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 https://lists.denx.de/pipermail/u-boot and
55 https://marc.info/?l=u-boot
57 Where to get source code:
58 =========================
60 The U-Boot source code is maintained in the Git repository at
61 https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
62 https://source.denx.de/u-boot/u-boot
64 The "Tags" links on this page allow you to download tarballs of
65 any version you might be interested in. Official releases are also
66 available from the DENX file server through HTTPS or FTP.
67 https://ftp.denx.de/pub/u-boot/
68 ftp://ftp.denx.de/pub/u-boot/
74 - start from 8xxrom sources
75 - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
77 - make it easier to add custom boards
78 - make it possible to add other [PowerPC] CPUs
79 - extend functions, especially:
80 * Provide extended interface to Linux boot loader
83 * ATA disk / SCSI ... boot
84 - create ARMBoot project (https://sourceforge.net/projects/armboot)
85 - add other CPU families (starting with ARM)
86 - create U-Boot project (https://sourceforge.net/projects/u-boot)
87 - current project page: see https://www.denx.de/wiki/U-Boot
93 The "official" name of this project is "Das U-Boot". The spelling
94 "U-Boot" shall be used in all written text (documentation, comments
95 in source files etc.). Example:
97 This is the README file for the U-Boot project.
99 File names etc. shall be based on the string "u-boot". Examples:
101 include/asm-ppc/u-boot.h
103 #include <asm/u-boot.h>
105 Variable names, preprocessor constants etc. shall be either based on
106 the string "u_boot" or on "U_BOOT". Example:
108 U_BOOT_VERSION u_boot_logo
109 IH_OS_U_BOOT u_boot_hush_start
115 Starting with the release in October 2008, the names of the releases
116 were changed from numerical release numbers without deeper meaning
117 into a time stamp based numbering. Regular releases are identified by
118 names consisting of the calendar year and month of the release date.
119 Additional fields (if present) indicate release candidates or bug fix
120 releases in "stable" maintenance trees.
123 U-Boot v2009.11 - Release November 2009
124 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
125 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 /arch Architecture-specific files
132 /arc Files generic to ARC architecture
133 /arm Files generic to ARM architecture
134 /m68k Files generic to m68k architecture
135 /microblaze Files generic to microblaze architecture
136 /mips Files generic to MIPS architecture
137 /nds32 Files generic to NDS32 architecture
138 /nios2 Files generic to Altera NIOS2 architecture
139 /powerpc Files generic to PowerPC architecture
140 /riscv Files generic to RISC-V architecture
141 /sandbox Files generic to HW-independent "sandbox"
142 /sh Files generic to SH architecture
143 /x86 Files generic to x86 architecture
144 /xtensa Files generic to Xtensa architecture
145 /api Machine/arch-independent API for external apps
146 /board Board-dependent files
147 /cmd U-Boot commands functions
148 /common Misc architecture-independent functions
149 /configs Board default configuration files
150 /disk Code for disk drive partition handling
151 /doc Documentation (a mix of ReST and READMEs)
152 /drivers Device drivers
153 /dts Makefile for building internal U-Boot fdt.
154 /env Environment support
155 /examples Example code for standalone applications, etc.
156 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
157 /include Header Files
158 /lib Library routines generic to all architectures
159 /Licenses Various license files
161 /post Power On Self Test
162 /scripts Various build scripts and Makefiles
163 /test Various unit test files
164 /tools Tools to build and sign FIT images, etc.
166 Software Configuration:
167 =======================
169 Configuration is usually done using C preprocessor defines; the
170 rationale behind that is to avoid dead code whenever possible.
172 There are two classes of configuration variables:
174 * Configuration _OPTIONS_:
175 These are selectable by the user and have names beginning with
178 * Configuration _SETTINGS_:
179 These depend on the hardware etc. and should not be meddled with if
180 you don't know what you're doing; they have names beginning with
183 Previously, all configuration was done by hand, which involved creating
184 symbolic links and editing configuration files manually. More recently,
185 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
186 allowing you to use the "make menuconfig" command to configure your
190 Selection of Processor Architecture and Board Type:
191 ---------------------------------------------------
193 For all supported boards there are ready-to-use default
194 configurations available; just type "make <board_name>_defconfig".
196 Example: For a TQM823L module type:
199 make TQM823L_defconfig
201 Note: If you're looking for the default configuration file for a board
202 you're sure used to be there but is now missing, check the file
203 doc/README.scrapyard for a list of no longer supported boards.
208 U-Boot can be built natively to run on a Linux host using the 'sandbox'
209 board. This allows feature development which is not board- or architecture-
210 specific to be undertaken on a native platform. The sandbox is also used to
211 run some of U-Boot's tests.
213 See doc/arch/sandbox.rst for more details.
216 Board Initialisation Flow:
217 --------------------------
219 This is the intended start-up flow for boards. This should apply for both
220 SPL and U-Boot proper (i.e. they both follow the same rules).
222 Note: "SPL" stands for "Secondary Program Loader," which is explained in
223 more detail later in this file.
225 At present, SPL mostly uses a separate code path, but the function names
226 and roles of each function are the same. Some boards or architectures
227 may not conform to this. At least most ARM boards which use
228 CONFIG_SPL_FRAMEWORK conform to this.
230 Execution typically starts with an architecture-specific (and possibly
231 CPU-specific) start.S file, such as:
233 - arch/arm/cpu/armv7/start.S
234 - arch/powerpc/cpu/mpc83xx/start.S
235 - arch/mips/cpu/start.S
237 and so on. From there, three functions are called; the purpose and
238 limitations of each of these functions are described below.
241 - purpose: essential init to permit execution to reach board_init_f()
242 - no global_data or BSS
243 - there is no stack (ARMv7 may have one but it will soon be removed)
244 - must not set up SDRAM or use console
245 - must only do the bare minimum to allow execution to continue to
247 - this is almost never needed
248 - return normally from this function
251 - purpose: set up the machine ready for running board_init_r():
252 i.e. SDRAM and serial UART
253 - global_data is available
255 - BSS is not available, so you cannot use global/static variables,
256 only stack variables and global_data
258 Non-SPL-specific notes:
259 - dram_init() is called to set up DRAM. If already done in SPL this
263 - you can override the entire board_init_f() function with your own
265 - preloader_console_init() can be called here in extremis
266 - should set up SDRAM, and anything needed to make the UART work
267 - there is no need to clear BSS, it will be done by crt0.S
268 - for specific scenarios on certain architectures an early BSS *can*
269 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
270 of BSS prior to entering board_init_f()) but doing so is discouraged.
271 Instead it is strongly recommended to architect any code changes
272 or additions such to not depend on the availability of BSS during
273 board_init_f() as indicated in other sections of this README to
274 maintain compatibility and consistency across the entire code base.
275 - must return normally from this function (don't call board_init_r()
278 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
279 this point the stack and global_data are relocated to below
280 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
284 - purpose: main execution, common code
285 - global_data is available
287 - BSS is available, all static/global variables can be used
288 - execution eventually continues to main_loop()
290 Non-SPL-specific notes:
291 - U-Boot is relocated to the top of memory and is now running from
295 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
296 CONFIG_SPL_STACK_R_ADDR points into SDRAM
297 - preloader_console_init() can be called here - typically this is
298 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
299 spl_board_init() function containing this call
300 - loads U-Boot or (in falcon mode) Linux
304 Configuration Options:
305 ----------------------
307 Configuration depends on the combination of board and CPU type; all
308 such information is kept in a configuration file
309 "include/configs/<board_name>.h".
311 Example: For a TQM823L module, all configuration settings are in
312 "include/configs/TQM823L.h".
315 Many of the options are named exactly as the corresponding Linux
316 kernel configuration options. The intention is to make it easier to
317 build a config tool - later.
319 - ARM Platform Bus Type(CCI):
320 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
321 provides full cache coherency between two clusters of multi-core
322 CPUs and I/O coherency for devices and I/O masters
324 CONFIG_SYS_FSL_HAS_CCI400
326 Defined For SoC that has cache coherent interconnect
329 CONFIG_SYS_FSL_HAS_CCN504
331 Defined for SoC that has cache coherent interconnect CCN-504
333 The following options need to be configured:
335 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
337 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
342 Specifies that the core is a 64-bit PowerPC implementation (implements
343 the "64" category of the Power ISA). This is necessary for ePAPR
344 compliance, among other possible reasons.
346 CONFIG_SYS_FSL_TBCLK_DIV
348 Defines the core time base clock divider ratio compared to the
349 system clock. On most PQ3 devices this is 8, on newer QorIQ
350 devices it can be 16 or 32. The ratio varies from SoC to Soc.
352 CONFIG_SYS_FSL_PCIE_COMPAT
354 Defines the string to utilize when trying to match PCIe device
355 tree nodes for the given platform.
357 CONFIG_SYS_FSL_ERRATUM_A004510
359 Enables a workaround for erratum A004510. If set,
360 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
361 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
364 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
366 Defines one or two SoC revisions (low 8 bits of SVR)
367 for which the A004510 workaround should be applied.
369 The rest of SVR is either not relevant to the decision
370 of whether the erratum is present (e.g. p2040 versus
371 p2041) or is implied by the build target, which controls
372 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
374 See Freescale App Note 4493 for more information about
377 CONFIG_A003399_NOR_WORKAROUND
378 Enables a workaround for IFC erratum A003399. It is only
379 required during NOR boot.
381 CONFIG_A008044_WORKAROUND
382 Enables a workaround for T1040/T1042 erratum A008044. It is only
383 required during NAND boot and valid for Rev 1.0 SoC revision
385 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
387 This is the value to write into CCSR offset 0x18600
388 according to the A004510 workaround.
390 CONFIG_SYS_FSL_DSP_DDR_ADDR
391 This value denotes start offset of DDR memory which is
392 connected exclusively to the DSP cores.
394 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
395 This value denotes start offset of M2 memory
396 which is directly connected to the DSP core.
398 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
399 This value denotes start offset of M3 memory which is directly
400 connected to the DSP core.
402 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
403 This value denotes start offset of DSP CCSR space.
405 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
406 Single Source Clock is clocking mode present in some of FSL SoC's.
407 In this mode, a single differential clock is used to supply
408 clocks to the sysclock, ddrclock and usbclock.
410 CONFIG_SYS_CPC_REINIT_F
411 This CONFIG is defined when the CPC is configured as SRAM at the
412 time of U-Boot entry and is required to be re-initialized.
415 Indicates this SoC supports deep sleep feature. If deep sleep is
416 supported, core will start to execute uboot when wakes up.
418 - Generic CPU options:
419 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
421 Defines the endianess of the CPU. Implementation of those
422 values is arch specific.
425 Freescale DDR driver in use. This type of DDR controller is
426 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
428 CONFIG_SYS_FSL_DDR_ADDR
429 Freescale DDR memory-mapped register base.
431 CONFIG_SYS_FSL_DDR_EMU
432 Specify emulator support for DDR. Some DDR features such as
433 deskew training are not available.
435 CONFIG_SYS_FSL_DDRC_GEN1
436 Freescale DDR1 controller.
438 CONFIG_SYS_FSL_DDRC_GEN2
439 Freescale DDR2 controller.
441 CONFIG_SYS_FSL_DDRC_GEN3
442 Freescale DDR3 controller.
444 CONFIG_SYS_FSL_DDRC_GEN4
445 Freescale DDR4 controller.
447 CONFIG_SYS_FSL_DDRC_ARM_GEN3
448 Freescale DDR3 controller for ARM-based SoCs.
451 Board config to use DDR1. It can be enabled for SoCs with
452 Freescale DDR1 or DDR2 controllers, depending on the board
456 Board config to use DDR2. It can be enabled for SoCs with
457 Freescale DDR2 or DDR3 controllers, depending on the board
461 Board config to use DDR3. It can be enabled for SoCs with
462 Freescale DDR3 or DDR3L controllers.
465 Board config to use DDR3L. It can be enabled for SoCs with
469 Board config to use DDR4. It can be enabled for SoCs with
472 CONFIG_SYS_FSL_IFC_BE
473 Defines the IFC controller register space as Big Endian
475 CONFIG_SYS_FSL_IFC_LE
476 Defines the IFC controller register space as Little Endian
478 CONFIG_SYS_FSL_IFC_CLK_DIV
479 Defines divider of platform clock(clock input to IFC controller).
481 CONFIG_SYS_FSL_LBC_CLK_DIV
482 Defines divider of platform clock(clock input to eLBC controller).
484 CONFIG_SYS_FSL_PBL_PBI
485 It enables addition of RCW (Power on reset configuration) in built image.
486 Please refer doc/README.pblimage for more details
488 CONFIG_SYS_FSL_PBL_RCW
489 It adds PBI(pre-boot instructions) commands in u-boot build image.
490 PBI commands can be used to configure SoC before it starts the execution.
491 Please refer doc/README.pblimage for more details
493 CONFIG_SYS_FSL_DDR_BE
494 Defines the DDR controller register space as Big Endian
496 CONFIG_SYS_FSL_DDR_LE
497 Defines the DDR controller register space as Little Endian
499 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
500 Physical address from the view of DDR controllers. It is the
501 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
502 it could be different for ARM SoCs.
504 CONFIG_SYS_FSL_DDR_INTLV_256B
505 DDR controller interleaving on 256-byte. This is a special
506 interleaving mode, handled by Dickens for Freescale layerscape
509 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
510 Number of controllers used as main memory.
512 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
513 Number of controllers used for other than main memory.
515 CONFIG_SYS_FSL_HAS_DP_DDR
516 Defines the SoC has DP-DDR used for DPAA.
518 CONFIG_SYS_FSL_SEC_BE
519 Defines the SEC controller register space as Big Endian
521 CONFIG_SYS_FSL_SEC_LE
522 Defines the SEC controller register space as Little Endian
525 CONFIG_SYS_INIT_SP_OFFSET
527 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
528 pointer. This is needed for the temporary stack before
531 CONFIG_XWAY_SWAP_BYTES
533 Enable compilation of tools/xway-swap-bytes needed for Lantiq
534 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
535 be swapped if a flash programmer is used.
538 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
540 Select high exception vectors of the ARM core, e.g., do not
541 clear the V bit of the c1 register of CP15.
544 Generic timer clock source frequency.
546 COUNTER_FREQUENCY_REAL
547 Generic timer clock source frequency if the real clock is
548 different from COUNTER_FREQUENCY, and can only be determined
552 CONFIG_TEGRA_SUPPORT_NON_SECURE
554 Support executing U-Boot in non-secure (NS) mode. Certain
555 impossible actions will be skipped if the CPU is in NS mode,
556 such as ARM architectural timer initialization.
558 - Linux Kernel Interface:
559 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
561 When transferring memsize parameter to Linux, some versions
562 expect it to be in bytes, others in MB.
563 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
567 New kernel versions are expecting firmware settings to be
568 passed using flattened device trees (based on open firmware
572 * New libfdt-based support
573 * Adds the "fdt" command
574 * The bootm command automatically updates the fdt
576 OF_TBCLK - The timebase frequency.
578 boards with QUICC Engines require OF_QE to set UCC MAC
581 CONFIG_OF_BOARD_SETUP
583 Board code has addition modification that it wants to make
584 to the flat device tree before handing it off to the kernel
586 CONFIG_OF_SYSTEM_SETUP
588 Other code has addition modification that it wants to make
589 to the flat device tree before handing it off to the kernel.
590 This causes ft_system_setup() to be called before booting
595 U-Boot can detect if an IDE device is present or not.
596 If not, and this new config option is activated, U-Boot
597 removes the ATA node from the DTS before booting Linux,
598 so the Linux IDE driver does not probe the device and
599 crash. This is needed for buggy hardware (uc101) where
600 no pull down resistor is connected to the signal IDE5V_DD7.
602 CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
604 This setting is mandatory for all boards that have only one
605 machine type and must be used to specify the machine type
606 number as it appears in the ARM machine registry
607 (see https://www.arm.linux.org.uk/developer/machines/).
608 Only boards that have multiple machine types supported
609 in a single configuration file and the machine type is
610 runtime discoverable, do not have to use this setting.
612 - vxWorks boot parameters:
614 bootvx constructs a valid bootline using the following
615 environments variables: bootdev, bootfile, ipaddr, netmask,
616 serverip, gatewayip, hostname, othbootargs.
617 It loads the vxWorks image pointed bootfile.
619 Note: If a "bootargs" environment is defined, it will override
620 the defaults discussed just above.
622 - Cache Configuration:
623 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
625 - Cache Configuration for ARM:
626 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
628 CONFIG_SYS_PL310_BASE - Physical base address of PL310
629 controller register space
634 Define this if you want support for Amba PrimeCell PL011 UARTs.
638 If you have Amba PrimeCell PL011 UARTs, set this variable to
639 the clock speed of the UARTs.
