameters. You can check and modify this variable using the
4047 "printenv" and "setenv" commands:
4050 => printenv bootargs
4051 bootargs=root=/dev/ram
4053 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4055 => printenv bootargs
4056 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4059 ## Booting Linux kernel at 40020000 ...
4060 Image Name: 2.2.13 for NFS on TQM850L
4061 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4062 Data Size: 381681 Bytes = 372 kB = 0 MB
4063 Load Address: 00000000
4064 Entry Point: 0000000c
4065 Verifying Checksum ... OK
4066 Uncompressing Kernel Image ... OK
4067 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
4068 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4069 time_init: decrementer frequency = 187500000/60
4070 Calibrating delay loop... 49.77 BogoMIPS
4071 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4074 If you want to boot a Linux kernel with initial RAM disk, you pass
4075 the memory addresses of both the kernel and the initrd image (PPBCOOT
4076 format!) to the "bootm" command:
4078 => imi 40100000 40200000
4080 ## Checking Image at 40100000 ...
4081 Image Name: 2.2.13 for initrd on TQM850L
4082 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4083 Data Size: 335725 Bytes = 327 kB = 0 MB
4084 Load Address: 00000000
4085 Entry Point: 0000000c
4086 Verifying Checksum ... OK
4088 ## Checking Image at 40200000 ...
4089 Image Name: Simple Ramdisk Image
4090 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4091 Data Size: 566530 Bytes = 553 kB = 0 MB
4092 Load Address: 00000000
4093 Entry Point: 00000000
4094 Verifying Checksum ... OK
4096 => bootm 40100000 40200000
4097 ## Booting Linux kernel at 40100000 ...
4098 Image Name: 2.2.13 for initrd on TQM850L
4099 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4100 Data Size: 335725 Bytes = 327 kB = 0 MB
4101 Load Address: 00000000
4102 Entry Point: 0000000c
4103 Verifying Checksum ... OK
4104 Uncompressing Kernel Image ... OK
4105 ## Loading RAMDisk Image at 40200000 ...
4106 Image Name: Simple Ramdisk Image
4107 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4108 Data Size: 566530 Bytes = 553 kB = 0 MB
4109 Load Address: 00000000
4110 Entry Point: 00000000
4111 Verifying Checksum ... OK
4112 Loading Ramdisk ... OK
4113 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
4114 Boot arguments: root=/dev/ram
4115 time_init: decrementer frequency = 187500000/60
4116 Calibrating delay loop... 49.77 BogoMIPS
4118 RAMDISK: Compressed image found at block 0
4119 VFS: Mounted root (ext2 filesystem).
4123 Boot Linux and pass a flat device tree:
4126 First, U-Boot must be compiled with the appropriate defines. See the section
4127 titled "Linux Kernel Interface" above for a more in depth explanation. The
4128 following is an example of how to start a kernel and pass an updated
4134 oft=oftrees/mpc8540ads.dtb
4135 => tftp $oftaddr $oft
4136 Speed: 1000, full duplex
4138 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4139 Filename 'oftrees/mpc8540ads.dtb'.
4140 Load address: 0x300000
4143 Bytes transferred = 4106 (100a hex)
4144 => tftp $loadaddr $bootfile
4145 Speed: 1000, full duplex
4147 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4149 Load address: 0x200000
4150 Loading:############
4152 Bytes transferred = 1029407 (fb51f hex)
4157 => bootm $loadaddr - $oftaddr
4158 ## Booting image at 00200000 ...
4159 Image Name: Linux-2.6.17-dirty
4160 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4161 Data Size: 1029343 Bytes = 1005.2 kB
4162 Load Address: 00000000
4163 Entry Point: 00000000
4164 Verifying Checksum ... OK
4165 Uncompressing Kernel Image ... OK
4166 Booting using flat device tree at 0x300000
4167 Using MPC85xx ADS machine description
4168 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4172 More About U-Boot Image Types:
4173 ------------------------------
4175 U-Boot supports the following image types:
4177 "Standalone Programs" are directly runnable in the environment
4178 provided by U-Boot; it is expected that (if they behave
4179 well) you can continue to work in U-Boot after return from
4180 the Standalone Program.
4181 "OS Kernel Images" are usually images of some Embedded OS which
4182 will take over control completely. Usually these programs
4183 will install their own set of exception handlers, device
4184 drivers, set up the MMU, etc. - this means, that you cannot
4185 expect to re-enter U-Boot except by resetting the CPU.
