1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see http://lists.denx.de/pipermail/u-boot and
55 http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
58 Where to get source code:
59 =========================
61 The U-Boot source code is maintained in the Git repository at
62 git://www.denx.de/git/u-boot.git ; you can browse it online at
63 http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
65 The "snapshot" links on this page allow you to download tarballs of
66 any version you might be interested in. Official releases are also
67 available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
70 Pre-built (and tested) images are available from
71 ftp://ftp.denx.de/pub/u-boot/images/
77 - start from 8xxrom sources
78 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
80 - make it easier to add custom boards
81 - make it possible to add other [PowerPC] CPUs
82 - extend functions, especially:
83 * Provide extended interface to Linux boot loader
86 * ATA disk / SCSI ... boot
87 - create ARMBoot project (http://sourceforge.net/projects/armboot)
88 - add other CPU families (starting with ARM)
89 - create U-Boot project (http://sourceforge.net/projects/u-boot)
90 - current project page: see http://www.denx.de/wiki/U-Boot
96 The "official" name of this project is "Das U-Boot". The spelling
97 "U-Boot" shall be used in all written text (documentation, comments
98 in source files etc.). Example:
100 This is the README file for the U-Boot project.
102 File names etc. shall be based on the string "u-boot". Examples:
104 include/asm-ppc/u-boot.h
106 #include <asm/u-boot.h>
108 Variable names, preprocessor constants etc. shall be either based on
109 the string "u_boot" or on "U_BOOT". Example:
111 U_BOOT_VERSION u_boot_logo
112 IH_OS_U_BOOT u_boot_hush_start
118 Starting with the release in October 2008, the names of the releases
119 were changed from numerical release numbers without deeper meaning
120 into a time stamp based numbering. Regular releases are identified by
121 names consisting of the calendar year and month of the release date.
122 Additional fields (if present) indicate release candidates or bug fix
123 releases in "stable" maintenance trees.
126 U-Boot v2009.11 - Release November 2009
127 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
128 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
134 /arch Architecture specific files
135 /arc Files generic to ARC architecture
136 /arm Files generic to ARM architecture
137 /m68k Files generic to m68k architecture
138 /microblaze Files generic to microblaze architecture
139 /mips Files generic to MIPS architecture
140 /nds32 Files generic to NDS32 architecture
141 /nios2 Files generic to Altera NIOS2 architecture
142 /openrisc Files generic to OpenRISC architecture
143 /powerpc Files generic to PowerPC architecture
144 /riscv Files generic to RISC-V architecture
145 /sandbox Files generic to HW-independent "sandbox"
146 /sh Files generic to SH architecture
147 /x86 Files generic to x86 architecture
148 /api Machine/arch independent API for external apps
149 /board Board dependent files
150 /cmd U-Boot commands functions
151 /common Misc architecture independent functions
152 /configs Board default configuration files
153 /disk Code for disk drive partition handling
154 /doc Documentation (don't expect too much)
155 /drivers Commonly used device drivers
156 /dts Contains Makefile for building internal U-Boot fdt.
157 /examples Example code for standalone applications, etc.
158 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
159 /include Header Files
160 /lib Library routines generic to all architectures
161 /Licenses Various license files
163 /post Power On Self Test
164 /scripts Various build scripts and Makefiles
165 /test Various unit test files
166 /tools Tools to build S-Record or U-Boot images, etc.
168 Software Configuration:
169 =======================
171 Configuration is usually done using C preprocessor defines; the
172 rationale behind that is to avoid dead code whenever possible.
174 There are two classes of configuration variables:
176 * Configuration _OPTIONS_:
177 These are selectable by the user and have names beginning with
180 * Configuration _SETTINGS_:
181 These depend on the hardware etc. and should not be meddled with if
182 you don't know what you're doing; they have names beginning with
185 Previously, all configuration was done by hand, which involved creating
186 symbolic links and editing configuration files manually. More recently,
187 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
188 allowing you to use the "make menuconfig" command to configure your
192 Selection of Processor Architecture and Board Type:
193 ---------------------------------------------------
195 For all supported boards there are ready-to-use default
196 configurations available; just type "make <board_name>_defconfig".
198 Example: For a TQM823L module type:
201 make TQM823L_defconfig
203 Note: If you're looking for the default configuration file for a board
204 you're sure used to be there but is now missing, check the file
205 doc/README.scrapyard for a list of no longer supported boards.
210 U-Boot can be built natively to run on a Linux host using the 'sandbox'
211 board. This allows feature development which is not board- or architecture-
212 specific to be undertaken on a native platform. The sandbox is also used to
213 run some of U-Boot's tests.
215 See doc/arch/index.rst for more details.
218 Board Initialisation Flow:
219 --------------------------
221 This is the intended start-up flow for boards. This should apply for both
222 SPL and U-Boot proper (i.e. they both follow the same rules).
224 Note: "SPL" stands for "Secondary Program Loader," which is explained in
225 more detail later in this file.
227 At present, SPL mostly uses a separate code path, but the function names
228 and roles of each function are the same. Some boards or architectures
229 may not conform to this. At least most ARM boards which use
230 CONFIG_SPL_FRAMEWORK conform to this.
232 Execution typically starts with an architecture-specific (and possibly
233 CPU-specific) start.S file, such as:
235 - arch/arm/cpu/armv7/start.S
236 - arch/powerpc/cpu/mpc83xx/start.S
237 - arch/mips/cpu/start.S
239 and so on. From there, three functions are called; the purpose and
240 limitations of each of these functions are described below.
243 - purpose: essential init to permit execution to reach board_init_f()
244 - no global_data or BSS
245 - there is no stack (ARMv7 may have one but it will soon be removed)
246 - must not set up SDRAM or use console
247 - must only do the bare minimum to allow execution to continue to
249 - this is almost never needed
250 - return normally from this function
253 - purpose: set up the machine ready for running board_init_r():
254 i.e. SDRAM and serial UART
255 - global_data is available
257 - BSS is not available, so you cannot use global/static variables,
258 only stack variables and global_data
260 Non-SPL-specific notes:
261 - dram_init() is called to set up DRAM. If already done in SPL this
265 - you can override the entire board_init_f() function with your own
267 - preloader_console_init() can be called here in extremis
268 - should set up SDRAM, and anything needed to make the UART work
269 - there is no need to clear BSS, it will be done by crt0.S
270 - for specific scenarios on certain architectures an early BSS *can*
271 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
272 of BSS prior to entering board_init_f()) but doing so is discouraged.
273 Instead it is strongly recommended to architect any code changes
274 or additions such to not depend on the availability of BSS during
275 board_init_f() as indicated in other sections of this README to
276 maintain compatibility and consistency across the entire code base.
277 - must return normally from this function (don't call board_init_r()
280 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
281 this point the stack and global_data are relocated to below
282 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
286 - purpose: main execution, common code
287 - global_data is available
289 - BSS is available, all static/global variables can be used
290 - execution eventually continues to main_loop()
292 Non-SPL-specific notes:
293 - U-Boot is relocated to the top of memory and is now running from
297 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
298 CONFIG_SPL_STACK_R_ADDR points into SDRAM
299 - preloader_console_init() can be called here - typically this is
300 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
301 spl_board_init() function containing this call
302 - loads U-Boot or (in falcon mode) Linux
306 Configuration Options:
307 ----------------------
309 Configuration depends on the combination of board and CPU type; all
310 such information is kept in a configuration file
311 "include/configs/<board_name>.h".
313 Example: For a TQM823L module, all configuration settings are in
314 "include/configs/TQM823L.h".
317 Many of the options are named exactly as the corresponding Linux
318 kernel configuration options. The intention is to make it easier to
319 build a config tool - later.
321 - ARM Platform Bus Type(CCI):
322 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
323 provides full cache coherency between two clusters of multi-core
324 CPUs and I/O coherency for devices and I/O masters
326 CONFIG_SYS_FSL_HAS_CCI400
328 Defined For SoC that has cache coherent interconnect
331 CONFIG_SYS_FSL_HAS_CCN504
333 Defined for SoC that has cache coherent interconnect CCN-504
335 The following options need to be configured:
337 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
339 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
344 Specifies that the core is a 64-bit PowerPC implementation (implements
345 the "64" category of the Power ISA). This is necessary for ePAPR
346 compliance, among other possible reasons.
348 CONFIG_SYS_FSL_TBCLK_DIV
350 Defines the core time base clock divider ratio compared to the
351 system clock. On most PQ3 devices this is 8, on newer QorIQ
352 devices it can be 16 or 32. The ratio varies from SoC to Soc.
354 CONFIG_SYS_FSL_PCIE_COMPAT
356 Defines the string to utilize when trying to match PCIe device
357 tree nodes for the given platform.
359 CONFIG_SYS_FSL_ERRATUM_A004510
361 Enables a workaround for erratum A004510. If set,
362 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
363 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
365 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
366 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
368 Defines one or two SoC revisions (low 8 bits of SVR)
369 for which the A004510 workaround should be applied.
371 The rest of SVR is either not relevant to the decision
372 of whether the erratum is present (e.g. p2040 versus
373 p2041) or is implied by the build target, which controls
374 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
376 See Freescale App Note 4493 for more information about
379 CONFIG_A003399_NOR_WORKAROUND
380 Enables a workaround for IFC erratum A003399. It is only
381 required during NOR boot.
383 CONFIG_A008044_WORKAROUND
384 Enables a workaround for T1040/T1042 erratum A008044. It is only
385 required during NAND boot and valid for Rev 1.0 SoC revision
387 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
389 This is the value to write into CCSR offset 0x18600
390 according to the A004510 workaround.
392 CONFIG_SYS_FSL_DSP_DDR_ADDR
393 This value denotes start offset of DDR memory which is
394 connected exclusively to the DSP cores.
396 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
397 This value denotes start offset of M2 memory
398 which is directly connected to the DSP core.
400 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
401 This value denotes start offset of M3 memory which is directly
402 connected to the DSP core.
404 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
405 This value denotes start offset of DSP CCSR space.
407 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
408 Single Source Clock is clocking mode present in some of FSL SoC's.
409 In this mode, a single differential clock is used to supply
410 clocks to the sysclock, ddrclock and usbclock.
412 CONFIG_SYS_CPC_REINIT_F
413 This CONFIG is defined when the CPC is configured as SRAM at the
414 time of U-Boot entry and is required to be re-initialized.
417 Indicates this SoC supports deep sleep feature. If deep sleep is
418 supported, core will start to execute uboot when wakes up.
420 - Generic CPU options:
421 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
423 Defines the endianess of the CPU. Implementation of those
424 values is arch specific.
427 Freescale DDR driver in use. This type of DDR controller is
428 found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
431 CONFIG_SYS_FSL_DDR_ADDR
432 Freescale DDR memory-mapped register base.
434 CONFIG_SYS_FSL_DDR_EMU
435 Specify emulator support for DDR. Some DDR features such as
436 deskew training are not available.
438 CONFIG_SYS_FSL_DDRC_GEN1
439 Freescale DDR1 controller.
441 CONFIG_SYS_FSL_DDRC_GEN2
442 Freescale DDR2 controller.
444 CONFIG_SYS_FSL_DDRC_GEN3
445 Freescale DDR3 controller.
447 CONFIG_SYS_FSL_DDRC_GEN4
448 Freescale DDR4 controller.
450 CONFIG_SYS_FSL_DDRC_ARM_GEN3
451 Freescale DDR3 controller for ARM-based SoCs.
454 Board config to use DDR1. It can be enabled for SoCs with
455 Freescale DDR1 or DDR2 controllers, depending on the board
459 Board config to use DDR2. It can be enabled for SoCs with
460 Freescale DDR2 or DDR3 controllers, depending on the board
464 Board config to use DDR3. It can be enabled for SoCs with
465 Freescale DDR3 or DDR3L controllers.
468 Board config to use DDR3L. It can be enabled for SoCs with
472 Board config to use DDR4. It can be enabled for SoCs with
475 CONFIG_SYS_FSL_IFC_BE
476 Defines the IFC controller register space as Big Endian
478 CONFIG_SYS_FSL_IFC_LE
479 Defines the IFC controller register space as Little Endian
481 CONFIG_SYS_FSL_IFC_CLK_DIV
482 Defines divider of platform clock(clock input to IFC controller).
484 CONFIG_SYS_FSL_LBC_CLK_DIV
485 Defines divider of platform clock(clock input to eLBC controller).
487 CONFIG_SYS_FSL_PBL_PBI
488 It enables addition of RCW (Power on reset configuration) in built image.
489 Please refer doc/README.pblimage for more details
491 CONFIG_SYS_FSL_PBL_RCW
492 It adds PBI(pre-boot instructions) commands in u-boot build image.
493 PBI commands can be used to configure SoC before it starts the execution.
494 Please refer doc/README.pblimage for more details
496 CONFIG_SYS_FSL_DDR_BE
497 Defines the DDR controller register space as Big Endian
499 CONFIG_SYS_FSL_DDR_LE
500 Defines the DDR controller register space as Little Endian
502 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
503 Physical address from the view of DDR controllers. It is the
504 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
505 it could be different for ARM SoCs.
507 CONFIG_SYS_FSL_DDR_INTLV_256B
508 DDR controller interleaving on 256-byte. This is a special
509 interleaving mode, handled by Dickens for Freescale layerscape
512 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
513 Number of controllers used as main memory.
515 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
516 Number of controllers used for other than main memory.
518 CONFIG_SYS_FSL_HAS_DP_DDR
519 Defines the SoC has DP-DDR used for DPAA.
521 CONFIG_SYS_FSL_SEC_BE
522 Defines the SEC controller register space as Big Endian
524 CONFIG_SYS_FSL_SEC_LE
525 Defines the SEC controller register space as Little Endian
528 CONFIG_SYS_INIT_SP_OFFSET
530 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
531 pointer. This is needed for the temporary stack before
534 CONFIG_XWAY_SWAP_BYTES
536 Enable compilation of tools/xway-swap-bytes needed for Lantiq
537 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
538 be swapped if a flash programmer is used.
541 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
543 Select high exception vectors of the ARM core, e.g., do not
544 clear the V bit of the c1 register of CP15.
547 Generic timer clock source frequency.
549 COUNTER_FREQUENCY_REAL
550 Generic timer clock source frequency if the real clock is
551 different from COUNTER_FREQUENCY, and can only be determined
555 CONFIG_TEGRA_SUPPORT_NON_SECURE
557 Support executing U-Boot in non-secure (NS) mode. Certain
558 impossible actions will be skipped if the CPU is in NS mode,
559 such as ARM architectural timer initialization.
561 - Linux Kernel Interface:
562 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
564 When transferring memsize parameter to Linux, some versions
565 expect it to be in bytes, others in MB.
566 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
570 New kernel versions are expecting firmware settings to be
571 passed using flattened device trees (based on open firmware
575 * New libfdt-based support
576 * Adds the "fdt" command
577 * The bootm command automatically updates the fdt
579 OF_TBCLK - The timebase frequency.
580 OF_STDOUT_PATH - The path to the console device
582 boards with QUICC Engines require OF_QE to set UCC MAC
585 CONFIG_OF_BOARD_SETUP
587 Board code has addition modification that it wants to make
588 to the flat device tree before handing it off to the kernel
590 CONFIG_OF_SYSTEM_SETUP
592 Other code has addition modification that it wants to make
593 to the flat device tree before handing it off to the kernel.
594 This causes ft_system_setup() to be called before booting
599 U-Boot can detect if an IDE device is present or not.
600 If not, and this new config option is activated, U-Boot
601 removes the ATA node from the DTS before booting Linux,
602 so the Linux IDE driver does not probe the device and
603 crash. This is needed for buggy hardware (uc101) where
604 no pull down resistor is connected to the signal IDE5V_DD7.
606 CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
608 This setting is mandatory for all boards that have only one
609 machine type and must be used to specify the machine type
610 number as it appears in the ARM machine registry
611 (see http://www.arm.linux.org.uk/developer/machines/).
612 Only boards that have multiple machine types supported
613 in a single configuration file and the machine type is
614 runtime discoverable, do not have to use this setting.
616 - vxWorks boot parameters:
618 bootvx constructs a valid bootline using the following
619 environments variables: bootdev, bootfile, ipaddr, netmask,
620 serverip, gatewayip, hostname, othbootargs.
621 It loads the vxWorks image pointed bootfile.
623 Note: If a "bootargs" environment is defined, it will overwride
624 the defaults discussed just above.
626 - Cache Configuration:
627 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
629 - Cache Configuration for ARM:
630 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
632 CONFIG_SYS_PL310_BASE - Physical base address of PL310
633 controller register space
638 Define this if you want support for Amba PrimeCell PL010 UARTs.
642 Define this if you want support for Amba PrimeCell PL011 UARTs.
646 If you have Amba PrimeCell PL011 UARTs, set this variable to
647 the clock speed of the UARTs.
651 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
652 define this to a list of base addresses for each (supported)
653 port. See e.g. include/configs/versatile.h
655 CONFIG_SERIAL_HW_FLOW_CONTROL
657 Define this variable to enable hw flow control in serial driver.
658 Current user of this option is drivers/serial/nsl16550.c driver
662 Only needed when CONFIG_BOOTDELAY is enabled;
663 define a command string that is automatically executed
664 when no character is read on the console interface
665 within "Boot Delay" after reset.