643 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
644 define this to a list of base addresses for each (supported)
645 port. See e.g. include/configs/versatile.h
647 CONFIG_SERIAL_HW_FLOW_CONTROL
649 Define this variable to enable hw flow control in serial driver.
650 Current user of this option is drivers/serial/nsl16550.c driver
654 Only needed when CONFIG_BOOTDELAY is enabled;
655 define a command string that is automatically executed
656 when no character is read on the console interface
657 within "Boot Delay" after reset.
659 CONFIG_RAMBOOT and CONFIG_NFSBOOT
660 The value of these goes into the environment as
661 "ramboot" and "nfsboot" respectively, and can be used
662 as a convenience, when switching between booting from
665 - Serial Download Echo Mode:
667 If defined to 1, all characters received during a
668 serial download (using the "loads" command) are
669 echoed back. This might be needed by some terminal
670 emulations (like "cu"), but may as well just take
671 time on others. This setting #define's the initial
672 value of the "loads_echo" environment variable.
674 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
676 Select one of the baudrates listed in
677 CONFIG_SYS_BAUDRATE_TABLE, see below.
679 - Removal of commands
680 If no commands are needed to boot, you can disable
681 CONFIG_CMDLINE to remove them. In this case, the command line
682 will not be available, and when U-Boot wants to execute the
683 boot command (on start-up) it will call board_run_command()
684 instead. This can reduce image size significantly for very
685 simple boot procedures.
687 - Regular expression support:
689 If this variable is defined, U-Boot is linked against
690 the SLRE (Super Light Regular Expression) library,
691 which adds regex support to some commands, as for
692 example "env grep" and "setexpr".
696 If this variable is defined, U-Boot will use a device tree
697 to configure its devices, instead of relying on statically
698 compiled #defines in the board file. This option is
699 experimental and only available on a few boards. The device
700 tree is available in the global data as gd->fdt_blob.
702 U-Boot needs to get its device tree from somewhere. This can
703 be done using one of the three options below:
706 If this variable is defined, U-Boot will embed a device tree
707 binary in its image. This device tree file should be in the
708 board directory and called <soc>-<board>.dts. The binary file
709 is then picked up in board_init_f() and made available through
710 the global data structure as gd->fdt_blob.
713 If this variable is defined, U-Boot will build a device tree
714 binary. It will be called u-boot.dtb. Architecture-specific
715 code will locate it at run-time. Generally this works by:
717 cat u-boot.bin u-boot.dtb >image.bin
719 and in fact, U-Boot does this for you, creating a file called
720 u-boot-dtb.bin which is useful in the common case. You can
721 still use the individual files if you need something more
725 If this variable is defined, U-Boot will use the device tree
726 provided by the board at runtime instead of embedding one with
727 the image. Only boards defining board_fdt_blob_setup() support
728 this option (see include/fdtdec.h file).
732 If this variable is defined, it enables watchdog
733 support for the SoC. There must be support in the SoC
734 specific code for a watchdog. For the 8xx
735 CPUs, the SIU Watchdog feature is enabled in the SYPCR
736 register. When supported for a specific SoC is
737 available, then no further board specific code should
741 When using a watchdog circuitry external to the used
742 SoC, then define this variable and provide board
743 specific code for the "hw_watchdog_reset" function.
745 CONFIG_SYS_WATCHDOG_FREQ
746 Some platforms automatically call WATCHDOG_RESET()
747 from the timer interrupt handler every
748 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
749 board configuration file, a default of CONFIG_SYS_HZ/2
750 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
751 to 0 disables calling WATCHDOG_RESET() from the timer
756 When CONFIG_CMD_DATE is selected, the type of the RTC
757 has to be selected, too. Define exactly one of the
760 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
761 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
762 CONFIG_RTC_MC146818 - use MC146818 RTC
763 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
764 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
765 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
766 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
767 CONFIG_RTC_DS164x - use Dallas DS164x RTC
768 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
769 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
770 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
771 CONFIG_SYS_RV3029_TCR - enable trickle charger on
774 Note that if the RTC uses I2C, then the I2C interface
775 must also be configured. See I2C Support, below.
778 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
780 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
781 chip-ngpio pairs that tell the PCA953X driver the number of
782 pins supported by a particular chip.
784 Note that if the GPIO device uses I2C, then the I2C interface
785 must also be configured. See I2C Support, below.
788 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
789 accesses and can checksum them or write a list of them out
790 to memory. See the 'iotrace' command for details. This is
791 useful for testing device drivers since it can confirm that
792 the driver behaves the same way before and after a code
793 change. Currently this is supported on sandbox and arm. To
794 add support for your architecture, add '#include <iotrace.h>'
795 to the bottom of arch/<arch>/include/asm/io.h and test.
797 Example output from the 'iotrace stats' command is below.
798 Note that if the trace buffer is exhausted, the checksum will
799 still continue to operate.
802 Start: 10000000 (buffer start address)
803 Size: 00010000 (buffer size)
804 Offset: 00000120 (current buffer offset)
805 Output: 10000120 (start + offset)
806 Count: 00000018 (number of trace records)
807 CRC32: 9526fb66 (CRC32 of all trace records)
811 When CONFIG_TIMESTAMP is selected, the timestamp
812 (date and time) of an image is printed by image
813 commands like bootm or iminfo. This option is
814 automatically enabled when you select CONFIG_CMD_DATE .
816 - Partition Labels (disklabels) Supported:
817 Zero or more of the following:
818 CONFIG_MAC_PARTITION Apple's MacOS partition table.
819 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
820 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
821 bootloader. Note 2TB partition limit; see
823 CONFIG_SCSI) you must configure support for at
824 least one non-MTD partition type as well.
827 CONFIG_IDE_RESET_ROUTINE - this is defined in several
828 board configurations files but used nowhere!
830 CONFIG_IDE_RESET - is this is defined, IDE Reset will
831 be performed by calling the function
832 ide_set_reset(int reset)
833 which has to be defined in a board specific file
838 Set this to enable ATAPI support.
843 Set this to enable support for disks larger than 137GB
844 Also look at CONFIG_SYS_64BIT_LBA.
845 Whithout these , LBA48 support uses 32bit variables and will 'only'
846 support disks up to 2.1TB.
848 CONFIG_SYS_64BIT_LBA:
849 When enabled, makes the IDE subsystem use 64bit sector addresses.
853 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
854 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
855 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
856 maximum numbers of LUNs, SCSI ID's and target
859 The environment variable 'scsidevs' is set to the number of
860 SCSI devices found during the last scan.
862 - NETWORK Support (PCI):
864 Support for Intel 8254x/8257x gigabit chips.
867 Utility code for direct access to the SPI bus on Intel 8257x.
868 This does not do anything useful unless you set at least one
869 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
871 CONFIG_E1000_SPI_GENERIC
872 Allow generic access to the SPI bus on the Intel 8257x, for
873 example with the "sspi" command.
876 Support for National dp83815 chips.
879 Support for National dp8382[01] gigabit chips.
881 - NETWORK Support (other):
883 CONFIG_DRIVER_AT91EMAC
884 Support for AT91RM9200 EMAC.
887 Define this to use reduced MII inteface
889 CONFIG_DRIVER_AT91EMAC_QUIET
890 If this defined, the driver is quiet.
891 The driver doen't show link status messages.
894 Support for the Calxeda XGMAC device
897 Support for SMSC's LAN91C96 chips.
899 CONFIG_LAN91C96_USE_32_BIT
900 Define this to enable 32 bit addressing
903 Support for SMSC's LAN91C111 chip
906 Define this to hold the physical address
907 of the device (I/O space)
909 CONFIG_SMC_USE_32_BIT
910 Define this if data bus is 32 bits
912 CONFIG_SMC_USE_IOFUNCS
913 Define this to use i/o functions instead of macros
914 (some hardware wont work with macros)
916 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
917 Define this if you have more then 3 PHYs.
920 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
922 CONFIG_FTGMAC100_EGIGA
923 Define this to use GE link update with gigabit PHY.
924 Define this if FTGMAC100 is connected to gigabit PHY.
925 If your system has 10/100 PHY only, it might not occur
926 wrong behavior. Because PHY usually return timeout or
927 useless data when polling gigabit status and gigabit
928 control registers. This behavior won't affect the
929 correctnessof 10/100 link speed update.
932 Support for Renesas on-chip Ethernet controller
934 CONFIG_SH_ETHER_USE_PORT
935 Define the number of ports to be used
937 CONFIG_SH_ETHER_PHY_ADDR
938 Define the ETH PHY's address
940 CONFIG_SH_ETHER_CACHE_WRITEBACK
941 If this option is set, the driver enables cache flush.
947 CONFIG_TPM_TIS_INFINEON
948 Support for Infineon i2c bus TPM devices. Only one device
949 per system is supported at this time.
951 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
952 Define the burst count bytes upper limit
955 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
957 CONFIG_TPM_ST33ZP24_I2C
958 Support for STMicroelectronics ST33ZP24 I2C devices.
959 Requires TPM_ST33ZP24 and I2C.
961 CONFIG_TPM_ST33ZP24_SPI
962 Support for STMicroelectronics ST33ZP24 SPI devices.
963 Requires TPM_ST33ZP24 and SPI.
966 Support for Atmel TWI TPM device. Requires I2C support.
969 Support for generic parallel port TPM devices. Only one device
970 per system is supported at this time.
972 CONFIG_TPM_TIS_BASE_ADDRESS
973 Base address where the generic TPM device is mapped
974 to. Contemporary x86 systems usually map it at
978 Define this to enable the TPM support library which provides
979 functional interfaces to some TPM commands.
980 Requires support for a TPM device.
982 CONFIG_TPM_AUTH_SESSIONS
983 Define this to enable authorized functions in the TPM library.
984 Requires CONFIG_TPM and CONFIG_SHA1.
987 At the moment only the UHCI host controller is
988 supported (PIP405, MIP405); define
989 CONFIG_USB_UHCI to enable it.
990 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
991 and define CONFIG_USB_STORAGE to enable the USB
994 Supported are USB Keyboards and USB Floppy drives
997 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
998 txfilltuning field in the EHCI controller on reset.
1000 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1001 HW module registers.
1004 Define the below if you wish to use the USB console.
1005 Once firmware is rebuilt from a serial console issue the
1006 command "setenv stdin usbtty; setenv stdout usbtty" and
1007 attach your USB cable. The Unix command "dmesg" should print
1008 it has found a new device. The environment variable usbtty
1009 can be set to gserial or cdc_acm to enable your device to
1010 appear to a USB host as a Linux gserial device or a
1011 Common Device Class Abstract Control Model serial device.
1012 If you select usbtty = gserial you should be able to enumerate
1014 # modprobe usbserial vendor=0xVendorID product=0xProductID
1015 else if using cdc_acm, simply setting the environment
1016 variable usbtty to be cdc_acm should suffice. The following
1017 might be defined in YourBoardName.h
1020 Define this to build a UDC device
1023 Define this to have a tty type of device available to
1024 talk to the UDC device
1027 Define this to enable the high speed support for usb
1028 device and usbtty. If this feature is enabled, a routine
1029 int is_usbd_high_speed(void)
1030 also needs to be defined by the driver to dynamically poll
1031 whether the enumeration has succeded at high speed or full
1034 CONFIG_SYS_CONSOLE_IS_IN_ENV
1035 Define this if you want stdin, stdout &/or stderr to
1038 If you have a USB-IF assigned VendorID then you may wish to
1039 define your own vendor specific values either in BoardName.h
1040 or directly in usbd_vendor_info.h. If you don't define
1041 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1042 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1043 should pretend to be a Linux device to it's target host.
1045 CONFIG_USBD_MANUFACTURER
1046 Define this string as the name of your company for
1047 - CONFIG_USBD_MANUFACTURER "my company"
1049 CONFIG_USBD_PRODUCT_NAME
1050 Define this string as the name of your product
1051 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1053 CONFIG_USBD_VENDORID
1054 Define this as your assigned Vendor ID from the USB
1055 Implementors Forum. This *must* be a genuine Vendor ID
1056 to avoid polluting the USB namespace.
1057 - CONFIG_USBD_VENDORID 0xFFFF
1059 CONFIG_USBD_PRODUCTID
1060 Define this as the unique Product ID
1062 - CONFIG_USBD_PRODUCTID 0xFFFF
1064 - ULPI Layer Support:
1065 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1066 the generic ULPI layer. The generic layer accesses the ULPI PHY
1067 via the platform viewport, so you need both the genric layer and
1068 the viewport enabled. Currently only Chipidea/ARC based
1069 viewport is supported.
1070 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1071 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1072 If your ULPI phy needs a different reference clock than the
1073 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1074 the appropriate value in Hz.
1077 The MMC controller on the Intel PXA is supported. To
1078 enable this define CONFIG_MMC. The MMC can be
1079 accessed from the boot prompt by mapping the device
1080 to physical memory similar to flash. Command line is
1081 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1082 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1085 Support for Renesas on-chip MMCIF controller
1087 CONFIG_SH_MMCIF_ADDR
1088 Define the base address of MMCIF registers
1091 Define the clock frequency for MMCIF
1093 - USB Device Firmware Update (DFU) class support:
1095 This enables the USB portion of the DFU USB class
1098 This enables support for exposing NAND devices via DFU.
1101 This enables support for exposing RAM via DFU.
1102 Note: DFU spec refer to non-volatile memory usage, but
1103 allow usages beyond the scope of spec - here RAM usage,
1104 one that would help mostly the developer.
1106 CONFIG_SYS_DFU_DATA_BUF_SIZE
1107 Dfu transfer uses a buffer before writing data to the
1108 raw storage device. Make the size (in bytes) of this buffer
1109 configurable. The size of this buffer is also configurable
1110 through the "dfu_bufsiz" environment variable.
1112 CONFIG_SYS_DFU_MAX_FILE_SIZE
1113 When updating files rather than the raw storage device,
1114 we use a static buffer to copy the file into and then write
1115 the buffer once we've been given the whole file. Define
1116 this to the maximum filesize (in bytes) for the buffer.
1117 Default is 4 MiB if undefined.
1119 DFU_DEFAULT_POLL_TIMEOUT
1120 Poll timeout [ms], is the timeout a device can send to the
1121 host. The host must wait for this timeout before sending
1122 a subsequent DFU_GET_STATUS request to the device.
1124 DFU_MANIFEST_POLL_TIMEOUT
1125 Poll timeout [ms], which the device sends to the host when
1126 entering dfuMANIFEST state. Host waits this timeout, before
1127 sending again an USB request to the device.
1129 - Journaling Flash filesystem support:
1131 Define these for a default partition on a NAND device
1133 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1134 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1135 Define these for a default partition on a NOR device
1138 See Kconfig help for available keyboard drivers.
1142 Define this to enable a custom keyboard support.
1143 This simply calls drv_keyboard_init() which must be
1144 defined in your board-specific files. This option is deprecated
1145 and is only used by novena. For new boards, use driver model
1150 Enable the Freescale DIU video driver. Reference boards for
1151 SOCs that have a DIU should define this macro to enable DIU
1152 support, and should also define these other macros:
1157 CONFIG_VIDEO_SW_CURSOR
1158 CONFIG_VGA_AS_SINGLE_DEVICE
1160 CONFIG_VIDEO_BMP_LOGO
1162 The DIU driver will look for the 'video-mode' environment
1163 variable, and if defined, enable the DIU as a console during
1164 boot. See the documentation file doc/README.video for a
1165 description of this variable.
1167 - LCD Support: CONFIG_LCD
1169 Define this to enable LCD support (for output to LCD
1170 display); also select one of the supported displays
1171 by defining one of these:
1175 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1177 CONFIG_NEC_NL6448AC33:
1179 NEC NL6448AC33-18. Active, color, single scan.
1181 CONFIG_NEC_NL6448BC20
1183 NEC NL6448BC20-08. 6.5", 640x480.
1184 Active, color, single scan.
1186 CONFIG_NEC_NL6448BC33_54
1188 NEC NL6448BC33-54. 10.4", 640x480.
1189 Active, color, single scan.
1193 Sharp 320x240. Active, color, single scan.
1194 It isn't 16x9, and I am not sure what it is.
1196 CONFIG_SHARP_LQ64D341
1198 Sharp LQ64D341 display, 640x480.
1199 Active, color, single scan.
1203 HLD1045 display, 640x480.
1204 Active, color, single scan.
1208 Optrex CBL50840-2 NF-FW 99 22 M5
1210 Hitachi LMG6912RPFC-00T
1214 320x240. Black & white.
1216 CONFIG_LCD_ALIGNMENT
1218 Normally the LCD is page-aligned (typically 4KB). If this is
1219 defined then the LCD will be aligned to this value instead.
1220 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1221 here, since it is cheaper to change data cache settings on
1222 a per-section basis.
1227 Sometimes, for example if the display is mounted in portrait
1228 mode or even if it's mounted landscape but rotated by 180degree,
1229 we need to rotate our content of the display relative to the
1230 framebuffer, so that user can read the messages which are
1232 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1233 initialized with a given rotation from "vl_rot" out of
1234 "vidinfo_t" which is provided by the board specific code.