4186 "RAMDisk Images" are more or less just data blocks, and their
4187 parameters (address, size) are passed to an OS kernel that is
4189 "Multi-File Images" contain several images, typically an OS
4190 (Linux) kernel image and one or more data images like
4191 RAMDisks. This construct is useful for instance when you want
4192 to boot over the network using BOOTP etc., where the boot
4193 server provides just a single image file, but you want to get
4194 for instance an OS kernel and a RAMDisk image.
4196 "Multi-File Images" start with a list of image sizes, each
4197 image size (in bytes) specified by an "uint32_t" in network
4198 byte order. This list is terminated by an "(uint32_t)0".
4199 Immediately after the terminating 0 follow the images, one by
4200 one, all aligned on "uint32_t" boundaries (size rounded up to
4201 a multiple of 4 bytes).
4203 "Firmware Images" are binary images containing firmware (like
4204 U-Boot or FPGA images) which usually will be programmed to
4207 "Script files" are command sequences that will be executed by
4208 U-Boot's command interpreter; this feature is especially
4209 useful when you configure U-Boot to use a real shell (hush)
4210 as command interpreter.
4212 Booting the Linux zImage:
4213 -------------------------
4215 On some platforms, it's possible to boot Linux zImage. This is done
4216 using the "bootz" command. The syntax of "bootz" command is the same
4217 as the syntax of "bootm" command.
4219 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
4220 kernel with raw initrd images. The syntax is slightly different, the
4221 address of the initrd must be augmented by it's size, in the following
4222 format: "<initrd addres>:<initrd size>".
4228 One of the features of U-Boot is that you can dynamically load and
4229 run "standalone" applications, which can use some resources of
4230 U-Boot like console I/O functions or interrupt services.
4232 Two simple examples are included with the sources:
4237 'examples/hello_world.c' contains a small "Hello World" Demo
4238 application; it is automatically compiled when you build U-Boot.
4239 It's configured to run at address 0x00040004, so you can play with it
4243 ## Ready for S-Record download ...
4244 ~>examples/hello_world.srec
4245 1 2 3 4 5 6 7 8 9 10 11 ...
4246 [file transfer complete]
4248 ## Start Addr = 0x00040004
4250 => go 40004 Hello World! This is a test.
4251 ## Starting application at 0x00040004 ...
4262 Hit any key to exit ...
4264 ## Application terminated, rc = 0x0
4266 Another example, which demonstrates how to register a CPM interrupt
4267 handler with the U-Boot code, can be found in 'examples/timer.c'.
4268 Here, a CPM timer is set up to generate an interrupt every second.
4269 The interrupt service routine is trivial, just printing a '.'
4270 character, but this is just a demo program. The application can be
4271 controlled by the following keys:
4273 ? - print current values og the CPM Timer registers
4274 b - enable interrupts and start timer
4275 e - stop timer and disable interrupts
4276 q - quit application
4279 ## Ready for S-Record download ...
4280 ~>examples/timer.srec
4281 1 2 3 4 5 6 7 8 9 10 11 ...
4282 [file transfer complete]
4284 ## Start Addr = 0x00040004
4287 ## Starting application at 0x00040004 ...
4290 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4293 [q, b, e, ?] Set interval 1000000 us
4296 [q, b, e, ?] ........
4297 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4300 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4303 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4306 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4308 [q, b, e, ?] ...Stopping timer
4310 [q, b, e, ?] ## Application terminated, rc = 0x0
4316 Over time, many people have reported problems when trying to use the
4317 "minicom" terminal emulation program for serial download. I (wd)
4318 consider minicom to be broken, and recommend not to use it. Under
4319 Unix, I recommend to use C-Kermit for general purpose use (and
4320 especially for kermit binary protocol download ("loadb" command), and
4321 use "cu" for S-Record download ("loads" command). See
4322 http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4323 for help with kermit.
4326 Nevertheless, if you absolutely want to use it try adding this
4327 configuration to your "File transfer protocols" section:
4329 Name Program Name U/D FullScr IO-Red. Multi
4330 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4331 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4337 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4338 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4340 Building requires a cross environment; it is known to work on
4341 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4342 need gmake since the Makefiles are not compatible with BSD make).
4343 Note that the cross-powerpc package does not install include files;
4344 attempting to build U-Boot will fail because <machine/ansi.h> is
4345 missing. This file has to be installed and patched manually:
4347 # cd /usr/pkg/cross/powerpc-netbsd/include
4349 # ln -s powerpc machine
4350 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4351 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4353 Native builds *don't* work due to incompatibilities between native
4354 and U-Boot include files.