667 CONFIG_RAMBOOT and CONFIG_NFSBOOT
668 The value of these goes into the environment as
669 "ramboot" and "nfsboot" respectively, and can be used
670 as a convenience, when switching between booting from
673 - Serial Download Echo Mode:
675 If defined to 1, all characters received during a
676 serial download (using the "loads" command) are
677 echoed back. This might be needed by some terminal
678 emulations (like "cu"), but may as well just take
679 time on others. This setting #define's the initial
680 value of the "loads_echo" environment variable.
682 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
684 Select one of the baudrates listed in
685 CONFIG_SYS_BAUDRATE_TABLE, see below.
687 - Removal of commands
688 If no commands are needed to boot, you can disable
689 CONFIG_CMDLINE to remove them. In this case, the command line
690 will not be available, and when U-Boot wants to execute the
691 boot command (on start-up) it will call board_run_command()
692 instead. This can reduce image size significantly for very
693 simple boot procedures.
695 - Regular expression support:
697 If this variable is defined, U-Boot is linked against
698 the SLRE (Super Light Regular Expression) library,
699 which adds regex support to some commands, as for
700 example "env grep" and "setexpr".
704 If this variable is defined, U-Boot will use a device tree
705 to configure its devices, instead of relying on statically
706 compiled #defines in the board file. This option is
707 experimental and only available on a few boards. The device
708 tree is available in the global data as gd->fdt_blob.
710 U-Boot needs to get its device tree from somewhere. This can
711 be done using one of the three options below:
714 If this variable is defined, U-Boot will embed a device tree
715 binary in its image. This device tree file should be in the
716 board directory and called <soc>-<board>.dts. The binary file
717 is then picked up in board_init_f() and made available through
718 the global data structure as gd->fdt_blob.
721 If this variable is defined, U-Boot will build a device tree
722 binary. It will be called u-boot.dtb. Architecture-specific
723 code will locate it at run-time. Generally this works by:
725 cat u-boot.bin u-boot.dtb >image.bin
727 and in fact, U-Boot does this for you, creating a file called
728 u-boot-dtb.bin which is useful in the common case. You can
729 still use the individual files if you need something more
733 If this variable is defined, U-Boot will use the device tree
734 provided by the board at runtime instead of embedding one with
735 the image. Only boards defining board_fdt_blob_setup() support
736 this option (see include/fdtdec.h file).
740 If this variable is defined, it enables watchdog
741 support for the SoC. There must be support in the SoC
742 specific code for a watchdog. For the 8xx
743 CPUs, the SIU Watchdog feature is enabled in the SYPCR
744 register. When supported for a specific SoC is
745 available, then no further board specific code should
749 When using a watchdog circuitry external to the used
750 SoC, then define this variable and provide board
751 specific code for the "hw_watchdog_reset" function.
755 When CONFIG_CMD_DATE is selected, the type of the RTC
756 has to be selected, too. Define exactly one of the
759 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
760 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
761 CONFIG_RTC_MC146818 - use MC146818 RTC
762 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
763 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
764 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
765 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
766 CONFIG_RTC_DS164x - use Dallas DS164x RTC
767 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
768 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
769 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
770 CONFIG_SYS_RV3029_TCR - enable trickle charger on
773 Note that if the RTC uses I2C, then the I2C interface
774 must also be configured. See I2C Support, below.
777 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
779 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
780 chip-ngpio pairs that tell the PCA953X driver the number of
781 pins supported by a particular chip.
783 Note that if the GPIO device uses I2C, then the I2C interface
784 must also be configured. See I2C Support, below.
787 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
788 accesses and can checksum them or write a list of them out
789 to memory. See the 'iotrace' command for details. This is
790 useful for testing device drivers since it can confirm that
791 the driver behaves the same way before and after a code
792 change. Currently this is supported on sandbox and arm. To
793 add support for your architecture, add '#include <iotrace.h>'
794 to the bottom of arch/<arch>/include/asm/io.h and test.
796 Example output from the 'iotrace stats' command is below.
797 Note that if the trace buffer is exhausted, the checksum will
798 still continue to operate.
801 Start: 10000000 (buffer start address)
802 Size: 00010000 (buffer size)
803 Offset: 00000120 (current buffer offset)
804 Output: 10000120 (start + offset)
805 Count: 00000018 (number of trace records)
806 CRC32: 9526fb66 (CRC32 of all trace records)
810 When CONFIG_TIMESTAMP is selected, the timestamp
811 (date and time) of an image is printed by image
812 commands like bootm or iminfo. This option is
813 automatically enabled when you select CONFIG_CMD_DATE .
815 - Partition Labels (disklabels) Supported:
816 Zero or more of the following:
817 CONFIG_MAC_PARTITION Apple's MacOS partition table.
818 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
819 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
820 bootloader. Note 2TB partition limit; see
822 CONFIG_SCSI) you must configure support for at
823 least one non-MTD partition type as well.
826 CONFIG_IDE_RESET_ROUTINE - this is defined in several
827 board configurations files but used nowhere!
829 CONFIG_IDE_RESET - is this is defined, IDE Reset will
830 be performed by calling the function
831 ide_set_reset(int reset)
832 which has to be defined in a board specific file
837 Set this to enable ATAPI support.
842 Set this to enable support for disks larger than 137GB
843 Also look at CONFIG_SYS_64BIT_LBA.
844 Whithout these , LBA48 support uses 32bit variables and will 'only'
845 support disks up to 2.1TB.
847 CONFIG_SYS_64BIT_LBA:
848 When enabled, makes the IDE subsystem use 64bit sector addresses.
852 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
853 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
854 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
855 maximum numbers of LUNs, SCSI ID's and target
858 The environment variable 'scsidevs' is set to the number of
859 SCSI devices found during the last scan.
861 - NETWORK Support (PCI):
863 Support for Intel 8254x/8257x gigabit chips.
866 Utility code for direct access to the SPI bus on Intel 8257x.
867 This does not do anything useful unless you set at least one
868 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
870 CONFIG_E1000_SPI_GENERIC
871 Allow generic access to the SPI bus on the Intel 8257x, for
872 example with the "sspi" command.
875 Support for National dp83815 chips.
878 Support for National dp8382[01] gigabit chips.
880 - NETWORK Support (other):
882 CONFIG_DRIVER_AT91EMAC
883 Support for AT91RM9200 EMAC.
886 Define this to use reduced MII inteface
888 CONFIG_DRIVER_AT91EMAC_QUIET
889 If this defined, the driver is quiet.
890 The driver doen't show link status messages.
893 Support for the Calxeda XGMAC device
896 Support for SMSC's LAN91C96 chips.
898 CONFIG_LAN91C96_USE_32_BIT
899 Define this to enable 32 bit addressing
902 Support for SMSC's LAN91C111 chip
905 Define this to hold the physical address
906 of the device (I/O space)
908 CONFIG_SMC_USE_32_BIT
909 Define this if data bus is 32 bits
911 CONFIG_SMC_USE_IOFUNCS
912 Define this to use i/o functions instead of macros
913 (some hardware wont work with macros)
915 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
916 Define this if you have more then 3 PHYs.
919 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
921 CONFIG_FTGMAC100_EGIGA
922 Define this to use GE link update with gigabit PHY.
923 Define this if FTGMAC100 is connected to gigabit PHY.
924 If your system has 10/100 PHY only, it might not occur
925 wrong behavior. Because PHY usually return timeout or
926 useless data when polling gigabit status and gigabit
927 control registers. This behavior won't affect the
928 correctnessof 10/100 link speed update.
931 Support for Renesas on-chip Ethernet controller
933 CONFIG_SH_ETHER_USE_PORT
934 Define the number of ports to be used
936 CONFIG_SH_ETHER_PHY_ADDR
937 Define the ETH PHY's address
939 CONFIG_SH_ETHER_CACHE_WRITEBACK
940 If this option is set, the driver enables cache flush.
946 CONFIG_TPM_TIS_INFINEON
947 Support for Infineon i2c bus TPM devices. Only one device
948 per system is supported at this time.
950 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
951 Define the burst count bytes upper limit
954 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
956 CONFIG_TPM_ST33ZP24_I2C
957 Support for STMicroelectronics ST33ZP24 I2C devices.
958 Requires TPM_ST33ZP24 and I2C.
960 CONFIG_TPM_ST33ZP24_SPI
961 Support for STMicroelectronics ST33ZP24 SPI devices.
962 Requires TPM_ST33ZP24 and SPI.
965 Support for Atmel TWI TPM device. Requires I2C support.
968 Support for generic parallel port TPM devices. Only one device
969 per system is supported at this time.
971 CONFIG_TPM_TIS_BASE_ADDRESS
972 Base address where the generic TPM device is mapped
973 to. Contemporary x86 systems usually map it at
977 Define this to enable the TPM support library which provides
978 functional interfaces to some TPM commands.
979 Requires support for a TPM device.
981 CONFIG_TPM_AUTH_SESSIONS
982 Define this to enable authorized functions in the TPM library.
983 Requires CONFIG_TPM and CONFIG_SHA1.
986 At the moment only the UHCI host controller is
987 supported (PIP405, MIP405); define
988 CONFIG_USB_UHCI to enable it.
989 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
990 and define CONFIG_USB_STORAGE to enable the USB
993 Supported are USB Keyboards and USB Floppy drives
996 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
997 txfilltuning field in the EHCI controller on reset.
999 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1000 HW module registers.
1003 Define the below if you wish to use the USB console.
1004 Once firmware is rebuilt from a serial console issue the
1005 command "setenv stdin usbtty; setenv stdout usbtty" and
1006 attach your USB cable. The Unix command "dmesg" should print
1007 it has found a new device. The environment variable usbtty
1008 can be set to gserial or cdc_acm to enable your device to
1009 appear to a USB host as a Linux gserial device or a
1010 Common Device Class Abstract Control Model serial device.
1011 If you select usbtty = gserial you should be able to enumerate
1013 # modprobe usbserial vendor=0xVendorID product=0xProductID
1014 else if using cdc_acm, simply setting the environment
1015 variable usbtty to be cdc_acm should suffice. The following
1016 might be defined in YourBoardName.h
1019 Define this to build a UDC device
1022 Define this to have a tty type of device available to
1023 talk to the UDC device
1026 Define this to enable the high speed support for usb
1027 device and usbtty. If this feature is enabled, a routine
1028 int is_usbd_high_speed(void)
1029 also needs to be defined by the driver to dynamically poll
1030 whether the enumeration has succeded at high speed or full
1033 CONFIG_SYS_CONSOLE_IS_IN_ENV
1034 Define this if you want stdin, stdout &/or stderr to
1037 If you have a USB-IF assigned VendorID then you may wish to
1038 define your own vendor specific values either in BoardName.h
1039 or directly in usbd_vendor_info.h. If you don't define
1040 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1041 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1042 should pretend to be a Linux device to it's target host.
1044 CONFIG_USBD_MANUFACTURER
1045 Define this string as the name of your company for
1046 - CONFIG_USBD_MANUFACTURER "my company"
1048 CONFIG_USBD_PRODUCT_NAME
1049 Define this string as the name of your product
1050 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1052 CONFIG_USBD_VENDORID
1053 Define this as your assigned Vendor ID from the USB
1054 Implementors Forum. This *must* be a genuine Vendor ID
1055 to avoid polluting the USB namespace.
1056 - CONFIG_USBD_VENDORID 0xFFFF
1058 CONFIG_USBD_PRODUCTID
1059 Define this as the unique Product ID
1061 - CONFIG_USBD_PRODUCTID 0xFFFF
1063 - ULPI Layer Support:
1064 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1065 the generic ULPI layer. The generic layer accesses the ULPI PHY
1066 via the platform viewport, so you need both the genric layer and
1067 the viewport enabled. Currently only Chipidea/ARC based
1068 viewport is supported.
1069 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1070 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1071 If your ULPI phy needs a different reference clock than the
1072 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1073 the appropriate value in Hz.
1076 The MMC controller on the Intel PXA is supported. To
1077 enable this define CONFIG_MMC. The MMC can be
1078 accessed from the boot prompt by mapping the device
1079 to physical memory similar to flash. Command line is
1080 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1081 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1084 Support for Renesas on-chip MMCIF controller
1086 CONFIG_SH_MMCIF_ADDR
1087 Define the base address of MMCIF registers
1090 Define the clock frequency for MMCIF
1092 - USB Device Firmware Update (DFU) class support:
1094 This enables the USB portion of the DFU USB class
1097 This enables support for exposing NAND devices via DFU.
1100 This enables support for exposing RAM via DFU.
1101 Note: DFU spec refer to non-volatile memory usage, but
1102 allow usages beyond the scope of spec - here RAM usage,
1103 one that would help mostly the developer.
1105 CONFIG_SYS_DFU_DATA_BUF_SIZE
1106 Dfu transfer uses a buffer before writing data to the
1107 raw storage device. Make the size (in bytes) of this buffer
1108 configurable. The size of this buffer is also configurable
1109 through the "dfu_bufsiz" environment variable.
1111 CONFIG_SYS_DFU_MAX_FILE_SIZE
1112 When updating files rather than the raw storage device,
1113 we use a static buffer to copy the file into and then write
1114 the buffer once we've been given the whole file. Define
1115 this to the maximum filesize (in bytes) for the buffer.
1116 Default is 4 MiB if undefined.
1118 DFU_DEFAULT_POLL_TIMEOUT
1119 Poll timeout [ms], is the timeout a device can send to the
1120 host. The host must wait for this timeout before sending
1121 a subsequent DFU_GET_STATUS request to the device.
1123 DFU_MANIFEST_POLL_TIMEOUT
1124 Poll timeout [ms], which the device sends to the host when
1125 entering dfuMANIFEST state. Host waits this timeout, before
1126 sending again an USB request to the device.
1128 - Journaling Flash filesystem support:
1130 Define these for a default partition on a NAND device
1132 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1133 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1134 Define these for a default partition on a NOR device
1137 See Kconfig help for available keyboard drivers.
1141 Define this to enable a custom keyboard support.
1142 This simply calls drv_keyboard_init() which must be
1143 defined in your board-specific files. This option is deprecated
1144 and is only used by novena. For new boards, use driver model
1149 Enable the Freescale DIU video driver. Reference boards for
1150 SOCs that have a DIU should define this macro to enable DIU
1151 support, and should also define these other macros:
1156 CONFIG_VIDEO_SW_CURSOR
1157 CONFIG_VGA_AS_SINGLE_DEVICE
1159 CONFIG_VIDEO_BMP_LOGO
1161 The DIU driver will look for the 'video-mode' environment
1162 variable, and if defined, enable the DIU as a console during
1163 boot. See the documentation file doc/README.video for a
1164 description of this variable.
1166 - LCD Support: CONFIG_LCD
1168 Define this to enable LCD support (for output to LCD
1169 display); also select one of the supported displays
1170 by defining one of these:
1174 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1176 CONFIG_NEC_NL6448AC33:
1178 NEC NL6448AC33-18. Active, color, single scan.
1180 CONFIG_NEC_NL6448BC20
1182 NEC NL6448BC20-08. 6.5", 640x480.
1183 Active, color, single scan.
1185 CONFIG_NEC_NL6448BC33_54
1187 NEC NL6448BC33-54. 10.4", 640x480.
1188 Active, color, single scan.
1192 Sharp 320x240. Active, color, single scan.
1193 It isn't 16x9, and I am not sure what it is.
1195 CONFIG_SHARP_LQ64D341
1197 Sharp LQ64D341 display, 640x480.
1198 Active, color, single scan.
1202 HLD1045 display, 640x480.
1203 Active, color, single scan.
1207 Optrex CBL50840-2 NF-FW 99 22 M5
1209 Hitachi LMG6912RPFC-00T
1213 320x240. Black & white.
1215 CONFIG_LCD_ALIGNMENT
1217 Normally the LCD is page-aligned (typically 4KB). If this is
1218 defined then the LCD will be aligned to this value instead.
1219 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1220 here, since it is cheaper to change data cache settings on
1221 a per-section basis.
1226 Sometimes, for example if the display is mounted in portrait
1227 mode or even if it's mounted landscape but rotated by 180degree,
1228 we need to rotate our content of the display relative to the
1229 framebuffer, so that user can read the messages which are
1231 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1232 initialized with a given rotation from "vl_rot" out of
1233 "vidinfo_t" which is provided by the board specific code.
1234 The value for vl_rot is coded as following (matching to
1235 fbcon=rotate:<n> linux-kernel commandline):
1236 0 = no rotation respectively 0 degree
1237 1 = 90 degree rotation
1238 2 = 180 degree rotation
1239 3 = 270 degree rotation
1241 If CONFIG_LCD_ROTATION is not defined, the console will be
1242 initialized with 0degree rotation.
1246 Support drawing of RLE8-compressed bitmaps on the LCD.
1250 Enables an 'i2c edid' command which can read EDID
1251 information over I2C from an attached LCD display.
1253 - Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1255 If this option is set, 8-bit RLE compressed BMP images
1256 can be displayed via the splashscreen support or the
1260 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1262 The clock frequency of the MII bus
1264 CONFIG_PHY_RESET_DELAY
1266 Some PHY like Intel LXT971A need extra delay after
1267 reset before any MII register access is possible.