1235 The value for vl_rot is coded as following (matching to
1236 fbcon=rotate:<n> linux-kernel commandline):
1237 0 = no rotation respectively 0 degree
1238 1 = 90 degree rotation
1239 2 = 180 degree rotation
1240 3 = 270 degree rotation
1242 If CONFIG_LCD_ROTATION is not defined, the console will be
1243 initialized with 0degree rotation.
1247 Support drawing of RLE8-compressed bitmaps on the LCD.
1251 Enables an 'i2c edid' command which can read EDID
1252 information over I2C from an attached LCD display.
1255 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1257 The clock frequency of the MII bus
1259 CONFIG_PHY_RESET_DELAY
1261 Some PHY like Intel LXT971A need extra delay after
1262 reset before any MII register access is possible.
1263 For such PHY, set this option to the usec delay
1264 required. (minimum 300usec for LXT971A)
1266 CONFIG_PHY_CMD_DELAY (ppc4xx)
1268 Some PHY like Intel LXT971A need extra delay after
1269 command issued before MII status register can be read
1274 Define a default value for the IP address to use for
1275 the default Ethernet interface, in case this is not
1276 determined through e.g. bootp.
1277 (Environment variable "ipaddr")
1279 - Server IP address:
1282 Defines a default value for the IP address of a TFTP
1283 server to contact when using the "tftboot" command.
1284 (Environment variable "serverip")
1286 CONFIG_KEEP_SERVERADDR
1288 Keeps the server's MAC address, in the env 'serveraddr'
1289 for passing to bootargs (like Linux's netconsole option)
1291 - Gateway IP address:
1294 Defines a default value for the IP address of the
1295 default router where packets to other networks are
1297 (Environment variable "gatewayip")
1302 Defines a default value for the subnet mask (or
1303 routing prefix) which is used to determine if an IP
1304 address belongs to the local subnet or needs to be
1305 forwarded through a router.
1306 (Environment variable "netmask")
1308 - BOOTP Recovery Mode:
1309 CONFIG_BOOTP_RANDOM_DELAY
1311 If you have many targets in a network that try to
1312 boot using BOOTP, you may want to avoid that all
1313 systems send out BOOTP requests at precisely the same
1314 moment (which would happen for instance at recovery
1315 from a power failure, when all systems will try to
1316 boot, thus flooding the BOOTP server. Defining
1317 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1318 inserted before sending out BOOTP requests. The
1319 following delays are inserted then:
1321 1st BOOTP request: delay 0 ... 1 sec
1322 2nd BOOTP request: delay 0 ... 2 sec
1323 3rd BOOTP request: delay 0 ... 4 sec
1325 BOOTP requests: delay 0 ... 8 sec
1327 CONFIG_BOOTP_ID_CACHE_SIZE
1329 BOOTP packets are uniquely identified using a 32-bit ID. The
1330 server will copy the ID from client requests to responses and
1331 U-Boot will use this to determine if it is the destination of
1332 an incoming response. Some servers will check that addresses
1333 aren't in use before handing them out (usually using an ARP
1334 ping) and therefore take up to a few hundred milliseconds to
1335 respond. Network congestion may also influence the time it
1336 takes for a response to make it back to the client. If that
1337 time is too long, U-Boot will retransmit requests. In order
1338 to allow earlier responses to still be accepted after these
1339 retransmissions, U-Boot's BOOTP client keeps a small cache of
1340 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1341 cache. The default is to keep IDs for up to four outstanding
1342 requests. Increasing this will allow U-Boot to accept offers
1343 from a BOOTP client in networks with unusually high latency.
1345 - DHCP Advanced Options:
1346 You can fine tune the DHCP functionality by defining
1347 CONFIG_BOOTP_* symbols:
1349 CONFIG_BOOTP_NISDOMAIN
1350 CONFIG_BOOTP_BOOTFILESIZE
1351 CONFIG_BOOTP_NTPSERVER
1352 CONFIG_BOOTP_TIMEOFFSET
1353 CONFIG_BOOTP_VENDOREX
1354 CONFIG_BOOTP_MAY_FAIL
1356 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1357 environment variable, not the BOOTP server.
1359 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1360 after the configured retry count, the call will fail
1361 instead of starting over. This can be used to fail over
1362 to Link-local IP address configuration if the DHCP server
1365 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1367 A 32bit value in microseconds for a delay between
1368 receiving a "DHCP Offer" and sending the "DHCP Request".
1369 This fixes a problem with certain DHCP servers that don't
1370 respond 100% of the time to a "DHCP request". E.g. On an
1371 AT91RM9200 processor running at 180MHz, this delay needed
1372 to be *at least* 15,000 usec before a Windows Server 2003
1373 DHCP server would reply 100% of the time. I recommend at
1374 least 50,000 usec to be safe. The alternative is to hope
1375 that one of the retries will be successful but note that
1376 the DHCP timeout and retry process takes a longer than
1379 - Link-local IP address negotiation:
1380 Negotiate with other link-local clients on the local network
1381 for an address that doesn't require explicit configuration.
1382 This is especially useful if a DHCP server cannot be guaranteed
1383 to exist in all environments that the device must operate.
1385 See doc/README.link-local for more information.
1387 - MAC address from environment variables
1389 FDT_SEQ_MACADDR_FROM_ENV
1391 Fix-up device tree with MAC addresses fetched sequentially from
1392 environment variables. This config work on assumption that
1393 non-usable ethernet node of device-tree are either not present
1394 or their status has been marked as "disabled".
1397 CONFIG_CDP_DEVICE_ID
1399 The device id used in CDP trigger frames.
1401 CONFIG_CDP_DEVICE_ID_PREFIX
1403 A two character string which is prefixed to the MAC address
1408 A printf format string which contains the ascii name of
1409 the port. Normally is set to "eth%d" which sets
1410 eth0 for the first Ethernet, eth1 for the second etc.
1412 CONFIG_CDP_CAPABILITIES
1414 A 32bit integer which indicates the device capabilities;
1415 0x00000010 for a normal host which does not forwards.
1419 An ascii string containing the version of the software.
1423 An ascii string containing the name of the platform.
1427 A 32bit integer sent on the trigger.
1429 CONFIG_CDP_POWER_CONSUMPTION
1431 A 16bit integer containing the power consumption of the
1432 device in .1 of milliwatts.
1434 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1436 A byte containing the id of the VLAN.
1438 - Status LED: CONFIG_LED_STATUS
1440 Several configurations allow to display the current
1441 status using a LED. For instance, the LED will blink
1442 fast while running U-Boot code, stop blinking as
1443 soon as a reply to a BOOTP request was received, and
1444 start blinking slow once the Linux kernel is running
1445 (supported by a status LED driver in the Linux
1446 kernel). Defining CONFIG_LED_STATUS enables this
1451 CONFIG_LED_STATUS_GPIO
1452 The status LED can be connected to a GPIO pin.
1453 In such cases, the gpio_led driver can be used as a
1454 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1455 to include the gpio_led driver in the U-Boot binary.
1457 CONFIG_GPIO_LED_INVERTED_TABLE
1458 Some GPIO connected LEDs may have inverted polarity in which
1459 case the GPIO high value corresponds to LED off state and
1460 GPIO low value corresponds to LED on state.
1461 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1462 with a list of GPIO LEDs that have inverted polarity.
1465 - drivers/i2c/fsl_i2c.c:
1466 - activate i2c driver with CONFIG_SYS_I2C_FSL
1467 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1468 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1469 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1471 - If your board supports a second fsl i2c bus, define
1472 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1473 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1474 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1477 - drivers/i2c/tegra_i2c.c:
1478 - activate this driver with CONFIG_SYS_I2C_TEGRA
1479 - This driver adds 4 i2c buses with a fix speed from
1480 100000 and the slave addr 0!
1482 - drivers/i2c/ppc4xx_i2c.c
1483 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1484 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1485 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1487 - drivers/i2c/i2c_mxc.c
1488 - activate this driver with CONFIG_SYS_I2C_MXC
1489 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1490 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1491 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1492 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1493 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1494 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1495 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1496 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1497 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1498 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1499 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1500 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1501 If those defines are not set, default value is 100000
1502 for speed, and 0 for slave.
1504 - drivers/i2c/rcar_i2c.c:
1505 - activate this driver with CONFIG_SYS_I2C_RCAR
1506 - This driver adds 4 i2c buses
1508 - drivers/i2c/sh_i2c.c:
1509 - activate this driver with CONFIG_SYS_I2C_SH
1510 - This driver adds from 2 to 5 i2c buses
1512 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1513 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1514 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1515 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1516 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1517 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1518 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1519 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1520 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1521 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1522 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1524 - drivers/i2c/s3c24x0_i2c.c:
1525 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1526 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1527 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1528 with a fix speed from 100000 and the slave addr 0!
1530 - drivers/i2c/ihs_i2c.c
1531 - activate this driver with CONFIG_SYS_I2C_IHS
1532 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1533 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1534 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1535 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1536 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1537 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1538 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1539 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1540 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1541 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1542 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1543 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1544 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1545 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1546 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1547 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1548 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1549 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1550 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1551 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1552 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1556 CONFIG_SYS_NUM_I2C_BUSES
1557 Hold the number of i2c buses you want to use.
1559 CONFIG_SYS_I2C_DIRECT_BUS
1560 define this, if you don't use i2c muxes on your hardware.
1561 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1564 CONFIG_SYS_I2C_MAX_HOPS
1565 define how many muxes are maximal consecutively connected
1566 on one i2c bus. If you not use i2c muxes, omit this
1569 CONFIG_SYS_I2C_BUSES
1570 hold a list of buses you want to use, only used if
1571 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1572 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1573 CONFIG_SYS_NUM_I2C_BUSES = 9:
1575 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1576 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1577 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1578 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1579 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1580 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1581 {1, {I2C_NULL_HOP}}, \
1582 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1583 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1587 bus 0 on adapter 0 without a mux
1588 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1589 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1590 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1591 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1592 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1593 bus 6 on adapter 1 without a mux
1594 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1595 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1597 If you do not have i2c muxes on your board, omit this define.
1599 - Legacy I2C Support:
1600 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1601 then the following macros need to be defined (examples are
1602 from include/configs/lwmon.h):
1606 (Optional). Any commands necessary to enable the I2C
1607 controller or configure ports.
1609 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1613 The code necessary to make the I2C data line active
1614 (driven). If the data line is open collector, this
1617 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1621 The code necessary to make the I2C data line tri-stated
1622 (inactive). If the data line is open collector, this
1625 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1629 Code that returns true if the I2C data line is high,
1632 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1636 If <bit> is true, sets the I2C data line high. If it
1637 is false, it clears it (low).
1639 eg: #define I2C_SDA(bit) \
1640 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1641 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1645 If <bit> is true, sets the I2C clock line high. If it
1646 is false, it clears it (low).
1648 eg: #define I2C_SCL(bit) \
1649 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1650 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1654 This delay is invoked four times per clock cycle so this
1655 controls the rate of data transfer. The data rate thus
1656 is 1 / (I2C_DELAY * 4). Often defined to be something
1659 #define I2C_DELAY udelay(2)
1661 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1663 If your arch supports the generic GPIO framework (asm/gpio.h),
1664 then you may alternatively define the two GPIOs that are to be
1665 used as SCL / SDA. Any of the previous I2C_xxx macros will
1666 have GPIO-based defaults assigned to them as appropriate.
1668 You should define these to the GPIO value as given directly to
1669 the generic GPIO functions.
1671 CONFIG_SYS_I2C_INIT_BOARD
1673 When a board is reset during an i2c bus transfer
1674 chips might think that the current transfer is still
1675 in progress. On some boards it is possible to access
1676 the i2c SCLK line directly, either by using the
1677 processor pin as a GPIO or by having a second pin
1678 connected to the bus. If this option is defined a
1679 custom i2c_init_board() routine in boards/xxx/board.c
1680 is run early in the boot sequence.
1682 CONFIG_I2C_MULTI_BUS
1684 This option allows the use of multiple I2C buses, each of which
1685 must have a controller. At any point in time, only one bus is
1686 active. To switch to a different bus, use the 'i2c dev' command.
1687 Note that bus numbering is zero-based.
1689 CONFIG_SYS_I2C_NOPROBES
1691 This option specifies a list of I2C devices that will be skipped
1692 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1693 is set, specify a list of bus-device pairs. Otherwise, specify
1694 a 1D array of device addresses
1697 #undef CONFIG_I2C_MULTI_BUS
1698 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1700 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1702 #define CONFIG_I2C_MULTI_BUS
1703 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1705 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1707 CONFIG_SYS_SPD_BUS_NUM
1709 If defined, then this indicates the I2C bus number for DDR SPD.
1710 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1712 CONFIG_SYS_RTC_BUS_NUM
1714 If defined, then this indicates the I2C bus number for the RTC.
1715 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1717 CONFIG_SOFT_I2C_READ_REPEATED_START
1719 defining this will force the i2c_read() function in
1720 the soft_i2c driver to perform an I2C repeated start
1721 between writing the address pointer and reading the
1722 data. If this define is omitted the default behaviour
1723 of doing a stop-start sequence will be used. Most I2C
1724 devices can use either method, but some require one or
1727 - SPI Support: CONFIG_SPI
1729 Enables SPI driver (so far only tested with
1730 SPI EEPROM, also an instance works with Crystal A/D and
1731 D/As on the SACSng board)
1735 Enables a software (bit-bang) SPI driver rather than
1736 using hardware support. This is a general purpose
1737 driver that only requires three general I/O port pins
1738 (two outputs, one input) to function. If this is
1739 defined, the board configuration must define several
1740 SPI configuration items (port pins to use, etc). For
1741 an example, see include/configs/sacsng.h.
1743 CONFIG_SYS_SPI_MXC_WAIT
1744 Timeout for waiting until spi transfer completed.
1745 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1747 - FPGA Support: CONFIG_FPGA
1749 Enables FPGA subsystem.
1751 CONFIG_FPGA_<vendor>
1753 Enables support for specific chip vendors.
1756 CONFIG_FPGA_<family>
1758 Enables support for FPGA family.
1759 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1763 Specify the number of FPGA devices to support.
1765 CONFIG_SYS_FPGA_PROG_FEEDBACK
1767 Enable printing of hash marks during FPGA configuration.
1769 CONFIG_SYS_FPGA_CHECK_BUSY
1771 Enable checks on FPGA configuration interface busy
1772 status by the configuration function. This option
1773 will require a board or device specific function to
1778 If defined, a function that provides delays in the FPGA
1779 configuration driver.
1781 CONFIG_SYS_FPGA_CHECK_CTRLC
1782 Allow Control-C to interrupt FPGA configuration
1784 CONFIG_SYS_FPGA_CHECK_ERROR
1786 Check for configuration errors during FPGA bitfile
1787 loading. For example, abort during Virtex II
1788 configuration if the INIT_B line goes low (which
1789 indicated a CRC error).
1791 CONFIG_SYS_FPGA_WAIT_INIT
1793 Maximum time to wait for the INIT_B line to de-assert
1794 after PROB_B has been de-asserted during a Virtex II
1795 FPGA configuration sequence. The default time is 500
1798 CONFIG_SYS_FPGA_WAIT_BUSY
1800 Maximum time to wait for BUSY to de-assert during
1801 Virtex II FPGA configuration. The default is 5 ms.
1803 CONFIG_SYS_FPGA_WAIT_CONFIG
1805 Time to wait after FPGA configuration. The default is
1808 - Configuration Management:
1812 If defined, this string will be added to the U-Boot
1813 version information (U_BOOT_VERSION)
1815 - Vendor Parameter Protection:
1817 U-Boot considers the values of the environment
1818 variables "serial#" (Board Serial Number) and
1819 "ethaddr" (Ethernet Address) to be parameters that
1820 are set once by the board vendor / manufacturer, and
1821 protects these variables from casual modification by
1822 the user. Once set, these variables are read-only,
1823 and write or delete attempts are rejected. You can
1824 change this behaviour:
1826 If CONFIG_ENV_OVERWRITE is #defined in your config
1827 file, the write protection for vendor parameters is
1828 completely disabled. Anybody can change or delete
1831 Alternatively, if you define _both_ an ethaddr in the
1832 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1833 Ethernet address is installed in the environment,
1834 which can be changed exactly ONCE by the user. [The
1835 serial# is unaffected by this, i. e. it remains
1838 The same can be accomplished in a more flexible way
1839 for any variable by configuring the type of access
1840 to allow for those variables in the ".flags" variable
1841 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1846 Define this variable to enable the reservation of
1847 "protected RAM", i. e. RAM which is not overwritten
1848 by U-Boot. Define CONFIG_PRAM to hold the number of
1849 kB you want to reserve for pRAM. You can overwrite
1850 this default value by defining an environment
1851 variable "pram" to the number of kB you want to
1852 reserve. Note that the board info structure will
1853 still show the full amount of RAM. If pRAM is
1854 reserved, a new environment variable "mem" will
1855 automatically be defined to hold the amount of
1856 remaining RAM in a form that can be passed as boot
1857 argument to Linux, for instance like that:
1859 setenv bootargs ... mem=\${mem}
1862 This way you can tell Linux not to use this memory,
1863 either, which results in a memory region that will
1864 not be affected by reboots.