4356 Booting assumes that (the first part of) the image booted is a
4357 stage-2 loader which in turn loads and then invokes the kernel
4358 proper. Loader sources will eventually appear in the NetBSD source
4359 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4360 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4363 Implementation Internals:
4364 =========================
4366 The following is not intended to be a complete description of every
4367 implementation detail. However, it should help to understand the
4368 inner workings of U-Boot and make it easier to port it to custom
4372 Initial Stack, Global Data:
4373 ---------------------------
4375 The implementation of U-Boot is complicated by the fact that U-Boot
4376 starts running out of ROM (flash memory), usually without access to
4377 system RAM (because the memory controller is not initialized yet).
4378 This means that we don't have writable Data or BSS segments, and BSS
4379 is not initialized as zero. To be able to get a C environment working
4380 at all, we have to allocate at least a minimal stack. Implementation
4381 options for this are defined and restricted by the CPU used: Some CPU
4382 models provide on-chip memory (like the IMMR area on MPC8xx and
4383 MPC826x processors), on others (parts of) the data cache can be
4384 locked as (mis-) used as memory, etc.
4386 Chris Hallinan posted a good summary of these issues to the
4387 U-Boot mailing list:
4389 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4390 From: "Chris Hallinan" <clh@net1plus.com>
4391 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4394 Correct me if I'm wrong, folks, but the way I understand it
4395 is this: Using DCACHE as initial RAM for Stack, etc, does not
4396 require any physical RAM backing up the cache. The cleverness
4397 is that the cache is being used as a temporary supply of
4398 necessary storage before the SDRAM controller is setup. It's
4399 beyond the scope of this list to explain the details, but you
4400 can see how this works by studying the cache architecture and
4401 operation in the architecture and processor-specific manuals.
4403 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4404 is another option for the system designer to use as an
4405 initial stack/RAM area prior to SDRAM being available. Either
4406 option should work for you. Using CS 4 should be fine if your
4407 board designers haven't used it for something that would
4408 cause you grief during the initial boot! It is frequently not
4411 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4412 with your processor/board/system design. The default value
4413 you will find in any recent u-boot distribution in
4414 walnut.h should work for you. I'd set it to a value larger
4415 than your SDRAM module. If you have a 64MB SDRAM module, set
4416 it above 400_0000. Just make sure your board has no resources
4417 that are supposed to respond to that address! That code in
4418 start.S has been around a while and should work as is when
4419 you get the config right.
4424 It is essential to remember this, since it has some impact on the C
4425 code for the initialization procedures:
4427 * Initialized global data (data segment) is read-only. Do not attempt
4430 * Do not use any uninitialized global data (or implicitly initialized
4431 as zero data - BSS segment) at all - this is undefined, initiali-
4432 zation is performed later (when relocating to RAM).
4434 * Stack space is very limited. Avoid big data buffers or things like
4437 Having only the stack as writable memory limits means we cannot use
4438 normal global data to share information between the code. But it
4439 turned out that the implementation of U-Boot can be greatly
4440 simplified by making a global data structure (gd_t) available to all
4441 functions. We could pass a pointer to this data as argument to _all_
4442 functions, but this would bloat the code. Instead we use a feature of
4443 the GCC compiler (Global Register Variables) to share the data: we
4444 place a pointer (gd) to the global data into a register which we
4445 reserve for this purpose.
4447 When choosing a register for such a purpose we are restricted by the
4448 relevant (E)ABI specifications for the current architecture, and by
4449 GCC's implementation.
4451 For PowerPC, the following registers have specific use:
4453 R2: reserved for system use
4454 R3-R4: parameter passing and return values
4455 R5-R10: parameter passing
4456 R13: small data area pointer
4460 (U-Boot also uses R12 as internal GOT pointer. r12
4461 is a volatile register so r12 needs to be reset when
4462 going back and forth between asm and C)
4464 ==> U-Boot will use R2 to hold a pointer to the global data
4466 Note: on PPC, we could use a static initializer (since the
4467 address of the global data structure is known at compile time),
4468 but it turned out that reserving a register results in somewhat
4469 smaller code - although the code savings are not that big (on
4470 average for all boards 752 bytes for the whole U-Boot image,
4471 624 text + 127 data).
