1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see https://lists.denx.de/pipermail/u-boot and
55 https://marc.info/?l=u-boot
57 Where to get source code:
58 =========================
60 The U-Boot source code is maintained in the Git repository at
61 https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
62 https://source.denx.de/u-boot/u-boot
64 The "Tags" links on this page allow you to download tarballs of
65 any version you might be interested in. Official releases are also
66 available from the DENX file server through HTTPS or FTP.
67 https://ftp.denx.de/pub/u-boot/
68 ftp://ftp.denx.de/pub/u-boot/
74 - start from 8xxrom sources
75 - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
77 - make it easier to add custom boards
78 - make it possible to add other [PowerPC] CPUs
79 - extend functions, especially:
80 * Provide extended interface to Linux boot loader
83 * ATA disk / SCSI ... boot
84 - create ARMBoot project (https://sourceforge.net/projects/armboot)
85 - add other CPU families (starting with ARM)
86 - create U-Boot project (https://sourceforge.net/projects/u-boot)
87 - current project page: see https://www.denx.de/wiki/U-Boot
93 The "official" name of this project is "Das U-Boot". The spelling
94 "U-Boot" shall be used in all written text (documentation, comments
95 in source files etc.). Example:
97 This is the README file for the U-Boot project.
99 File names etc. shall be based on the string "u-boot". Examples:
101 include/asm-ppc/u-boot.h
103 #include <asm/u-boot.h>
105 Variable names, preprocessor constants etc. shall be either based on
106 the string "u_boot" or on "U_BOOT". Example:
108 U_BOOT_VERSION u_boot_logo
109 IH_OS_U_BOOT u_boot_hush_start
115 Starting with the release in October 2008, the names of the releases
116 were changed from numerical release numbers without deeper meaning
117 into a time stamp based numbering. Regular releases are identified by
118 names consisting of the calendar year and month of the release date.
119 Additional fields (if present) indicate release candidates or bug fix
120 releases in "stable" maintenance trees.
123 U-Boot v2009.11 - Release November 2009
124 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
125 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 /arch Architecture-specific files
132 /arc Files generic to ARC architecture
133 /arm Files generic to ARM architecture
134 /m68k Files generic to m68k architecture
135 /microblaze Files generic to microblaze architecture
136 /mips Files generic to MIPS architecture
137 /nds32 Files generic to NDS32 architecture
138 /nios2 Files generic to Altera NIOS2 architecture
139 /powerpc Files generic to PowerPC architecture
140 /riscv Files generic to RISC-V architecture
141 /sandbox Files generic to HW-independent "sandbox"
142 /sh Files generic to SH architecture
143 /x86 Files generic to x86 architecture
144 /xtensa Files generic to Xtensa architecture
145 /api Machine/arch-independent API for external apps
146 /board Board-dependent files
147 /cmd U-Boot commands functions
148 /common Misc architecture-independent functions
149 /configs Board default configuration files
150 /disk Code for disk drive partition handling
151 /doc Documentation (a mix of ReST and READMEs)
152 /drivers Device drivers
153 /dts Makefile for building internal U-Boot fdt.
154 /env Environment support
155 /examples Example code for standalone applications, etc.
156 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
157 /include Header Files
158 /lib Library routines generic to all architectures
159 /Licenses Various license files
161 /post Power On Self Test
162 /scripts Various build scripts and Makefiles
163 /test Various unit test files
164 /tools Tools to build and sign FIT images, etc.
166 Software Configuration:
167 =======================
169 Configuration is usually done using C preprocessor defines; the
170 rationale behind that is to avoid dead code whenever possible.
172 There are two classes of configuration variables:
174 * Configuration _OPTIONS_:
175 These are selectable by the user and have names beginning with
178 * Configuration _SETTINGS_:
179 These depend on the hardware etc. and should not be meddled with if
180 you don't know what you're doing; they have names beginning with
183 Previously, all configuration was done by hand, which involved creating
184 symbolic links and editing configuration files manually. More recently,
185 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
186 allowing you to use the "make menuconfig" command to configure your
190 Selection of Processor Architecture and Board Type:
191 ---------------------------------------------------
193 For all supported boards there are ready-to-use default
194 configurations available; just type "make <board_name>_defconfig".
196 Example: For a TQM823L module type:
199 make TQM823L_defconfig
201 Note: If you're looking for the default configuration file for a board
202 you're sure used to be there but is now missing, check the file
203 doc/README.scrapyard for a list of no longer supported boards.
208 U-Boot can be built natively to run on a Linux host using the 'sandbox'
209 board. This allows feature development which is not board- or architecture-
210 specific to be undertaken on a native platform. The sandbox is also used to
211 run some of U-Boot's tests.
213 See doc/arch/sandbox.rst for more details.
216 Board Initialisation Flow:
217 --------------------------
219 This is the intended start-up flow for boards. This should apply for both
220 SPL and U-Boot proper (i.e. they both follow the same rules).
222 Note: "SPL" stands for "Secondary Program Loader," which is explained in
223 more detail later in this file.
225 At present, SPL mostly uses a separate code path, but the function names
226 and roles of each function are the same. Some boards or architectures
227 may not conform to this. At least most ARM boards which use
228 CONFIG_SPL_FRAMEWORK conform to this.
230 Execution typically starts with an architecture-specific (and possibly
231 CPU-specific) start.S file, such as:
233 - arch/arm/cpu/armv7/start.S
234 - arch/powerpc/cpu/mpc83xx/start.S
235 - arch/mips/cpu/start.S
237 and so on. From there, three functions are called; the purpose and
238 limitations of each of these functions are described below.
241 - purpose: essential init to permit execution to reach board_init_f()
242 - no global_data or BSS
243 - there is no stack (ARMv7 may have one but it will soon be removed)
244 - must not set up SDRAM or use console
245 - must only do the bare minimum to allow execution to continue to
247 - this is almost never needed
248 - return normally from this function
251 - purpose: set up the machine ready for running board_init_r():
252 i.e. SDRAM and serial UART
253 - global_data is available
255 - BSS is not available, so you cannot use global/static variables,
256 only stack variables and global_data
258 Non-SPL-specific notes:
259 - dram_init() is called to set up DRAM. If already done in SPL this
263 - you can override the entire board_init_f() function with your own
265 - preloader_console_init() can be called here in extremis
266 - should set up SDRAM, and anything needed to make the UART work
267 - there is no need to clear BSS, it will be done by crt0.S
268 - for specific scenarios on certain architectures an early BSS *can*
269 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
270 of BSS prior to entering board_init_f()) but doing so is discouraged.
271 Instead it is strongly recommended to architect any code changes
272 or additions such to not depend on the availability of BSS during
273 board_init_f() as indicated in other sections of this README to
274 maintain compatibility and consistency across the entire code base.
275 - must return normally from this function (don't call board_init_r()
278 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
279 this point the stack and global_data are relocated to below
280 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
284 - purpose: main execution, common code
285 - global_data is available
287 - BSS is available, all static/global variables can be used
288 - execution eventually continues to main_loop()
290 Non-SPL-specific notes:
291 - U-Boot is relocated to the top of memory and is now running from
295 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
296 CONFIG_SPL_STACK_R_ADDR points into SDRAM
297 - preloader_console_init() can be called here - typically this is
298 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
299 spl_board_init() function containing this call
300 - loads U-Boot or (in falcon mode) Linux
304 Configuration Options:
305 ----------------------
307 Configuration depends on the combination of board and CPU type; all
308 such information is kept in a configuration file
309 "include/configs/<board_name>.h".
311 Example: For a TQM823L module, all configuration settings are in
312 "include/configs/TQM823L.h".
315 Many of the options are named exactly as the corresponding Linux
316 kernel configuration options. The intention is to make it easier to
317 build a config tool - later.
319 - ARM Platform Bus Type(CCI):
320 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
321 provides full cache coherency between two clusters of multi-core
322 CPUs and I/O coherency for devices and I/O masters
324 CONFIG_SYS_FSL_HAS_CCI400
326 Defined For SoC that has cache coherent interconnect
329 CONFIG_SYS_FSL_HAS_CCN504
331 Defined for SoC that has cache coherent interconnect CCN-504
333 The following options need to be configured:
335 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
337 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
342 Specifies that the core is a 64-bit PowerPC implementation (implements
343 the "64" category of the Power ISA). This is necessary for ePAPR
344 compliance, among other possible reasons.
346 CONFIG_SYS_FSL_TBCLK_DIV
348 Defines the core time base clock divider ratio compared to the
349 system clock. On most PQ3 devices this is 8, on newer QorIQ
350 devices it can be 16 or 32. The ratio varies from SoC to Soc.
352 CONFIG_SYS_FSL_PCIE_COMPAT
354 Defines the string to utilize when trying to match PCIe device
355 tree nodes for the given platform.
357 CONFIG_SYS_FSL_ERRATUM_A004510
359 Enables a workaround for erratum A004510. If set,
360 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
361 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
364 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
366 Defines one or two SoC revisions (low 8 bits of SVR)
367 for which the A004510 workaround should be applied.
369 The rest of SVR is either not relevant to the decision
370 of whether the erratum is present (e.g. p2040 versus
371 p2041) or is implied by the build target, which controls
372 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
374 See Freescale App Note 4493 for more information about
377 CONFIG_A003399_NOR_WORKAROUND
378 Enables a workaround for IFC erratum A003399. It is only
379 required during NOR boot.