1268 For such PHY, set this option to the usec delay
1269 required. (minimum 300usec for LXT971A)
1271 CONFIG_PHY_CMD_DELAY (ppc4xx)
1273 Some PHY like Intel LXT971A need extra delay after
1274 command issued before MII status register can be read
1279 Define a default value for the IP address to use for
1280 the default Ethernet interface, in case this is not
1281 determined through e.g. bootp.
1282 (Environment variable "ipaddr")
1284 - Server IP address:
1287 Defines a default value for the IP address of a TFTP
1288 server to contact when using the "tftboot" command.
1289 (Environment variable "serverip")
1291 CONFIG_KEEP_SERVERADDR
1293 Keeps the server's MAC address, in the env 'serveraddr'
1294 for passing to bootargs (like Linux's netconsole option)
1296 - Gateway IP address:
1299 Defines a default value for the IP address of the
1300 default router where packets to other networks are
1302 (Environment variable "gatewayip")
1307 Defines a default value for the subnet mask (or
1308 routing prefix) which is used to determine if an IP
1309 address belongs to the local subnet or needs to be
1310 forwarded through a router.
1311 (Environment variable "netmask")
1313 - BOOTP Recovery Mode:
1314 CONFIG_BOOTP_RANDOM_DELAY
1316 If you have many targets in a network that try to
1317 boot using BOOTP, you may want to avoid that all
1318 systems send out BOOTP requests at precisely the same
1319 moment (which would happen for instance at recovery
1320 from a power failure, when all systems will try to
1321 boot, thus flooding the BOOTP server. Defining
1322 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1323 inserted before sending out BOOTP requests. The
1324 following delays are inserted then:
1326 1st BOOTP request: delay 0 ... 1 sec
1327 2nd BOOTP request: delay 0 ... 2 sec
1328 3rd BOOTP request: delay 0 ... 4 sec
1330 BOOTP requests: delay 0 ... 8 sec
1332 CONFIG_BOOTP_ID_CACHE_SIZE
1334 BOOTP packets are uniquely identified using a 32-bit ID. The
1335 server will copy the ID from client requests to responses and
1336 U-Boot will use this to determine if it is the destination of
1337 an incoming response. Some servers will check that addresses
1338 aren't in use before handing them out (usually using an ARP
1339 ping) and therefore take up to a few hundred milliseconds to
1340 respond. Network congestion may also influence the time it
1341 takes for a response to make it back to the client. If that
1342 time is too long, U-Boot will retransmit requests. In order
1343 to allow earlier responses to still be accepted after these
1344 retransmissions, U-Boot's BOOTP client keeps a small cache of
1345 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1346 cache. The default is to keep IDs for up to four outstanding
1347 requests. Increasing this will allow U-Boot to accept offers
1348 from a BOOTP client in networks with unusually high latency.
1350 - DHCP Advanced Options:
1351 You can fine tune the DHCP functionality by defining
1352 CONFIG_BOOTP_* symbols:
1354 CONFIG_BOOTP_NISDOMAIN
1355 CONFIG_BOOTP_BOOTFILESIZE
1356 CONFIG_BOOTP_NTPSERVER
1357 CONFIG_BOOTP_TIMEOFFSET
1358 CONFIG_BOOTP_VENDOREX
1359 CONFIG_BOOTP_MAY_FAIL
1361 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1362 environment variable, not the BOOTP server.
1364 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1365 after the configured retry count, the call will fail
1366 instead of starting over. This can be used to fail over
1367 to Link-local IP address configuration if the DHCP server
1370 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1372 A 32bit value in microseconds for a delay between
1373 receiving a "DHCP Offer" and sending the "DHCP Request".
1374 This fixes a problem with certain DHCP servers that don't
1375 respond 100% of the time to a "DHCP request". E.g. On an
1376 AT91RM9200 processor running at 180MHz, this delay needed
1377 to be *at least* 15,000 usec before a Windows Server 2003
1378 DHCP server would reply 100% of the time. I recommend at
1379 least 50,000 usec to be safe. The alternative is to hope
1380 that one of the retries will be successful but note that
1381 the DHCP timeout and retry process takes a longer than
1384 - Link-local IP address negotiation:
1385 Negotiate with other link-local clients on the local network
1386 for an address that doesn't require explicit configuration.
1387 This is especially useful if a DHCP server cannot be guaranteed
1388 to exist in all environments that the device must operate.
1390 See doc/README.link-local for more information.
1392 - MAC address from environment variables
1394 FDT_SEQ_MACADDR_FROM_ENV
1396 Fix-up device tree with MAC addresses fetched sequentially from
1397 environment variables. This config work on assumption that
1398 non-usable ethernet node of device-tree are either not present
1399 or their status has been marked as "disabled".
1402 CONFIG_CDP_DEVICE_ID
1404 The device id used in CDP trigger frames.
1406 CONFIG_CDP_DEVICE_ID_PREFIX
1408 A two character string which is prefixed to the MAC address
1413 A printf format string which contains the ascii name of
1414 the port. Normally is set to "eth%d" which sets
1415 eth0 for the first Ethernet, eth1 for the second etc.
1417 CONFIG_CDP_CAPABILITIES
1419 A 32bit integer which indicates the device capabilities;
1420 0x00000010 for a normal host which does not forwards.
1424 An ascii string containing the version of the software.
1428 An ascii string containing the name of the platform.
1432 A 32bit integer sent on the trigger.
1434 CONFIG_CDP_POWER_CONSUMPTION
1436 A 16bit integer containing the power consumption of the
1437 device in .1 of milliwatts.
1439 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1441 A byte containing the id of the VLAN.
1443 - Status LED: CONFIG_LED_STATUS
1445 Several configurations allow to display the current
1446 status using a LED. For instance, the LED will blink
1447 fast while running U-Boot code, stop blinking as
1448 soon as a reply to a BOOTP request was received, and
1449 start blinking slow once the Linux kernel is running
1450 (supported by a status LED driver in the Linux
1451 kernel). Defining CONFIG_LED_STATUS enables this
1456 CONFIG_LED_STATUS_GPIO
1457 The status LED can be connected to a GPIO pin.
1458 In such cases, the gpio_led driver can be used as a
1459 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1460 to include the gpio_led driver in the U-Boot binary.
1462 CONFIG_GPIO_LED_INVERTED_TABLE
1463 Some GPIO connected LEDs may have inverted polarity in which
1464 case the GPIO high value corresponds to LED off state and
1465 GPIO low value corresponds to LED on state.
1466 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1467 with a list of GPIO LEDs that have inverted polarity.
1469 - I2C Support: CONFIG_SYS_I2C
1471 This enable the NEW i2c subsystem, and will allow you to use
1472 i2c commands at the u-boot command line (as long as you set
1473 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1474 for defining speed and slave address
1475 - activate second bus with I2C_SOFT_DECLARATIONS2 define
1476 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1477 for defining speed and slave address
1478 - activate third bus with I2C_SOFT_DECLARATIONS3 define
1479 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1480 for defining speed and slave address
1481 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1482 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1483 for defining speed and slave address
1485 - drivers/i2c/fsl_i2c.c:
1486 - activate i2c driver with CONFIG_SYS_I2C_FSL
1487 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1488 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1489 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1491 - If your board supports a second fsl i2c bus, define
1492 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1493 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1494 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1497 - drivers/i2c/tegra_i2c.c:
1498 - activate this driver with CONFIG_SYS_I2C_TEGRA
1499 - This driver adds 4 i2c buses with a fix speed from
1500 100000 and the slave addr 0!
1502 - drivers/i2c/ppc4xx_i2c.c
1503 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1504 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1505 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1507 - drivers/i2c/i2c_mxc.c
1508 - activate this driver with CONFIG_SYS_I2C_MXC
1509 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1510 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1511 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1512 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1513 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1514 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1515 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1516 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1517 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1518 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1519 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1520 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1521 If those defines are not set, default value is 100000
1522 for speed, and 0 for slave.
1524 - drivers/i2c/rcar_i2c.c:
1525 - activate this driver with CONFIG_SYS_I2C_RCAR
1526 - This driver adds 4 i2c buses
1528 - drivers/i2c/sh_i2c.c:
1529 - activate this driver with CONFIG_SYS_I2C_SH
1530 - This driver adds from 2 to 5 i2c buses
1532 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1533 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1534 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1535 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1536 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1537 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1538 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1539 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1540 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1541 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1542 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1544 - drivers/i2c/omap24xx_i2c.c
1545 - activate this driver with CONFIG_SYS_I2C_OMAP24XX
1546 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
1547 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
1548 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
1549 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
1550 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
1551 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
1552 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
1553 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
1554 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
1555 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
1557 - drivers/i2c/s3c24x0_i2c.c:
1558 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1559 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1560 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1561 with a fix speed from 100000 and the slave addr 0!
1563 - drivers/i2c/ihs_i2c.c
1564 - activate this driver with CONFIG_SYS_I2C_IHS
1565 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1566 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1567 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1568 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1569 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1570 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1571 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1572 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1573 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1574 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1575 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1576 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1577 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1578 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1579 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1580 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1581 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1582 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1583 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1584 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1585 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1589 CONFIG_SYS_NUM_I2C_BUSES
1590 Hold the number of i2c buses you want to use.
1592 CONFIG_SYS_I2C_DIRECT_BUS
1593 define this, if you don't use i2c muxes on your hardware.
1594 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1597 CONFIG_SYS_I2C_MAX_HOPS
1598 define how many muxes are maximal consecutively connected
1599 on one i2c bus. If you not use i2c muxes, omit this
1602 CONFIG_SYS_I2C_BUSES
1603 hold a list of buses you want to use, only used if
1604 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1605 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1606 CONFIG_SYS_NUM_I2C_BUSES = 9:
1608 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1609 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1610 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1611 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1612 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1613 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1614 {1, {I2C_NULL_HOP}}, \
1615 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1616 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1620 bus 0 on adapter 0 without a mux
1621 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1622 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1623 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1624 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1625 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1626 bus 6 on adapter 1 without a mux
1627 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1628 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1630 If you do not have i2c muxes on your board, omit this define.
1632 - Legacy I2C Support:
1633 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1634 then the following macros need to be defined (examples are
1635 from include/configs/lwmon.h):
1639 (Optional). Any commands necessary to enable the I2C
1640 controller or configure ports.
1642 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1646 The code necessary to make the I2C data line active
1647 (driven). If the data line is open collector, this
1650 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1654 The code necessary to make the I2C data line tri-stated
1655 (inactive). If the data line is open collector, this
1658 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1662 Code that returns true if the I2C data line is high,
1665 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1669 If <bit> is true, sets the I2C data line high. If it
1670 is false, it clears it (low).
1672 eg: #define I2C_SDA(bit) \
1673 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1674 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1678 If <bit> is true, sets the I2C clock line high. If it
1679 is false, it clears it (low).
1681 eg: #define I2C_SCL(bit) \
1682 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1683 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1687 This delay is invoked four times per clock cycle so this
1688 controls the rate of data transfer. The data rate thus
1689 is 1 / (I2C_DELAY * 4). Often defined to be something
1692 #define I2C_DELAY udelay(2)
1694 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1696 If your arch supports the generic GPIO framework (asm/gpio.h),
1697 then you may alternatively define the two GPIOs that are to be
1698 used as SCL / SDA. Any of the previous I2C_xxx macros will
1699 have GPIO-based defaults assigned to them as appropriate.
1701 You should define these to the GPIO value as given directly to
1702 the generic GPIO functions.
1704 CONFIG_SYS_I2C_INIT_BOARD
1706 When a board is reset during an i2c bus transfer
1707 chips might think that the current transfer is still
1708 in progress. On some boards it is possible to access
1709 the i2c SCLK line directly, either by using the
1710 processor pin as a GPIO or by having a second pin
1711 connected to the bus. If this option is defined a
1712 custom i2c_init_board() routine in boards/xxx/board.c
1713 is run early in the boot sequence.
1715 CONFIG_I2C_MULTI_BUS
1717 This option allows the use of multiple I2C buses, each of which
1718 must have a controller. At any point in time, only one bus is
1719 active. To switch to a different bus, use the 'i2c dev' command.
1720 Note that bus numbering is zero-based.
1722 CONFIG_SYS_I2C_NOPROBES
1724 This option specifies a list of I2C devices that will be skipped
1725 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1726 is set, specify a list of bus-device pairs. Otherwise, specify
1727 a 1D array of device addresses
1730 #undef CONFIG_I2C_MULTI_BUS
1731 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1733 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1735 #define CONFIG_I2C_MULTI_BUS
1736 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1738 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1740 CONFIG_SYS_SPD_BUS_NUM
1742 If defined, then this indicates the I2C bus number for DDR SPD.
1743 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1745 CONFIG_SYS_RTC_BUS_NUM
1747 If defined, then this indicates the I2C bus number for the RTC.
1748 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1750 CONFIG_SOFT_I2C_READ_REPEATED_START
1752 defining this will force the i2c_read() function in
1753 the soft_i2c driver to perform an I2C repeated start
1754 between writing the address pointer and reading the
1755 data. If this define is omitted the default behaviour
1756 of doing a stop-start sequence will be used. Most I2C
1757 devices can use either method, but some require one or
1760 - SPI Support: CONFIG_SPI
1762 Enables SPI driver (so far only tested with
1763 SPI EEPROM, also an instance works with Crystal A/D and
1764 D/As on the SACSng board)
1768 Enables a software (bit-bang) SPI driver rather than
1769 using hardware support. This is a general purpose
1770 driver that only requires three general I/O port pins
1771 (two outputs, one input) to function. If this is
1772 defined, the board configuration must define several
1773 SPI configuration items (port pins to use, etc). For
1774 an example, see include/configs/sacsng.h.
1776 CONFIG_SYS_SPI_MXC_WAIT
1777 Timeout for waiting until spi transfer completed.
1778 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1780 - FPGA Support: CONFIG_FPGA
1782 Enables FPGA subsystem.
1784 CONFIG_FPGA_<vendor>
1786 Enables support for specific chip vendors.
1789 CONFIG_FPGA_<family>
1791 Enables support for FPGA family.
1792 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1796 Specify the number of FPGA devices to support.
1798 CONFIG_SYS_FPGA_PROG_FEEDBACK
1800 Enable printing of hash marks during FPGA configuration.
1802 CONFIG_SYS_FPGA_CHECK_BUSY
1804 Enable checks on FPGA configuration interface busy
1805 status by the configuration function. This option
1806 will require a board or device specific function to
1811 If defined, a function that provides delays in the FPGA
1812 configuration driver.
1814 CONFIG_SYS_FPGA_CHECK_CTRLC
1815 Allow Control-C to interrupt FPGA configuration
1817 CONFIG_SYS_FPGA_CHECK_ERROR
1819 Check for configuration errors during FPGA bitfile
1820 loading. For example, abort during Virtex II
1821 configuration if the INIT_B line goes low (which
1822 indicated a CRC error).
1824 CONFIG_SYS_FPGA_WAIT_INIT
1826 Maximum time to wait for the INIT_B line to de-assert
1827 after PROB_B has been de-asserted during a Virtex II
1828 FPGA configuration sequence. The default time is 500
1831 CONFIG_SYS_FPGA_WAIT_BUSY
1833 Maximum time to wait for BUSY to de-assert during
1834 Virtex II FPGA configuration. The default is 5 ms.
1836 CONFIG_SYS_FPGA_WAIT_CONFIG
1838 Time to wait after FPGA configuration. The default is
1841 - Configuration Management:
1845 If defined, this string will be added to the U-Boot
1846 version information (U_BOOT_VERSION)
1848 - Vendor Parameter Protection:
1850 U-Boot considers the values of the environment
1851 variables "serial#" (Board Serial Number) and
1852 "ethaddr" (Ethernet Address) to be parameters that
1853 are set once by the board vendor / manufacturer, and
1854 protects these variables from casual modification by
1855 the user. Once set, these variables are read-only,
1856 and write or delete attempts are rejected. You can
1857 change this behaviour:
1859 If CONFIG_ENV_OVERWRITE is #defined in your config
1860 file, the write protection for vendor parameters is
1861 completely disabled. Anybody can change or delete
1864 Alternatively, if you define _both_ an ethaddr in the
1865 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1866 Ethernet address is installed in the environment,
1867 which can be changed exactly ONCE by the user. [The
1868 serial# is unaffected by this, i. e. it remains
1871 The same can be accomplished in a more flexible way
1872 for any variable by configuring the type of access
1873 to allow for those variables in the ".flags" variable
1874 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1879 Define this variable to enable the reservation of
1880 "protected RAM", i. e. RAM which is not overwritten
1881 by U-Boot. Define CONFIG_PRAM to hold the number of
1882 kB you want to reserve for pRAM. You can overwrite
1883 this default value by defining an environment
1884 variable "pram" to the number of kB you want to
1885 reserve. Note that the board info structure will
1886 still show the full amount of RAM. If pRAM is
1887 reserved, a new environment variable "mem" will
1888 automatically be defined to hold the amount of
1889 remaining RAM in a form that can be passed as boot
1890 argument to Linux, for instance like that:
1892 setenv bootargs ... mem=\${mem}
1895 This way you can tell Linux not to use this memory,
1896 either, which results in a memory region that will
1897 not be affected by reboots.