1866 *WARNING* If your board configuration uses automatic
1867 detection of the RAM size, you must make sure that
1868 this memory test is non-destructive. So far, the
1869 following board configurations are known to be
1872 IVMS8, IVML24, SPD8xx,
1873 HERMES, IP860, RPXlite, LWMON,
1876 - Access to physical memory region (> 4GB)
1877 Some basic support is provided for operations on memory not
1878 normally accessible to U-Boot - e.g. some architectures
1879 support access to more than 4GB of memory on 32-bit
1880 machines using physical address extension or similar.
1881 Define CONFIG_PHYSMEM to access this basic support, which
1882 currently only supports clearing the memory.
1885 CONFIG_NET_RETRY_COUNT
1887 This variable defines the number of retries for
1888 network operations like ARP, RARP, TFTP, or BOOTP
1889 before giving up the operation. If not defined, a
1890 default value of 5 is used.
1894 Timeout waiting for an ARP reply in milliseconds.
1898 Timeout in milliseconds used in NFS protocol.
1899 If you encounter "ERROR: Cannot umount" in nfs command,
1900 try longer timeout such as
1901 #define CONFIG_NFS_TIMEOUT 10000UL
1905 In the current implementation, the local variables
1906 space and global environment variables space are
1907 separated. Local variables are those you define by
1908 simply typing `name=value'. To access a local
1909 variable later on, you have write `$name' or
1910 `${name}'; to execute the contents of a variable
1911 directly type `$name' at the command prompt.
1913 Global environment variables are those you use
1914 setenv/printenv to work with. To run a command stored
1915 in such a variable, you need to use the run command,
1916 and you must not use the '$' sign to access them.
1918 To store commands and special characters in a
1919 variable, please use double quotation marks
1920 surrounding the whole text of the variable, instead
1921 of the backslashes before semicolons and special
1924 - Command Line Editing and History:
1925 CONFIG_CMDLINE_PS_SUPPORT
1927 Enable support for changing the command prompt string
1928 at run-time. Only static string is supported so far.
1929 The string is obtained from environment variables PS1
1932 - Default Environment:
1933 CONFIG_EXTRA_ENV_SETTINGS
1935 Define this to contain any number of null terminated
1936 strings (variable = value pairs) that will be part of
1937 the default environment compiled into the boot image.
1939 For example, place something like this in your
1940 board's config file:
1942 #define CONFIG_EXTRA_ENV_SETTINGS \
1946 Warning: This method is based on knowledge about the
1947 internal format how the environment is stored by the
1948 U-Boot code. This is NOT an official, exported
1949 interface! Although it is unlikely that this format
1950 will change soon, there is no guarantee either.
1951 You better know what you are doing here.
1953 Note: overly (ab)use of the default environment is
1954 discouraged. Make sure to check other ways to preset
1955 the environment like the "source" command or the
1958 CONFIG_DELAY_ENVIRONMENT
1960 Normally the environment is loaded when the board is
1961 initialised so that it is available to U-Boot. This inhibits
1962 that so that the environment is not available until
1963 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1964 this is instead controlled by the value of
1965 /config/load-environment.
1967 - TFTP Fixed UDP Port:
1970 If this is defined, the environment variable tftpsrcp
1971 is used to supply the TFTP UDP source port value.
1972 If tftpsrcp isn't defined, the normal pseudo-random port
1973 number generator is used.
1975 Also, the environment variable tftpdstp is used to supply
1976 the TFTP UDP destination port value. If tftpdstp isn't
1977 defined, the normal port 69 is used.
1979 The purpose for tftpsrcp is to allow a TFTP server to
1980 blindly start the TFTP transfer using the pre-configured
1981 target IP address and UDP port. This has the effect of
1982 "punching through" the (Windows XP) firewall, allowing
1983 the remainder of the TFTP transfer to proceed normally.
1984 A better solution is to properly configure the firewall,
1985 but sometimes that is not allowed.
1987 CONFIG_STANDALONE_LOAD_ADDR
1989 This option defines a board specific value for the
1990 address where standalone program gets loaded, thus
1991 overwriting the architecture dependent default
1994 - Frame Buffer Address:
1997 Define CONFIG_FB_ADDR if you want to use specific
1998 address for frame buffer. This is typically the case
1999 when using a graphics controller has separate video
2000 memory. U-Boot will then place the frame buffer at
2001 the given address instead of dynamically reserving it
2002 in system RAM by calling lcd_setmem(), which grabs
2003 the memory for the frame buffer depending on the
2004 configured panel size.
2006 Please see board_init_f function.
2008 - Automatic software updates via TFTP server
2010 CONFIG_UPDATE_TFTP_CNT_MAX
2011 CONFIG_UPDATE_TFTP_MSEC_MAX
2013 These options enable and control the auto-update feature;
2014 for a more detailed description refer to doc/README.update.
2016 - MTD Support (mtdparts command, UBI support)
2017 CONFIG_MTD_UBI_WL_THRESHOLD
2018 This parameter defines the maximum difference between the highest
2019 erase counter value and the lowest erase counter value of eraseblocks
2020 of UBI devices. When this threshold is exceeded, UBI starts performing
2021 wear leveling by means of moving data from eraseblock with low erase
2022 counter to eraseblocks with high erase counter.
2024 The default value should be OK for SLC NAND flashes, NOR flashes and
2025 other flashes which have eraseblock life-cycle 100000 or more.
2026 However, in case of MLC NAND flashes which typically have eraseblock
2027 life-cycle less than 10000, the threshold should be lessened (e.g.,
2028 to 128 or 256, although it does not have to be power of 2).
2032 CONFIG_MTD_UBI_BEB_LIMIT
2033 This option specifies the maximum bad physical eraseblocks UBI
2034 expects on the MTD device (per 1024 eraseblocks). If the
2035 underlying flash does not admit of bad eraseblocks (e.g. NOR
2036 flash), this value is ignored.
2038 NAND datasheets often specify the minimum and maximum NVM
2039 (Number of Valid Blocks) for the flashes' endurance lifetime.
2040 The maximum expected bad eraseblocks per 1024 eraseblocks
2041 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2042 which gives 20 for most NANDs (MaxNVB is basically the total
2043 count of eraseblocks on the chip).
2045 To put it differently, if this value is 20, UBI will try to
2046 reserve about 1.9% of physical eraseblocks for bad blocks
2047 handling. And that will be 1.9% of eraseblocks on the entire
2048 NAND chip, not just the MTD partition UBI attaches. This means
2049 that if you have, say, a NAND flash chip admits maximum 40 bad
2050 eraseblocks, and it is split on two MTD partitions of the same
2051 size, UBI will reserve 40 eraseblocks when attaching a
2056 CONFIG_MTD_UBI_FASTMAP
2057 Fastmap is a mechanism which allows attaching an UBI device
2058 in nearly constant time. Instead of scanning the whole MTD device it
2059 only has to locate a checkpoint (called fastmap) on the device.
2060 The on-flash fastmap contains all information needed to attach
2061 the device. Using fastmap makes only sense on large devices where
2062 attaching by scanning takes long. UBI will not automatically install
2063 a fastmap on old images, but you can set the UBI parameter
2064 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2065 that fastmap-enabled images are still usable with UBI implementations
2066 without fastmap support. On typical flash devices the whole fastmap
2067 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2069 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2070 Set this parameter to enable fastmap automatically on images
2074 CONFIG_MTD_UBI_FM_DEBUG
2075 Enable UBI fastmap debug
2080 Enable building of SPL globally.
2083 LDSCRIPT for linking the SPL binary.
2085 CONFIG_SPL_MAX_FOOTPRINT
2086 Maximum size in memory allocated to the SPL, BSS included.
2087 When defined, the linker checks that the actual memory
2088 used by SPL from _start to __bss_end does not exceed it.
2089 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2090 must not be both defined at the same time.
2093 Maximum size of the SPL image (text, data, rodata, and
2094 linker lists sections), BSS excluded.
2095 When defined, the linker checks that the actual size does
2098 CONFIG_SPL_RELOC_TEXT_BASE
2099 Address to relocate to. If unspecified, this is equal to
2100 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2102 CONFIG_SPL_BSS_START_ADDR
2103 Link address for the BSS within the SPL binary.
2105 CONFIG_SPL_BSS_MAX_SIZE
2106 Maximum size in memory allocated to the SPL BSS.
2107 When defined, the linker checks that the actual memory used
2108 by SPL from __bss_start to __bss_end does not exceed it.
2109 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2110 must not be both defined at the same time.
2113 Adress of the start of the stack SPL will use
2115 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2116 When defined, SPL will panic() if the image it has
2117 loaded does not have a signature.
2118 Defining this is useful when code which loads images
2119 in SPL cannot guarantee that absolutely all read errors
2121 An example is the LPC32XX MLC NAND driver, which will
2122 consider that a completely unreadable NAND block is bad,
2123 and thus should be skipped silently.
2125 CONFIG_SPL_RELOC_STACK
2126 Adress of the start of the stack SPL will use after
2127 relocation. If unspecified, this is equal to
2130 CONFIG_SYS_SPL_MALLOC_START
2131 Starting address of the malloc pool used in SPL.
2132 When this option is set the full malloc is used in SPL and
2133 it is set up by spl_init() and before that, the simple malloc()
2134 can be used if CONFIG_SYS_MALLOC_F is defined.
2136 CONFIG_SYS_SPL_MALLOC_SIZE
2137 The size of the malloc pool used in SPL.
2140 Enable booting directly to an OS from SPL.
2141 See also: doc/README.falcon
2143 CONFIG_SPL_DISPLAY_PRINT
2144 For ARM, enable an optional function to print more information
2145 about the running system.
2147 CONFIG_SPL_INIT_MINIMAL
2148 Arch init code should be built for a very small image
2150 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2151 Partition on the MMC to load U-Boot from when the MMC is being
2154 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2155 Sector to load kernel uImage from when MMC is being
2156 used in raw mode (for Falcon mode)
2158 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2159 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2160 Sector and number of sectors to load kernel argument
2161 parameters from when MMC is being used in raw mode
2164 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2165 Filename to read to load U-Boot when reading from filesystem
2167 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2168 Filename to read to load kernel uImage when reading
2169 from filesystem (for Falcon mode)
2171 CONFIG_SPL_FS_LOAD_ARGS_NAME
2172 Filename to read to load kernel argument parameters
2173 when reading from filesystem (for Falcon mode)
2175 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2176 Set this for NAND SPL on PPC mpc83xx targets, so that
2177 start.S waits for the rest of the SPL to load before
2178 continuing (the hardware starts execution after just
2179 loading the first page rather than the full 4K).
2181 CONFIG_SPL_SKIP_RELOCATE
2182 Avoid SPL relocation
2184 CONFIG_SPL_NAND_IDENT
2185 SPL uses the chip ID list to identify the NAND flash.
2186 Requires CONFIG_SPL_NAND_BASE.
2189 Support for a lightweight UBI (fastmap) scanner and
2192 CONFIG_SPL_NAND_RAW_ONLY
2193 Support to boot only raw u-boot.bin images. Use this only
2194 if you need to save space.
2196 CONFIG_SPL_COMMON_INIT_DDR
2197 Set for common ddr init with serial presence detect in
2200 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2201 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2202 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2203 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2204 CONFIG_SYS_NAND_ECCBYTES
2205 Defines the size and behavior of the NAND that SPL uses
2208 CONFIG_SYS_NAND_U_BOOT_OFFS
2209 Location in NAND to read U-Boot from
2211 CONFIG_SYS_NAND_U_BOOT_DST
2212 Location in memory to load U-Boot to
2214 CONFIG_SYS_NAND_U_BOOT_SIZE
2215 Size of image to load
2217 CONFIG_SYS_NAND_U_BOOT_START
2218 Entry point in loaded image to jump to
2220 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2221 Define this if you need to first read the OOB and then the
2222 data. This is used, for example, on davinci platforms.
2224 CONFIG_SPL_RAM_DEVICE
2225 Support for running image already present in ram, in SPL binary
2228 Image offset to which the SPL should be padded before appending
2229 the SPL payload. By default, this is defined as
2230 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2231 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2232 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2235 Final target image containing SPL and payload. Some SPLs
2236 use an arch-specific makefile fragment instead, for
2237 example if more than one image needs to be produced.
2239 CONFIG_SPL_FIT_PRINT
2240 Printing information about a FIT image adds quite a bit of
2241 code to SPL. So this is normally disabled in SPL. Use this
2242 option to re-enable it. This will affect the output of the
2243 bootm command when booting a FIT image.
2247 Enable building of TPL globally.
2250 Image offset to which the TPL should be padded before appending
2251 the TPL payload. By default, this is defined as
2252 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2253 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2254 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2256 - Interrupt support (PPC):
2258 There are common interrupt_init() and timer_interrupt()
2259 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2260 for CPU specific initialization. interrupt_init_cpu()
2261 should set decrementer_count to appropriate value. If
2262 CPU resets decrementer automatically after interrupt
2263 (ppc4xx) it should set decrementer_count to zero.
2264 timer_interrupt() calls timer_interrupt_cpu() for CPU
2265 specific handling. If board has watchdog / status_led
2266 / other_activity_monitor it works automatically from
2267 general timer_interrupt().
2270 Board initialization settings:
2271 ------------------------------
2273 During Initialization u-boot calls a number of board specific functions
2274 to allow the preparation of board specific prerequisites, e.g. pin setup
2275 before drivers are initialized. To enable these callbacks the
2276 following configuration macros have to be defined. Currently this is
2277 architecture specific, so please check arch/your_architecture/lib/board.c
2278 typically in board_init_f() and board_init_r().
2280 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2281 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2282 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2283 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2285 Configuration Settings:
2286 -----------------------
2288 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2289 Optionally it can be defined to support 64-bit memory commands.
2291 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2292 undefine this when you're short of memory.
2294 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2295 width of the commands listed in the 'help' command output.
2297 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2298 prompt for user input.
2300 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2302 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2304 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2306 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2307 the application (usually a Linux kernel) when it is
2310 - CONFIG_SYS_BAUDRATE_TABLE:
2311 List of legal baudrate settings for this board.
2313 - CONFIG_SYS_MEM_RESERVE_SECURE
2314 Only implemented for ARMv8 for now.
2315 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2316 is substracted from total RAM and won't be reported to OS.
2317 This memory can be used as secure memory. A variable
2318 gd->arch.secure_ram is used to track the location. In systems
2319 the RAM base is not zero, or RAM is divided into banks,
2320 this variable needs to be recalcuated to get the address.
2322 - CONFIG_SYS_MEM_TOP_HIDE:
2323 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2324 this specified memory area will get subtracted from the top
2325 (end) of RAM and won't get "touched" at all by U-Boot. By
2326 fixing up gd->ram_size the Linux kernel should gets passed
2327 the now "corrected" memory size and won't touch it either.
2328 This should work for arch/ppc and arch/powerpc. Only Linux
2329 board ports in arch/powerpc with bootwrapper support that
2330 recalculate the memory size from the SDRAM controller setup
2331 will have to get fixed in Linux additionally.
2333 This option can be used as a workaround for the 440EPx/GRx
2334 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2337 WARNING: Please make sure that this value is a multiple of
2338 the Linux page size (normally 4k). If this is not the case,
2339 then the end address of the Linux memory will be located at a
2340 non page size aligned address and this could cause major
2343 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2344 Enable temporary baudrate change while serial download
2346 - CONFIG_SYS_SDRAM_BASE:
2347 Physical start address of SDRAM. _Must_ be 0 here.
2349 - CONFIG_SYS_FLASH_BASE:
2350 Physical start address of Flash memory.
2352 - CONFIG_SYS_MONITOR_BASE:
2353 Physical start address of boot monitor code (set by
2354 make config files to be same as the text base address
2355 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2356 CONFIG_SYS_FLASH_BASE when booting from flash.
2358 - CONFIG_SYS_MONITOR_LEN:
2359 Size of memory reserved for monitor code, used to
2360 determine _at_compile_time_ (!) if the environment is
2361 embedded within the U-Boot image, or in a separate
2364 - CONFIG_SYS_MALLOC_LEN:
2365 Size of DRAM reserved for malloc() use.
2367 - CONFIG_SYS_MALLOC_F_LEN
2368 Size of the malloc() pool for use before relocation. If
2369 this is defined, then a very simple malloc() implementation
2370 will become available before relocation. The address is just
2371 below the global data, and the stack is moved down to make
2374 This feature allocates regions with increasing addresses
2375 within the region. calloc() is supported, but realloc()
2376 is not available. free() is supported but does nothing.