381 CONFIG_A008044_WORKAROUND
382 Enables a workaround for T1040/T1042 erratum A008044. It is only
383 required during NAND boot and valid for Rev 1.0 SoC revision
385 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
387 This is the value to write into CCSR offset 0x18600
388 according to the A004510 workaround.
390 CONFIG_SYS_FSL_DSP_DDR_ADDR
391 This value denotes start offset of DDR memory which is
392 connected exclusively to the DSP cores.
394 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
395 This value denotes start offset of M2 memory
396 which is directly connected to the DSP core.
398 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
399 This value denotes start offset of M3 memory which is directly
400 connected to the DSP core.
402 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
403 This value denotes start offset of DSP CCSR space.
405 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
406 Single Source Clock is clocking mode present in some of FSL SoC's.
407 In this mode, a single differential clock is used to supply
408 clocks to the sysclock, ddrclock and usbclock.
410 CONFIG_SYS_CPC_REINIT_F
411 This CONFIG is defined when the CPC is configured as SRAM at the
412 time of U-Boot entry and is required to be re-initialized.
415 Indicates this SoC supports deep sleep feature. If deep sleep is
416 supported, core will start to execute uboot when wakes up.
418 - Generic CPU options:
419 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
421 Defines the endianess of the CPU. Implementation of those
422 values is arch specific.
425 Freescale DDR driver in use. This type of DDR controller is
426 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
428 CONFIG_SYS_FSL_DDR_ADDR
429 Freescale DDR memory-mapped register base.
431 CONFIG_SYS_FSL_DDR_EMU
432 Specify emulator support for DDR. Some DDR features such as
433 deskew training are not available.
435 CONFIG_SYS_FSL_DDRC_GEN1
436 Freescale DDR1 controller.
438 CONFIG_SYS_FSL_DDRC_GEN2
439 Freescale DDR2 controller.
441 CONFIG_SYS_FSL_DDRC_GEN3
442 Freescale DDR3 controller.
444 CONFIG_SYS_FSL_DDRC_GEN4
445 Freescale DDR4 controller.
447 CONFIG_SYS_FSL_DDRC_ARM_GEN3
448 Freescale DDR3 controller for ARM-based SoCs.
451 Board config to use DDR1. It can be enabled for SoCs with
452 Freescale DDR1 or DDR2 controllers, depending on the board
456 Board config to use DDR2. It can be enabled for SoCs with
457 Freescale DDR2 or DDR3 controllers, depending on the board
461 Board config to use DDR3. It can be enabled for SoCs with
462 Freescale DDR3 or DDR3L controllers.
465 Board config to use DDR3L. It can be enabled for SoCs with
468 CONFIG_SYS_FSL_IFC_BE
469 Defines the IFC controller register space as Big Endian
471 CONFIG_SYS_FSL_IFC_LE
472 Defines the IFC controller register space as Little Endian
474 CONFIG_SYS_FSL_IFC_CLK_DIV
475 Defines divider of platform clock(clock input to IFC controller).
477 CONFIG_SYS_FSL_LBC_CLK_DIV
478 Defines divider of platform clock(clock input to eLBC controller).
480 CONFIG_SYS_FSL_PBL_PBI
481 It enables addition of RCW (Power on reset configuration) in built image.
482 Please refer doc/README.pblimage for more details
484 CONFIG_SYS_FSL_PBL_RCW
485 It adds PBI(pre-boot instructions) commands in u-boot build image.
486 PBI commands can be used to configure SoC before it starts the execution.
487 Please refer doc/README.pblimage for more details
489 CONFIG_SYS_FSL_DDR_BE
490 Defines the DDR controller register space as Big Endian
492 CONFIG_SYS_FSL_DDR_LE
493 Defines the DDR controller register space as Little Endian
495 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
496 Physical address from the view of DDR controllers. It is the
497 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
498 it could be different for ARM SoCs.
500 CONFIG_SYS_FSL_DDR_INTLV_256B
501 DDR controller interleaving on 256-byte. This is a special
502 interleaving mode, handled by Dickens for Freescale layerscape
505 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
506 Number of controllers used as main memory.
508 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
509 Number of controllers used for other than main memory.
511 CONFIG_SYS_FSL_HAS_DP_DDR
512 Defines the SoC has DP-DDR used for DPAA.
514 CONFIG_SYS_FSL_SEC_BE
515 Defines the SEC controller register space as Big Endian
517 CONFIG_SYS_FSL_SEC_LE
518 Defines the SEC controller register space as Little Endian
521 CONFIG_SYS_INIT_SP_OFFSET
523 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
524 pointer. This is needed for the temporary stack before
527 CONFIG_XWAY_SWAP_BYTES
529 Enable compilation of tools/xway-swap-bytes needed for Lantiq
530 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
531 be swapped if a flash programmer is used.
534 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
536 Select high exception vectors of the ARM core, e.g., do not
537 clear the V bit of the c1 register of CP15.
540 Generic timer clock source frequency.
542 COUNTER_FREQUENCY_REAL
543 Generic timer clock source frequency if the real clock is
544 different from COUNTER_FREQUENCY, and can only be determined
548 CONFIG_TEGRA_SUPPORT_NON_SECURE
550 Support executing U-Boot in non-secure (NS) mode. Certain
551 impossible actions will be skipped if the CPU is in NS mode,
552 such as ARM architectural timer initialization.
554 - Linux Kernel Interface:
555 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
557 When transferring memsize parameter to Linux, some versions
558 expect it to be in bytes, others in MB.
559 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
563 New kernel versions are expecting firmware settings to be
564 passed using flattened device trees (based on open firmware
568 * New libfdt-based support
569 * Adds the "fdt" command
570 * The bootm command automatically updates the fdt
572 OF_TBCLK - The timebase frequency.
574 boards with QUICC Engines require OF_QE to set UCC MAC
577 CONFIG_OF_BOARD_SETUP
579 Board code has addition modification that it wants to make
580 to the flat device tree before handing it off to the kernel
582 CONFIG_OF_SYSTEM_SETUP
584 Other code has addition modification that it wants to make
585 to the flat device tree before handing it off to the kernel.
586 This causes ft_system_setup() to be called before booting
591 U-Boot can detect if an IDE device is present or not.
592 If not, and this new config option is activated, U-Boot
593 removes the ATA node from the DTS before booting Linux,
594 so the Linux IDE driver does not probe the device and
595 crash. This is needed for buggy hardware (uc101) where
596 no pull down resistor is connected to the signal IDE5V_DD7.
598 CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
600 This setting is mandatory for all boards that have only one
601 machine type and must be used to specify the machine type
602 number as it appears in the ARM machine registry
603 (see https://www.arm.linux.org.uk/developer/machines/).
604 Only boards that have multiple machine types supported
605 in a single configuration file and the machine type is
606 runtime discoverable, do not have to use this setting.
608 - vxWorks boot parameters:
610 bootvx constructs a valid bootline using the following
611 environments variables: bootdev, bootfile, ipaddr, netmask,
612 serverip, gatewayip, hostname, othbootargs.
613 It loads the vxWorks image pointed bootfile.
615 Note: If a "bootargs" environment is defined, it will override
616 the defaults discussed just above.
618 - Cache Configuration:
619 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
621 - Cache Configuration for ARM:
622 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
624 CONFIG_SYS_PL310_BASE - Physical base address of PL310
625 controller register space
630 Define this if you want support for Amba PrimeCell PL011 UARTs.
634 If you have Amba PrimeCell PL011 UARTs, set this variable to
635 the clock speed of the UARTs.
639 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
640 define this to a list of base addresses for each (supported)
641 port. See e.g. include/configs/versatile.h
643 CONFIG_SERIAL_HW_FLOW_CONTROL
645 Define this variable to enable hw flow control in serial driver.
646 Current user of this option is drivers/serial/nsl16550.c driver
650 Only needed when CONFIG_BOOTDELAY is enabled;
651 define a command string that is automatically executed
652 when no character is read on the console interface
653 within "Boot Delay" after reset.
655 CONFIG_RAMBOOT and CONFIG_NFSBOOT
656 The value of these goes into the environment as
657 "ramboot" and "nfsboot" respectively, and can be used
658 as a convenience, when switching between booting from
661 - Serial Download Echo Mode:
663 If defined to 1, all characters received during a
664 serial download (using the "loads" command) are
665 echoed back. This might be needed by some terminal
666 emulations (like "cu"), but may as well just take
667 time on others. This setting #define's the initial
668 value of the "loads_echo" environment variable.
670 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
672 Select one of the baudrates listed in
673 CONFIG_SYS_BAUDRATE_TABLE, see below.
675 - Removal of commands
676 If no commands are needed to boot, you can disable
677 CONFIG_CMDLINE to remove them. In this case, the command line
678 will not be available, and when U-Boot wants to execute the
679 boot command (on start-up) it will call board_run_command()
680 instead. This can reduce image size significantly for very
681 simple boot procedures.
683 - Regular expression support:
685 If this variable is defined, U-Boot is linked against
686 the SLRE (Super Light Regular Expression) library,
687 which adds regex support to some commands, as for
688 example "env grep" and "setexpr".
692 If this variable is defined, U-Boot will use a device tree
693 to configure its devices, instead of relying on statically
694 compiled #defines in the board file. This option is
695 experimental and only available on a few boards. The device
696 tree is available in the global data as gd->fdt_blob.
698 U-Boot needs to get its device tree from somewhere. This can
699 be done using one of the three options below:
702 If this variable is defined, U-Boot will embed a device tree
703 binary in its image. This device tree file should be in the
704 board directory and called <soc>-<board>.dts. The binary file
705 is then picked up in board_init_f() and made available through
706 the global data structure as gd->fdt_blob.