1899 *WARNING* If your board configuration uses automatic
1900 detection of the RAM size, you must make sure that
1901 this memory test is non-destructive. So far, the
1902 following board configurations are known to be
1905 IVMS8, IVML24, SPD8xx,
1906 HERMES, IP860, RPXlite, LWMON,
1909 - Access to physical memory region (> 4GB)
1910 Some basic support is provided for operations on memory not
1911 normally accessible to U-Boot - e.g. some architectures
1912 support access to more than 4GB of memory on 32-bit
1913 machines using physical address extension or similar.
1914 Define CONFIG_PHYSMEM to access this basic support, which
1915 currently only supports clearing the memory.
1918 CONFIG_NET_RETRY_COUNT
1920 This variable defines the number of retries for
1921 network operations like ARP, RARP, TFTP, or BOOTP
1922 before giving up the operation. If not defined, a
1923 default value of 5 is used.
1927 Timeout waiting for an ARP reply in milliseconds.
1931 Timeout in milliseconds used in NFS protocol.
1932 If you encounter "ERROR: Cannot umount" in nfs command,
1933 try longer timeout such as
1934 #define CONFIG_NFS_TIMEOUT 10000UL
1936 - Command Interpreter:
1937 CONFIG_SYS_PROMPT_HUSH_PS2
1939 This defines the secondary prompt string, which is
1940 printed when the command interpreter needs more input
1941 to complete a command. Usually "> ".
1945 In the current implementation, the local variables
1946 space and global environment variables space are
1947 separated. Local variables are those you define by
1948 simply typing `name=value'. To access a local
1949 variable later on, you have write `$name' or
1950 `${name}'; to execute the contents of a variable
1951 directly type `$name' at the command prompt.
1953 Global environment variables are those you use
1954 setenv/printenv to work with. To run a command stored
1955 in such a variable, you need to use the run command,
1956 and you must not use the '$' sign to access them.
1958 To store commands and special characters in a
1959 variable, please use double quotation marks
1960 surrounding the whole text of the variable, instead
1961 of the backslashes before semicolons and special
1964 - Command Line Editing and History:
1965 CONFIG_CMDLINE_PS_SUPPORT
1967 Enable support for changing the command prompt string
1968 at run-time. Only static string is supported so far.
1969 The string is obtained from environment variables PS1
1972 - Default Environment:
1973 CONFIG_EXTRA_ENV_SETTINGS
1975 Define this to contain any number of null terminated
1976 strings (variable = value pairs) that will be part of
1977 the default environment compiled into the boot image.
1979 For example, place something like this in your
1980 board's config file:
1982 #define CONFIG_EXTRA_ENV_SETTINGS \
1986 Warning: This method is based on knowledge about the
1987 internal format how the environment is stored by the
1988 U-Boot code. This is NOT an official, exported
1989 interface! Although it is unlikely that this format
1990 will change soon, there is no guarantee either.
1991 You better know what you are doing here.
1993 Note: overly (ab)use of the default environment is
1994 discouraged. Make sure to check other ways to preset
1995 the environment like the "source" command or the
1998 CONFIG_DELAY_ENVIRONMENT
2000 Normally the environment is loaded when the board is
2001 initialised so that it is available to U-Boot. This inhibits
2002 that so that the environment is not available until
2003 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2004 this is instead controlled by the value of
2005 /config/load-environment.
2007 - TFTP Fixed UDP Port:
2010 If this is defined, the environment variable tftpsrcp
2011 is used to supply the TFTP UDP source port value.
2012 If tftpsrcp isn't defined, the normal pseudo-random port
2013 number generator is used.
2015 Also, the environment variable tftpdstp is used to supply
2016 the TFTP UDP destination port value. If tftpdstp isn't
2017 defined, the normal port 69 is used.
2019 The purpose for tftpsrcp is to allow a TFTP server to
2020 blindly start the TFTP transfer using the pre-configured
2021 target IP address and UDP port. This has the effect of
2022 "punching through" the (Windows XP) firewall, allowing
2023 the remainder of the TFTP transfer to proceed normally.
2024 A better solution is to properly configure the firewall,
2025 but sometimes that is not allowed.
2027 CONFIG_STANDALONE_LOAD_ADDR
2029 This option defines a board specific value for the
2030 address where standalone program gets loaded, thus
2031 overwriting the architecture dependent default
2034 - Frame Buffer Address:
2037 Define CONFIG_FB_ADDR if you want to use specific
2038 address for frame buffer. This is typically the case
2039 when using a graphics controller has separate video
2040 memory. U-Boot will then place the frame buffer at
2041 the given address instead of dynamically reserving it
2042 in system RAM by calling lcd_setmem(), which grabs
2043 the memory for the frame buffer depending on the
2044 configured panel size.
2046 Please see board_init_f function.
2048 - Automatic software updates via TFTP server
2050 CONFIG_UPDATE_TFTP_CNT_MAX
2051 CONFIG_UPDATE_TFTP_MSEC_MAX
2053 These options enable and control the auto-update feature;
2054 for a more detailed description refer to doc/README.update.
2056 - MTD Support (mtdparts command, UBI support)
2057 CONFIG_MTD_UBI_WL_THRESHOLD
2058 This parameter defines the maximum difference between the highest
2059 erase counter value and the lowest erase counter value of eraseblocks
2060 of UBI devices. When this threshold is exceeded, UBI starts performing
2061 wear leveling by means of moving data from eraseblock with low erase
2062 counter to eraseblocks with high erase counter.
2064 The default value should be OK for SLC NAND flashes, NOR flashes and
2065 other flashes which have eraseblock life-cycle 100000 or more.
2066 However, in case of MLC NAND flashes which typically have eraseblock
2067 life-cycle less than 10000, the threshold should be lessened (e.g.,
2068 to 128 or 256, although it does not have to be power of 2).
2072 CONFIG_MTD_UBI_BEB_LIMIT
2073 This option specifies the maximum bad physical eraseblocks UBI
2074 expects on the MTD device (per 1024 eraseblocks). If the
2075 underlying flash does not admit of bad eraseblocks (e.g. NOR
2076 flash), this value is ignored.
2078 NAND datasheets often specify the minimum and maximum NVM
2079 (Number of Valid Blocks) for the flashes' endurance lifetime.
2080 The maximum expected bad eraseblocks per 1024 eraseblocks
2081 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2082 which gives 20 for most NANDs (MaxNVB is basically the total
2083 count of eraseblocks on the chip).
2085 To put it differently, if this value is 20, UBI will try to
2086 reserve about 1.9% of physical eraseblocks for bad blocks
2087 handling. And that will be 1.9% of eraseblocks on the entire
2088 NAND chip, not just the MTD partition UBI attaches. This means
2089 that if you have, say, a NAND flash chip admits maximum 40 bad
2090 eraseblocks, and it is split on two MTD partitions of the same
2091 size, UBI will reserve 40 eraseblocks when attaching a
2096 CONFIG_MTD_UBI_FASTMAP
2097 Fastmap is a mechanism which allows attaching an UBI device
2098 in nearly constant time. Instead of scanning the whole MTD device it
2099 only has to locate a checkpoint (called fastmap) on the device.
2100 The on-flash fastmap contains all information needed to attach
2101 the device. Using fastmap makes only sense on large devices where
2102 attaching by scanning takes long. UBI will not automatically install
2103 a fastmap on old images, but you can set the UBI parameter
2104 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2105 that fastmap-enabled images are still usable with UBI implementations
2106 without fastmap support. On typical flash devices the whole fastmap
2107 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2109 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2110 Set this parameter to enable fastmap automatically on images
2114 CONFIG_MTD_UBI_FM_DEBUG
2115 Enable UBI fastmap debug
2120 Enable building of SPL globally.
2123 LDSCRIPT for linking the SPL binary.
2125 CONFIG_SPL_MAX_FOOTPRINT
2126 Maximum size in memory allocated to the SPL, BSS included.
2127 When defined, the linker checks that the actual memory
2128 used by SPL from _start to __bss_end does not exceed it.
2129 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2130 must not be both defined at the same time.
2133 Maximum size of the SPL image (text, data, rodata, and
2134 linker lists sections), BSS excluded.
2135 When defined, the linker checks that the actual size does
2138 CONFIG_SPL_RELOC_TEXT_BASE
2139 Address to relocate to. If unspecified, this is equal to
2140 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2142 CONFIG_SPL_BSS_START_ADDR
2143 Link address for the BSS within the SPL binary.
2145 CONFIG_SPL_BSS_MAX_SIZE
2146 Maximum size in memory allocated to the SPL BSS.
2147 When defined, the linker checks that the actual memory used
2148 by SPL from __bss_start to __bss_end does not exceed it.
2149 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2150 must not be both defined at the same time.
2153 Adress of the start of the stack SPL will use
2155 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2156 When defined, SPL will panic() if the image it has
2157 loaded does not have a signature.
2158 Defining this is useful when code which loads images
2159 in SPL cannot guarantee that absolutely all read errors
2161 An example is the LPC32XX MLC NAND driver, which will
2162 consider that a completely unreadable NAND block is bad,
2163 and thus should be skipped silently.
2165 CONFIG_SPL_RELOC_STACK
2166 Adress of the start of the stack SPL will use after
2167 relocation. If unspecified, this is equal to
2170 CONFIG_SYS_SPL_MALLOC_START
2171 Starting address of the malloc pool used in SPL.
2172 When this option is set the full malloc is used in SPL and
2173 it is set up by spl_init() and before that, the simple malloc()
2174 can be used if CONFIG_SYS_MALLOC_F is defined.
2176 CONFIG_SYS_SPL_MALLOC_SIZE
2177 The size of the malloc pool used in SPL.
2180 Enable booting directly to an OS from SPL.
2181 See also: doc/README.falcon
2183 CONFIG_SPL_DISPLAY_PRINT
2184 For ARM, enable an optional function to print more information
2185 about the running system.
2187 CONFIG_SPL_INIT_MINIMAL
2188 Arch init code should be built for a very small image
2190 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2191 Partition on the MMC to load U-Boot from when the MMC is being
2194 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2195 Sector to load kernel uImage from when MMC is being
2196 used in raw mode (for Falcon mode)
2198 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2199 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2200 Sector and number of sectors to load kernel argument
2201 parameters from when MMC is being used in raw mode
2204 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2205 Filename to read to load U-Boot when reading from filesystem
2207 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2208 Filename to read to load kernel uImage when reading
2209 from filesystem (for Falcon mode)
2211 CONFIG_SPL_FS_LOAD_ARGS_NAME
2212 Filename to read to load kernel argument parameters
2213 when reading from filesystem (for Falcon mode)
2215 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2216 Set this for NAND SPL on PPC mpc83xx targets, so that
2217 start.S waits for the rest of the SPL to load before
2218 continuing (the hardware starts execution after just
2219 loading the first page rather than the full 4K).
2221 CONFIG_SPL_SKIP_RELOCATE
2222 Avoid SPL relocation
2224 CONFIG_SPL_NAND_IDENT
2225 SPL uses the chip ID list to identify the NAND flash.
2226 Requires CONFIG_SPL_NAND_BASE.
2229 Support for a lightweight UBI (fastmap) scanner and
2232 CONFIG_SPL_NAND_RAW_ONLY
2233 Support to boot only raw u-boot.bin images. Use this only
2234 if you need to save space.
2236 CONFIG_SPL_COMMON_INIT_DDR
2237 Set for common ddr init with serial presence detect in
2240 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2241 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2242 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2243 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2244 CONFIG_SYS_NAND_ECCBYTES
2245 Defines the size and behavior of the NAND that SPL uses
2248 CONFIG_SYS_NAND_U_BOOT_OFFS
2249 Location in NAND to read U-Boot from
2251 CONFIG_SYS_NAND_U_BOOT_DST
2252 Location in memory to load U-Boot to
2254 CONFIG_SYS_NAND_U_BOOT_SIZE
2255 Size of image to load
2257 CONFIG_SYS_NAND_U_BOOT_START
2258 Entry point in loaded image to jump to
2260 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2261 Define this if you need to first read the OOB and then the
2262 data. This is used, for example, on davinci platforms.
2264 CONFIG_SPL_RAM_DEVICE
2265 Support for running image already present in ram, in SPL binary
2268 Image offset to which the SPL should be padded before appending
2269 the SPL payload. By default, this is defined as
2270 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2271 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2272 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2275 Final target image containing SPL and payload. Some SPLs
2276 use an arch-specific makefile fragment instead, for
2277 example if more than one image needs to be produced.
2279 CONFIG_SPL_FIT_PRINT
2280 Printing information about a FIT image adds quite a bit of
2281 code to SPL. So this is normally disabled in SPL. Use this
2282 option to re-enable it. This will affect the output of the
2283 bootm command when booting a FIT image.
2287 Enable building of TPL globally.
2290 Image offset to which the TPL should be padded before appending
2291 the TPL payload. By default, this is defined as
2292 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2293 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2294 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2296 - Interrupt support (PPC):
2298 There are common interrupt_init() and timer_interrupt()
2299 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2300 for CPU specific initialization. interrupt_init_cpu()
2301 should set decrementer_count to appropriate value. If
2302 CPU resets decrementer automatically after interrupt
2303 (ppc4xx) it should set decrementer_count to zero.
2304 timer_interrupt() calls timer_interrupt_cpu() for CPU
2305 specific handling. If board has watchdog / status_led
2306 / other_activity_monitor it works automatically from
2307 general timer_interrupt().
2310 Board initialization settings:
2311 ------------------------------
2313 During Initialization u-boot calls a number of board specific functions
2314 to allow the preparation of board specific prerequisites, e.g. pin setup
2315 before drivers are initialized. To enable these callbacks the
2316 following configuration macros have to be defined. Currently this is
2317 architecture specific, so please check arch/your_architecture/lib/board.c
2318 typically in board_init_f() and board_init_r().
2320 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2321 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2322 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2323 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2325 Configuration Settings:
2326 -----------------------
2328 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2329 Optionally it can be defined to support 64-bit memory commands.
2331 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2332 undefine this when you're short of memory.
2334 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2335 width of the commands listed in the 'help' command output.
2337 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2338 prompt for user input.
2340 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2342 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2344 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2346 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2347 the application (usually a Linux kernel) when it is
2350 - CONFIG_SYS_BAUDRATE_TABLE:
2351 List of legal baudrate settings for this board.
2353 - CONFIG_SYS_MEM_RESERVE_SECURE
2354 Only implemented for ARMv8 for now.
2355 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2356 is substracted from total RAM and won't be reported to OS.
2357 This memory can be used as secure memory. A variable
2358 gd->arch.secure_ram is used to track the location. In systems
2359 the RAM base is not zero, or RAM is divided into banks,
2360 this variable needs to be recalcuated to get the address.
2362 - CONFIG_SYS_MEM_TOP_HIDE:
2363 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2364 this specified memory area will get subtracted from the top
2365 (end) of RAM and won't get "touched" at all by U-Boot. By
2366 fixing up gd->ram_size the Linux kernel should gets passed
2367 the now "corrected" memory size and won't touch it either.
2368 This should work for arch/ppc and arch/powerpc. Only Linux
2369 board ports in arch/powerpc with bootwrapper support that
2370 recalculate the memory size from the SDRAM controller setup
2371 will have to get fixed in Linux additionally.
2373 This option can be used as a workaround for the 440EPx/GRx
2374 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2377 WARNING: Please make sure that this value is a multiple of
2378 the Linux page size (normally 4k). If this is not the case,
2379 then the end address of the Linux memory will be located at a
2380 non page size aligned address and this could cause major
2383 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2384 Enable temporary baudrate change while serial download
2386 - CONFIG_SYS_SDRAM_BASE:
2387 Physical start address of SDRAM. _Must_ be 0 here.
2389 - CONFIG_SYS_FLASH_BASE:
2390 Physical start address of Flash memory.
2392 - CONFIG_SYS_MONITOR_BASE:
2393 Physical start address of boot monitor code (set by
2394 make config files to be same as the text base address
2395 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2396 CONFIG_SYS_FLASH_BASE when booting from flash.
2398 - CONFIG_SYS_MONITOR_LEN:
2399 Size of memory reserved for monitor code, used to
2400 determine _at_compile_time_ (!) if the environment is
2401 embedded within the U-Boot image, or in a separate
2404 - CONFIG_SYS_MALLOC_LEN:
2405 Size of DRAM reserved for malloc() use.
2407 - CONFIG_SYS_MALLOC_F_LEN
2408 Size of the malloc() pool for use before relocation. If
2409 this is defined, then a very simple malloc() implementation
2410 will become available before relocation. The address is just
2411 below the global data, and the stack is moved down to make
2414 This feature allocates regions with increasing addresses
2415 within the region. calloc() is supported, but realloc()
2416 is not available. free() is supported but does nothing.
2417 The memory will be freed (or in fact just forgotten) when
2418 U-Boot relocates itself.
2420 - CONFIG_SYS_MALLOC_SIMPLE
2421 Provides a simple and small malloc() and calloc() for those
2422 boards which do not use the full malloc in SPL (which is
2423 enabled with CONFIG_SYS_SPL_MALLOC_START).