4473 On ARM, the following registers are used:
4475 R0: function argument word/integer result
4476 R1-R3: function argument word
4477 R9: platform specific
4478 R10: stack limit (used only if stack checking is enabled)
4479 R11: argument (frame) pointer
4480 R12: temporary workspace
4483 R15: program counter
4485 ==> U-Boot will use R9 to hold a pointer to the global data
4487 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4489 On Nios II, the ABI is documented here:
4490 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4492 ==> U-Boot will use gp to hold a pointer to the global data
4494 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4495 to access small data sections, so gp is free.
4497 On NDS32, the following registers are used:
4499 R0-R1: argument/return
4501 R15: temporary register for assembler
4502 R16: trampoline register
4503 R28: frame pointer (FP)
4504 R29: global pointer (GP)
4505 R30: link register (LP)
4506 R31: stack pointer (SP)
4507 PC: program counter (PC)
4509 ==> U-Boot will use R10 to hold a pointer to the global data
4511 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4512 or current versions of GCC may "optimize" the code too much.
4514 On RISC-V, the following registers are used:
4516 x0: hard-wired zero (zero)
4517 x1: return address (ra)
4518 x2: stack pointer (sp)
4519 x3: global pointer (gp)
4520 x4: thread pointer (tp)
4521 x5: link register (t0)
4522 x8: frame pointer (fp)
4523 x10-x11: arguments/return values (a0-1)
4524 x12-x17: arguments (a2-7)
4525 x28-31: temporaries (t3-6)
4526 pc: program counter (pc)
4528 ==> U-Boot will use gp to hold a pointer to the global data
4533 U-Boot runs in system state and uses physical addresses, i.e. the
4534 MMU is not used either for address mapping nor for memory protection.
4536 The available memory is mapped to fixed addresses using the memory
4537 controller. In this process, a contiguous block is formed for each
4538 memory type (Flash, SDRAM, SRAM), even when it consists of several
4539 physical memory banks.
4541 U-Boot is installed in the first 128 kB of the first Flash bank (on
4542 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4543 booting and sizing and initializing DRAM, the code relocates itself
4544 to the upper end of DRAM. Immediately below the U-Boot code some
4545 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4546 configuration setting]. Below that, a structure with global Board
4547 Info data is placed, followed by the stack (growing downward).
4549 Additionally, some exception handler code is copied to the low 8 kB
4550 of DRAM (0x00000000 ... 0x00001FFF).
4552 So a typical memory configuration with 16 MB of DRAM could look like
4555 0x0000 0000 Exception Vector code
4558 0x0000 2000 Free for Application Use
4564 0x00FB FF20 Monitor Stack (Growing downward)
4565 0x00FB FFAC Board Info Data and permanent copy of global data
4566 0x00FC 0000 Malloc Arena
4569 0x00FE 0000 RAM Copy of Monitor Code
4570 ... eventually: LCD or video framebuffer
4571 ... eventually: pRAM (Protected RAM - unchanged by reset)
4572 0x00FF FFFF [End of RAM]
4575 System Initialization:
4576 ----------------------
4578 In the reset configuration, U-Boot starts at the reset entry point
4579 (on most PowerPC systems at address 0x00000100). Because of the reset
4580 configuration for CS0# this is a mirror of the on board Flash memory.
4581 To be able to re-map memory U-Boot then jumps to its link address.
4582 To be able to implement the initialization code in C, a (small!)
4583 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4584 which provide such a feature like), or in a locked part of the data
4585 cache. After that, U-Boot initializes the CPU core, the caches and
4588 Next, all (potentially) available memory banks are mapped using a
4589 preliminary mapping. For example, we put them on 512 MB boundaries
4590 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4591 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4592 programmed for SDRAM access. Using the temporary configuration, a
4593 simple memory test is run that determines the size of the SDRAM
4596 When there is more than one SDRAM bank, and the banks are of
4597 different size, the largest is mapped first. For equal size, the first
4598 bank (CS2#) is mapped first. The first mapping is always for address
4599 0x00000000, with any additional banks following immediately to create
4600 contiguous memory starting from 0.
4602 Then, the monitor installs itself at the upper end of the SDRAM area
4603 and allocates memory for use by malloc() and for the global Board
4604 Info data; also, the exception vector code is copied to the low RAM
4605 pages, and the final stack is set up.