709 If this variable is defined, U-Boot will build a device tree
710 binary. It will be called u-boot.dtb. Architecture-specific
711 code will locate it at run-time. Generally this works by:
713 cat u-boot.bin u-boot.dtb >image.bin
715 and in fact, U-Boot does this for you, creating a file called
716 u-boot-dtb.bin which is useful in the common case. You can
717 still use the individual files if you need something more
721 If this variable is defined, U-Boot will use the device tree
722 provided by the board at runtime instead of embedding one with
723 the image. Only boards defining board_fdt_blob_setup() support
724 this option (see include/fdtdec.h file).
728 If this variable is defined, it enables watchdog
729 support for the SoC. There must be support in the SoC
730 specific code for a watchdog. For the 8xx
731 CPUs, the SIU Watchdog feature is enabled in the SYPCR
732 register. When supported for a specific SoC is
733 available, then no further board specific code should
737 When using a watchdog circuitry external to the used
738 SoC, then define this variable and provide board
739 specific code for the "hw_watchdog_reset" function.
741 CONFIG_SYS_WATCHDOG_FREQ
742 Some platforms automatically call WATCHDOG_RESET()
743 from the timer interrupt handler every
744 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
745 board configuration file, a default of CONFIG_SYS_HZ/2
746 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
747 to 0 disables calling WATCHDOG_RESET() from the timer
752 When CONFIG_CMD_DATE is selected, the type of the RTC
753 has to be selected, too. Define exactly one of the
756 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
757 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
758 CONFIG_RTC_MC146818 - use MC146818 RTC
759 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
760 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
761 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
762 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
763 CONFIG_RTC_DS164x - use Dallas DS164x RTC
764 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
765 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
766 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
767 CONFIG_SYS_RV3029_TCR - enable trickle charger on
770 Note that if the RTC uses I2C, then the I2C interface
771 must also be configured. See I2C Support, below.
774 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
776 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
777 chip-ngpio pairs that tell the PCA953X driver the number of
778 pins supported by a particular chip.
780 Note that if the GPIO device uses I2C, then the I2C interface
781 must also be configured. See I2C Support, below.
784 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
785 accesses and can checksum them or write a list of them out
786 to memory. See the 'iotrace' command for details. This is
787 useful for testing device drivers since it can confirm that
788 the driver behaves the same way before and after a code
789 change. Currently this is supported on sandbox and arm. To
790 add support for your architecture, add '#include <iotrace.h>'
791 to the bottom of arch/<arch>/include/asm/io.h and test.
793 Example output from the 'iotrace stats' command is below.
794 Note that if the trace buffer is exhausted, the checksum will
795 still continue to operate.
798 Start: 10000000 (buffer start address)
799 Size: 00010000 (buffer size)
800 Offset: 00000120 (current buffer offset)
801 Output: 10000120 (start + offset)
802 Count: 00000018 (number of trace records)
803 CRC32: 9526fb66 (CRC32 of all trace records)
807 When CONFIG_TIMESTAMP is selected, the timestamp
808 (date and time) of an image is printed by image
809 commands like bootm or iminfo. This option is
810 automatically enabled when you select CONFIG_CMD_DATE .
812 - Partition Labels (disklabels) Supported:
813 Zero or more of the following:
814 CONFIG_MAC_PARTITION Apple's MacOS partition table.
815 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
816 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
817 bootloader. Note 2TB partition limit; see
819 CONFIG_SCSI) you must configure support for at
820 least one non-MTD partition type as well.
823 CONFIG_IDE_RESET_ROUTINE - this is defined in several
824 board configurations files but used nowhere!
826 CONFIG_IDE_RESET - is this is defined, IDE Reset will
827 be performed by calling the function
828 ide_set_reset(int reset)
829 which has to be defined in a board specific file
834 Set this to enable ATAPI support.
839 Set this to enable support for disks larger than 137GB
840 Also look at CONFIG_SYS_64BIT_LBA.
841 Whithout these , LBA48 support uses 32bit variables and will 'only'
842 support disks up to 2.1TB.
844 CONFIG_SYS_64BIT_LBA:
845 When enabled, makes the IDE subsystem use 64bit sector addresses.
849 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
850 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
851 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
852 maximum numbers of LUNs, SCSI ID's and target
855 The environment variable 'scsidevs' is set to the number of
856 SCSI devices found during the last scan.
858 - NETWORK Support (PCI):
860 Support for Intel 8254x/8257x gigabit chips.
863 Utility code for direct access to the SPI bus on Intel 8257x.
864 This does not do anything useful unless you set at least one
865 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
867 CONFIG_E1000_SPI_GENERIC
868 Allow generic access to the SPI bus on the Intel 8257x, for
869 example with the "sspi" command.
872 Support for National dp83815 chips.
875 Support for National dp8382[01] gigabit chips.
877 - NETWORK Support (other):
879 CONFIG_DRIVER_AT91EMAC
880 Support for AT91RM9200 EMAC.
883 Define this to use reduced MII inteface
885 CONFIG_DRIVER_AT91EMAC_QUIET
886 If this defined, the driver is quiet.
887 The driver doen't show link status messages.
890 Support for the Calxeda XGMAC device
893 Support for SMSC's LAN91C96 chips.
895 CONFIG_LAN91C96_USE_32_BIT
896 Define this to enable 32 bit addressing
899 Support for SMSC's LAN91C111 chip
902 Define this to hold the physical address
903 of the device (I/O space)
905 CONFIG_SMC_USE_32_BIT
906 Define this if data bus is 32 bits
908 CONFIG_SMC_USE_IOFUNCS
909 Define this to use i/o functions instead of macros
910 (some hardware wont work with macros)
912 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
913 Define this if you have more then 3 PHYs.
916 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
918 CONFIG_FTGMAC100_EGIGA
919 Define this to use GE link update with gigabit PHY.
920 Define this if FTGMAC100 is connected to gigabit PHY.
921 If your system has 10/100 PHY only, it might not occur
922 wrong behavior. Because PHY usually return timeout or
923 useless data when polling gigabit status and gigabit
924 control registers. This behavior won't affect the
925 correctnessof 10/100 link speed update.
928 Support for Renesas on-chip Ethernet controller
930 CONFIG_SH_ETHER_USE_PORT
931 Define the number of ports to be used
933 CONFIG_SH_ETHER_PHY_ADDR
934 Define the ETH PHY's address
936 CONFIG_SH_ETHER_CACHE_WRITEBACK
937 If this option is set, the driver enables cache flush.
943 CONFIG_TPM_TIS_INFINEON
944 Support for Infineon i2c bus TPM devices. Only one device
945 per system is supported at this time.
947 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
948 Define the burst count bytes upper limit
951 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
953 CONFIG_TPM_ST33ZP24_I2C
954 Support for STMicroelectronics ST33ZP24 I2C devices.
955 Requires TPM_ST33ZP24 and I2C.
957 CONFIG_TPM_ST33ZP24_SPI
958 Support for STMicroelectronics ST33ZP24 SPI devices.
959 Requires TPM_ST33ZP24 and SPI.
962 Support for Atmel TWI TPM device. Requires I2C support.
965 Support for generic parallel port TPM devices. Only one device
966 per system is supported at this time.
968 CONFIG_TPM_TIS_BASE_ADDRESS
969 Base address where the generic TPM device is mapped
970 to. Contemporary x86 systems usually map it at
974 Define this to enable the TPM support library which provides
975 functional interfaces to some TPM commands.
976 Requires support for a TPM device.
978 CONFIG_TPM_AUTH_SESSIONS
979 Define this to enable authorized functions in the TPM library.
980 Requires CONFIG_TPM and CONFIG_SHA1.
983 At the moment only the UHCI host controller is
984 supported (PIP405, MIP405); define
985 CONFIG_USB_UHCI to enable it.
986 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
987 and define CONFIG_USB_STORAGE to enable the USB
990 Supported are USB Keyboards and USB Floppy drives
993 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
994 txfilltuning field in the EHCI controller on reset.
996 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1000 Define the below if you wish to use the USB console.
1001 Once firmware is rebuilt from a serial console issue the
1002 command "setenv stdin usbtty; setenv stdout usbtty" and
1003 attach your USB cable. The Unix command "dmesg" should print
1004 it has found a new device. The environment variable usbtty
1005 can be set to gserial or cdc_acm to enable your device to
1006 appear to a USB host as a Linux gserial device or a
1007 Common Device Class Abstract Control Model serial device.
1008 If you select usbtty = gserial you should be able to enumerate
1010 # modprobe usbserial vendor=0xVendorID product=0xProductID
1011 else if using cdc_acm, simply setting the environment
1012 variable usbtty to be cdc_acm should suffice. The following
1013 might be defined in YourBoardName.h
1016 Define this to build a UDC device
1019 Define this to have a tty type of device available to
1020 talk to the UDC device
1023 Define this to enable the high speed support for usb
1024 device and usbtty. If this feature is enabled, a routine
1025 int is_usbd_high_speed(void)
1026 also needs to be defined by the driver to dynamically poll
1027 whether the enumeration has succeded at high speed or full
1030 CONFIG_SYS_CONSOLE_IS_IN_ENV
1031 Define this if you want stdin, stdout &/or stderr to
1034 If you have a USB-IF assigned VendorID then you may wish to
1035 define your own vendor specific values either in BoardName.h
1036 or directly in usbd_vendor_info.h. If you don't define
1037 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1038 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1039 should pretend to be a Linux device to it's target host.