2425 - CONFIG_SYS_NONCACHED_MEMORY:
2426 Size of non-cached memory area. This area of memory will be
2427 typically located right below the malloc() area and mapped
2428 uncached in the MMU. This is useful for drivers that would
2429 otherwise require a lot of explicit cache maintenance. For
2430 some drivers it's also impossible to properly maintain the
2431 cache. For example if the regions that need to be flushed
2432 are not a multiple of the cache-line size, *and* padding
2433 cannot be allocated between the regions to align them (i.e.
2434 if the HW requires a contiguous array of regions, and the
2435 size of each region is not cache-aligned), then a flush of
2436 one region may result in overwriting data that hardware has
2437 written to another region in the same cache-line. This can
2438 happen for example in network drivers where descriptors for
2439 buffers are typically smaller than the CPU cache-line (e.g.
2440 16 bytes vs. 32 or 64 bytes).
2442 Non-cached memory is only supported on 32-bit ARM at present.
2444 - CONFIG_SYS_BOOTM_LEN:
2445 Normally compressed uImages are limited to an
2446 uncompressed size of 8 MBytes. If this is not enough,
2447 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2448 to adjust this setting to your needs.
2450 - CONFIG_SYS_BOOTMAPSZ:
2451 Maximum size of memory mapped by the startup code of
2452 the Linux kernel; all data that must be processed by
2453 the Linux kernel (bd_info, boot arguments, FDT blob if
2454 used) must be put below this limit, unless "bootm_low"
2455 environment variable is defined and non-zero. In such case
2456 all data for the Linux kernel must be between "bootm_low"
2457 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2458 variable "bootm_mapsize" will override the value of
2459 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2460 then the value in "bootm_size" will be used instead.
2462 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2463 Enable initrd_high functionality. If defined then the
2464 initrd_high feature is enabled and the bootm ramdisk subcommand
2467 - CONFIG_SYS_BOOT_GET_CMDLINE:
2468 Enables allocating and saving kernel cmdline in space between
2469 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2471 - CONFIG_SYS_BOOT_GET_KBD:
2472 Enables allocating and saving a kernel copy of the bd_info in
2473 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2475 - CONFIG_SYS_MAX_FLASH_BANKS:
2476 Max number of Flash memory banks
2478 - CONFIG_SYS_MAX_FLASH_SECT:
2479 Max number of sectors on a Flash chip
2481 - CONFIG_SYS_FLASH_ERASE_TOUT:
2482 Timeout for Flash erase operations (in ms)
2484 - CONFIG_SYS_FLASH_WRITE_TOUT:
2485 Timeout for Flash write operations (in ms)
2487 - CONFIG_SYS_FLASH_LOCK_TOUT
2488 Timeout for Flash set sector lock bit operation (in ms)
2490 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2491 Timeout for Flash clear lock bits operation (in ms)
2493 - CONFIG_SYS_FLASH_PROTECTION
2494 If defined, hardware flash sectors protection is used
2495 instead of U-Boot software protection.
2497 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2499 Enable TFTP transfers directly to flash memory;
2500 without this option such a download has to be
2501 performed in two steps: (1) download to RAM, and (2)
2502 copy from RAM to flash.
2504 The two-step approach is usually more reliable, since
2505 you can check if the download worked before you erase
2506 the flash, but in some situations (when system RAM is
2507 too limited to allow for a temporary copy of the
2508 downloaded image) this option may be very useful.
2510 - CONFIG_SYS_FLASH_CFI:
2511 Define if the flash driver uses extra elements in the
2512 common flash structure for storing flash geometry.
2514 - CONFIG_FLASH_CFI_DRIVER
2515 This option also enables the building of the cfi_flash driver
2516 in the drivers directory
2518 - CONFIG_FLASH_CFI_MTD
2519 This option enables the building of the cfi_mtd driver
2520 in the drivers directory. The driver exports CFI flash
2523 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2524 Use buffered writes to flash.
2526 - CONFIG_FLASH_SPANSION_S29WS_N
2527 s29ws-n MirrorBit flash has non-standard addresses for buffered
2530 - CONFIG_SYS_FLASH_QUIET_TEST
2531 If this option is defined, the common CFI flash doesn't
2532 print it's warning upon not recognized FLASH banks. This
2533 is useful, if some of the configured banks are only
2534 optionally available.
2536 - CONFIG_FLASH_SHOW_PROGRESS
2537 If defined (must be an integer), print out countdown
2538 digits and dots. Recommended value: 45 (9..1) for 80
2539 column displays, 15 (3..1) for 40 column displays.
2541 - CONFIG_FLASH_VERIFY
2542 If defined, the content of the flash (destination) is compared
2543 against the source after the write operation. An error message
2544 will be printed when the contents are not identical.
2545 Please note that this option is useless in nearly all cases,
2546 since such flash programming errors usually are detected earlier
2547 while unprotecting/erasing/programming. Please only enable
2548 this option if you really know what you are doing.
2550 - CONFIG_SYS_RX_ETH_BUFFER:
2551 Defines the number of Ethernet receive buffers. On some
2552 Ethernet controllers it is recommended to set this value
2553 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2554 buffers can be full shortly after enabling the interface
2555 on high Ethernet traffic.
2556 Defaults to 4 if not defined.
2558 - CONFIG_ENV_MAX_ENTRIES
2560 Maximum number of entries in the hash table that is used
2561 internally to store the environment settings. The default
2562 setting is supposed to be generous and should work in most
2563 cases. This setting can be used to tune behaviour; see
2564 lib/hashtable.c for details.
2566 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2567 - CONFIG_ENV_FLAGS_LIST_STATIC
2568 Enable validation of the values given to environment variables when
2569 calling env set. Variables can be restricted to only decimal,
2570 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2571 the variables can also be restricted to IP address or MAC address.
2573 The format of the list is:
2574 type_attribute = [s|d|x|b|i|m]
2575 access_attribute = [a|r|o|c]
2576 attributes = type_attribute[access_attribute]
2577 entry = variable_name[:attributes]
2580 The type attributes are:
2581 s - String (default)
2584 b - Boolean ([1yYtT|0nNfF])
2588 The access attributes are:
2594 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2595 Define this to a list (string) to define the ".flags"
2596 environment variable in the default or embedded environment.
2598 - CONFIG_ENV_FLAGS_LIST_STATIC
2599 Define this to a list (string) to define validation that
2600 should be done if an entry is not found in the ".flags"
2601 environment variable. To override a setting in the static
2602 list, simply add an entry for the same variable name to the
2605 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2606 regular expression. This allows multiple variables to define the same
2607 flags without explicitly listing them for each variable.
2609 The following definitions that deal with the placement and management
2610 of environment data (variable area); in general, we support the
2611 following configurations:
2613 - CONFIG_BUILD_ENVCRC:
2615 Builds up envcrc with the target environment so that external utils
2616 may easily extract it and embed it in final U-Boot images.
2618 BE CAREFUL! The first access to the environment happens quite early
2619 in U-Boot initialization (when we try to get the setting of for the
2620 console baudrate). You *MUST* have mapped your NVRAM area then, or
2623 Please note that even with NVRAM we still use a copy of the
2624 environment in RAM: we could work on NVRAM directly, but we want to
2625 keep settings there always unmodified except somebody uses "saveenv"
2626 to save the current settings.
2628 BE CAREFUL! For some special cases, the local device can not use
2629 "saveenv" command. For example, the local device will get the
2630 environment stored in a remote NOR flash by SRIO or PCIE link,
2631 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2633 - CONFIG_NAND_ENV_DST
2635 Defines address in RAM to which the nand_spl code should copy the
2636 environment. If redundant environment is used, it will be copied to
2637 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2639 Please note that the environment is read-only until the monitor
2640 has been relocated to RAM and a RAM copy of the environment has been
2641 created; also, when using EEPROM you will have to use env_get_f()
2642 until then to read environment variables.
2644 The environment is protected by a CRC32 checksum. Before the monitor
2645 is relocated into RAM, as a result of a bad CRC you will be working
2646 with the compiled-in default environment - *silently*!!! [This is
2647 necessary, because the first environment variable we need is the
2648 "baudrate" setting for the console - if we have a bad CRC, we don't
2649 have any device yet where we could complain.]
2651 Note: once the monitor has been relocated, then it will complain if
2652 the default environment is used; a new CRC is computed as soon as you
2653 use the "saveenv" command to store a valid environment.
2655 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2656 Echo the inverted Ethernet link state to the fault LED.
2658 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2659 also needs to be defined.
2661 - CONFIG_SYS_FAULT_MII_ADDR:
2662 MII address of the PHY to check for the Ethernet link state.
2664 - CONFIG_NS16550_MIN_FUNCTIONS:
2665 Define this if you desire to only have use of the NS16550_init
2666 and NS16550_putc functions for the serial driver located at
2667 drivers/serial/ns16550.c. This option is useful for saving
2668 space for already greatly restricted images, including but not
2669 limited to NAND_SPL configurations.
2671 - CONFIG_DISPLAY_BOARDINFO
2672 Display information about the board that U-Boot is running on
2673 when U-Boot starts up. The board function checkboard() is called
2676 - CONFIG_DISPLAY_BOARDINFO_LATE
2677 Similar to the previous option, but display this information
2678 later, once stdio is running and output goes to the LCD, if
2681 - CONFIG_BOARD_SIZE_LIMIT:
2682 Maximum size of the U-Boot image. When defined, the
2683 build system checks that the actual size does not
2686 Low Level (hardware related) configuration options:
2687 ---------------------------------------------------
2689 - CONFIG_SYS_CACHELINE_SIZE:
2690 Cache Line Size of the CPU.
2692 - CONFIG_SYS_CCSRBAR_DEFAULT:
2693 Default (power-on reset) physical address of CCSR on Freescale
2696 - CONFIG_SYS_CCSRBAR:
2697 Virtual address of CCSR. On a 32-bit build, this is typically
2698 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2700 - CONFIG_SYS_CCSRBAR_PHYS:
2701 Physical address of CCSR. CCSR can be relocated to a new
2702 physical address, if desired. In this case, this macro should
2703 be set to that address. Otherwise, it should be set to the
2704 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2705 is typically relocated on 36-bit builds. It is recommended
2706 that this macro be defined via the _HIGH and _LOW macros:
2708 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2709 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2711 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2712 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2713 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2714 used in assembly code, so it must not contain typecasts or
2715 integer size suffixes (e.g. "ULL").
2717 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2718 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2719 used in assembly code, so it must not contain typecasts or
2720 integer size suffixes (e.g. "ULL").
2722 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2723 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2724 forced to a value that ensures that CCSR is not relocated.
2727 Most IDE controllers were designed to be connected with PCI
2728 interface. Only few of them were designed for AHB interface.
2729 When software is doing ATA command and data transfer to
2730 IDE devices through IDE-AHB controller, some additional
2731 registers accessing to these kind of IDE-AHB controller
2734 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2735 DO NOT CHANGE unless you know exactly what you're
2736 doing! (11-4) [MPC8xx systems only]
2738 - CONFIG_SYS_INIT_RAM_ADDR:
2740 Start address of memory area that can be used for
2741 initial data and stack; please note that this must be
2742 writable memory that is working WITHOUT special
2743 initialization, i. e. you CANNOT use normal RAM which
2744 will become available only after programming the
2745 memory controller and running certain initialization
2748 U-Boot uses the following memory types:
2749 - MPC8xx: IMMR (internal memory of the CPU)
2751 - CONFIG_SYS_GBL_DATA_OFFSET:
2753 Offset of the initial data structure in the memory
2754 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2755 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2756 data is located at the end of the available space
2757 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2758 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2759 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2760 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2763 On the MPC824X (or other systems that use the data
2764 cache for initial memory) the address chosen for
2765 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2766 point to an otherwise UNUSED address space between
2767 the top of RAM and the start of the PCI space.
2769 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2771 - CONFIG_SYS_OR_TIMING_SDRAM:
2774 - CONFIG_SYS_MAMR_PTA:
2775 periodic timer for refresh
2777 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2778 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2779 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2780 CONFIG_SYS_BR1_PRELIM:
2781 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2783 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2784 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2785 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2786 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2788 - CONFIG_PCI_ENUM_ONLY
2789 Only scan through and get the devices on the buses.
2790 Don't do any setup work, presumably because someone or
2791 something has already done it, and we don't need to do it
2792 a second time. Useful for platforms that are pre-booted
2793 by coreboot or similar.
2795 - CONFIG_PCI_INDIRECT_BRIDGE:
2796 Enable support for indirect PCI bridges.
2799 Chip has SRIO or not
2802 Board has SRIO 1 port available
2805 Board has SRIO 2 port available
2807 - CONFIG_SRIO_PCIE_BOOT_MASTER
2808 Board can support master function for Boot from SRIO and PCIE
2810 - CONFIG_SYS_SRIOn_MEM_VIRT:
2811 Virtual Address of SRIO port 'n' memory region
2813 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2814 Physical Address of SRIO port 'n' memory region
2816 - CONFIG_SYS_SRIOn_MEM_SIZE:
2817 Size of SRIO port 'n' memory region
2819 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2820 Defined to tell the NAND controller that the NAND chip is using
2822 Not all NAND drivers use this symbol.
2823 Example of drivers that use it:
2824 - drivers/mtd/nand/raw/ndfc.c
2825 - drivers/mtd/nand/raw/mxc_nand.c
2827 - CONFIG_SYS_NDFC_EBC0_CFG
2828 Sets the EBC0_CFG register for the NDFC. If not defined
2829 a default value will be used.
2832 Get DDR timing information from an I2C EEPROM. Common
2833 with pluggable memory modules such as SODIMMs
2836 I2C address of the SPD EEPROM
2838 - CONFIG_SYS_SPD_BUS_NUM
2839 If SPD EEPROM is on an I2C bus other than the first
2840 one, specify here. Note that the value must resolve
2841 to something your driver can deal with.
2843 - CONFIG_SYS_DDR_RAW_TIMING
2844 Get DDR timing information from other than SPD. Common with
2845 soldered DDR chips onboard without SPD. DDR raw timing
2846 parameters are extracted from datasheet and hard-coded into
2847 header files or board specific files.
2849 - CONFIG_FSL_DDR_INTERACTIVE
2850 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2852 - CONFIG_FSL_DDR_SYNC_REFRESH
2853 Enable sync of refresh for multiple controllers.
2855 - CONFIG_FSL_DDR_BIST
2856 Enable built-in memory test for Freescale DDR controllers.
2858 - CONFIG_SYS_83XX_DDR_USES_CS0
2859 Only for 83xx systems. If specified, then DDR should
2860 be configured using CS0 and CS1 instead of CS2 and CS3.
2863 Enable RMII mode for all FECs.
2864 Note that this is a global option, we can't
2865 have one FEC in standard MII mode and another in RMII mode.
2867 - CONFIG_CRC32_VERIFY
2868 Add a verify option to the crc32 command.
2871 => crc32 -v <address> <count> <crc32>
2873 Where address/count indicate a memory area
2874 and crc32 is the correct crc32 which the
2878 Add the "loopw" memory command. This only takes effect if
2879 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2881 - CONFIG_CMD_MX_CYCLIC
2882 Add the "mdc" and "mwc" memory commands. These are cyclic
2887 This command will print 4 bytes (10,11,12,13) each 500 ms.
2889 => mwc.l 100 12345678 10
2890 This command will write 12345678 to address 100 all 10 ms.
2892 This only takes effect if the memory commands are activated
2893 globally (CONFIG_CMD_MEMORY).
2895 - CONFIG_SKIP_LOWLEVEL_INIT
2896 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
2897 low level initializations (like setting up the memory
2898 controller) are omitted and/or U-Boot does not
2899 relocate itself into RAM.
2901 Normally this variable MUST NOT be defined. The only
2902 exception is when U-Boot is loaded (to RAM) by some
2903 other boot loader or by a debugger which performs
2904 these initializations itself.
2906 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
2907 [ARM926EJ-S only] This allows just the call to lowlevel_init()
2908 to be skipped. The normal CP15 init (such as enabling the
2909 instruction cache) is still performed.
2912 Set when the currently-running compilation is for an artifact
2913 that will end up in the SPL (as opposed to the TPL or U-Boot
2914 proper). Code that needs stage-specific behavior should check
2918 Set when the currently-running compilation is for an artifact
2919 that will end up in the TPL (as opposed to the SPL or U-Boot
2920 proper). Code that needs stage-specific behavior should check
2923 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2924 Only for 85xx systems. If this variable is specified, the section
2925 .resetvec is not kept and the section .bootpg is placed in the
2926 previous 4k of the .text section.
2928 - CONFIG_ARCH_MAP_SYSMEM
2929 Generally U-Boot (and in particular the md command) uses
2930 effective address. It is therefore not necessary to regard
2931 U-Boot address as virtual addresses that need to be translated
2932 to physical addresses. However, sandbox requires this, since
2933 it maintains its own little RAM buffer which contains all
2934 addressable memory. This option causes some memory accesses
2935 to be mapped through map_sysmem() / unmap_sysmem().
2937 - CONFIG_X86_RESET_VECTOR
2938 If defined, the x86 reset vector code is included. This is not
2939 needed when U-Boot is running from Coreboot.
2941 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2942 Option to disable subpage write in NAND driver
2943 driver that uses this:
2944 drivers/mtd/nand/raw/davinci_nand.c
2946 Freescale QE/FMAN Firmware Support:
2947 -----------------------------------
2949 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2950 loading of "firmware", which is encoded in the QE firmware binary format.