4607 Only after this relocation will you have a "normal" C environment;
4608 until that you are restricted in several ways, mostly because you are
4609 running from ROM, and because the code will have to be relocated to a
4613 U-Boot Porting Guide:
4614 ----------------------
4616 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4620 int main(int argc, char *argv[])
4622 sighandler_t no_more_time;
4624 signal(SIGALRM, no_more_time);
4625 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4627 if (available_money > available_manpower) {
4628 Pay consultant to port U-Boot;
4632 Download latest U-Boot source;
4634 Subscribe to u-boot mailing list;
4637 email("Hi, I am new to U-Boot, how do I get started?");
4640 Read the README file in the top level directory;
4641 Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4642 Read applicable doc/README.*;
4643 Read the source, Luke;
4644 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4647 if (available_money > toLocalCurrency ($2500))
4650 Add a lot of aggravation and time;
4652 if (a similar board exists) { /* hopefully... */
4653 cp -a board/<similar> board/<myboard>
4654 cp include/configs/<similar>.h include/configs/<myboard>.h
4656 Create your own board support subdirectory;
4657 Create your own board include/configs/<myboard>.h file;
4659 Edit new board/<myboard> files
4660 Edit new include/configs/<myboard>.h
4665 Add / modify source code;
4669 email("Hi, I am having problems...");
4671 Send patch file to the U-Boot email list;
4672 if (reasonable critiques)
4673 Incorporate improvements from email list code review;
4675 Defend code as written;
4681 void no_more_time (int sig)
4690 All contributions to U-Boot should conform to the Linux kernel
4691 coding style; see the kernel coding style guide at
4692 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4693 script "scripts/Lindent" in your Linux kernel source directory.
4695 Source files originating from a different project (for example the
4696 MTD subsystem) are generally exempt from these guidelines and are not
4697 reformatted to ease subsequent migration to newer versions of those
4700 Please note that U-Boot is implemented in C (and to some small parts in
4701 Assembler); no C++ is used, so please do not use C++ style comments (//)
4704 Please also stick to the following formatting rules:
4705 - remove any trailing white space
4706 - use TAB characters for indentation and vertical alignment, not spaces
4707 - make sure NOT to use DOS '\r\n' line feeds
4708 - do not add more than 2 consecutive empty lines to source files
4709 - do not add trailing empty lines to source files
4711 Submissions which do not conform to the standards may be returned
4712 with a request to reformat the changes.
4718 Since the number of patches for U-Boot is growing, we need to
4719 establish some rules. Submissions which do not conform to these rules
4720 may be rejected, even when they contain important and valuable stuff.
4722 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4724 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4725 see https://lists.denx.de/listinfo/u-boot
4727 When you send a patch, please include the following information with
4730 * For bug fixes: a description of the bug and how your patch fixes
4731 this bug. Please try to include a way of demonstrating that the
4732 patch actually fixes something.
4734 * For new features: a description of the feature and your
4737 * For major contributions, add a MAINTAINERS file with your
4738 information and associated file and directory references.
4740 * When you add support for a new board, don't forget to add a
4741 maintainer e-mail address to the boards.cfg file, too.
4743 * If your patch adds new configuration options, don't forget to
4744 document these in the README file.
4746 * The patch itself. If you are using git (which is *strongly*
4747 recommended) you can easily generate the patch using the
4748 "git format-patch". If you then use "git send-email" to send it to
4749 the U-Boot mailing list, you will avoid most of the common problems
4750 with some other mail clients.
4752 If you cannot use git, use "diff -purN OLD NEW". If your version of
4753 diff does not support these options, then get the latest version of
4756 The current directory when running this command shall be the parent
4757 directory of the U-Boot source tree (i. e. please make sure that
4758 your patch includes sufficient directory information for the
4761 We prefer patches as plain text. MIME attachments are discouraged,
4762 and compressed attachments must not be used.
4764 * If one logical set of modifications affects or creates several
4765 files, all these changes shall be submitted in a SINGLE patch file.
4767 * Changesets that contain different, unrelated modifications shall be
4768 submitted as SEPARATE patches, one patch per changeset.
4773 * Before sending the patch, run the buildman script on your patched
4774 source tree and make sure that no errors or warnings are reported
4775 for any of the boards.
4777 * Keep your modifications to the necessary minimum: A patch
4778 containing several unrelated changes or arbitrary reformats will be
4779 returned with a request to re-formatting / split it.
4781 * If you modify existing code, make sure that your new code does not
4782 add to the memory footprint of the code ;-) Small is beautiful!
4783 When adding new features, these should compile conditionally only
4784 (using #ifdef), and the resulting code with the new feature
4785 disabled must not need more memory than the old code without your
4788 * Remember that there is a size limit of 100 kB per message on the
4789 u-boot mailing list. Bigger patches will be moderated. If they are
4790 reasonable and not too big, they will be acknowledged. But patches
4791 bigger than the size limit should be avoided.
projects / platform / kernel / u-boot.git / blob