1041 CONFIG_USBD_MANUFACTURER
1042 Define this string as the name of your company for
1043 - CONFIG_USBD_MANUFACTURER "my company"
1045 CONFIG_USBD_PRODUCT_NAME
1046 Define this string as the name of your product
1047 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1049 CONFIG_USBD_VENDORID
1050 Define this as your assigned Vendor ID from the USB
1051 Implementors Forum. This *must* be a genuine Vendor ID
1052 to avoid polluting the USB namespace.
1053 - CONFIG_USBD_VENDORID 0xFFFF
1055 CONFIG_USBD_PRODUCTID
1056 Define this as the unique Product ID
1058 - CONFIG_USBD_PRODUCTID 0xFFFF
1060 - ULPI Layer Support:
1061 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1062 the generic ULPI layer. The generic layer accesses the ULPI PHY
1063 via the platform viewport, so you need both the genric layer and
1064 the viewport enabled. Currently only Chipidea/ARC based
1065 viewport is supported.
1066 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1067 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1068 If your ULPI phy needs a different reference clock than the
1069 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1070 the appropriate value in Hz.
1073 The MMC controller on the Intel PXA is supported. To
1074 enable this define CONFIG_MMC. The MMC can be
1075 accessed from the boot prompt by mapping the device
1076 to physical memory similar to flash. Command line is
1077 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1078 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1081 Support for Renesas on-chip MMCIF controller
1083 CONFIG_SH_MMCIF_ADDR
1084 Define the base address of MMCIF registers
1087 Define the clock frequency for MMCIF
1089 - USB Device Firmware Update (DFU) class support:
1091 This enables the USB portion of the DFU USB class
1094 This enables support for exposing NAND devices via DFU.
1097 This enables support for exposing RAM via DFU.
1098 Note: DFU spec refer to non-volatile memory usage, but
1099 allow usages beyond the scope of spec - here RAM usage,
1100 one that would help mostly the developer.
1102 CONFIG_SYS_DFU_DATA_BUF_SIZE
1103 Dfu transfer uses a buffer before writing data to the
1104 raw storage device. Make the size (in bytes) of this buffer
1105 configurable. The size of this buffer is also configurable
1106 through the "dfu_bufsiz" environment variable.
1108 CONFIG_SYS_DFU_MAX_FILE_SIZE
1109 When updating files rather than the raw storage device,
1110 we use a static buffer to copy the file into and then write
1111 the buffer once we've been given the whole file. Define
1112 this to the maximum filesize (in bytes) for the buffer.
1113 Default is 4 MiB if undefined.
1115 DFU_DEFAULT_POLL_TIMEOUT
1116 Poll timeout [ms], is the timeout a device can send to the
1117 host. The host must wait for this timeout before sending
1118 a subsequent DFU_GET_STATUS request to the device.
1120 DFU_MANIFEST_POLL_TIMEOUT
1121 Poll timeout [ms], which the device sends to the host when
1122 entering dfuMANIFEST state. Host waits this timeout, before
1123 sending again an USB request to the device.
1125 - Journaling Flash filesystem support:
1127 Define these for a default partition on a NAND device
1129 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1130 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1131 Define these for a default partition on a NOR device
1134 See Kconfig help for available keyboard drivers.
1138 Define this to enable a custom keyboard support.
1139 This simply calls drv_keyboard_init() which must be
1140 defined in your board-specific files. This option is deprecated
1141 and is only used by novena. For new boards, use driver model
1146 Enable the Freescale DIU video driver. Reference boards for
1147 SOCs that have a DIU should define this macro to enable DIU
1148 support, and should also define these other macros:
1153 CONFIG_VIDEO_SW_CURSOR
1154 CONFIG_VGA_AS_SINGLE_DEVICE
1156 CONFIG_VIDEO_BMP_LOGO
1158 The DIU driver will look for the 'video-mode' environment
1159 variable, and if defined, enable the DIU as a console during
1160 boot. See the documentation file doc/README.video for a
1161 description of this variable.
1163 - LCD Support: CONFIG_LCD
1165 Define this to enable LCD support (for output to LCD
1166 display); also select one of the supported displays
1167 by defining one of these:
1171 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1173 CONFIG_NEC_NL6448AC33:
1175 NEC NL6448AC33-18. Active, color, single scan.
1177 CONFIG_NEC_NL6448BC20
1179 NEC NL6448BC20-08. 6.5", 640x480.
1180 Active, color, single scan.
1182 CONFIG_NEC_NL6448BC33_54
1184 NEC NL6448BC33-54. 10.4", 640x480.
1185 Active, color, single scan.
1189 Sharp 320x240. Active, color, single scan.
1190 It isn't 16x9, and I am not sure what it is.
1192 CONFIG_SHARP_LQ64D341
1194 Sharp LQ64D341 display, 640x480.
1195 Active, color, single scan.
1199 HLD1045 display, 640x480.
1200 Active, color, single scan.
1204 Optrex CBL50840-2 NF-FW 99 22 M5
1206 Hitachi LMG6912RPFC-00T
1210 320x240. Black & white.
1212 CONFIG_LCD_ALIGNMENT
1214 Normally the LCD is page-aligned (typically 4KB). If this is
1215 defined then the LCD will be aligned to this value instead.
1216 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1217 here, since it is cheaper to change data cache settings on
1218 a per-section basis.
1223 Sometimes, for example if the display is mounted in portrait
1224 mode or even if it's mounted landscape but rotated by 180degree,
1225 we need to rotate our content of the display relative to the
1226 framebuffer, so that user can read the messages which are
1228 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1229 initialized with a given rotation from "vl_rot" out of
1230 "vidinfo_t" which is provided by the board specific code.
1231 The value for vl_rot is coded as following (matching to
1232 fbcon=rotate:<n> linux-kernel commandline):
1233 0 = no rotation respectively 0 degree
1234 1 = 90 degree rotation
1235 2 = 180 degree rotation
1236 3 = 270 degree rotation
1238 If CONFIG_LCD_ROTATION is not defined, the console will be
1239 initialized with 0degree rotation.
1243 Support drawing of RLE8-compressed bitmaps on the LCD.
1247 Enables an 'i2c edid' command which can read EDID
1248 information over I2C from an attached LCD display.
1251 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1253 The clock frequency of the MII bus
1255 CONFIG_PHY_RESET_DELAY
1257 Some PHY like Intel LXT971A need extra delay after
1258 reset before any MII register access is possible.
1259 For such PHY, set this option to the usec delay
1260 required. (minimum 300usec for LXT971A)
1262 CONFIG_PHY_CMD_DELAY (ppc4xx)
1264 Some PHY like Intel LXT971A need extra delay after
1265 command issued before MII status register can be read
1270 Define a default value for the IP address to use for
1271 the default Ethernet interface, in case this is not
1272 determined through e.g. bootp.
1273 (Environment variable "ipaddr")
1275 - Server IP address:
1278 Defines a default value for the IP address of a TFTP
1279 server to contact when using the "tftboot" command.
1280 (Environment variable "serverip")
1282 CONFIG_KEEP_SERVERADDR
1284 Keeps the server's MAC address, in the env 'serveraddr'
1285 for passing to bootargs (like Linux's netconsole option)
1287 - Gateway IP address:
1290 Defines a default value for the IP address of the
1291 default router where packets to other networks are
1293 (Environment variable "gatewayip")
1298 Defines a default value for the subnet mask (or
1299 routing prefix) which is used to determine if an IP
1300 address belongs to the local subnet or needs to be
1301 forwarded through a router.
1302 (Environment variable "netmask")
1304 - BOOTP Recovery Mode:
1305 CONFIG_BOOTP_RANDOM_DELAY
1307 If you have many targets in a network that try to
1308 boot using BOOTP, you may want to avoid that all
1309 systems send out BOOTP requests at precisely the same
1310 moment (which would happen for instance at recovery
1311 from a power failure, when all systems will try to
1312 boot, thus flooding the BOOTP server. Defining
1313 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1314 inserted before sending out BOOTP requests. The
1315 following delays are inserted then:
1317 1st BOOTP request: delay 0 ... 1 sec
1318 2nd BOOTP request: delay 0 ... 2 sec
1319 3rd BOOTP request: delay 0 ... 4 sec
1321 BOOTP requests: delay 0 ... 8 sec
1323 CONFIG_BOOTP_ID_CACHE_SIZE
1325 BOOTP packets are uniquely identified using a 32-bit ID. The
1326 server will copy the ID from client requests to responses and
1327 U-Boot will use this to determine if it is the destination of
1328 an incoming response. Some servers will check that addresses
1329 aren't in use before handing them out (usually using an ARP
1330 ping) and therefore take up to a few hundred milliseconds to
1331 respond. Network congestion may also influence the time it
1332 takes for a response to make it back to the client. If that
1333 time is too long, U-Boot will retransmit requests. In order
1334 to allow earlier responses to still be accepted after these
1335 retransmissions, U-Boot's BOOTP client keeps a small cache of
1336 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1337 cache. The default is to keep IDs for up to four outstanding
1338 requests. Increasing this will allow U-Boot to accept offers
1339 from a BOOTP client in networks with unusually high latency.
1341 - DHCP Advanced Options:
1342 You can fine tune the DHCP functionality by defining
1343 CONFIG_BOOTP_* symbols:
1345 CONFIG_BOOTP_NISDOMAIN
1346 CONFIG_BOOTP_BOOTFILESIZE
1347 CONFIG_BOOTP_NTPSERVER
1348 CONFIG_BOOTP_TIMEOFFSET
1349 CONFIG_BOOTP_VENDOREX
1350 CONFIG_BOOTP_MAY_FAIL
1352 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1353 environment variable, not the BOOTP server.