2377 The memory will be freed (or in fact just forgotten) when
2378 U-Boot relocates itself.
2380 - CONFIG_SYS_MALLOC_SIMPLE
2381 Provides a simple and small malloc() and calloc() for those
2382 boards which do not use the full malloc in SPL (which is
2383 enabled with CONFIG_SYS_SPL_MALLOC_START).
2385 - CONFIG_SYS_NONCACHED_MEMORY:
2386 Size of non-cached memory area. This area of memory will be
2387 typically located right below the malloc() area and mapped
2388 uncached in the MMU. This is useful for drivers that would
2389 otherwise require a lot of explicit cache maintenance. For
2390 some drivers it's also impossible to properly maintain the
2391 cache. For example if the regions that need to be flushed
2392 are not a multiple of the cache-line size, *and* padding
2393 cannot be allocated between the regions to align them (i.e.
2394 if the HW requires a contiguous array of regions, and the
2395 size of each region is not cache-aligned), then a flush of
2396 one region may result in overwriting data that hardware has
2397 written to another region in the same cache-line. This can
2398 happen for example in network drivers where descriptors for
2399 buffers are typically smaller than the CPU cache-line (e.g.
2400 16 bytes vs. 32 or 64 bytes).
2402 Non-cached memory is only supported on 32-bit ARM at present.
2404 - CONFIG_SYS_BOOTM_LEN:
2405 Normally compressed uImages are limited to an
2406 uncompressed size of 8 MBytes. If this is not enough,
2407 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2408 to adjust this setting to your needs.
2410 - CONFIG_SYS_BOOTMAPSZ:
2411 Maximum size of memory mapped by the startup code of
2412 the Linux kernel; all data that must be processed by
2413 the Linux kernel (bd_info, boot arguments, FDT blob if
2414 used) must be put below this limit, unless "bootm_low"
2415 environment variable is defined and non-zero. In such case
2416 all data for the Linux kernel must be between "bootm_low"
2417 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2418 variable "bootm_mapsize" will override the value of
2419 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2420 then the value in "bootm_size" will be used instead.
2422 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2423 Enable initrd_high functionality. If defined then the
2424 initrd_high feature is enabled and the bootm ramdisk subcommand
2427 - CONFIG_SYS_BOOT_GET_CMDLINE:
2428 Enables allocating and saving kernel cmdline in space between
2429 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2431 - CONFIG_SYS_BOOT_GET_KBD:
2432 Enables allocating and saving a kernel copy of the bd_info in
2433 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2435 - CONFIG_SYS_MAX_FLASH_BANKS:
2436 Max number of Flash memory banks
2438 - CONFIG_SYS_MAX_FLASH_SECT:
2439 Max number of sectors on a Flash chip
2441 - CONFIG_SYS_FLASH_ERASE_TOUT:
2442 Timeout for Flash erase operations (in ms)
2444 - CONFIG_SYS_FLASH_WRITE_TOUT:
2445 Timeout for Flash write operations (in ms)
2447 - CONFIG_SYS_FLASH_LOCK_TOUT
2448 Timeout for Flash set sector lock bit operation (in ms)
2450 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2451 Timeout for Flash clear lock bits operation (in ms)
2453 - CONFIG_SYS_FLASH_PROTECTION
2454 If defined, hardware flash sectors protection is used
2455 instead of U-Boot software protection.
2457 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2459 Enable TFTP transfers directly to flash memory;
2460 without this option such a download has to be
2461 performed in two steps: (1) download to RAM, and (2)
2462 copy from RAM to flash.
2464 The two-step approach is usually more reliable, since
2465 you can check if the download worked before you erase
2466 the flash, but in some situations (when system RAM is
2467 too limited to allow for a temporary copy of the
2468 downloaded image) this option may be very useful.
2470 - CONFIG_SYS_FLASH_CFI:
2471 Define if the flash driver uses extra elements in the
2472 common flash structure for storing flash geometry.
2474 - CONFIG_FLASH_CFI_DRIVER
2475 This option also enables the building of the cfi_flash driver
2476 in the drivers directory
2478 - CONFIG_FLASH_CFI_MTD
2479 This option enables the building of the cfi_mtd driver
2480 in the drivers directory. The driver exports CFI flash
2483 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2484 Use buffered writes to flash.
2486 - CONFIG_FLASH_SPANSION_S29WS_N
2487 s29ws-n MirrorBit flash has non-standard addresses for buffered
2490 - CONFIG_SYS_FLASH_QUIET_TEST
2491 If this option is defined, the common CFI flash doesn't
2492 print it's warning upon not recognized FLASH banks. This
2493 is useful, if some of the configured banks are only
2494 optionally available.
2496 - CONFIG_FLASH_SHOW_PROGRESS
2497 If defined (must be an integer), print out countdown
2498 digits and dots. Recommended value: 45 (9..1) for 80
2499 column displays, 15 (3..1) for 40 column displays.
2501 - CONFIG_FLASH_VERIFY
2502 If defined, the content of the flash (destination) is compared
2503 against the source after the write operation. An error message
2504 will be printed when the contents are not identical.
2505 Please note that this option is useless in nearly all cases,
2506 since such flash programming errors usually are detected earlier
2507 while unprotecting/erasing/programming. Please only enable
2508 this option if you really know what you are doing.
2510 - CONFIG_SYS_RX_ETH_BUFFER:
2511 Defines the number of Ethernet receive buffers. On some
2512 Ethernet controllers it is recommended to set this value
2513 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2514 buffers can be full shortly after enabling the interface
2515 on high Ethernet traffic.
2516 Defaults to 4 if not defined.
2518 - CONFIG_ENV_MAX_ENTRIES
2520 Maximum number of entries in the hash table that is used
2521 internally to store the environment settings. The default
2522 setting is supposed to be generous and should work in most
2523 cases. This setting can be used to tune behaviour; see
2524 lib/hashtable.c for details.
2526 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2527 - CONFIG_ENV_FLAGS_LIST_STATIC
2528 Enable validation of the values given to environment variables when
2529 calling env set. Variables can be restricted to only decimal,
2530 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2531 the variables can also be restricted to IP address or MAC address.
2533 The format of the list is:
2534 type_attribute = [s|d|x|b|i|m]
2535 access_attribute = [a|r|o|c]
2536 attributes = type_attribute[access_attribute]
2537 entry = variable_name[:attributes]
2540 The type attributes are:
2541 s - String (default)
2544 b - Boolean ([1yYtT|0nNfF])
2548 The access attributes are:
2554 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2555 Define this to a list (string) to define the ".flags"
2556 environment variable in the default or embedded environment.
2558 - CONFIG_ENV_FLAGS_LIST_STATIC
2559 Define this to a list (string) to define validation that
2560 should be done if an entry is not found in the ".flags"
2561 environment variable. To override a setting in the static
2562 list, simply add an entry for the same variable name to the
2565 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2566 regular expression. This allows multiple variables to define the same
2567 flags without explicitly listing them for each variable.
2569 The following definitions that deal with the placement and management
2570 of environment data (variable area); in general, we support the
2571 following configurations:
2573 - CONFIG_BUILD_ENVCRC:
2575 Builds up envcrc with the target environment so that external utils
2576 may easily extract it and embed it in final U-Boot images.
2578 BE CAREFUL! The first access to the environment happens quite early
2579 in U-Boot initialization (when we try to get the setting of for the
2580 console baudrate). You *MUST* have mapped your NVRAM area then, or
2583 Please note that even with NVRAM we still use a copy of the
2584 environment in RAM: we could work on NVRAM directly, but we want to
2585 keep settings there always unmodified except somebody uses "saveenv"
2586 to save the current settings.
2588 BE CAREFUL! For some special cases, the local device can not use
2589 "saveenv" command. For example, the local device will get the
2590 environment stored in a remote NOR flash by SRIO or PCIE link,
2591 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2593 - CONFIG_NAND_ENV_DST
2595 Defines address in RAM to which the nand_spl code should copy the
2596 environment. If redundant environment is used, it will be copied to
2597 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2599 Please note that the environment is read-only until the monitor
2600 has been relocated to RAM and a RAM copy of the environment has been
2601 created; also, when using EEPROM you will have to use env_get_f()
2602 until then to read environment variables.
2604 The environment is protected by a CRC32 checksum. Before the monitor
2605 is relocated into RAM, as a result of a bad CRC you will be working
2606 with the compiled-in default environment - *silently*!!! [This is
2607 necessary, because the first environment variable we need is the
2608 "baudrate" setting for the console - if we have a bad CRC, we don't
2609 have any device yet where we could complain.]
2611 Note: once the monitor has been relocated, then it will complain if
2612 the default environment is used; a new CRC is computed as soon as you
2613 use the "saveenv" command to store a valid environment.
2615 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2616 Echo the inverted Ethernet link state to the fault LED.
2618 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2619 also needs to be defined.
2621 - CONFIG_SYS_FAULT_MII_ADDR:
2622 MII address of the PHY to check for the Ethernet link state.
2624 - CONFIG_NS16550_MIN_FUNCTIONS:
2625 Define this if you desire to only have use of the NS16550_init
2626 and NS16550_putc functions for the serial driver located at
2627 drivers/serial/ns16550.c. This option is useful for saving
2628 space for already greatly restricted images, including but not
2629 limited to NAND_SPL configurations.
2631 - CONFIG_DISPLAY_BOARDINFO
2632 Display information about the board that U-Boot is running on
2633 when U-Boot starts up. The board function checkboard() is called
2636 - CONFIG_DISPLAY_BOARDINFO_LATE
2637 Similar to the previous option, but display this information
2638 later, once stdio is running and output goes to the LCD, if
2641 - CONFIG_BOARD_SIZE_LIMIT:
2642 Maximum size of the U-Boot image. When defined, the
2643 build system checks that the actual size does not
2646 Low Level (hardware related) configuration options:
2647 ---------------------------------------------------
2649 - CONFIG_SYS_CACHELINE_SIZE:
2650 Cache Line Size of the CPU.
2652 - CONFIG_SYS_CCSRBAR_DEFAULT:
2653 Default (power-on reset) physical address of CCSR on Freescale
2656 - CONFIG_SYS_CCSRBAR:
2657 Virtual address of CCSR. On a 32-bit build, this is typically
2658 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2660 - CONFIG_SYS_CCSRBAR_PHYS:
2661 Physical address of CCSR. CCSR can be relocated to a new
2662 physical address, if desired. In this case, this macro should
2663 be set to that address. Otherwise, it should be set to the
2664 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2665 is typically relocated on 36-bit builds. It is recommended
2666 that this macro be defined via the _HIGH and _LOW macros:
2668 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2669 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2671 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2672 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2673 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2674 used in assembly code, so it must not contain typecasts or
2675 integer size suffixes (e.g. "ULL").
2677 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2678 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2679 used in assembly code, so it must not contain typecasts or
2680 integer size suffixes (e.g. "ULL").
2682 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2683 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2684 forced to a value that ensures that CCSR is not relocated.
2687 Most IDE controllers were designed to be connected with PCI
2688 interface. Only few of them were designed for AHB interface.
2689 When software is doing ATA command and data transfer to
2690 IDE devices through IDE-AHB controller, some additional
2691 registers accessing to these kind of IDE-AHB controller
2694 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2695 DO NOT CHANGE unless you know exactly what you're
2696 doing! (11-4) [MPC8xx systems only]
2698 - CONFIG_SYS_INIT_RAM_ADDR:
2700 Start address of memory area that can be used for
2701 initial data and stack; please note that this must be
2702 writable memory that is working WITHOUT special
2703 initialization, i. e. you CANNOT use normal RAM which
2704 will become available only after programming the
2705 memory controller and running certain initialization
2708 U-Boot uses the following memory types:
2709 - MPC8xx: IMMR (internal memory of the CPU)
2711 - CONFIG_SYS_GBL_DATA_OFFSET:
2713 Offset of the initial data structure in the memory
2714 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2715 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2716 data is located at the end of the available space
2717 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2718 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2719 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2720 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2723 On the MPC824X (or other systems that use the data
2724 cache for initial memory) the address chosen for
2725 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2726 point to an otherwise UNUSED address space between
2727 the top of RAM and the start of the PCI space.
2729 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2731 - CONFIG_SYS_OR_TIMING_SDRAM:
2734 - CONFIG_SYS_MAMR_PTA:
2735 periodic timer for refresh
2737 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2738 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2739 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2740 CONFIG_SYS_BR1_PRELIM:
2741 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2743 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2744 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2745 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2746 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2748 - CONFIG_PCI_INDIRECT_BRIDGE:
2749 Enable support for indirect PCI bridges.
2752 Chip has SRIO or not
2755 Board has SRIO 1 port available
2758 Board has SRIO 2 port available
2760 - CONFIG_SRIO_PCIE_BOOT_MASTER
2761 Board can support master function for Boot from SRIO and PCIE
2763 - CONFIG_SYS_SRIOn_MEM_VIRT:
2764 Virtual Address of SRIO port 'n' memory region
2766 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2767 Physical Address of SRIO port 'n' memory region
2769 - CONFIG_SYS_SRIOn_MEM_SIZE:
2770 Size of SRIO port 'n' memory region
2772 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2773 Defined to tell the NAND controller that the NAND chip is using
2775 Not all NAND drivers use this symbol.
2776 Example of drivers that use it:
2777 - drivers/mtd/nand/raw/ndfc.c
2778 - drivers/mtd/nand/raw/mxc_nand.c
2780 - CONFIG_SYS_NDFC_EBC0_CFG
2781 Sets the EBC0_CFG register for the NDFC. If not defined
2782 a default value will be used.
2785 Get DDR timing information from an I2C EEPROM. Common
2786 with pluggable memory modules such as SODIMMs
2789 I2C address of the SPD EEPROM
2791 - CONFIG_SYS_SPD_BUS_NUM
2792 If SPD EEPROM is on an I2C bus other than the first
2793 one, specify here. Note that the value must resolve
2794 to something your driver can deal with.
2796 - CONFIG_SYS_DDR_RAW_TIMING
2797 Get DDR timing information from other than SPD. Common with
2798 soldered DDR chips onboard without SPD. DDR raw timing
2799 parameters are extracted from datasheet and hard-coded into
2800 header files or board specific files.
2802 - CONFIG_FSL_DDR_INTERACTIVE
2803 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2805 - CONFIG_FSL_DDR_SYNC_REFRESH
2806 Enable sync of refresh for multiple controllers.
2808 - CONFIG_FSL_DDR_BIST
2809 Enable built-in memory test for Freescale DDR controllers.
2811 - CONFIG_SYS_83XX_DDR_USES_CS0
2812 Only for 83xx systems. If specified, then DDR should
2813 be configured using CS0 and CS1 instead of CS2 and CS3.
2816 Enable RMII mode for all FECs.
2817 Note that this is a global option, we can't
2818 have one FEC in standard MII mode and another in RMII mode.
2820 - CONFIG_CRC32_VERIFY
2821 Add a verify option to the crc32 command.
2824 => crc32 -v <address> <count> <crc32>
2826 Where address/count indicate a memory area
2827 and crc32 is the correct crc32 which the
2831 Add the "loopw" memory command. This only takes effect if
2832 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2834 - CONFIG_CMD_MX_CYCLIC
2835 Add the "mdc" and "mwc" memory commands. These are cyclic
2840 This command will print 4 bytes (10,11,12,13) each 500 ms.
2842 => mwc.l 100 12345678 10
2843 This command will write 12345678 to address 100 all 10 ms.
2845 This only takes effect if the memory commands are activated
2846 globally (CONFIG_CMD_MEMORY).
2848 - CONFIG_SKIP_LOWLEVEL_INIT
2849 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
2850 low level initializations (like setting up the memory
2851 controller) are omitted and/or U-Boot does not
2852 relocate itself into RAM.
2854 Normally this variable MUST NOT be defined. The only
2855 exception is when U-Boot is loaded (to RAM) by some
2856 other boot loader or by a debugger which performs
2857 these initializations itself.
2859 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
2860 [ARM926EJ-S only] This allows just the call to lowlevel_init()
2861 to be skipped. The normal CP15 init (such as enabling the
2862 instruction cache) is still performed.
2865 Set when the currently-running compilation is for an artifact
2866 that will end up in the SPL (as opposed to the TPL or U-Boot
2867 proper). Code that needs stage-specific behavior should check
2871 Set when the currently-running compilation is for an artifact
2872 that will end up in the TPL (as opposed to the SPL or U-Boot
2873 proper). Code that needs stage-specific behavior should check
2876 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2877 Only for 85xx systems. If this variable is specified, the section
2878 .resetvec is not kept and the section .bootpg is placed in the
2879 previous 4k of the .text section.
2881 - CONFIG_ARCH_MAP_SYSMEM
2882 Generally U-Boot (and in particular the md command) uses
2883 effective address. It is therefore not necessary to regard
2884 U-Boot address as virtual addresses that need to be translated
2885 to physical addresses. However, sandbox requires this, since
2886 it maintains its own little RAM buffer which contains all
2887 addressable memory. This option causes some memory accesses
2888 to be mapped through map_sysmem() / unmap_sysmem().