2951 This firmware often needs to be loaded during U-Boot booting, so macros
2952 are used to identify the storage device (NOR flash, SPI, etc) and the address
2955 - CONFIG_SYS_FMAN_FW_ADDR
2956 The address in the storage device where the FMAN microcode is located. The
2957 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2960 - CONFIG_SYS_QE_FW_ADDR
2961 The address in the storage device where the QE microcode is located. The
2962 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2965 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2966 The maximum possible size of the firmware. The firmware binary format
2967 has a field that specifies the actual size of the firmware, but it
2968 might not be possible to read any part of the firmware unless some
2969 local storage is allocated to hold the entire firmware first.
2971 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2972 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2973 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2974 virtual address in NOR flash.
2976 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2977 Specifies that QE/FMAN firmware is located in NAND flash.
2978 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2980 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2981 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2982 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2984 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2985 Specifies that QE/FMAN firmware is located in the remote (master)
2986 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2987 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2988 window->master inbound window->master LAW->the ucode address in
2989 master's memory space.
2991 Freescale Layerscape Management Complex Firmware Support:
2992 ---------------------------------------------------------
2993 The Freescale Layerscape Management Complex (MC) supports the loading of
2995 This firmware often needs to be loaded during U-Boot booting, so macros
2996 are used to identify the storage device (NOR flash, SPI, etc) and the address
2999 - CONFIG_FSL_MC_ENET
3000 Enable the MC driver for Layerscape SoCs.
3002 Freescale Layerscape Debug Server Support:
3003 -------------------------------------------
3004 The Freescale Layerscape Debug Server Support supports the loading of
3005 "Debug Server firmware" and triggering SP boot-rom.
3006 This firmware often needs to be loaded during U-Boot booting.
3008 - CONFIG_SYS_MC_RSV_MEM_ALIGN
3009 Define alignment of reserved memory MC requires
3014 In order to achieve reproducible builds, timestamps used in the U-Boot build
3015 process have to be set to a fixed value.
3017 This is done using the SOURCE_DATE_EPOCH environment variable.
3018 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
3019 option for U-Boot or an environment variable in U-Boot.
3021 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
3023 Building the Software:
3024 ======================
3026 Building U-Boot has been tested in several native build environments
3027 and in many different cross environments. Of course we cannot support
3028 all possibly existing versions of cross development tools in all
3029 (potentially obsolete) versions. In case of tool chain problems we
3030 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3031 which is extensively used to build and test U-Boot.
3033 If you are not using a native environment, it is assumed that you
3034 have GNU cross compiling tools available in your path. In this case,
3035 you must set the environment variable CROSS_COMPILE in your shell.
3036 Note that no changes to the Makefile or any other source files are
3037 necessary. For example using the ELDK on a 4xx CPU, please enter:
3039 $ CROSS_COMPILE=ppc_4xx-
3040 $ export CROSS_COMPILE
3042 U-Boot is intended to be simple to build. After installing the
3043 sources you must configure U-Boot for one specific board type. This
3048 where "NAME_defconfig" is the name of one of the existing configu-
3049 rations; see configs/*_defconfig for supported names.
3051 Note: for some boards special configuration names may exist; check if
3052 additional information is available from the board vendor; for
3053 instance, the TQM823L systems are available without (standard)
3054 or with LCD support. You can select such additional "features"
3055 when choosing the configuration, i. e.
3057 make TQM823L_defconfig
3058 - will configure for a plain TQM823L, i. e. no LCD support
3060 make TQM823L_LCD_defconfig
3061 - will configure for a TQM823L with U-Boot console on LCD
3066 Finally, type "make all", and you should get some working U-Boot
3067 images ready for download to / installation on your system:
3069 - "u-boot.bin" is a raw binary image
3070 - "u-boot" is an image in ELF binary format
3071 - "u-boot.srec" is in Motorola S-Record format
3073 By default the build is performed locally and the objects are saved
3074 in the source directory. One of the two methods can be used to change
3075 this behavior and build U-Boot to some external directory:
3077 1. Add O= to the make command line invocations:
3079 make O=/tmp/build distclean
3080 make O=/tmp/build NAME_defconfig
3081 make O=/tmp/build all
3083 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3085 export KBUILD_OUTPUT=/tmp/build
3090 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3093 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3094 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3095 For example to treat all compiler warnings as errors:
3097 make KCFLAGS=-Werror
3099 Please be aware that the Makefiles assume you are using GNU make, so
3100 for instance on NetBSD you might need to use "gmake" instead of
3104 If the system board that you have is not listed, then you will need
3105 to port U-Boot to your hardware platform. To do this, follow these
3108 1. Create a new directory to hold your board specific code. Add any
3109 files you need. In your board directory, you will need at least
3110 the "Makefile" and a "<board>.c".
3111 2. Create a new configuration file "include/configs/<board>.h" for
3113 3. If you're porting U-Boot to a new CPU, then also create a new
3114 directory to hold your CPU specific code. Add any files you need.
3115 4. Run "make <board>_defconfig" with your new name.
3116 5. Type "make", and you should get a working "u-boot.srec" file
3117 to be installed on your target system.
3118 6. Debug and solve any problems that might arise.
3119 [Of course, this last step is much harder than it sounds.]
3122 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3123 ==============================================================
3125 If you have modified U-Boot sources (for instance added a new board
3126 or support for new devices, a new CPU, etc.) you are expected to
3127 provide feedback to the other developers. The feedback normally takes
3128 the form of a "patch", i.e. a context diff against a certain (latest
3129 official or latest in the git repository) version of U-Boot sources.
3131 But before you submit such a patch, please verify that your modifi-
3132 cation did not break existing code. At least make sure that *ALL* of
3133 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3134 just run the buildman script (tools/buildman/buildman), which will
3135 configure and build U-Boot for ALL supported system. Be warned, this
3136 will take a while. Please see the buildman README, or run 'buildman -H'
3140 See also "U-Boot Porting Guide" below.
3143 Monitor Commands - Overview:
3144 ============================
3146 go - start application at address 'addr'
3147 run - run commands in an environment variable
3148 bootm - boot application image from memory
3149 bootp - boot image via network using BootP/TFTP protocol
3150 bootz - boot zImage from memory
3151 tftpboot- boot image via network using TFTP protocol
3152 and env variables "ipaddr" and "serverip"
3153 (and eventually "gatewayip")
3154 tftpput - upload a file via network using TFTP protocol
3155 rarpboot- boot image via network using RARP/TFTP protocol
3156 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3157 loads - load S-Record file over serial line
3158 loadb - load binary file over serial line (kermit mode)
3160 mm - memory modify (auto-incrementing)
3161 nm - memory modify (constant address)
3162 mw - memory write (fill)
3165 cmp - memory compare
3166 crc32 - checksum calculation
3167 i2c - I2C sub-system
3168 sspi - SPI utility commands
3169 base - print or set address offset
3170 printenv- print environment variables
3171 setenv - set environment variables
3172 saveenv - save environment variables to persistent storage
3173 protect - enable or disable FLASH write protection
3174 erase - erase FLASH memory
3175 flinfo - print FLASH memory information
3176 nand - NAND memory operations (see doc/README.nand)
3177 bdinfo - print Board Info structure
3178 iminfo - print header information for application image
3179 coninfo - print console devices and informations
3180 ide - IDE sub-system
3181 loop - infinite loop on address range
3182 loopw - infinite write loop on address range
3183 mtest - simple RAM test
3184 icache - enable or disable instruction cache
3185 dcache - enable or disable data cache
3186 reset - Perform RESET of the CPU
3187 echo - echo args to console
3188 version - print monitor version
3189 help - print online help
3190 ? - alias for 'help'
3193 Monitor Commands - Detailed Description:
3194 ========================================
3198 For now: just type "help <command>".
3201 Environment Variables:
3202 ======================
3204 U-Boot supports user configuration using Environment Variables which
3205 can be made persistent by saving to Flash memory.
3207 Environment Variables are set using "setenv", printed using
3208 "printenv", and saved to Flash using "saveenv". Using "setenv"
3209 without a value can be used to delete a variable from the
3210 environment. As long as you don't save the environment you are
3211 working with an in-memory copy. In case the Flash area containing the
3212 environment is erased by accident, a default environment is provided.
3214 Some configuration options can be set using Environment Variables.
3216 List of environment variables (most likely not complete):
3218 baudrate - see CONFIG_BAUDRATE
3220 bootdelay - see CONFIG_BOOTDELAY
3222 bootcmd - see CONFIG_BOOTCOMMAND
3224 bootargs - Boot arguments when booting an RTOS image
3226 bootfile - Name of the image to load with TFTP
3228 bootm_low - Memory range available for image processing in the bootm
3229 command can be restricted. This variable is given as
3230 a hexadecimal number and defines lowest address allowed
3231 for use by the bootm command. See also "bootm_size"
3232 environment variable. Address defined by "bootm_low" is
3233 also the base of the initial memory mapping for the Linux
3234 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3237 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3238 This variable is given as a hexadecimal number and it
3239 defines the size of the memory region starting at base
3240 address bootm_low that is accessible by the Linux kernel
3241 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3242 as the default value if it is defined, and bootm_size is
3245 bootm_size - Memory range available for image processing in the bootm
3246 command can be restricted. This variable is given as
3247 a hexadecimal number and defines the size of the region
3248 allowed for use by the bootm command. See also "bootm_low"
3249 environment variable.
3251 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3253 updatefile - Location of the software update file on a TFTP server, used
3254 by the automatic software update feature. Please refer to
3255 documentation in doc/README.update for more details.
3257 autoload - if set to "no" (any string beginning with 'n'),
3258 "bootp" will just load perform a lookup of the
3259 configuration from the BOOTP server, but not try to
3260 load any image using TFTP
3262 autostart - if set to "yes", an image loaded using the "bootp",
3263 "rarpboot", "tftpboot" or "diskboot" commands will
3264 be automatically started (by internally calling
3267 If set to "no", a standalone image passed to the
3268 "bootm" command will be copied to the load address
3269 (and eventually uncompressed), but NOT be started.
3270 This can be used to load and uncompress arbitrary
3273 fdt_high - if set this restricts the maximum address that the
3274 flattened device tree will be copied into upon boot.
3275 For example, if you have a system with 1 GB memory
3276 at physical address 0x10000000, while Linux kernel
3277 only recognizes the first 704 MB as low memory, you
3278 may need to set fdt_high as 0x3C000000 to have the
3279 device tree blob be copied to the maximum address
3280 of the 704 MB low memory, so that Linux kernel can
3281 access it during the boot procedure.
3283 If this is set to the special value 0xFFFFFFFF then
3284 the fdt will not be copied at all on boot. For this
3285 to work it must reside in writable memory, have
3286 sufficient padding on the end of it for u-boot to
3287 add the information it needs into it, and the memory
3288 must be accessible by the kernel.
3290 fdtcontroladdr- if set this is the address of the control flattened
3291 device tree used by U-Boot when CONFIG_OF_CONTROL is
3294 i2cfast - (PPC405GP|PPC405EP only)
3295 if set to 'y' configures Linux I2C driver for fast
3296 mode (400kHZ). This environment variable is used in
3297 initialization code. So, for changes to be effective
3298 it must be saved and board must be reset.
3300 initrd_high - restrict positioning of initrd images:
3301 If this variable is not set, initrd images will be
3302 copied to the highest possible address in RAM; this
3303 is usually what you want since it allows for
3304 maximum initrd size. If for some reason you want to
3305 make sure that the initrd image is loaded below the
3306 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3307 variable to a value of "no" or "off" or "0".
3308 Alternatively, you can set it to a maximum upper
3309 address to use (U-Boot will still check that it
3310 does not overwrite the U-Boot stack and data).
3312 For instance, when you have a system with 16 MB
3313 RAM, and want to reserve 4 MB from use by Linux,
3314 you can do this by adding "mem=12M" to the value of
3315 the "bootargs" variable. However, now you must make
3316 sure that the initrd image is placed in the first
3317 12 MB as well - this can be done with
3319 setenv initrd_high 00c00000
3321 If you set initrd_high to 0xFFFFFFFF, this is an
3322 indication to U-Boot that all addresses are legal
3323 for the Linux kernel, including addresses in flash
3324 memory. In this case U-Boot will NOT COPY the
3325 ramdisk at all. This may be useful to reduce the
3326 boot time on your system, but requires that this
3327 feature is supported by your Linux kernel.
3329 ipaddr - IP address; needed for tftpboot command
3331 loadaddr - Default load address for commands like "bootp",
3332 "rarpboot", "tftpboot", "loadb" or "diskboot"
3334 loads_echo - see CONFIG_LOADS_ECHO
3336 serverip - TFTP server IP address; needed for tftpboot command
3338 bootretry - see CONFIG_BOOT_RETRY_TIME
3340 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3342 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3344 ethprime - controls which interface is used first.
3346 ethact - controls which interface is currently active.
3347 For example you can do the following
3349 => setenv ethact FEC
3350 => ping 192.168.0.1 # traffic sent on FEC
3351 => setenv ethact SCC
3352 => ping 10.0.0.1 # traffic sent on SCC
3354 ethrotate - When set to "no" U-Boot does not go through all
3355 available network interfaces.
3356 It just stays at the currently selected interface.
3358 netretry - When set to "no" each network operation will
3359 either succeed or fail without retrying.
3360 When set to "once" the network operation will
3361 fail when all the available network interfaces
3362 are tried once without success.
3363 Useful on scripts which control the retry operation
3366 npe_ucode - set load address for the NPE microcode
3368 silent_linux - If set then Linux will be told to boot silently, by
3369 changing the console to be empty. If "yes" it will be
3370 made silent. If "no" it will not be made silent. If
3371 unset, then it will be made silent if the U-Boot console
3374 tftpsrcp - If this is set, the value is used for TFTP's
3377 tftpdstp - If this is set, the value is used for TFTP's UDP
3378 destination port instead of the Well Know Port 69.
3380 tftpblocksize - Block size to use for TFTP transfers; if not set,
3381 we use the TFTP server's default block size
3383 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3384 seconds, minimum value is 1000 = 1 second). Defines
3385 when a packet is considered to be lost so it has to
3386 be retransmitted. The default is 5000 = 5 seconds.
3387 Lowering this value may make downloads succeed
3388 faster in networks with high packet loss rates or
3389 with unreliable TFTP servers.
3391 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3392 unit, minimum value = 0). Defines how many timeouts
3393 can happen during a single file transfer before that
3394 transfer is aborted. The default is 10, and 0 means
3395 'no timeouts allowed'. Increasing this value may help
3396 downloads succeed with high packet loss rates, or with
3397 unreliable TFTP servers or client hardware.
3399 tftpwindowsize - if this is set, the value is used for TFTP's
3400 window size as described by RFC 7440.
3401 This means the count of blocks we can receive before
3402 sending ack to server.
3404 vlan - When set to a value < 4095 the traffic over
3405 Ethernet is encapsulated/received over 802.1q
3408 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3409 Unsigned value, in milliseconds. If not set, the period will
3410 be either the default (28000), or a value based on
3411 CONFIG_NET_RETRY_COUNT, if defined. This value has
3412 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3414 memmatches - Number of matches found by the last 'ms' command, in hex
3416 memaddr - Address of the last match found by the 'ms' command, in hex,
3419 mempos - Index position of the last match found by the 'ms' command,
3420 in units of the size (.b, .w, .l) of the search
3422 zbootbase - (x86 only) Base address of the bzImage 'setup' block
3424 zbootaddr - (x86 only) Address of the loaded bzImage, typically
3425 BZIMAGE_LOAD_ADDR which is 0x100000
3427 The following image location variables contain the location of images
3428 used in booting. The "Image" column gives the role of the image and is
3429 not an environment variable name. The other columns are environment
3430 variable names. "File Name" gives the name of the file on a TFTP
3431 server, "RAM Address" gives the location in RAM the image will be
3432 loaded to, and "Flash Location" gives the image's address in NOR
3433 flash or offset in NAND flash.
3435 *Note* - these variables don't have to be defined for all boards, some
3436 boards currently use other variables for these purposes, and some
3437 boards use these variables for other purposes.
3439 Image File Name RAM Address Flash Location
3440 ----- --------- ----------- --------------
3441 u-boot u-boot u-boot_addr_r u-boot_addr
3442 Linux kernel bootfile kernel_addr_r kernel_addr
3443 device tree blob fdtfile fdt_addr_r fdt_addr
3444 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3446 The following environment variables may be used and automatically
3447 updated by the network boot commands ("bootp" and "rarpboot"),
3448 depending the information provided by your boot server:
3450 bootfile - see above
3451 dnsip - IP address of your Domain Name Server
3452 dnsip2 - IP address of your secondary Domain Name Server
3453 gatewayip - IP address of the Gateway (Router) to use
3454 hostname - Target hostname
3456 netmask - Subnet Mask
3457 rootpath - Pathname of the root filesystem on the NFS server
3458 serverip - see above
3461 There are two special Environment Variables:
3463 serial# - contains hardware identification information such
3464 as type string and/or serial number
3465 ethaddr - Ethernet address
3467 These variables can be set only once (usually during manufacturing of
3468 the board). U-Boot refuses to delete or overwrite these variables
3469 once they have been set once.