1355 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1356 after the configured retry count, the call will fail
1357 instead of starting over. This can be used to fail over
1358 to Link-local IP address configuration if the DHCP server
1361 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1363 A 32bit value in microseconds for a delay between
1364 receiving a "DHCP Offer" and sending the "DHCP Request".
1365 This fixes a problem with certain DHCP servers that don't
1366 respond 100% of the time to a "DHCP request". E.g. On an
1367 AT91RM9200 processor running at 180MHz, this delay needed
1368 to be *at least* 15,000 usec before a Windows Server 2003
1369 DHCP server would reply 100% of the time. I recommend at
1370 least 50,000 usec to be safe. The alternative is to hope
1371 that one of the retries will be successful but note that
1372 the DHCP timeout and retry process takes a longer than
1375 - Link-local IP address negotiation:
1376 Negotiate with other link-local clients on the local network
1377 for an address that doesn't require explicit configuration.
1378 This is especially useful if a DHCP server cannot be guaranteed
1379 to exist in all environments that the device must operate.
1381 See doc/README.link-local for more information.
1383 - MAC address from environment variables
1385 FDT_SEQ_MACADDR_FROM_ENV
1387 Fix-up device tree with MAC addresses fetched sequentially from
1388 environment variables. This config work on assumption that
1389 non-usable ethernet node of device-tree are either not present
1390 or their status has been marked as "disabled".
1393 CONFIG_CDP_DEVICE_ID
1395 The device id used in CDP trigger frames.
1397 CONFIG_CDP_DEVICE_ID_PREFIX
1399 A two character string which is prefixed to the MAC address
1404 A printf format string which contains the ascii name of
1405 the port. Normally is set to "eth%d" which sets
1406 eth0 for the first Ethernet, eth1 for the second etc.
1408 CONFIG_CDP_CAPABILITIES
1410 A 32bit integer which indicates the device capabilities;
1411 0x00000010 for a normal host which does not forwards.
1415 An ascii string containing the version of the software.
1419 An ascii string containing the name of the platform.
1423 A 32bit integer sent on the trigger.
1425 CONFIG_CDP_POWER_CONSUMPTION
1427 A 16bit integer containing the power consumption of the
1428 device in .1 of milliwatts.
1430 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1432 A byte containing the id of the VLAN.
1434 - Status LED: CONFIG_LED_STATUS
1436 Several configurations allow to display the current
1437 status using a LED. For instance, the LED will blink
1438 fast while running U-Boot code, stop blinking as
1439 soon as a reply to a BOOTP request was received, and
1440 start blinking slow once the Linux kernel is running
1441 (supported by a status LED driver in the Linux
1442 kernel). Defining CONFIG_LED_STATUS enables this
1447 CONFIG_LED_STATUS_GPIO
1448 The status LED can be connected to a GPIO pin.
1449 In such cases, the gpio_led driver can be used as a
1450 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1451 to include the gpio_led driver in the U-Boot binary.
1453 CONFIG_GPIO_LED_INVERTED_TABLE
1454 Some GPIO connected LEDs may have inverted polarity in which
1455 case the GPIO high value corresponds to LED off state and
1456 GPIO low value corresponds to LED on state.
1457 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1458 with a list of GPIO LEDs that have inverted polarity.
1461 CONFIG_SYS_NUM_I2C_BUSES
1462 Hold the number of i2c buses you want to use.
1464 CONFIG_SYS_I2C_DIRECT_BUS
1465 define this, if you don't use i2c muxes on your hardware.
1466 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1469 CONFIG_SYS_I2C_MAX_HOPS
1470 define how many muxes are maximal consecutively connected
1471 on one i2c bus. If you not use i2c muxes, omit this
1474 CONFIG_SYS_I2C_BUSES
1475 hold a list of buses you want to use, only used if
1476 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1477 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1478 CONFIG_SYS_NUM_I2C_BUSES = 9:
1480 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1481 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1482 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1483 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1484 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1485 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1486 {1, {I2C_NULL_HOP}}, \
1487 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1488 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1492 bus 0 on adapter 0 without a mux
1493 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1494 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1495 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1496 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1497 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1498 bus 6 on adapter 1 without a mux
1499 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1500 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1502 If you do not have i2c muxes on your board, omit this define.
1504 - Legacy I2C Support:
1505 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1506 then the following macros need to be defined (examples are
1507 from include/configs/lwmon.h):
1511 (Optional). Any commands necessary to enable the I2C
1512 controller or configure ports.
1514 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1518 The code necessary to make the I2C data line active
1519 (driven). If the data line is open collector, this
1522 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1526 The code necessary to make the I2C data line tri-stated
1527 (inactive). If the data line is open collector, this
1530 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1534 Code that returns true if the I2C data line is high,
1537 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1541 If <bit> is true, sets the I2C data line high. If it
1542 is false, it clears it (low).
1544 eg: #define I2C_SDA(bit) \
1545 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1546 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1550 If <bit> is true, sets the I2C clock line high. If it
1551 is false, it clears it (low).
1553 eg: #define I2C_SCL(bit) \
1554 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1555 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1559 This delay is invoked four times per clock cycle so this
1560 controls the rate of data transfer. The data rate thus
1561 is 1 / (I2C_DELAY * 4). Often defined to be something
1564 #define I2C_DELAY udelay(2)
1566 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1568 If your arch supports the generic GPIO framework (asm/gpio.h),
1569 then you may alternatively define the two GPIOs that are to be
1570 used as SCL / SDA. Any of the previous I2C_xxx macros will
1571 have GPIO-based defaults assigned to them as appropriate.
1573 You should define these to the GPIO value as given directly to
1574 the generic GPIO functions.
1576 CONFIG_SYS_I2C_INIT_BOARD
1578 When a board is reset during an i2c bus transfer
1579 chips might think that the current transfer is still
1580 in progress. On some boards it is possible to access
1581 the i2c SCLK line directly, either by using the
1582 processor pin as a GPIO or by having a second pin
1583 connected to the bus. If this option is defined a
1584 custom i2c_init_board() routine in boards/xxx/board.c
1585 is run early in the boot sequence.
1587 CONFIG_I2C_MULTI_BUS
1589 This option allows the use of multiple I2C buses, each of which
1590 must have a controller. At any point in time, only one bus is
1591 active. To switch to a different bus, use the 'i2c dev' command.
1592 Note that bus numbering is zero-based.
1594 CONFIG_SYS_I2C_NOPROBES
1596 This option specifies a list of I2C devices that will be skipped
1597 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1598 is set, specify a list of bus-device pairs. Otherwise, specify
1599 a 1D array of device addresses
1602 #undef CONFIG_I2C_MULTI_BUS
1603 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1605 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1607 #define CONFIG_I2C_MULTI_BUS
1608 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1610 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1612 CONFIG_SYS_SPD_BUS_NUM
1614 If defined, then this indicates the I2C bus number for DDR SPD.
1615 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1617 CONFIG_SYS_RTC_BUS_NUM
1619 If defined, then this indicates the I2C bus number for the RTC.
1620 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1622 CONFIG_SOFT_I2C_READ_REPEATED_START
1624 defining this will force the i2c_read() function in
1625 the soft_i2c driver to perform an I2C repeated start
1626 between writing the address pointer and reading the
1627 data. If this define is omitted the default behaviour
1628 of doing a stop-start sequence will be used. Most I2C
1629 devices can use either method, but some require one or
1632 - SPI Support: CONFIG_SPI
1634 Enables SPI driver (so far only tested with
1635 SPI EEPROM, also an instance works with Crystal A/D and
1636 D/As on the SACSng board)
1640 Enables a software (bit-bang) SPI driver rather than
1641 using hardware support. This is a general purpose
1642 driver that only requires three general I/O port pins
1643 (two outputs, one input) to function. If this is
1644 defined, the board configuration must define several
1645 SPI configuration items (port pins to use, etc). For
1646 an example, see include/configs/sacsng.h.
1648 CONFIG_SYS_SPI_MXC_WAIT
1649 Timeout for waiting until spi transfer completed.
1650 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1652 - FPGA Support: CONFIG_FPGA
1654 Enables FPGA subsystem.
1656 CONFIG_FPGA_<vendor>
1658 Enables support for specific chip vendors.
1661 CONFIG_FPGA_<family>
1663 Enables support for FPGA family.
1664 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1668 Specify the number of FPGA devices to support.
1670 CONFIG_SYS_FPGA_PROG_FEEDBACK
1672 Enable printing of hash marks during FPGA configuration.
1674 CONFIG_SYS_FPGA_CHECK_BUSY
1676 Enable checks on FPGA configuration interface busy
1677 status by the configuration function. This option
1678 will require a board or device specific function to
1683 If defined, a function that provides delays in the FPGA
1684 configuration driver.
1686 CONFIG_SYS_FPGA_CHECK_CTRLC
1687 Allow Control-C to interrupt FPGA configuration
1689 CONFIG_SYS_FPGA_CHECK_ERROR
1691 Check for configuration errors during FPGA bitfile
1692 loading. For example, abort during Virtex II
1693 configuration if the INIT_B line goes low (which
1694 indicated a CRC error).