2890 - CONFIG_X86_RESET_VECTOR
2891 If defined, the x86 reset vector code is included. This is not
2892 needed when U-Boot is running from Coreboot.
2894 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2895 Option to disable subpage write in NAND driver
2896 driver that uses this:
2897 drivers/mtd/nand/raw/davinci_nand.c
2899 Freescale QE/FMAN Firmware Support:
2900 -----------------------------------
2902 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2903 loading of "firmware", which is encoded in the QE firmware binary format.
2904 This firmware often needs to be loaded during U-Boot booting, so macros
2905 are used to identify the storage device (NOR flash, SPI, etc) and the address
2908 - CONFIG_SYS_FMAN_FW_ADDR
2909 The address in the storage device where the FMAN microcode is located. The
2910 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2913 - CONFIG_SYS_QE_FW_ADDR
2914 The address in the storage device where the QE microcode is located. The
2915 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2918 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2919 The maximum possible size of the firmware. The firmware binary format
2920 has a field that specifies the actual size of the firmware, but it
2921 might not be possible to read any part of the firmware unless some
2922 local storage is allocated to hold the entire firmware first.
2924 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2925 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2926 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2927 virtual address in NOR flash.
2929 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2930 Specifies that QE/FMAN firmware is located in NAND flash.
2931 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2933 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2934 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2935 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2937 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2938 Specifies that QE/FMAN firmware is located in the remote (master)
2939 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2940 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2941 window->master inbound window->master LAW->the ucode address in
2942 master's memory space.
2944 Freescale Layerscape Management Complex Firmware Support:
2945 ---------------------------------------------------------
2946 The Freescale Layerscape Management Complex (MC) supports the loading of
2948 This firmware often needs to be loaded during U-Boot booting, so macros
2949 are used to identify the storage device (NOR flash, SPI, etc) and the address
2952 - CONFIG_FSL_MC_ENET
2953 Enable the MC driver for Layerscape SoCs.
2955 Freescale Layerscape Debug Server Support:
2956 -------------------------------------------
2957 The Freescale Layerscape Debug Server Support supports the loading of
2958 "Debug Server firmware" and triggering SP boot-rom.
2959 This firmware often needs to be loaded during U-Boot booting.
2961 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2962 Define alignment of reserved memory MC requires
2967 In order to achieve reproducible builds, timestamps used in the U-Boot build
2968 process have to be set to a fixed value.
2970 This is done using the SOURCE_DATE_EPOCH environment variable.
2971 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2972 option for U-Boot or an environment variable in U-Boot.
2974 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2976 Building the Software:
2977 ======================
2979 Building U-Boot has been tested in several native build environments
2980 and in many different cross environments. Of course we cannot support
2981 all possibly existing versions of cross development tools in all
2982 (potentially obsolete) versions. In case of tool chain problems we
2983 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2984 which is extensively used to build and test U-Boot.
2986 If you are not using a native environment, it is assumed that you
2987 have GNU cross compiling tools available in your path. In this case,
2988 you must set the environment variable CROSS_COMPILE in your shell.
2989 Note that no changes to the Makefile or any other source files are
2990 necessary. For example using the ELDK on a 4xx CPU, please enter:
2992 $ CROSS_COMPILE=ppc_4xx-
2993 $ export CROSS_COMPILE
2995 U-Boot is intended to be simple to build. After installing the
2996 sources you must configure U-Boot for one specific board type. This
3001 where "NAME_defconfig" is the name of one of the existing configu-
3002 rations; see configs/*_defconfig for supported names.
3004 Note: for some boards special configuration names may exist; check if
3005 additional information is available from the board vendor; for
3006 instance, the TQM823L systems are available without (standard)
3007 or with LCD support. You can select such additional "features"
3008 when choosing the configuration, i. e.
3010 make TQM823L_defconfig
3011 - will configure for a plain TQM823L, i. e. no LCD support
3013 make TQM823L_LCD_defconfig
3014 - will configure for a TQM823L with U-Boot console on LCD
3019 Finally, type "make all", and you should get some working U-Boot
3020 images ready for download to / installation on your system:
3022 - "u-boot.bin" is a raw binary image
3023 - "u-boot" is an image in ELF binary format
3024 - "u-boot.srec" is in Motorola S-Record format
3026 By default the build is performed locally and the objects are saved
3027 in the source directory. One of the two methods can be used to change
3028 this behavior and build U-Boot to some external directory:
3030 1. Add O= to the make command line invocations:
3032 make O=/tmp/build distclean
3033 make O=/tmp/build NAME_defconfig
3034 make O=/tmp/build all
3036 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3038 export KBUILD_OUTPUT=/tmp/build
3043 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3046 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3047 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3048 For example to treat all compiler warnings as errors:
3050 make KCFLAGS=-Werror
3052 Please be aware that the Makefiles assume you are using GNU make, so
3053 for instance on NetBSD you might need to use "gmake" instead of
3057 If the system board that you have is not listed, then you will need
3058 to port U-Boot to your hardware platform. To do this, follow these
3061 1. Create a new directory to hold your board specific code. Add any
3062 files you need. In your board directory, you will need at least
3063 the "Makefile" and a "<board>.c".
3064 2. Create a new configuration file "include/configs/<board>.h" for
3066 3. If you're porting U-Boot to a new CPU, then also create a new
3067 directory to hold your CPU specific code. Add any files you need.
3068 4. Run "make <board>_defconfig" with your new name.
3069 5. Type "make", and you should get a working "u-boot.srec" file
3070 to be installed on your target system.
3071 6. Debug and solve any problems that might arise.
3072 [Of course, this last step is much harder than it sounds.]
3075 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3076 ==============================================================
3078 If you have modified U-Boot sources (for instance added a new board
3079 or support for new devices, a new CPU, etc.) you are expected to
3080 provide feedback to the other developers. The feedback normally takes
3081 the form of a "patch", i.e. a context diff against a certain (latest
3082 official or latest in the git repository) version of U-Boot sources.
3084 But before you submit such a patch, please verify that your modifi-
3085 cation did not break existing code. At least make sure that *ALL* of
3086 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3087 just run the buildman script (tools/buildman/buildman), which will
3088 configure and build U-Boot for ALL supported system. Be warned, this
3089 will take a while. Please see the buildman README, or run 'buildman -H'
3093 See also "U-Boot Porting Guide" below.
3096 Monitor Commands - Overview:
3097 ============================
3099 go - start application at address 'addr'
3100 run - run commands in an environment variable
3101 bootm - boot application image from memory
3102 bootp - boot image via network using BootP/TFTP protocol
3103 bootz - boot zImage from memory
3104 tftpboot- boot image via network using TFTP protocol
3105 and env variables "ipaddr" and "serverip"
3106 (and eventually "gatewayip")
3107 tftpput - upload a file via network using TFTP protocol
3108 rarpboot- boot image via network using RARP/TFTP protocol
3109 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3110 loads - load S-Record file over serial line
3111 loadb - load binary file over serial line (kermit mode)
3113 mm - memory modify (auto-incrementing)
3114 nm - memory modify (constant address)
3115 mw - memory write (fill)
3118 cmp - memory compare
3119 crc32 - checksum calculation
3120 i2c - I2C sub-system
3121 sspi - SPI utility commands
3122 base - print or set address offset
3123 printenv- print environment variables
3124 pwm - control pwm channels
3125 setenv - set environment variables
3126 saveenv - save environment variables to persistent storage
3127 protect - enable or disable FLASH write protection
3128 erase - erase FLASH memory
3129 flinfo - print FLASH memory information
3130 nand - NAND memory operations (see doc/README.nand)
3131 bdinfo - print Board Info structure
3132 iminfo - print header information for application image
3133 coninfo - print console devices and informations
3134 ide - IDE sub-system
3135 loop - infinite loop on address range
3136 loopw - infinite write loop on address range
3137 mtest - simple RAM test
3138 icache - enable or disable instruction cache
3139 dcache - enable or disable data cache
3140 reset - Perform RESET of the CPU
3141 echo - echo args to console
3142 version - print monitor version
3143 help - print online help
3144 ? - alias for 'help'
3147 Monitor Commands - Detailed Description:
3148 ========================================
3152 For now: just type "help <command>".
3155 Environment Variables:
3156 ======================
3158 U-Boot supports user configuration using Environment Variables which
3159 can be made persistent by saving to Flash memory.
3161 Environment Variables are set using "setenv", printed using
3162 "printenv", and saved to Flash using "saveenv". Using "setenv"
3163 without a value can be used to delete a variable from the
3164 environment. As long as you don't save the environment you are
3165 working with an in-memory copy. In case the Flash area containing the
3166 environment is erased by accident, a default environment is provided.
3168 Some configuration options can be set using Environment Variables.
3170 List of environment variables (most likely not complete):
3172 baudrate - see CONFIG_BAUDRATE
3174 bootdelay - see CONFIG_BOOTDELAY
3176 bootcmd - see CONFIG_BOOTCOMMAND
3178 bootargs - Boot arguments when booting an RTOS image
3180 bootfile - Name of the image to load with TFTP
3182 bootm_low - Memory range available for image processing in the bootm
3183 command can be restricted. This variable is given as
3184 a hexadecimal number and defines lowest address allowed
3185 for use by the bootm command. See also "bootm_size"
3186 environment variable. Address defined by "bootm_low" is
3187 also the base of the initial memory mapping for the Linux
3188 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3191 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3192 This variable is given as a hexadecimal number and it
3193 defines the size of the memory region starting at base
3194 address bootm_low that is accessible by the Linux kernel
3195 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3196 as the default value if it is defined, and bootm_size is
3199 bootm_size - Memory range available for image processing in the bootm
3200 command can be restricted. This variable is given as
3201 a hexadecimal number and defines the size of the region
3202 allowed for use by the bootm command. See also "bootm_low"
3203 environment variable.
3205 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3207 updatefile - Location of the software update file on a TFTP server, used
3208 by the automatic software update feature. Please refer to
3209 documentation in doc/README.update for more details.
3211 autoload - if set to "no" (any string beginning with 'n'),
3212 "bootp" will just load perform a lookup of the
3213 configuration from the BOOTP server, but not try to
3214 load any image using TFTP
3216 autostart - if set to "yes", an image loaded using the "bootp",
3217 "rarpboot", "tftpboot" or "diskboot" commands will
3218 be automatically started (by internally calling
3221 If set to "no", a standalone image passed to the
3222 "bootm" command will be copied to the load address
3223 (and eventually uncompressed), but NOT be started.
3224 This can be used to load and uncompress arbitrary
3227 fdt_high - if set this restricts the maximum address that the
3228 flattened device tree will be copied into upon boot.
3229 For example, if you have a system with 1 GB memory
3230 at physical address 0x10000000, while Linux kernel
3231 only recognizes the first 704 MB as low memory, you
3232 may need to set fdt_high as 0x3C000000 to have the
3233 device tree blob be copied to the maximum address
3234 of the 704 MB low memory, so that Linux kernel can
3235 access it during the boot procedure.
3237 If this is set to the special value 0xFFFFFFFF then
3238 the fdt will not be copied at all on boot. For this
3239 to work it must reside in writable memory, have
3240 sufficient padding on the end of it for u-boot to
3241 add the information it needs into it, and the memory
3242 must be accessible by the kernel.
3244 fdtcontroladdr- if set this is the address of the control flattened
3245 device tree used by U-Boot when CONFIG_OF_CONTROL is
3248 i2cfast - (PPC405GP|PPC405EP only)
3249 if set to 'y' configures Linux I2C driver for fast
3250 mode (400kHZ). This environment variable is used in
3251 initialization code. So, for changes to be effective
3252 it must be saved and board must be reset.
3254 initrd_high - restrict positioning of initrd images:
3255 If this variable is not set, initrd images will be
3256 copied to the highest possible address in RAM; this
3257 is usually what you want since it allows for
3258 maximum initrd size. If for some reason you want to
3259 make sure that the initrd image is loaded below the
3260 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3261 variable to a value of "no" or "off" or "0".
3262 Alternatively, you can set it to a maximum upper
3263 address to use (U-Boot will still check that it
3264 does not overwrite the U-Boot stack and data).
3266 For instance, when you have a system with 16 MB
3267 RAM, and want to reserve 4 MB from use by Linux,
3268 you can do this by adding "mem=12M" to the value of
3269 the "bootargs" variable. However, now you must make
3270 sure that the initrd image is placed in the first
3271 12 MB as well - this can be done with
3273 setenv initrd_high 00c00000
3275 If you set initrd_high to 0xFFFFFFFF, this is an
3276 indication to U-Boot that all addresses are legal
3277 for the Linux kernel, including addresses in flash
3278 memory. In this case U-Boot will NOT COPY the
3279 ramdisk at all. This may be useful to reduce the
3280 boot time on your system, but requires that this
3281 feature is supported by your Linux kernel.
3283 ipaddr - IP address; needed for tftpboot command
3285 loadaddr - Default load address for commands like "bootp",
3286 "rarpboot", "tftpboot", "loadb" or "diskboot"
3288 loads_echo - see CONFIG_LOADS_ECHO
3290 serverip - TFTP server IP address; needed for tftpboot command
3292 bootretry - see CONFIG_BOOT_RETRY_TIME
3294 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3296 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3298 ethprime - controls which interface is used first.
3300 ethact - controls which interface is currently active.
3301 For example you can do the following
3303 => setenv ethact FEC
3304 => ping 192.168.0.1 # traffic sent on FEC
3305 => setenv ethact SCC
3306 => ping 10.0.0.1 # traffic sent on SCC
3308 ethrotate - When set to "no" U-Boot does not go through all
3309 available network interfaces.
3310 It just stays at the currently selected interface.
3312 netretry - When set to "no" each network operation will
3313 either succeed or fail without retrying.
3314 When set to "once" the network operation will
3315 fail when all the available network interfaces
3316 are tried once without success.
3317 Useful on scripts which control the retry operation
3320 npe_ucode - set load address for the NPE microcode
3322 silent_linux - If set then Linux will be told to boot silently, by
3323 changing the console to be empty. If "yes" it will be
3324 made silent. If "no" it will not be made silent. If
3325 unset, then it will be made silent if the U-Boot console
3328 tftpsrcp - If this is set, the value is used for TFTP's
3331 tftpdstp - If this is set, the value is used for TFTP's UDP
3332 destination port instead of the Well Know Port 69.
3334 tftpblocksize - Block size to use for TFTP transfers; if not set,
3335 we use the TFTP server's default block size
3337 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3338 seconds, minimum value is 1000 = 1 second). Defines
3339 when a packet is considered to be lost so it has to
3340 be retransmitted. The default is 5000 = 5 seconds.
3341 Lowering this value may make downloads succeed
3342 faster in networks with high packet loss rates or
3343 with unreliable TFTP servers.
3345 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3346 unit, minimum value = 0). Defines how many timeouts
3347 can happen during a single file transfer before that
3348 transfer is aborted. The default is 10, and 0 means
3349 'no timeouts allowed'. Increasing this value may help
3350 downloads succeed with high packet loss rates, or with
3351 unreliable TFTP servers or client hardware.
3353 tftpwindowsize - if this is set, the value is used for TFTP's
3354 window size as described by RFC 7440.
3355 This means the count of blocks we can receive before
3356 sending ack to server.
3358 vlan - When set to a value < 4095 the traffic over
3359 Ethernet is encapsulated/received over 802.1q
3362 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3363 Unsigned value, in milliseconds. If not set, the period will
3364 be either the default (28000), or a value based on
3365 CONFIG_NET_RETRY_COUNT, if defined. This value has
3366 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3368 memmatches - Number of matches found by the last 'ms' command, in hex
3370 memaddr - Address of the last match found by the 'ms' command, in hex,
3373 mempos - Index position of the last match found by the 'ms' command,
3374 in units of the size (.b, .w, .l) of the search
3376 zbootbase - (x86 only) Base address of the bzImage 'setup' block
3378 zbootaddr - (x86 only) Address of the loaded bzImage, typically
3379 BZIMAGE_LOAD_ADDR which is 0x100000
3381 The following image location variables contain the location of images
3382 used in booting. The "Image" column gives the role of the image and is
3383 not an environment variable name. The other columns are environment
3384 variable names. "File Name" gives the name of the file on a TFTP
3385 server, "RAM Address" gives the location in RAM the image will be
3386 loaded to, and "Flash Location" gives the image's address in NOR
3387 flash or offset in NAND flash.
3389 *Note* - these variables don't have to be defined for all boards, some
3390 boards currently use other variables for these purposes, and some
3391 boards use these variables for other purposes.