3472 Further special Environment Variables:
3474 ver - Contains the U-Boot version string as printed
3475 with the "version" command. This variable is
3476 readonly (see CONFIG_VERSION_VARIABLE).
3479 Please note that changes to some configuration parameters may take
3480 only effect after the next boot (yes, that's just like Windoze :-).
3483 Callback functions for environment variables:
3484 ---------------------------------------------
3486 For some environment variables, the behavior of u-boot needs to change
3487 when their values are changed. This functionality allows functions to
3488 be associated with arbitrary variables. On creation, overwrite, or
3489 deletion, the callback will provide the opportunity for some side
3490 effect to happen or for the change to be rejected.
3492 The callbacks are named and associated with a function using the
3493 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3495 These callbacks are associated with variables in one of two ways. The
3496 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3497 in the board configuration to a string that defines a list of
3498 associations. The list must be in the following format:
3500 entry = variable_name[:callback_name]
3503 If the callback name is not specified, then the callback is deleted.
3504 Spaces are also allowed anywhere in the list.
3506 Callbacks can also be associated by defining the ".callbacks" variable
3507 with the same list format above. Any association in ".callbacks" will
3508 override any association in the static list. You can define
3509 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3510 ".callbacks" environment variable in the default or embedded environment.
3512 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3513 regular expression. This allows multiple variables to be connected to
3514 the same callback without explicitly listing them all out.
3516 The signature of the callback functions is:
3518 int callback(const char *name, const char *value, enum env_op op, int flags)
3520 * name - changed environment variable
3521 * value - new value of the environment variable
3522 * op - operation (create, overwrite, or delete)
3523 * flags - attributes of the environment variable change, see flags H_* in
3526 The return value is 0 if the variable change is accepted and 1 otherwise.
3528 Command Line Parsing:
3529 =====================
3531 There are two different command line parsers available with U-Boot:
3532 the old "simple" one, and the much more powerful "hush" shell:
3534 Old, simple command line parser:
3535 --------------------------------
3537 - supports environment variables (through setenv / saveenv commands)
3538 - several commands on one line, separated by ';'
3539 - variable substitution using "... ${name} ..." syntax
3540 - special characters ('$', ';') can be escaped by prefixing with '\',
3542 setenv bootcmd bootm \${address}
3543 - You can also escape text by enclosing in single apostrophes, for example:
3544 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3549 - similar to Bourne shell, with control structures like
3550 if...then...else...fi, for...do...done; while...do...done,
3551 until...do...done, ...
3552 - supports environment ("global") variables (through setenv / saveenv
3553 commands) and local shell variables (through standard shell syntax
3554 "name=value"); only environment variables can be used with "run"
3560 (1) If a command line (or an environment variable executed by a "run"
3561 command) contains several commands separated by semicolon, and
3562 one of these commands fails, then the remaining commands will be
3565 (2) If you execute several variables with one call to run (i. e.
3566 calling run with a list of variables as arguments), any failing
3567 command will cause "run" to terminate, i. e. the remaining
3568 variables are not executed.
3570 Note for Redundant Ethernet Interfaces:
3571 =======================================
3573 Some boards come with redundant Ethernet interfaces; U-Boot supports
3574 such configurations and is capable of automatic selection of a
3575 "working" interface when needed. MAC assignment works as follows:
3577 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3578 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3579 "eth1addr" (=>eth1), "eth2addr", ...
3581 If the network interface stores some valid MAC address (for instance
3582 in SROM), this is used as default address if there is NO correspon-
3583 ding setting in the environment; if the corresponding environment
3584 variable is set, this overrides the settings in the card; that means:
3586 o If the SROM has a valid MAC address, and there is no address in the
3587 environment, the SROM's address is used.
3589 o If there is no valid address in the SROM, and a definition in the
3590 environment exists, then the value from the environment variable is
3593 o If both the SROM and the environment contain a MAC address, and
3594 both addresses are the same, this MAC address is used.
3596 o If both the SROM and the environment contain a MAC address, and the
3597 addresses differ, the value from the environment is used and a
3600 o If neither SROM nor the environment contain a MAC address, an error
3601 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3602 a random, locally-assigned MAC is used.
3604 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3605 will be programmed into hardware as part of the initialization process. This
3606 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3607 The naming convention is as follows:
3608 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3613 U-Boot is capable of booting (and performing other auxiliary operations on)
3614 images in two formats:
3616 New uImage format (FIT)
3617 -----------------------
3619 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3620 to Flattened Device Tree). It allows the use of images with multiple
3621 components (several kernels, ramdisks, etc.), with contents protected by
3622 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3628 Old image format is based on binary files which can be basically anything,
3629 preceded by a special header; see the definitions in include/image.h for
3630 details; basically, the header defines the following image properties:
3632 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3633 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3634 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3635 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3637 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3638 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3639 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3640 * Compression Type (uncompressed, gzip, bzip2)
3646 The header is marked by a special Magic Number, and both the header
3647 and the data portions of the image are secured against corruption by
3654 Although U-Boot should support any OS or standalone application
3655 easily, the main focus has always been on Linux during the design of
3658 U-Boot includes many features that so far have been part of some
3659 special "boot loader" code within the Linux kernel. Also, any
3660 "initrd" images to be used are no longer part of one big Linux image;
3661 instead, kernel and "initrd" are separate images. This implementation
3662 serves several purposes:
3664 - the same features can be used for other OS or standalone
3665 applications (for instance: using compressed images to reduce the
3666 Flash memory footprint)
3668 - it becomes much easier to port new Linux kernel versions because
3669 lots of low-level, hardware dependent stuff are done by U-Boot
3671 - the same Linux kernel image can now be used with different "initrd"
3672 images; of course this also means that different kernel images can
3673 be run with the same "initrd". This makes testing easier (you don't
3674 have to build a new "zImage.initrd" Linux image when you just
3675 change a file in your "initrd"). Also, a field-upgrade of the
3676 software is easier now.
3682 Porting Linux to U-Boot based systems:
3683 ---------------------------------------
3685 U-Boot cannot save you from doing all the necessary modifications to
3686 configure the Linux device drivers for use with your target hardware
3687 (no, we don't intend to provide a full virtual machine interface to
3690 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3692 Just make sure your machine specific header file (for instance
3693 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3694 Information structure as we define in include/asm-<arch>/u-boot.h,
3695 and make sure that your definition of IMAP_ADDR uses the same value
3696 as your U-Boot configuration in CONFIG_SYS_IMMR.
3698 Note that U-Boot now has a driver model, a unified model for drivers.
3699 If you are adding a new driver, plumb it into driver model. If there
3700 is no uclass available, you are encouraged to create one. See
3704 Configuring the Linux kernel:
3705 -----------------------------
3707 No specific requirements for U-Boot. Make sure you have some root
3708 device (initial ramdisk, NFS) for your target system.
3711 Building a Linux Image:
3712 -----------------------
3714 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3715 not used. If you use recent kernel source, a new build target
3716 "uImage" will exist which automatically builds an image usable by
3717 U-Boot. Most older kernels also have support for a "pImage" target,
3718 which was introduced for our predecessor project PPCBoot and uses a
3719 100% compatible format.
3723 make TQM850L_defconfig
3728 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3729 encapsulate a compressed Linux kernel image with header information,
3730 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3732 * build a standard "vmlinux" kernel image (in ELF binary format):
3734 * convert the kernel into a raw binary image:
3736 ${CROSS_COMPILE}-objcopy -O binary \
3737 -R .note -R .comment \
3738 -S vmlinux linux.bin
3740 * compress the binary image:
3744 * package compressed binary image for U-Boot:
3746 mkimage -A ppc -O linux -T kernel -C gzip \
3747 -a 0 -e 0 -n "Linux Kernel Image" \
3748 -d linux.bin.gz uImage
3751 The "mkimage" tool can also be used to create ramdisk images for use
3752 with U-Boot, either separated from the Linux kernel image, or
3753 combined into one file. "mkimage" encapsulates the images with a 64
3754 byte header containing information about target architecture,
3755 operating system, image type, compression method, entry points, time
3756 stamp, CRC32 checksums, etc.
3758 "mkimage" can be called in two ways: to verify existing images and
3759 print the header information, or to build new images.
3761 In the first form (with "-l" option) mkimage lists the information
3762 contained in the header of an existing U-Boot image; this includes
3763 checksum verification:
3765 tools/mkimage -l image
3766 -l ==> list image header information
3768 The second form (with "-d" option) is used to build a U-Boot image
3769 from a "data file" which is used as image payload:
3771 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3772 -n name -d data_file image
3773 -A ==> set architecture to 'arch'
3774 -O ==> set operating system to 'os'
3775 -T ==> set image type to 'type'
3776 -C ==> set compression type 'comp'
3777 -a ==> set load address to 'addr' (hex)
3778 -e ==> set entry point to 'ep' (hex)
3779 -n ==> set image name to 'name'
3780 -d ==> use image data from 'datafile'
3782 Right now, all Linux kernels for PowerPC systems use the same load
3783 address (0x00000000), but the entry point address depends on the
3786 - 2.2.x kernels have the entry point at 0x0000000C,
3787 - 2.3.x and later kernels have the entry point at 0x00000000.
3789 So a typical call to build a U-Boot image would read:
3791 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3792 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3793 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3794 > examples/uImage.TQM850L
3795 Image Name: 2.4.4 kernel for TQM850L
3796 Created: Wed Jul 19 02:34:59 2000
3797 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3798 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3799 Load Address: 0x00000000
3800 Entry Point: 0x00000000
3802 To verify the contents of the image (or check for corruption):
3804 -> tools/mkimage -l examples/uImage.TQM850L
3805 Image Name: 2.4.4 kernel for TQM850L
3806 Created: Wed Jul 19 02:34:59 2000
3807 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3808 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3809 Load Address: 0x00000000
3810 Entry Point: 0x00000000
3812 NOTE: for embedded systems where boot time is critical you can trade
3813 speed for memory and install an UNCOMPRESSED image instead: this
3814 needs more space in Flash, but boots much faster since it does not
3815 need to be uncompressed:
3817 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3818 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3819 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3820 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3821 > examples/uImage.TQM850L-uncompressed
3822 Image Name: 2.4.4 kernel for TQM850L
3823 Created: Wed Jul 19 02:34:59 2000
3824 Image Type: PowerPC Linux Kernel Image (uncompressed)
3825 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3826 Load Address: 0x00000000
3827 Entry Point: 0x00000000
3830 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3831 when your kernel is intended to use an initial ramdisk:
3833 -> tools/mkimage -n 'Simple Ramdisk Image' \
3834 > -A ppc -O linux -T ramdisk -C gzip \
3835 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3836 Image Name: Simple Ramdisk Image
3837 Created: Wed Jan 12 14:01:50 2000
3838 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3839 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3840 Load Address: 0x00000000
3841 Entry Point: 0x00000000
3843 The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
3844 option performs the converse operation of the mkimage's second form (the "-d"
3845 option). Given an image built by mkimage, the dumpimage extracts a "data file"
3848 tools/dumpimage -i image -T type -p position data_file
3849 -i ==> extract from the 'image' a specific 'data_file'
3850 -T ==> set image type to 'type'
3851 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
3854 Installing a Linux Image:
3855 -------------------------
3857 To downloading a U-Boot image over the serial (console) interface,
3858 you must convert the image to S-Record format:
3860 objcopy -I binary -O srec examples/image examples/image.srec
3862 The 'objcopy' does not understand the information in the U-Boot
3863 image header, so the resulting S-Record file will be relative to
3864 address 0x00000000. To load it to a given address, you need to
3865 specify the target address as 'offset' parameter with the 'loads'
3868 Example: install the image to address 0x40100000 (which on the
3869 TQM8xxL is in the first Flash bank):
3871 => erase 40100000 401FFFFF
3877 ## Ready for S-Record download ...
3878 ~>examples/image.srec
3879 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3881 15989 15990 15991 15992
3882 [file transfer complete]
3884 ## Start Addr = 0x00000000
3887 You can check the success of the download using the 'iminfo' command;
3888 this includes a checksum verification so you can be sure no data
3889 corruption happened:
3893 ## Checking Image at 40100000 ...
3894 Image Name: 2.2.13 for initrd on TQM850L
3895 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3896 Data Size: 335725 Bytes = 327 kB = 0 MB
3897 Load Address: 00000000
3898 Entry Point: 0000000c
3899 Verifying Checksum ... OK
3905 The "bootm" command is used to boot an application that is stored in
3906 memory (RAM or Flash). In case of a Linux kernel image, the contents
3907 of the "bootargs" environment variable is passed to the kernel as
3908 parameters. You can check and modify this variable using the
3909 "printenv" and "setenv" commands:
3912 => printenv bootargs
3913 bootargs=root=/dev/ram
3915 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3917 => printenv bootargs
3918 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3921 ## Booting Linux kernel at 40020000 ...
3922 Image Name: 2.2.13 for NFS on TQM850L
3923 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3924 Data Size: 381681 Bytes = 372 kB = 0 MB
3925 Load Address: 00000000
3926 Entry Point: 0000000c
3927 Verifying Checksum ... OK
3928 Uncompressing Kernel Image ... OK
3929 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
3930 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3931 time_init: decrementer frequency = 187500000/60
3932 Calibrating delay loop... 49.77 BogoMIPS
3933 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3936 If you want to boot a Linux kernel with initial RAM disk, you pass
3937 the memory addresses of both the kernel and the initrd image (PPBCOOT
3938 format!) to the "bootm" command:
3940 => imi 40100000 40200000
3942 ## Checking Image at 40100000 ...
3943 Image Name: 2.2.13 for initrd on TQM850L
3944 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3945 Data Size: 335725 Bytes = 327 kB = 0 MB
3946 Load Address: 00000000
3947 Entry Point: 0000000c
3948 Verifying Checksum ... OK
3950 ## Checking Image at 40200000 ...
3951 Image Name: Simple Ramdisk Image
3952 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3953 Data Size: 566530 Bytes = 553 kB = 0 MB
3954 Load Address: 00000000
3955 Entry Point: 00000000
3956 Verifying Checksum ... OK
3958 => bootm 40100000 40200000
3959 ## Booting Linux kernel at 40100000 ...
3960 Image Name: 2.2.13 for initrd on TQM850L
3961 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3962 Data Size: 335725 Bytes = 327 kB = 0 MB
3963 Load Address: 00000000
3964 Entry Point: 0000000c
3965 Verifying Checksum ... OK
3966 Uncompressing Kernel Image ... OK
3967 ## Loading RAMDisk Image at 40200000 ...
3968 Image Name: Simple Ramdisk Image
3969 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3970 Data Size: 566530 Bytes = 553 kB = 0 MB
3971 Load Address: 00000000
3972 Entry Point: 00000000
3973 Verifying Checksum ... OK
3974 Loading Ramdisk ... OK
3975 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
3976 Boot arguments: root=/dev/ram
3977 time_init: decrementer frequency = 187500000/60
3978 Calibrating delay loop... 49.77 BogoMIPS
3980 RAMDISK: Compressed image found at block 0
3981 VFS: Mounted root (ext2 filesystem).
3985 Boot Linux and pass a flat device tree:
3988 First, U-Boot must be compiled with the appropriate defines. See the section
3989 titled "Linux Kernel Interface" above for a more in depth explanation. The
3990 following is an example of how to start a kernel and pass an updated
3996 oft=oftrees/mpc8540ads.dtb
3997 => tftp $oftaddr $oft
3998 Speed: 1000, full duplex
4000 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4001 Filename 'oftrees/mpc8540ads.dtb'.
4002 Load address: 0x300000
4005 Bytes transferred = 4106 (100a hex)
4006 => tftp $loadaddr $bootfile
4007 Speed: 1000, full duplex
4009 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4011 Load address: 0x200000
4012 Loading:############
4014 Bytes transferred = 1029407 (fb51f hex)
4019 => bootm $loadaddr - $oftaddr
4020 ## Booting image at 00200000 ...
4021 Image Name: Linux-2.6.17-dirty
4022 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4023 Data Size: 1029343 Bytes = 1005.2 kB
4024 Load Address: 00000000
4025 Entry Point: 00000000
4026 Verifying Checksum ... OK
4027 Uncompressing Kernel Image ... OK
4028 Booting using flat device tree at 0x300000
4029 Using MPC85xx ADS machine description
4030 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4034 More About U-Boot Image Types:
4035 ------------------------------
4037 U-Boot supports the following image types:
4039 "Standalone Programs" are directly runnable in the environment
4040 provided by U-Boot; it is expected that (if they behave
4041 well) you can continue to work in U-Boot after return from
4042 the Standalone Program.
4043 "OS Kernel Images" are usually images of some Embedded OS which
4044 will take over control completely. Usually these programs
4045 will install their own set of exception handlers, device
4046 drivers, set up the MMU, etc. - this means, that you cannot
4047 expect to re-enter U-Boot except by resetting the CPU.
4048 "RAMDisk Images" are more or less just data blocks, and their
4049 parameters (address, size) are passed to an OS kernel that is
4051 "Multi-File Images" contain several images, typically an OS
4052 (Linux) kernel image and one or more data images like
4053 RAMDisks. This construct is useful for instance when you want
4054 to boot over the network using BOOTP etc., where the boot
4055 server provides just a single image file, but you want to get
4056 for instance an OS kernel and a RAMDisk image.