1696 CONFIG_SYS_FPGA_WAIT_INIT
1698 Maximum time to wait for the INIT_B line to de-assert
1699 after PROB_B has been de-asserted during a Virtex II
1700 FPGA configuration sequence. The default time is 500
1703 CONFIG_SYS_FPGA_WAIT_BUSY
1705 Maximum time to wait for BUSY to de-assert during
1706 Virtex II FPGA configuration. The default is 5 ms.
1708 CONFIG_SYS_FPGA_WAIT_CONFIG
1710 Time to wait after FPGA configuration. The default is
1713 - Configuration Management:
1717 If defined, this string will be added to the U-Boot
1718 version information (U_BOOT_VERSION)
1720 - Vendor Parameter Protection:
1722 U-Boot considers the values of the environment
1723 variables "serial#" (Board Serial Number) and
1724 "ethaddr" (Ethernet Address) to be parameters that
1725 are set once by the board vendor / manufacturer, and
1726 protects these variables from casual modification by
1727 the user. Once set, these variables are read-only,
1728 and write or delete attempts are rejected. You can
1729 change this behaviour:
1731 If CONFIG_ENV_OVERWRITE is #defined in your config
1732 file, the write protection for vendor parameters is
1733 completely disabled. Anybody can change or delete
1736 Alternatively, if you define _both_ an ethaddr in the
1737 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1738 Ethernet address is installed in the environment,
1739 which can be changed exactly ONCE by the user. [The
1740 serial# is unaffected by this, i. e. it remains
1743 The same can be accomplished in a more flexible way
1744 for any variable by configuring the type of access
1745 to allow for those variables in the ".flags" variable
1746 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1751 Define this variable to enable the reservation of
1752 "protected RAM", i. e. RAM which is not overwritten
1753 by U-Boot. Define CONFIG_PRAM to hold the number of
1754 kB you want to reserve for pRAM. You can overwrite
1755 this default value by defining an environment
1756 variable "pram" to the number of kB you want to
1757 reserve. Note that the board info structure will
1758 still show the full amount of RAM. If pRAM is
1759 reserved, a new environment variable "mem" will
1760 automatically be defined to hold the amount of
1761 remaining RAM in a form that can be passed as boot
1762 argument to Linux, for instance like that:
1764 setenv bootargs ... mem=\${mem}
1767 This way you can tell Linux not to use this memory,
1768 either, which results in a memory region that will
1769 not be affected by reboots.
1771 *WARNING* If your board configuration uses automatic
1772 detection of the RAM size, you must make sure that
1773 this memory test is non-destructive. So far, the
1774 following board configurations are known to be
1777 IVMS8, IVML24, SPD8xx,
1778 HERMES, IP860, RPXlite, LWMON,
1781 - Access to physical memory region (> 4GB)
1782 Some basic support is provided for operations on memory not
1783 normally accessible to U-Boot - e.g. some architectures
1784 support access to more than 4GB of memory on 32-bit
1785 machines using physical address extension or similar.
1786 Define CONFIG_PHYSMEM to access this basic support, which
1787 currently only supports clearing the memory.
1790 CONFIG_NET_RETRY_COUNT
1792 This variable defines the number of retries for
1793 network operations like ARP, RARP, TFTP, or BOOTP
1794 before giving up the operation. If not defined, a
1795 default value of 5 is used.
1799 Timeout waiting for an ARP reply in milliseconds.
1803 Timeout in milliseconds used in NFS protocol.
1804 If you encounter "ERROR: Cannot umount" in nfs command,
1805 try longer timeout such as
1806 #define CONFIG_NFS_TIMEOUT 10000UL
1810 In the current implementation, the local variables
1811 space and global environment variables space are
1812 separated. Local variables are those you define by
1813 simply typing `name=value'. To access a local
1814 variable later on, you have write `$name' or
1815 `${name}'; to execute the contents of a variable
1816 directly type `$name' at the command prompt.
1818 Global environment variables are those you use
1819 setenv/printenv to work with. To run a command stored
1820 in such a variable, you need to use the run command,
1821 and you must not use the '$' sign to access them.
1823 To store commands and special characters in a
1824 variable, please use double quotation marks
1825 surrounding the whole text of the variable, instead
1826 of the backslashes before semicolons and special
1829 - Command Line Editing and History:
1830 CONFIG_CMDLINE_PS_SUPPORT
1832 Enable support for changing the command prompt string
1833 at run-time. Only static string is supported so far.
1834 The string is obtained from environment variables PS1
1837 - Default Environment:
1838 CONFIG_EXTRA_ENV_SETTINGS
1840 Define this to contain any number of null terminated
1841 strings (variable = value pairs) that will be part of
1842 the default environment compiled into the boot image.
1844 For example, place something like this in your
1845 board's config file:
1847 #define CONFIG_EXTRA_ENV_SETTINGS \
1851 Warning: This method is based on knowledge about the
1852 internal format how the environment is stored by the
1853 U-Boot code. This is NOT an official, exported
1854 interface! Although it is unlikely that this format
1855 will change soon, there is no guarantee either.
1856 You better know what you are doing here.
1858 Note: overly (ab)use of the default environment is
1859 discouraged. Make sure to check other ways to preset
1860 the environment like the "source" command or the
1863 CONFIG_DELAY_ENVIRONMENT
1865 Normally the environment is loaded when the board is
1866 initialised so that it is available to U-Boot. This inhibits
1867 that so that the environment is not available until
1868 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1869 this is instead controlled by the value of
1870 /config/load-environment.
1872 - TFTP Fixed UDP Port:
1875 If this is defined, the environment variable tftpsrcp
1876 is used to supply the TFTP UDP source port value.
1877 If tftpsrcp isn't defined, the normal pseudo-random port
1878 number generator is used.
1880 Also, the environment variable tftpdstp is used to supply
1881 the TFTP UDP destination port value. If tftpdstp isn't
1882 defined, the normal port 69 is used.
1884 The purpose for tftpsrcp is to allow a TFTP server to
1885 blindly start the TFTP transfer using the pre-configured
1886 target IP address and UDP port. This has the effect of
1887 "punching through" the (Windows XP) firewall, allowing
1888 the remainder of the TFTP transfer to proceed normally.
1889 A better solution is to properly configure the firewall,
1890 but sometimes that is not allowed.
1892 CONFIG_STANDALONE_LOAD_ADDR
1894 This option defines a board specific value for the
1895 address where standalone program gets loaded, thus
1896 overwriting the architecture dependent default
1899 - Frame Buffer Address:
1902 Define CONFIG_FB_ADDR if you want to use specific
1903 address for frame buffer. This is typically the case
1904 when using a graphics controller has separate video
1905 memory. U-Boot will then place the frame buffer at
1906 the given address instead of dynamically reserving it
1907 in system RAM by calling lcd_setmem(), which grabs
1908 the memory for the frame buffer depending on the
1909 configured panel size.
1911 Please see board_init_f function.
1913 - Automatic software updates via TFTP server
1915 CONFIG_UPDATE_TFTP_CNT_MAX
1916 CONFIG_UPDATE_TFTP_MSEC_MAX
1918 These options enable and control the auto-update feature;
1919 for a more detailed description refer to doc/README.update.
1921 - MTD Support (mtdparts command, UBI support)
1922 CONFIG_MTD_UBI_WL_THRESHOLD
1923 This parameter defines the maximum difference between the highest
1924 erase counter value and the lowest erase counter value of eraseblocks
1925 of UBI devices. When this threshold is exceeded, UBI starts performing
1926 wear leveling by means of moving data from eraseblock with low erase
1927 counter to eraseblocks with high erase counter.
1929 The default value should be OK for SLC NAND flashes, NOR flashes and
1930 other flashes which have eraseblock life-cycle 100000 or more.
1931 However, in case of MLC NAND flashes which typically have eraseblock
1932 life-cycle less than 10000, the threshold should be lessened (e.g.,
1933 to 128 or 256, although it does not have to be power of 2).
1937 CONFIG_MTD_UBI_BEB_LIMIT
1938 This option specifies the maximum bad physical eraseblocks UBI
1939 expects on the MTD device (per 1024 eraseblocks). If the
1940 underlying flash does not admit of bad eraseblocks (e.g. NOR
1941 flash), this value is ignored.
1943 NAND datasheets often specify the minimum and maximum NVM
1944 (Number of Valid Blocks) for the flashes' endurance lifetime.
1945 The maximum expected bad eraseblocks per 1024 eraseblocks
1946 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1947 which gives 20 for most NANDs (MaxNVB is basically the total
1948 count of eraseblocks on the chip).
1950 To put it differently, if this value is 20, UBI will try to
1951 reserve about 1.9% of physical eraseblocks for bad blocks
1952 handling. And that will be 1.9% of eraseblocks on the entire
1953 NAND chip, not just the MTD partition UBI attaches. This means
1954 that if you have, say, a NAND flash chip admits maximum 40 bad
1955 eraseblocks, and it is split on two MTD partitions of the same
1956 size, UBI will reserve 40 eraseblocks when attaching a
1961 CONFIG_MTD_UBI_FASTMAP
1962 Fastmap is a mechanism which allows attaching an UBI device
1963 in nearly constant time. Instead of scanning the whole MTD device it
1964 only has to locate a checkpoint (called fastmap) on the device.
1965 The on-flash fastmap contains all information needed to attach
1966 the device. Using fastmap makes only sense on large devices where
1967 attaching by scanning takes long. UBI will not automatically install
1968 a fastmap on old images, but you can set the UBI parameter
1969 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1970 that fastmap-enabled images are still usable with UBI implementations
1971 without fastmap support. On typical flash devices the whole fastmap
1972 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1974 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1975 Set this parameter to enable fastmap automatically on images
1979 CONFIG_MTD_UBI_FM_DEBUG
1980 Enable UBI fastmap debug
1985 Enable building of SPL globally.
1988 LDSCRIPT for linking the SPL binary.
1990 CONFIG_SPL_MAX_FOOTPRINT
1991 Maximum size in memory allocated to the SPL, BSS included.
1992 When defined, the linker checks that the actual memory
1993 used by SPL from _start to __bss_end does not exceed it.