3393 Image File Name RAM Address Flash Location
3394 ----- --------- ----------- --------------
3395 u-boot u-boot u-boot_addr_r u-boot_addr
3396 Linux kernel bootfile kernel_addr_r kernel_addr
3397 device tree blob fdtfile fdt_addr_r fdt_addr
3398 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3400 The following environment variables may be used and automatically
3401 updated by the network boot commands ("bootp" and "rarpboot"),
3402 depending the information provided by your boot server:
3404 bootfile - see above
3405 dnsip - IP address of your Domain Name Server
3406 dnsip2 - IP address of your secondary Domain Name Server
3407 gatewayip - IP address of the Gateway (Router) to use
3408 hostname - Target hostname
3410 netmask - Subnet Mask
3411 rootpath - Pathname of the root filesystem on the NFS server
3412 serverip - see above
3415 There are two special Environment Variables:
3417 serial# - contains hardware identification information such
3418 as type string and/or serial number
3419 ethaddr - Ethernet address
3421 These variables can be set only once (usually during manufacturing of
3422 the board). U-Boot refuses to delete or overwrite these variables
3423 once they have been set once.
3426 Further special Environment Variables:
3428 ver - Contains the U-Boot version string as printed
3429 with the "version" command. This variable is
3430 readonly (see CONFIG_VERSION_VARIABLE).
3433 Please note that changes to some configuration parameters may take
3434 only effect after the next boot (yes, that's just like Windoze :-).
3437 Callback functions for environment variables:
3438 ---------------------------------------------
3440 For some environment variables, the behavior of u-boot needs to change
3441 when their values are changed. This functionality allows functions to
3442 be associated with arbitrary variables. On creation, overwrite, or
3443 deletion, the callback will provide the opportunity for some side
3444 effect to happen or for the change to be rejected.
3446 The callbacks are named and associated with a function using the
3447 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3449 These callbacks are associated with variables in one of two ways. The
3450 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3451 in the board configuration to a string that defines a list of
3452 associations. The list must be in the following format:
3454 entry = variable_name[:callback_name]
3457 If the callback name is not specified, then the callback is deleted.
3458 Spaces are also allowed anywhere in the list.
3460 Callbacks can also be associated by defining the ".callbacks" variable
3461 with the same list format above. Any association in ".callbacks" will
3462 override any association in the static list. You can define
3463 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3464 ".callbacks" environment variable in the default or embedded environment.
3466 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3467 regular expression. This allows multiple variables to be connected to
3468 the same callback without explicitly listing them all out.
3470 The signature of the callback functions is:
3472 int callback(const char *name, const char *value, enum env_op op, int flags)
3474 * name - changed environment variable
3475 * value - new value of the environment variable
3476 * op - operation (create, overwrite, or delete)
3477 * flags - attributes of the environment variable change, see flags H_* in
3480 The return value is 0 if the variable change is accepted and 1 otherwise.
3483 Note for Redundant Ethernet Interfaces:
3484 =======================================
3486 Some boards come with redundant Ethernet interfaces; U-Boot supports
3487 such configurations and is capable of automatic selection of a
3488 "working" interface when needed. MAC assignment works as follows:
3490 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3491 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3492 "eth1addr" (=>eth1), "eth2addr", ...
3494 If the network interface stores some valid MAC address (for instance
3495 in SROM), this is used as default address if there is NO correspon-
3496 ding setting in the environment; if the corresponding environment
3497 variable is set, this overrides the settings in the card; that means:
3499 o If the SROM has a valid MAC address, and there is no address in the
3500 environment, the SROM's address is used.
3502 o If there is no valid address in the SROM, and a definition in the
3503 environment exists, then the value from the environment variable is
3506 o If both the SROM and the environment contain a MAC address, and
3507 both addresses are the same, this MAC address is used.
3509 o If both the SROM and the environment contain a MAC address, and the
3510 addresses differ, the value from the environment is used and a
3513 o If neither SROM nor the environment contain a MAC address, an error
3514 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3515 a random, locally-assigned MAC is used.
3517 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3518 will be programmed into hardware as part of the initialization process. This
3519 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3520 The naming convention is as follows:
3521 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3526 U-Boot is capable of booting (and performing other auxiliary operations on)
3527 images in two formats:
3529 New uImage format (FIT)
3530 -----------------------
3532 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3533 to Flattened Device Tree). It allows the use of images with multiple
3534 components (several kernels, ramdisks, etc.), with contents protected by
3535 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3541 Old image format is based on binary files which can be basically anything,
3542 preceded by a special header; see the definitions in include/image.h for
3543 details; basically, the header defines the following image properties:
3545 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3546 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3547 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3548 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3550 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3551 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3552 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3553 * Compression Type (uncompressed, gzip, bzip2)
3559 The header is marked by a special Magic Number, and both the header
3560 and the data portions of the image are secured against corruption by
3567 Although U-Boot should support any OS or standalone application
3568 easily, the main focus has always been on Linux during the design of
3571 U-Boot includes many features that so far have been part of some
3572 special "boot loader" code within the Linux kernel. Also, any
3573 "initrd" images to be used are no longer part of one big Linux image;
3574 instead, kernel and "initrd" are separate images. This implementation
3575 serves several purposes:
3577 - the same features can be used for other OS or standalone
3578 applications (for instance: using compressed images to reduce the
3579 Flash memory footprint)
3581 - it becomes much easier to port new Linux kernel versions because
3582 lots of low-level, hardware dependent stuff are done by U-Boot
3584 - the same Linux kernel image can now be used with different "initrd"
3585 images; of course this also means that different kernel images can
3586 be run with the same "initrd". This makes testing easier (you don't
3587 have to build a new "zImage.initrd" Linux image when you just
3588 change a file in your "initrd"). Also, a field-upgrade of the
3589 software is easier now.
3595 Porting Linux to U-Boot based systems:
3596 ---------------------------------------
3598 U-Boot cannot save you from doing all the necessary modifications to
3599 configure the Linux device drivers for use with your target hardware
3600 (no, we don't intend to provide a full virtual machine interface to
3603 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3605 Just make sure your machine specific header file (for instance
3606 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3607 Information structure as we define in include/asm-<arch>/u-boot.h,
3608 and make sure that your definition of IMAP_ADDR uses the same value
3609 as your U-Boot configuration in CONFIG_SYS_IMMR.
3611 Note that U-Boot now has a driver model, a unified model for drivers.
3612 If you are adding a new driver, plumb it into driver model. If there
3613 is no uclass available, you are encouraged to create one. See
3617 Configuring the Linux kernel:
3618 -----------------------------
3620 No specific requirements for U-Boot. Make sure you have some root
3621 device (initial ramdisk, NFS) for your target system.
3624 Building a Linux Image:
3625 -----------------------
3627 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3628 not used. If you use recent kernel source, a new build target
3629 "uImage" will exist which automatically builds an image usable by
3630 U-Boot. Most older kernels also have support for a "pImage" target,
3631 which was introduced for our predecessor project PPCBoot and uses a
3632 100% compatible format.
3636 make TQM850L_defconfig
3641 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3642 encapsulate a compressed Linux kernel image with header information,
3643 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3645 * build a standard "vmlinux" kernel image (in ELF binary format):
3647 * convert the kernel into a raw binary image:
3649 ${CROSS_COMPILE}-objcopy -O binary \
3650 -R .note -R .comment \
3651 -S vmlinux linux.bin
3653 * compress the binary image:
3657 * package compressed binary image for U-Boot:
3659 mkimage -A ppc -O linux -T kernel -C gzip \
3660 -a 0 -e 0 -n "Linux Kernel Image" \
3661 -d linux.bin.gz uImage
3664 The "mkimage" tool can also be used to create ramdisk images for use
3665 with U-Boot, either separated from the Linux kernel image, or
3666 combined into one file. "mkimage" encapsulates the images with a 64
3667 byte header containing information about target architecture,
3668 operating system, image type, compression method, entry points, time
3669 stamp, CRC32 checksums, etc.
3671 "mkimage" can be called in two ways: to verify existing images and
3672 print the header information, or to build new images.
3674 In the first form (with "-l" option) mkimage lists the information
3675 contained in the header of an existing U-Boot image; this includes
3676 checksum verification:
3678 tools/mkimage -l image
3679 -l ==> list image header information
3681 The second form (with "-d" option) is used to build a U-Boot image
3682 from a "data file" which is used as image payload:
3684 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3685 -n name -d data_file image
3686 -A ==> set architecture to 'arch'
3687 -O ==> set operating system to 'os'
3688 -T ==> set image type to 'type'
3689 -C ==> set compression type 'comp'
3690 -a ==> set load address to 'addr' (hex)
3691 -e ==> set entry point to 'ep' (hex)
3692 -n ==> set image name to 'name'
3693 -d ==> use image data from 'datafile'
3695 Right now, all Linux kernels for PowerPC systems use the same load
3696 address (0x00000000), but the entry point address depends on the
3699 - 2.2.x kernels have the entry point at 0x0000000C,
3700 - 2.3.x and later kernels have the entry point at 0x00000000.
3702 So a typical call to build a U-Boot image would read:
3704 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3705 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3706 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3707 > examples/uImage.TQM850L
3708 Image Name: 2.4.4 kernel for TQM850L
3709 Created: Wed Jul 19 02:34:59 2000
3710 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3711 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3712 Load Address: 0x00000000
3713 Entry Point: 0x00000000
3715 To verify the contents of the image (or check for corruption):
3717 -> tools/mkimage -l examples/uImage.TQM850L
3718 Image Name: 2.4.4 kernel for TQM850L
3719 Created: Wed Jul 19 02:34:59 2000
3720 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3721 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3722 Load Address: 0x00000000
3723 Entry Point: 0x00000000
3725 NOTE: for embedded systems where boot time is critical you can trade
3726 speed for memory and install an UNCOMPRESSED image instead: this
3727 needs more space in Flash, but boots much faster since it does not
3728 need to be uncompressed:
3730 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3731 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3732 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3733 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3734 > examples/uImage.TQM850L-uncompressed
3735 Image Name: 2.4.4 kernel for TQM850L
3736 Created: Wed Jul 19 02:34:59 2000
3737 Image Type: PowerPC Linux Kernel Image (uncompressed)
3738 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3739 Load Address: 0x00000000
3740 Entry Point: 0x00000000
3743 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3744 when your kernel is intended to use an initial ramdisk:
3746 -> tools/mkimage -n 'Simple Ramdisk Image' \
3747 > -A ppc -O linux -T ramdisk -C gzip \
3748 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3749 Image Name: Simple Ramdisk Image
3750 Created: Wed Jan 12 14:01:50 2000
3751 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3752 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3753 Load Address: 0x00000000
3754 Entry Point: 0x00000000
3756 The "dumpimage" tool can be used to disassemble or list the contents of images
3757 built by mkimage. See dumpimage's help output (-h) for details.
3759 Installing a Linux Image:
3760 -------------------------
3762 To downloading a U-Boot image over the serial (console) interface,
3763 you must convert the image to S-Record format:
3765 objcopy -I binary -O srec examples/image examples/image.srec
3767 The 'objcopy' does not understand the information in the U-Boot
3768 image header, so the resulting S-Record file will be relative to
3769 address 0x00000000. To load it to a given address, you need to
3770 specify the target address as 'offset' parameter with the 'loads'
3773 Example: install the image to address 0x40100000 (which on the
3774 TQM8xxL is in the first Flash bank):
3776 => erase 40100000 401FFFFF
3782 ## Ready for S-Record download ...
3783 ~>examples/image.srec
3784 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3786 15989 15990 15991 15992
3787 [file transfer complete]
3789 ## Start Addr = 0x00000000
3792 You can check the success of the download using the 'iminfo' command;
3793 this includes a checksum verification so you can be sure no data
3794 corruption happened:
3798 ## Checking Image at 40100000 ...
3799 Image Name: 2.2.13 for initrd on TQM850L
3800 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3801 Data Size: 335725 Bytes = 327 kB = 0 MB
3802 Load Address: 00000000
3803 Entry Point: 0000000c
3804 Verifying Checksum ... OK
3810 The "bootm" command is used to boot an application that is stored in
3811 memory (RAM or Flash). In case of a Linux kernel image, the contents
3812 of the "bootargs" environment variable is passed to the kernel as
3813 parameters. You can check and modify this variable using the
3814 "printenv" and "setenv" commands:
3817 => printenv bootargs
3818 bootargs=root=/dev/ram
3820 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3822 => printenv bootargs
3823 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3826 ## Booting Linux kernel at 40020000 ...
3827 Image Name: 2.2.13 for NFS on TQM850L
3828 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3829 Data Size: 381681 Bytes = 372 kB = 0 MB
3830 Load Address: 00000000
3831 Entry Point: 0000000c
3832 Verifying Checksum ... OK
3833 Uncompressing Kernel Image ... OK
3834 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
3835 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3836 time_init: decrementer frequency = 187500000/60
3837 Calibrating delay loop... 49.77 BogoMIPS
3838 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3841 If you want to boot a Linux kernel with initial RAM disk, you pass
3842 the memory addresses of both the kernel and the initrd image (PPBCOOT
3843 format!) to the "bootm" command:
3845 => imi 40100000 40200000
3847 ## Checking Image at 40100000 ...
3848 Image Name: 2.2.13 for initrd on TQM850L
3849 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3850 Data Size: 335725 Bytes = 327 kB = 0 MB
3851 Load Address: 00000000
3852 Entry Point: 0000000c
3853 Verifying Checksum ... OK
3855 ## Checking Image at 40200000 ...
3856 Image Name: Simple Ramdisk Image
3857 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3858 Data Size: 566530 Bytes = 553 kB = 0 MB
3859 Load Address: 00000000
3860 Entry Point: 00000000
3861 Verifying Checksum ... OK
3863 => bootm 40100000 40200000
3864 ## Booting Linux kernel at 40100000 ...
3865 Image Name: 2.2.13 for initrd on TQM850L
3866 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3867 Data Size: 335725 Bytes = 327 kB = 0 MB
3868 Load Address: 00000000
3869 Entry Point: 0000000c
3870 Verifying Checksum ... OK
3871 Uncompressing Kernel Image ... OK
3872 ## Loading RAMDisk Image at 40200000 ...
3873 Image Name: Simple Ramdisk Image
3874 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3875 Data Size: 566530 Bytes = 553 kB = 0 MB
3876 Load Address: 00000000
3877 Entry Point: 00000000
3878 Verifying Checksum ... OK
3879 Loading Ramdisk ... OK
3880 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
3881 Boot arguments: root=/dev/ram
3882 time_init: decrementer frequency = 187500000/60
3883 Calibrating delay loop... 49.77 BogoMIPS
3885 RAMDISK: Compressed image found at block 0
3886 VFS: Mounted root (ext2 filesystem).
3890 Boot Linux and pass a flat device tree:
3893 First, U-Boot must be compiled with the appropriate defines. See the section
3894 titled "Linux Kernel Interface" above for a more in depth explanation. The
3895 following is an example of how to start a kernel and pass an updated
3901 oft=oftrees/mpc8540ads.dtb
3902 => tftp $oftaddr $oft
3903 Speed: 1000, full duplex
3905 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3906 Filename 'oftrees/mpc8540ads.dtb'.
3907 Load address: 0x300000
3910 Bytes transferred = 4106 (100a hex)
3911 => tftp $loadaddr $bootfile
3912 Speed: 1000, full duplex
3914 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3916 Load address: 0x200000
3917 Loading:############
3919 Bytes transferred = 1029407 (fb51f hex)
3924 => bootm $loadaddr - $oftaddr
3925 ## Booting image at 00200000 ...
3926 Image Name: Linux-2.6.17-dirty
3927 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3928 Data Size: 1029343 Bytes = 1005.2 kB
3929 Load Address: 00000000
3930 Entry Point: 00000000
3931 Verifying Checksum ... OK
3932 Uncompressing Kernel Image ... OK
3933 Booting using flat device tree at 0x300000
3934 Using MPC85xx ADS machine description
3935 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3939 More About U-Boot Image Types:
3940 ------------------------------
3942 U-Boot supports the following image types:
3944 "Standalone Programs" are directly runnable in the environment
3945 provided by U-Boot; it is expected that (if they behave
3946 well) you can continue to work in U-Boot after return from
3947 the Standalone Program.
3948 "OS Kernel Images" are usually images of some Embedded OS which
3949 will take over control completely. Usually these programs
3950 will install their own set of exception handlers, device
3951 drivers, set up the MMU, etc. - this means, that you cannot
3952 expect to re-enter U-Boot except by resetting the CPU.
3953 "RAMDisk Images" are more or less just data blocks, and their
3954 parameters (address, size) are passed to an OS kernel that is
3956 "Multi-File Images" contain several images, typically an OS
3957 (Linux) kernel image and one or more data images like
3958 RAMDisks. This construct is useful for instance when you want
3959 to boot over the network using BOOTP etc., where the boot
3960 server provides just a single image file, but you want to get
3961 for instance an OS kernel and a RAMDisk image.
3963 "Multi-File Images" start with a list of image sizes, each
3964 image size (in bytes) specified by an "uint32_t" in network
3965 byte order. This list is terminated by an "(uint32_t)0".