4058 "Multi-File Images" start with a list of image sizes, each
4059 image size (in bytes) specified by an "uint32_t" in network
4060 byte order. This list is terminated by an "(uint32_t)0".
4061 Immediately after the terminating 0 follow the images, one by
4062 one, all aligned on "uint32_t" boundaries (size rounded up to
4063 a multiple of 4 bytes).
4065 "Firmware Images" are binary images containing firmware (like
4066 U-Boot or FPGA images) which usually will be programmed to
4069 "Script files" are command sequences that will be executed by
4070 U-Boot's command interpreter; this feature is especially
4071 useful when you configure U-Boot to use a real shell (hush)
4072 as command interpreter.
4074 Booting the Linux zImage:
4075 -------------------------
4077 On some platforms, it's possible to boot Linux zImage. This is done
4078 using the "bootz" command. The syntax of "bootz" command is the same
4079 as the syntax of "bootm" command.
4081 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
4082 kernel with raw initrd images. The syntax is slightly different, the
4083 address of the initrd must be augmented by it's size, in the following
4084 format: "<initrd addres>:<initrd size>".
4090 One of the features of U-Boot is that you can dynamically load and
4091 run "standalone" applications, which can use some resources of
4092 U-Boot like console I/O functions or interrupt services.
4094 Two simple examples are included with the sources:
4099 'examples/hello_world.c' contains a small "Hello World" Demo
4100 application; it is automatically compiled when you build U-Boot.
4101 It's configured to run at address 0x00040004, so you can play with it
4105 ## Ready for S-Record download ...
4106 ~>examples/hello_world.srec
4107 1 2 3 4 5 6 7 8 9 10 11 ...
4108 [file transfer complete]
4110 ## Start Addr = 0x00040004
4112 => go 40004 Hello World! This is a test.
4113 ## Starting application at 0x00040004 ...
4124 Hit any key to exit ...
4126 ## Application terminated, rc = 0x0
4128 Another example, which demonstrates how to register a CPM interrupt
4129 handler with the U-Boot code, can be found in 'examples/timer.c'.
4130 Here, a CPM timer is set up to generate an interrupt every second.
4131 The interrupt service routine is trivial, just printing a '.'
4132 character, but this is just a demo program. The application can be
4133 controlled by the following keys:
4135 ? - print current values og the CPM Timer registers
4136 b - enable interrupts and start timer
4137 e - stop timer and disable interrupts
4138 q - quit application
4141 ## Ready for S-Record download ...
4142 ~>examples/timer.srec
4143 1 2 3 4 5 6 7 8 9 10 11 ...
4144 [file transfer complete]
4146 ## Start Addr = 0x00040004
4149 ## Starting application at 0x00040004 ...
4152 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4155 [q, b, e, ?] Set interval 1000000 us
4158 [q, b, e, ?] ........
4159 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4162 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4165 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4168 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4170 [q, b, e, ?] ...Stopping timer
4172 [q, b, e, ?] ## Application terminated, rc = 0x0
4178 Over time, many people have reported problems when trying to use the
4179 "minicom" terminal emulation program for serial download. I (wd)
4180 consider minicom to be broken, and recommend not to use it. Under
4181 Unix, I recommend to use C-Kermit for general purpose use (and
4182 especially for kermit binary protocol download ("loadb" command), and
4183 use "cu" for S-Record download ("loads" command). See
4184 http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4185 for help with kermit.
4188 Nevertheless, if you absolutely want to use it try adding this
4189 configuration to your "File transfer protocols" section:
4191 Name Program Name U/D FullScr IO-Red. Multi
4192 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4193 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4199 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4200 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4202 Building requires a cross environment; it is known to work on
4203 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4204 need gmake since the Makefiles are not compatible with BSD make).
4205 Note that the cross-powerpc package does not install include files;
4206 attempting to build U-Boot will fail because <machine/ansi.h> is
4207 missing. This file has to be installed and patched manually:
4209 # cd /usr/pkg/cross/powerpc-netbsd/include
4211 # ln -s powerpc machine
4212 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4213 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4215 Native builds *don't* work due to incompatibilities between native
4216 and U-Boot include files.
4218 Booting assumes that (the first part of) the image booted is a
4219 stage-2 loader which in turn loads and then invokes the kernel
4220 proper. Loader sources will eventually appear in the NetBSD source
4221 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4222 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4225 Implementation Internals:
4226 =========================
4228 The following is not intended to be a complete description of every
4229 implementation detail. However, it should help to understand the
4230 inner workings of U-Boot and make it easier to port it to custom
4234 Initial Stack, Global Data:
4235 ---------------------------
4237 The implementation of U-Boot is complicated by the fact that U-Boot
4238 starts running out of ROM (flash memory), usually without access to
4239 system RAM (because the memory controller is not initialized yet).
4240 This means that we don't have writable Data or BSS segments, and BSS
4241 is not initialized as zero. To be able to get a C environment working
4242 at all, we have to allocate at least a minimal stack. Implementation
4243 options for this are defined and restricted by the CPU used: Some CPU
4244 models provide on-chip memory (like the IMMR area on MPC8xx and
4245 MPC826x processors), on others (parts of) the data cache can be
4246 locked as (mis-) used as memory, etc.
4248 Chris Hallinan posted a good summary of these issues to the
4249 U-Boot mailing list:
4251 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4252 From: "Chris Hallinan" <clh@net1plus.com>
4253 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4256 Correct me if I'm wrong, folks, but the way I understand it
4257 is this: Using DCACHE as initial RAM for Stack, etc, does not
4258 require any physical RAM backing up the cache. The cleverness
4259 is that the cache is being used as a temporary supply of
4260 necessary storage before the SDRAM controller is setup. It's
4261 beyond the scope of this list to explain the details, but you
4262 can see how this works by studying the cache architecture and
4263 operation in the architecture and processor-specific manuals.
4265 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4266 is another option for the system designer to use as an
4267 initial stack/RAM area prior to SDRAM being available. Either
4268 option should work for you. Using CS 4 should be fine if your
4269 board designers haven't used it for something that would
4270 cause you grief during the initial boot! It is frequently not
4273 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4274 with your processor/board/system design. The default value
4275 you will find in any recent u-boot distribution in
4276 walnut.h should work for you. I'd set it to a value larger
4277 than your SDRAM module. If you have a 64MB SDRAM module, set
4278 it above 400_0000. Just make sure your board has no resources
4279 that are supposed to respond to that address! That code in
4280 start.S has been around a while and should work as is when
4281 you get the config right.
4286 It is essential to remember this, since it has some impact on the C
4287 code for the initialization procedures:
4289 * Initialized global data (data segment) is read-only. Do not attempt
4292 * Do not use any uninitialized global data (or implicitly initialized
4293 as zero data - BSS segment) at all - this is undefined, initiali-
4294 zation is performed later (when relocating to RAM).
4296 * Stack space is very limited. Avoid big data buffers or things like
4299 Having only the stack as writable memory limits means we cannot use
4300 normal global data to share information between the code. But it
4301 turned out that the implementation of U-Boot can be greatly
4302 simplified by making a global data structure (gd_t) available to all
4303 functions. We could pass a pointer to this data as argument to _all_
4304 functions, but this would bloat the code. Instead we use a feature of
4305 the GCC compiler (Global Register Variables) to share the data: we
4306 place a pointer (gd) to the global data into a register which we
4307 reserve for this purpose.
4309 When choosing a register for such a purpose we are restricted by the
4310 relevant (E)ABI specifications for the current architecture, and by
4311 GCC's implementation.
4313 For PowerPC, the following registers have specific use:
4315 R2: reserved for system use
4316 R3-R4: parameter passing and return values
4317 R5-R10: parameter passing
4318 R13: small data area pointer
4322 (U-Boot also uses R12 as internal GOT pointer. r12
4323 is a volatile register so r12 needs to be reset when
4324 going back and forth between asm and C)
4326 ==> U-Boot will use R2 to hold a pointer to the global data
4328 Note: on PPC, we could use a static initializer (since the
4329 address of the global data structure is known at compile time),
4330 but it turned out that reserving a register results in somewhat
4331 smaller code - although the code savings are not that big (on
4332 average for all boards 752 bytes for the whole U-Boot image,
4333 624 text + 127 data).
4335 On ARM, the following registers are used:
4337 R0: function argument word/integer result
4338 R1-R3: function argument word
4339 R9: platform specific
4340 R10: stack limit (used only if stack checking is enabled)
4341 R11: argument (frame) pointer
4342 R12: temporary workspace
4345 R15: program counter
4347 ==> U-Boot will use R9 to hold a pointer to the global data
4349 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4351 On Nios II, the ABI is documented here:
4352 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4354 ==> U-Boot will use gp to hold a pointer to the global data
4356 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4357 to access small data sections, so gp is free.
4359 On NDS32, the following registers are used:
4361 R0-R1: argument/return
4363 R15: temporary register for assembler
4364 R16: trampoline register
4365 R28: frame pointer (FP)
4366 R29: global pointer (GP)
4367 R30: link register (LP)
4368 R31: stack pointer (SP)
4369 PC: program counter (PC)
4371 ==> U-Boot will use R10 to hold a pointer to the global data
4373 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4374 or current versions of GCC may "optimize" the code too much.
4376 On RISC-V, the following registers are used:
4378 x0: hard-wired zero (zero)
4379 x1: return address (ra)
4380 x2: stack pointer (sp)
4381 x3: global pointer (gp)
4382 x4: thread pointer (tp)
4383 x5: link register (t0)
4384 x8: frame pointer (fp)
4385 x10-x11: arguments/return values (a0-1)
4386 x12-x17: arguments (a2-7)
4387 x28-31: temporaries (t3-6)
4388 pc: program counter (pc)
4390 ==> U-Boot will use gp to hold a pointer to the global data
4395 U-Boot runs in system state and uses physical addresses, i.e. the
4396 MMU is not used either for address mapping nor for memory protection.
4398 The available memory is mapped to fixed addresses using the memory
4399 controller. In this process, a contiguous block is formed for each
4400 memory type (Flash, SDRAM, SRAM), even when it consists of several
4401 physical memory banks.
4403 U-Boot is installed in the first 128 kB of the first Flash bank (on
4404 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4405 booting and sizing and initializing DRAM, the code relocates itself
4406 to the upper end of DRAM. Immediately below the U-Boot code some
4407 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4408 configuration setting]. Below that, a structure with global Board
4409 Info data is placed, followed by the stack (growing downward).
4411 Additionally, some exception handler code is copied to the low 8 kB
4412 of DRAM (0x00000000 ... 0x00001FFF).
4414 So a typical memory configuration with 16 MB of DRAM could look like
4417 0x0000 0000 Exception Vector code
4420 0x0000 2000 Free for Application Use
4426 0x00FB FF20 Monitor Stack (Growing downward)
4427 0x00FB FFAC Board Info Data and permanent copy of global data
4428 0x00FC 0000 Malloc Arena
4431 0x00FE 0000 RAM Copy of Monitor Code
4432 ... eventually: LCD or video framebuffer
4433 ... eventually: pRAM (Protected RAM - unchanged by reset)
4434 0x00FF FFFF [End of RAM]
4437 System Initialization:
4438 ----------------------
4440 In the reset configuration, U-Boot starts at the reset entry point
4441 (on most PowerPC systems at address 0x00000100). Because of the reset
4442 configuration for CS0# this is a mirror of the on board Flash memory.
4443 To be able to re-map memory U-Boot then jumps to its link address.
4444 To be able to implement the initialization code in C, a (small!)
4445 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4446 which provide such a feature like), or in a locked part of the data
4447 cache. After that, U-Boot initializes the CPU core, the caches and
4450 Next, all (potentially) available memory banks are mapped using a
4451 preliminary mapping. For example, we put them on 512 MB boundaries
4452 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4453 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4454 programmed for SDRAM access. Using the temporary configuration, a
4455 simple memory test is run that determines the size of the SDRAM
4458 When there is more than one SDRAM bank, and the banks are of
4459 different size, the largest is mapped first. For equal size, the first
4460 bank (CS2#) is mapped first. The first mapping is always for address
4461 0x00000000, with any additional banks following immediately to create
4462 contiguous memory starting from 0.
4464 Then, the monitor installs itself at the upper end of the SDRAM area
4465 and allocates memory for use by malloc() and for the global Board
4466 Info data; also, the exception vector code is copied to the low RAM
4467 pages, and the final stack is set up.
4469 Only after this relocation will you have a "normal" C environment;
4470 until that you are restricted in several ways, mostly because you are
4471 running from ROM, and because the code will have to be relocated to a
4475 U-Boot Porting Guide:
4476 ----------------------
4478 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4482 int main(int argc, char *argv[])
4484 sighandler_t no_more_time;
4486 signal(SIGALRM, no_more_time);
4487 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4489 if (available_money > available_manpower) {
4490 Pay consultant to port U-Boot;
4494 Download latest U-Boot source;
4496 Subscribe to u-boot mailing list;
4499 email("Hi, I am new to U-Boot, how do I get started?");
4502 Read the README file in the top level directory;
4503 Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4504 Read applicable doc/README.*;
4505 Read the source, Luke;
4506 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4509 if (available_money > toLocalCurrency ($2500))
4512 Add a lot of aggravation and time;
4514 if (a similar board exists) { /* hopefully... */
4515 cp -a board/<similar> board/<myboard>
4516 cp include/configs/<similar>.h include/configs/<myboard>.h
4518 Create your own board support subdirectory;
4519 Create your own board include/configs/<myboard>.h file;
4521 Edit new board/<myboard> files
4522 Edit new include/configs/<myboard>.h
4527 Add / modify source code;
4531 email("Hi, I am having problems...");
4533 Send patch file to the U-Boot email list;
4534 if (reasonable critiques)
4535 Incorporate improvements from email list code review;
4537 Defend code as written;
4543 void no_more_time (int sig)
4552 All contributions to U-Boot should conform to the Linux kernel
4553 coding style; see the kernel coding style guide at
4554 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4555 script "scripts/Lindent" in your Linux kernel source directory.
4557 Source files originating from a different project (for example the
4558 MTD subsystem) are generally exempt from these guidelines and are not
4559 reformatted to ease subsequent migration to newer versions of those
4562 Please note that U-Boot is implemented in C (and to some small parts in
4563 Assembler); no C++ is used, so please do not use C++ style comments (//)
4566 Please also stick to the following formatting rules:
4567 - remove any trailing white space
4568 - use TAB characters for indentation and vertical alignment, not spaces
4569 - make sure NOT to use DOS '\r\n' line feeds
4570 - do not add more than 2 consecutive empty lines to source files
4571 - do not add trailing empty lines to source files
4573 Submissions which do not conform to the standards may be returned
4574 with a request to reformat the changes.
4580 Since the number of patches for U-Boot is growing, we need to
4581 establish some rules. Submissions which do not conform to these rules
4582 may be rejected, even when they contain important and valuable stuff.
4584 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4586 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4587 see https://lists.denx.de/listinfo/u-boot
4589 When you send a patch, please include the following information with
4592 * For bug fixes: a description of the bug and how your patch fixes
4593 this bug. Please try to include a way of demonstrating that the
4594 patch actually fixes something.
4596 * For new features: a description of the feature and your
4599 * For major contributions, add a MAINTAINERS file with your
4600 information and associated file and directory references.
4602 * When you add support for a new board, don't forget to add a
4603 maintainer e-mail address to the boards.cfg file, too.
4605 * If your patch adds new configuration options, don't forget to
4606 document these in the README file.
4608 * The patch itself. If you are using git (which is *strongly*
4609 recommended) you can easily generate the patch using the
4610 "git format-patch". If you then use "git send-email" to send it to
4611 the U-Boot mailing list, you will avoid most of the common problems
4612 with some other mail clients.
4614 If you cannot use git, use "diff -purN OLD NEW". If your version of
4615 diff does not support these options, then get the latest version of
4618 The current directory when running this command shall be the parent
4619 directory of the U-Boot source tree (i. e. please make sure that
4620 your patch includes sufficient directory information for the
4623 We prefer patches as plain text. MIME attachments are discouraged,
4624 and compressed attachments must not be used.
4626 * If one logical set of modifications affects or creates several
4627 files, all these changes shall be submitted in a SINGLE patch file.
4629 * Changesets that contain different, unrelated modifications shall be
4630 submitted as SEPARATE patches, one patch per changeset.
4635 * Before sending the patch, run the buildman script on your patched
4636 source tree and make sure that no errors or warnings are reported
4637 for any of the boards.
4639 * Keep your modifications to the necessary minimum: A patch
4640 containing several unrelated changes or arbitrary reformats will be
4641 returned with a request to re-formatting / split it.
4643 * If you modify existing code, make sure that your new code does not
4644 add to the memory footprint of the code ;-) Small is beautiful!
4645 When adding new features, these should compile conditionally only
4646 (using #ifdef), and the resulting code with the new feature
4647 disabled must not need more memory than the old code without your
4650 * Remember that there is a size limit of 100 kB per message on the
4651 u-boot mailing list. Bigger patches will be moderated. If they are
4652 reasonable and not too big, they will be acknowledged. But patches
4653 bigger than the size limit should be avoided.