1994 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1995 must not be both defined at the same time.
1998 Maximum size of the SPL image (text, data, rodata, and
1999 linker lists sections), BSS excluded.
2000 When defined, the linker checks that the actual size does
2003 CONFIG_SPL_RELOC_TEXT_BASE
2004 Address to relocate to. If unspecified, this is equal to
2005 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2007 CONFIG_SPL_BSS_START_ADDR
2008 Link address for the BSS within the SPL binary.
2010 CONFIG_SPL_BSS_MAX_SIZE
2011 Maximum size in memory allocated to the SPL BSS.
2012 When defined, the linker checks that the actual memory used
2013 by SPL from __bss_start to __bss_end does not exceed it.
2014 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2015 must not be both defined at the same time.
2018 Adress of the start of the stack SPL will use
2020 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2021 When defined, SPL will panic() if the image it has
2022 loaded does not have a signature.
2023 Defining this is useful when code which loads images
2024 in SPL cannot guarantee that absolutely all read errors
2026 An example is the LPC32XX MLC NAND driver, which will
2027 consider that a completely unreadable NAND block is bad,
2028 and thus should be skipped silently.
2030 CONFIG_SPL_RELOC_STACK
2031 Adress of the start of the stack SPL will use after
2032 relocation. If unspecified, this is equal to
2035 CONFIG_SYS_SPL_MALLOC_START
2036 Starting address of the malloc pool used in SPL.
2037 When this option is set the full malloc is used in SPL and
2038 it is set up by spl_init() and before that, the simple malloc()
2039 can be used if CONFIG_SYS_MALLOC_F is defined.
2041 CONFIG_SYS_SPL_MALLOC_SIZE
2042 The size of the malloc pool used in SPL.
2045 Enable booting directly to an OS from SPL.
2046 See also: doc/README.falcon
2048 CONFIG_SPL_DISPLAY_PRINT
2049 For ARM, enable an optional function to print more information
2050 about the running system.
2052 CONFIG_SPL_INIT_MINIMAL
2053 Arch init code should be built for a very small image
2055 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2056 Partition on the MMC to load U-Boot from when the MMC is being
2059 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2060 Sector to load kernel uImage from when MMC is being
2061 used in raw mode (for Falcon mode)
2063 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2064 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2065 Sector and number of sectors to load kernel argument
2066 parameters from when MMC is being used in raw mode
2069 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2070 Filename to read to load U-Boot when reading from filesystem
2072 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2073 Filename to read to load kernel uImage when reading
2074 from filesystem (for Falcon mode)
2076 CONFIG_SPL_FS_LOAD_ARGS_NAME
2077 Filename to read to load kernel argument parameters
2078 when reading from filesystem (for Falcon mode)
2080 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2081 Set this for NAND SPL on PPC mpc83xx targets, so that
2082 start.S waits for the rest of the SPL to load before
2083 continuing (the hardware starts execution after just
2084 loading the first page rather than the full 4K).
2086 CONFIG_SPL_SKIP_RELOCATE
2087 Avoid SPL relocation
2089 CONFIG_SPL_NAND_IDENT
2090 SPL uses the chip ID list to identify the NAND flash.
2091 Requires CONFIG_SPL_NAND_BASE.
2094 Support for a lightweight UBI (fastmap) scanner and
2097 CONFIG_SPL_NAND_RAW_ONLY
2098 Support to boot only raw u-boot.bin images. Use this only
2099 if you need to save space.
2101 CONFIG_SPL_COMMON_INIT_DDR
2102 Set for common ddr init with serial presence detect in
2105 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2106 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2107 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2108 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2109 CONFIG_SYS_NAND_ECCBYTES
2110 Defines the size and behavior of the NAND that SPL uses
2113 CONFIG_SYS_NAND_U_BOOT_OFFS
2114 Location in NAND to read U-Boot from
2116 CONFIG_SYS_NAND_U_BOOT_DST
2117 Location in memory to load U-Boot to
2119 CONFIG_SYS_NAND_U_BOOT_SIZE
2120 Size of image to load
2122 CONFIG_SYS_NAND_U_BOOT_START
2123 Entry point in loaded image to jump to
2125 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2126 Define this if you need to first read the OOB and then the
2127 data. This is used, for example, on davinci platforms.
2129 CONFIG_SPL_RAM_DEVICE
2130 Support for running image already present in ram, in SPL binary
2133 Image offset to which the SPL should be padded before appending
2134 the SPL payload. By default, this is defined as
2135 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2136 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2137 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2140 Final target image containing SPL and payload. Some SPLs
2141 use an arch-specific makefile fragment instead, for
2142 example if more than one image needs to be produced.
2144 CONFIG_SPL_FIT_PRINT
2145 Printing information about a FIT image adds quite a bit of
2146 code to SPL. So this is normally disabled in SPL. Use this
2147 option to re-enable it. This will affect the output of the
2148 bootm command when booting a FIT image.
2152 Enable building of TPL globally.
2155 Image offset to which the TPL should be padded before appending
2156 the TPL payload. By default, this is defined as
2157 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2158 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2159 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2161 - Interrupt support (PPC):
2163 There are common interrupt_init() and timer_interrupt()
2164 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2165 for CPU specific initialization. interrupt_init_cpu()
2166 should set decrementer_count to appropriate value. If
2167 CPU resets decrementer automatically after interrupt
2168 (ppc4xx) it should set decrementer_count to zero.
2169 timer_interrupt() calls timer_interrupt_cpu() for CPU
2170 specific handling. If board has watchdog / status_led
2171 / other_activity_monitor it works automatically from
2172 general timer_interrupt().
2175 Board initialization settings:
2176 ------------------------------
2178 During Initialization u-boot calls a number of board specific functions
2179 to allow the preparation of board specific prerequisites, e.g. pin setup
2180 before drivers are initialized. To enable these callbacks the
2181 following configuration macros have to be defined. Currently this is
2182 architecture specific, so please check arch/your_architecture/lib/board.c
2183 typically in board_init_f() and board_init_r().
2185 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2186 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2187 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2188 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2190 Configuration Settings:
2191 -----------------------
2193 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2194 Optionally it can be defined to support 64-bit memory commands.
2196 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2197 undefine this when you're short of memory.
2199 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2200 width of the commands listed in the 'help' command output.
2202 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2203 prompt for user input.
2205 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2207 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2209 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2211 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2212 the application (usually a Linux kernel) when it is
2215 - CONFIG_SYS_BAUDRATE_TABLE:
2216 List of legal baudrate settings for this board.
2218 - CONFIG_SYS_MEM_RESERVE_SECURE
2219 Only implemented for ARMv8 for now.
2220 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2221 is substracted from total RAM and won't be reported to OS.
2222 This memory can be used as secure memory. A variable
2223 gd->arch.secure_ram is used to track the location. In systems
2224 the RAM base is not zero, or RAM is divided into banks,
2225 this variable needs to be recalcuated to get the address.
2227 - CONFIG_SYS_MEM_TOP_HIDE:
2228 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2229 this specified memory area will get subtracted from the top
2230 (end) of RAM and won't get "touched" at all by U-Boot. By
2231 fixing up gd->ram_size the Linux kernel should gets passed
2232 the now "corrected" memory size and won't touch it either.
2233 This should work for arch/ppc and arch/powerpc. Only Linux
2234 board ports in arch/powerpc with bootwrapper support that
2235 recalculate the memory size from the SDRAM controller setup
2236 will have to get fixed in Linux additionally.
2238 This option can be used as a workaround for the 440EPx/GRx
2239 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2242 WARNING: Please make sure that this value is a multiple of
2243 the Linux page size (normally 4k). If this is not the case,
2244 then the end address of the Linux memory will be located at a
2245 non page size aligned address and this could cause major
2248 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2249 Enable temporary baudrate change while serial download
2251 - CONFIG_SYS_SDRAM_BASE:
2252 Physical start address of SDRAM. _Must_ be 0 here.
2254 - CONFIG_SYS_FLASH_BASE:
2255 Physical start address of Flash memory.
2257 - CONFIG_SYS_MONITOR_BASE:
2258 Physical start address of boot monitor code (set by
2259 make config files to be same as the text base address
2260 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2261 CONFIG_SYS_FLASH_BASE when booting from flash.
2263 - CONFIG_SYS_MONITOR_LEN:
2264 Size of memory reserved for monitor code, used to
2265 determine _at_compile_time_ (!) if the environment is
2266 embedded within the U-Boot image, or in a separate
2269 - CONFIG_SYS_MALLOC_LEN:
2270 Size of DRAM reserved for malloc() use.
2272 - CONFIG_SYS_MALLOC_F_LEN
2273 Size of the malloc() pool for use before relocation. If
2274 this is defined, then a very simple malloc() implementation
2275 will become available before relocation. The address is just
2276 below the global data, and the stack is moved down to make
2279 This feature allocates regions with increasing addresses
2280 within the region. calloc() is supported, but realloc()
2281 is not available. free() is supported but does nothing.
2282 The memory will be freed (or in fact just forgotten) when
2283 U-Boot relocates itself.
2285 - CONFIG_SYS_MALLOC_SIMPLE
2286 Provides a simple and small malloc() and calloc() for those
2287 boards which do not use the full malloc in SPL (which is
2288 enabled with CONFIG_SYS_SPL_MALLOC_START).