3966 Immediately after the terminating 0 follow the images, one by
3967 one, all aligned on "uint32_t" boundaries (size rounded up to
3968 a multiple of 4 bytes).
3970 "Firmware Images" are binary images containing firmware (like
3971 U-Boot or FPGA images) which usually will be programmed to
3974 "Script files" are command sequences that will be executed by
3975 U-Boot's command interpreter; this feature is especially
3976 useful when you configure U-Boot to use a real shell (hush)
3977 as command interpreter.
3979 Booting the Linux zImage:
3980 -------------------------
3982 On some platforms, it's possible to boot Linux zImage. This is done
3983 using the "bootz" command. The syntax of "bootz" command is the same
3984 as the syntax of "bootm" command.
3986 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3987 kernel with raw initrd images. The syntax is slightly different, the
3988 address of the initrd must be augmented by it's size, in the following
3989 format: "<initrd addres>:<initrd size>".
3995 One of the features of U-Boot is that you can dynamically load and
3996 run "standalone" applications, which can use some resources of
3997 U-Boot like console I/O functions or interrupt services.
3999 Two simple examples are included with the sources:
4004 'examples/hello_world.c' contains a small "Hello World" Demo
4005 application; it is automatically compiled when you build U-Boot.
4006 It's configured to run at address 0x00040004, so you can play with it
4010 ## Ready for S-Record download ...
4011 ~>examples/hello_world.srec
4012 1 2 3 4 5 6 7 8 9 10 11 ...
4013 [file transfer complete]
4015 ## Start Addr = 0x00040004
4017 => go 40004 Hello World! This is a test.
4018 ## Starting application at 0x00040004 ...
4029 Hit any key to exit ...
4031 ## Application terminated, rc = 0x0
4033 Another example, which demonstrates how to register a CPM interrupt
4034 handler with the U-Boot code, can be found in 'examples/timer.c'.
4035 Here, a CPM timer is set up to generate an interrupt every second.
4036 The interrupt service routine is trivial, just printing a '.'
4037 character, but this is just a demo program. The application can be
4038 controlled by the following keys:
4040 ? - print current values og the CPM Timer registers
4041 b - enable interrupts and start timer
4042 e - stop timer and disable interrupts
4043 q - quit application
4046 ## Ready for S-Record download ...
4047 ~>examples/timer.srec
4048 1 2 3 4 5 6 7 8 9 10 11 ...
4049 [file transfer complete]
4051 ## Start Addr = 0x00040004
4054 ## Starting application at 0x00040004 ...
4057 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4060 [q, b, e, ?] Set interval 1000000 us
4063 [q, b, e, ?] ........
4064 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4067 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4070 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4073 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4075 [q, b, e, ?] ...Stopping timer
4077 [q, b, e, ?] ## Application terminated, rc = 0x0
4083 Over time, many people have reported problems when trying to use the
4084 "minicom" terminal emulation program for serial download. I (wd)
4085 consider minicom to be broken, and recommend not to use it. Under
4086 Unix, I recommend to use C-Kermit for general purpose use (and
4087 especially for kermit binary protocol download ("loadb" command), and
4088 use "cu" for S-Record download ("loads" command). See
4089 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4090 for help with kermit.
4093 Nevertheless, if you absolutely want to use it try adding this
4094 configuration to your "File transfer protocols" section:
4096 Name Program Name U/D FullScr IO-Red. Multi
4097 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4098 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4104 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4105 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4107 Building requires a cross environment; it is known to work on
4108 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4109 need gmake since the Makefiles are not compatible with BSD make).
4110 Note that the cross-powerpc package does not install include files;
4111 attempting to build U-Boot will fail because <machine/ansi.h> is
4112 missing. This file has to be installed and patched manually:
4114 # cd /usr/pkg/cross/powerpc-netbsd/include
4116 # ln -s powerpc machine
4117 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4118 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4120 Native builds *don't* work due to incompatibilities between native
4121 and U-Boot include files.
4123 Booting assumes that (the first part of) the image booted is a
4124 stage-2 loader which in turn loads and then invokes the kernel
4125 proper. Loader sources will eventually appear in the NetBSD source
4126 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4127 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4130 Implementation Internals:
4131 =========================
4133 The following is not intended to be a complete description of every
4134 implementation detail. However, it should help to understand the
4135 inner workings of U-Boot and make it easier to port it to custom
4139 Initial Stack, Global Data:
4140 ---------------------------
4142 The implementation of U-Boot is complicated by the fact that U-Boot
4143 starts running out of ROM (flash memory), usually without access to
4144 system RAM (because the memory controller is not initialized yet).
4145 This means that we don't have writable Data or BSS segments, and BSS
4146 is not initialized as zero. To be able to get a C environment working
4147 at all, we have to allocate at least a minimal stack. Implementation
4148 options for this are defined and restricted by the CPU used: Some CPU
4149 models provide on-chip memory (like the IMMR area on MPC8xx and
4150 MPC826x processors), on others (parts of) the data cache can be
4151 locked as (mis-) used as memory, etc.
4153 Chris Hallinan posted a good summary of these issues to the
4154 U-Boot mailing list:
4156 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4157 From: "Chris Hallinan" <clh@net1plus.com>
4158 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4161 Correct me if I'm wrong, folks, but the way I understand it
4162 is this: Using DCACHE as initial RAM for Stack, etc, does not
4163 require any physical RAM backing up the cache. The cleverness
4164 is that the cache is being used as a temporary supply of
4165 necessary storage before the SDRAM controller is setup. It's
4166 beyond the scope of this list to explain the details, but you
4167 can see how this works by studying the cache architecture and
4168 operation in the architecture and processor-specific manuals.
4170 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4171 is another option for the system designer to use as an
4172 initial stack/RAM area prior to SDRAM being available. Either
4173 option should work for you. Using CS 4 should be fine if your
4174 board designers haven't used it for something that would
4175 cause you grief during the initial boot! It is frequently not
4178 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4179 with your processor/board/system design. The default value
4180 you will find in any recent u-boot distribution in
4181 walnut.h should work for you. I'd set it to a value larger
4182 than your SDRAM module. If you have a 64MB SDRAM module, set
4183 it above 400_0000. Just make sure your board has no resources
4184 that are supposed to respond to that address! That code in
4185 start.S has been around a while and should work as is when
4186 you get the config right.
4191 It is essential to remember this, since it has some impact on the C
4192 code for the initialization procedures:
4194 * Initialized global data (data segment) is read-only. Do not attempt
4197 * Do not use any uninitialized global data (or implicitly initialized
4198 as zero data - BSS segment) at all - this is undefined, initiali-
4199 zation is performed later (when relocating to RAM).
4201 * Stack space is very limited. Avoid big data buffers or things like
4204 Having only the stack as writable memory limits means we cannot use
4205 normal global data to share information between the code. But it
4206 turned out that the implementation of U-Boot can be greatly
4207 simplified by making a global data structure (gd_t) available to all
4208 functions. We could pass a pointer to this data as argument to _all_
4209 functions, but this would bloat the code. Instead we use a feature of
4210 the GCC compiler (Global Register Variables) to share the data: we
4211 place a pointer (gd) to the global data into a register which we
4212 reserve for this purpose.
4214 When choosing a register for such a purpose we are restricted by the
4215 relevant (E)ABI specifications for the current architecture, and by
4216 GCC's implementation.
4218 For PowerPC, the following registers have specific use:
4220 R2: reserved for system use
4221 R3-R4: parameter passing and return values
4222 R5-R10: parameter passing
4223 R13: small data area pointer
4227 (U-Boot also uses R12 as internal GOT pointer. r12
4228 is a volatile register so r12 needs to be reset when
4229 going back and forth between asm and C)
4231 ==> U-Boot will use R2 to hold a pointer to the global data
4233 Note: on PPC, we could use a static initializer (since the
4234 address of the global data structure is known at compile time),
4235 but it turned out that reserving a register results in somewhat
4236 smaller code - although the code savings are not that big (on
4237 average for all boards 752 bytes for the whole U-Boot image,
4238 624 text + 127 data).
4240 On ARM, the following registers are used:
4242 R0: function argument word/integer result
4243 R1-R3: function argument word
4244 R9: platform specific
4245 R10: stack limit (used only if stack checking is enabled)
4246 R11: argument (frame) pointer
4247 R12: temporary workspace
4250 R15: program counter
4252 ==> U-Boot will use R9 to hold a pointer to the global data
4254 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4256 On Nios II, the ABI is documented here:
4257 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4259 ==> U-Boot will use gp to hold a pointer to the global data
4261 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4262 to access small data sections, so gp is free.
4264 On NDS32, the following registers are used:
4266 R0-R1: argument/return
4268 R15: temporary register for assembler
4269 R16: trampoline register
4270 R28: frame pointer (FP)
4271 R29: global pointer (GP)
4272 R30: link register (LP)
4273 R31: stack pointer (SP)
4274 PC: program counter (PC)
4276 ==> U-Boot will use R10 to hold a pointer to the global data
4278 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4279 or current versions of GCC may "optimize" the code too much.
4281 On RISC-V, the following registers are used:
4283 x0: hard-wired zero (zero)
4284 x1: return address (ra)
4285 x2: stack pointer (sp)
4286 x3: global pointer (gp)
4287 x4: thread pointer (tp)
4288 x5: link register (t0)
4289 x8: frame pointer (fp)
4290 x10-x11: arguments/return values (a0-1)
4291 x12-x17: arguments (a2-7)
4292 x28-31: temporaries (t3-6)
4293 pc: program counter (pc)
4295 ==> U-Boot will use gp to hold a pointer to the global data
4300 U-Boot runs in system state and uses physical addresses, i.e. the
4301 MMU is not used either for address mapping nor for memory protection.
4303 The available memory is mapped to fixed addresses using the memory
4304 controller. In this process, a contiguous block is formed for each
4305 memory type (Flash, SDRAM, SRAM), even when it consists of several
4306 physical memory banks.
4308 U-Boot is installed in the first 128 kB of the first Flash bank (on
4309 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4310 booting and sizing and initializing DRAM, the code relocates itself
4311 to the upper end of DRAM. Immediately below the U-Boot code some
4312 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4313 configuration setting]. Below that, a structure with global Board
4314 Info data is placed, followed by the stack (growing downward).
4316 Additionally, some exception handler code is copied to the low 8 kB
4317 of DRAM (0x00000000 ... 0x00001FFF).
4319 So a typical memory configuration with 16 MB of DRAM could look like
4322 0x0000 0000 Exception Vector code
4325 0x0000 2000 Free for Application Use
4331 0x00FB FF20 Monitor Stack (Growing downward)
4332 0x00FB FFAC Board Info Data and permanent copy of global data
4333 0x00FC 0000 Malloc Arena
4336 0x00FE 0000 RAM Copy of Monitor Code
4337 ... eventually: LCD or video framebuffer
4338 ... eventually: pRAM (Protected RAM - unchanged by reset)
4339 0x00FF FFFF [End of RAM]
4342 System Initialization:
4343 ----------------------
4345 In the reset configuration, U-Boot starts at the reset entry point
4346 (on most PowerPC systems at address 0x00000100). Because of the reset
4347 configuration for CS0# this is a mirror of the on board Flash memory.
4348 To be able to re-map memory U-Boot then jumps to its link address.
4349 To be able to implement the initialization code in C, a (small!)
4350 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4351 which provide such a feature like), or in a locked part of the data
4352 cache. After that, U-Boot initializes the CPU core, the caches and
4355 Next, all (potentially) available memory banks are mapped using a
4356 preliminary mapping. For example, we put them on 512 MB boundaries
4357 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4358 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4359 programmed for SDRAM access. Using the temporary configuration, a
4360 simple memory test is run that determines the size of the SDRAM
4363 When there is more than one SDRAM bank, and the banks are of
4364 different size, the largest is mapped first. For equal size, the first
4365 bank (CS2#) is mapped first. The first mapping is always for address
4366 0x00000000, with any additional banks following immediately to create
4367 contiguous memory starting from 0.
4369 Then, the monitor installs itself at the upper end of the SDRAM area
4370 and allocates memory for use by malloc() and for the global Board
4371 Info data; also, the exception vector code is copied to the low RAM
4372 pages, and the final stack is set up.
4374 Only after this relocation will you have a "normal" C environment;
4375 until that you are restricted in several ways, mostly because you are
4376 running from ROM, and because the code will have to be relocated to a
4380 U-Boot Porting Guide:
4381 ----------------------
4383 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4387 int main(int argc, char *argv[])
4389 sighandler_t no_more_time;
4391 signal(SIGALRM, no_more_time);
4392 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4394 if (available_money > available_manpower) {
4395 Pay consultant to port U-Boot;
4399 Download latest U-Boot source;
4401 Subscribe to u-boot mailing list;
4404 email("Hi, I am new to U-Boot, how do I get started?");
4407 Read the README file in the top level directory;
4408 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
4409 Read applicable doc/README.*;
4410 Read the source, Luke;
4411 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4414 if (available_money > toLocalCurrency ($2500))
4417 Add a lot of aggravation and time;
4419 if (a similar board exists) { /* hopefully... */
4420 cp -a board/<similar> board/<myboard>
4421 cp include/configs/<similar>.h include/configs/<myboard>.h
4423 Create your own board support subdirectory;
4424 Create your own board include/configs/<myboard>.h file;
4426 Edit new board/<myboard> files
4427 Edit new include/configs/<myboard>.h
4432 Add / modify source code;
4436 email("Hi, I am having problems...");
4438 Send patch file to the U-Boot email list;
4439 if (reasonable critiques)
4440 Incorporate improvements from email list code review;
4442 Defend code as written;
4448 void no_more_time (int sig)
4457 All contributions to U-Boot should conform to the Linux kernel
4458 coding style; see the kernel coding style guide at
4459 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4460 script "scripts/Lindent" in your Linux kernel source directory.
4462 Source files originating from a different project (for example the
4463 MTD subsystem) are generally exempt from these guidelines and are not
4464 reformatted to ease subsequent migration to newer versions of those
4467 Please note that U-Boot is implemented in C (and to some small parts in
4468 Assembler); no C++ is used, so please do not use C++ style comments (//)
4471 Please also stick to the following formatting rules:
4472 - remove any trailing white space
4473 - use TAB characters for indentation and vertical alignment, not spaces
4474 - make sure NOT to use DOS '\r\n' line feeds
4475 - do not add more than 2 consecutive empty lines to source files
4476 - do not add trailing empty lines to source files
4478 Submissions which do not conform to the standards may be returned
4479 with a request to reformat the changes.
4485 Since the number of patches for U-Boot is growing, we need to
4486 establish some rules. Submissions which do not conform to these rules
4487 may be rejected, even when they contain important and valuable stuff.
4489 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
4491 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4492 see https://lists.denx.de/listinfo/u-boot
4494 When you send a patch, please include the following information with
4497 * For bug fixes: a description of the bug and how your patch fixes
4498 this bug. Please try to include a way of demonstrating that the
4499 patch actually fixes something.
4501 * For new features: a description of the feature and your
4504 * For major contributions, add a MAINTAINERS file with your
4505 information and associated file and directory references.
4507 * When you add support for a new board, don't forget to add a
4508 maintainer e-mail address to the boards.cfg file, too.
4510 * If your patch adds new configuration options, don't forget to
4511 document these in the README file.
4513 * The patch itself. If you are using git (which is *strongly*
4514 recommended) you can easily generate the patch using the
4515 "git format-patch". If you then use "git send-email" to send it to
4516 the U-Boot mailing list, you will avoid most of the common problems
4517 with some other mail clients.
4519 If you cannot use git, use "diff -purN OLD NEW". If your version of
4520 diff does not support these options, then get the latest version of
4523 The current directory when running this command shall be the parent
4524 directory of the U-Boot source tree (i. e. please make sure that
4525 your patch includes sufficient directory information for the
4528 We prefer patches as plain text. MIME attachments are discouraged,
4529 and compressed attachments must not be used.
4531 * If one logical set of modifications affects or creates several
4532 files, all these changes shall be submitted in a SINGLE patch file.
4534 * Changesets that contain different, unrelated modifications shall be
4535 submitted as SEPARATE patches, one patch per changeset.
4540 * Before sending the patch, run the buildman script on your patched
4541 source tree and make sure that no errors or warnings are reported
4542 for any of the boards.
4544 * Keep your modifications to the necessary minimum: A patch
4545 containing several unrelated changes or arbitrary reformats will be
4546 returned with a request to re-formatting / split it.
4548 * If you modify existing code, make sure that your new code does not
4549 add to the memory footprint of the code ;-) Small is beautiful!
4550 When adding new features, these should compile conditionally only
4551 (using #ifdef), and the resulting code with the new feature
4552 disabled must not need more memory than the old code without your
4555 * Remember that there is a size limit of 100 kB per message on the
4556 u-boot mailing list. Bigger patches will be moderated. If they are
4557 reasonable and not too big, they will be acknowledged. But patches
4558 bigger than the size limit should be avoided.