2290 - CONFIG_SYS_NONCACHED_MEMORY:
2291 Size of non-cached memory area. This area of memory will be
2292 typically located right below the malloc() area and mapped
2293 uncached in the MMU. This is useful for drivers that would
2294 otherwise require a lot of explicit cache maintenance. For
2295 some drivers it's also impossible to properly maintain the
2296 cache. For example if the regions that need to be flushed
2297 are not a multiple of the cache-line size, *and* padding
2298 cannot be allocated between the regions to align them (i.e.
2299 if the HW requires a contiguous array of regions, and the
2300 size of each region is not cache-aligned), then a flush of
2301 one region may result in overwriting data that hardware has
2302 written to another region in the same cache-line. This can
2303 happen for example in network drivers where descriptors for
2304 buffers are typically smaller than the CPU cache-line (e.g.
2305 16 bytes vs. 32 or 64 bytes).
2307 Non-cached memory is only supported on 32-bit ARM at present.
2309 - CONFIG_SYS_BOOTM_LEN:
2310 Normally compressed uImages are limited to an
2311 uncompressed size of 8 MBytes. If this is not enough,
2312 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2313 to adjust this setting to your needs.
2315 - CONFIG_SYS_BOOTMAPSZ:
2316 Maximum size of memory mapped by the startup code of
2317 the Linux kernel; all data that must be processed by
2318 the Linux kernel (bd_info, boot arguments, FDT blob if
2319 used) must be put below this limit, unless "bootm_low"
2320 environment variable is defined and non-zero. In such case
2321 all data for the Linux kernel must be between "bootm_low"
2322 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2323 variable "bootm_mapsize" will override the value of
2324 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2325 then the value in "bootm_size" will be used instead.
2327 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2328 Enable initrd_high functionality. If defined then the
2329 initrd_high feature is enabled and the bootm ramdisk subcommand
2332 - CONFIG_SYS_BOOT_GET_CMDLINE:
2333 Enables allocating and saving kernel cmdline in space between
2334 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2336 - CONFIG_SYS_BOOT_GET_KBD:
2337 Enables allocating and saving a kernel copy of the bd_info in
2338 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2340 - CONFIG_SYS_MAX_FLASH_BANKS:
2341 Max number of Flash memory banks
2343 - CONFIG_SYS_MAX_FLASH_SECT:
2344 Max number of sectors on a Flash chip
2346 - CONFIG_SYS_FLASH_ERASE_TOUT:
2347 Timeout for Flash erase operations (in ms)
2349 - CONFIG_SYS_FLASH_WRITE_TOUT:
2350 Timeout for Flash write operations (in ms)
2352 - CONFIG_SYS_FLASH_LOCK_TOUT
2353 Timeout for Flash set sector lock bit operation (in ms)
2355 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2356 Timeout for Flash clear lock bits operation (in ms)
2358 - CONFIG_SYS_FLASH_PROTECTION
2359 If defined, hardware flash sectors protection is used
2360 instead of U-Boot software protection.
2362 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2364 Enable TFTP transfers directly to flash memory;
2365 without this option such a download has to be
2366 performed in two steps: (1) download to RAM, and (2)
2367 copy from RAM to flash.
2369 The two-step approach is usually more reliable, since
2370 you can check if the download worked before you erase
2371 the flash, but in some situations (when system RAM is
2372 too limited to allow for a temporary copy of the
2373 downloaded image) this option may be very useful.
2375 - CONFIG_SYS_FLASH_CFI:
2376 Define if the flash driver uses extra elements in the
2377 common flash structure for storing flash geometry.
2379 - CONFIG_FLASH_CFI_DRIVER
2380 This option also enables the building of the cfi_flash driver
2381 in the drivers directory
2383 - CONFIG_FLASH_CFI_MTD
2384 This option enables the building of the cfi_mtd driver
2385 in the drivers directory. The driver exports CFI flash
2388 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2389 Use buffered writes to flash.
2391 - CONFIG_FLASH_SPANSION_S29WS_N
2392 s29ws-n MirrorBit flash has non-standard addresses for buffered
2395 - CONFIG_SYS_FLASH_QUIET_TEST
2396 If this option is defined, the common CFI flash doesn't
2397 print it's warning upon not recognized FLASH banks. This
2398 is useful, if some of the configured banks are only
2399 optionally available.
2401 - CONFIG_FLASH_SHOW_PROGRESS
2402 If defined (must be an integer), print out countdown
2403 digits and dots. Recommended value: 45 (9..1) for 80
2404 column displays, 15 (3..1) for 40 column displays.
2406 - CONFIG_FLASH_VERIFY
2407 If defined, the content of the flash (destination) is compared
2408 against the source after the write operation. An error message
2409 will be printed when the contents are not identical.
2410 Please note that this option is useless in nearly all cases,
2411 since such flash programming errors usually are detected earlier
2412 while unprotecting/erasing/programming. Please only enable
2413 this option if you really know what you are doing.
2415 - CONFIG_SYS_RX_ETH_BUFFER:
2416 Defines the number of Ethernet receive buffers. On some
2417 Ethernet controllers it is recommended to set this value
2418 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2419 buffers can be full shortly after enabling the interface
2420 on high Ethernet traffic.
2421 Defaults to 4 if not defined.
2423 - CONFIG_ENV_MAX_ENTRIES
2425 Maximum number of entries in the hash table that is used
2426 internally to store the environment settings. The default
2427 setting is supposed to be generous and should work in most
2428 cases. This setting can be used to tune behaviour; see
2429 lib/hashtable.c for details.
2431 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2432 - CONFIG_ENV_FLAGS_LIST_STATIC
2433 Enable validation of the values given to environment variables when
2434 calling env set. Variables can be restricted to only decimal,
2435 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2436 the variables can also be restricted to IP address or MAC address.
2438 The format of the list is:
2439 type_attribute = [s|d|x|b|i|m]
2440 access_attribute = [a|r|o|c]
2441 attributes = type_attribute[access_attribute]
2442 entry = variable_name[:attributes]
2445 The type attributes are:
2446 s - String (default)
2449 b - Boolean ([1yYtT|0nNfF])
2453 The access attributes are:
2459 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2460 Define this to a list (string) to define the ".flags"
2461 environment variable in the default or embedded environment.
2463 - CONFIG_ENV_FLAGS_LIST_STATIC
2464 Define this to a list (string) to define validation that
2465 should be done if an entry is not found in the ".flags"
2466 environment variable. To override a setting in the static
2467 list, simply add an entry for the same variable name to the
2470 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2471 regular expression. This allows multiple variables to define the same
2472 flags without explicitly listing them for each variable.
2474 The following definitions that deal with the placement and management
2475 of environment data (variable area); in general, we support the
2476 following configurations:
2478 - CONFIG_BUILD_ENVCRC:
2480 Builds up envcrc with the target environment so that external utils
2481 may easily extract it and embed it in final U-Boot images.
2483 BE CAREFUL! The first access to the environment happens quite early
2484 in U-Boot initialization (when we try to get the setting of for the
2485 console baudrate). You *MUST* have mapped your NVRAM area then, or
2488 Please note that even with NVRAM we still use a copy of the
2489 environment in RAM: we could work on NVRAM directly, but we want to
2490 keep settings there always unmodified except somebody uses "saveenv"
2491 to save the current settings.
2493 BE CAREFUL! For some special cases, the local device can not use
2494 "saveenv" command. For example, the local device will get the
2495 environment stored in a remote NOR flash by SRIO or PCIE link,
2496 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2498 - CONFIG_NAND_ENV_DST
2500 Defines address in RAM to which the nand_spl code should copy the
2501 environment. If redundant environment is used, it will be copied to
2502 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2504 Please note that the environment is read-only until the monitor
2505 has been relocated to RAM and a RAM copy of the environment has been
2506 created; also, when using EEPROM you will have to use env_get_f()
2507 until then to read environment variables.
2509 The environment is protected by a CRC32 checksum. Before the monitor
2510 is relocated into RAM, as a result of a bad CRC you will be working
2511 with the compiled-in default environment - *silently*!!! [This is
2512 necessary, because the first environment variable we need is the
2513 "baudrate" setting for the console - if we have a bad CRC, we don't
2514 have any device yet where we could complain.]
2516 Note: once the monitor has been relocated, then it will complain if
2517 the default environment is used; a new CRC is computed as soon as you
2518 use the "saveenv" command to store a valid environment.
2520 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2521 Echo the inverted Ethernet link state to the fault LED.
2523 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2524 also needs to be defined.
2526 - CONFIG_SYS_FAULT_MII_ADDR:
2527 MII address of the PHY to check for the Ethernet link state.
2529 - CONFIG_NS16550_MIN_FUNCTIONS:
2530 Define this if you desire to only have use of the NS16550_init
2531 and NS16550_putc functions for the serial driver located at
2532 drivers/serial/ns16550.c. This option is useful for saving
2533 space for already greatly restricted images, including but not
2534 limited to NAND_SPL configurations.
2536 - CONFIG_DISPLAY_BOARDINFO
2537 Display information about the board that U-Boot is running on
2538 when U-Boot starts up. The board function checkboard() is called
2541 - CONFIG_DISPLAY_BOARDINFO_LATE
2542 Similar to the previous option, but display this information
2543 later, once stdio is running and output goes to the LCD, if
2546 - CONFIG_BOARD_SIZE_LIMIT:
2547 Maximum size of the U-Boot image. When defined, the
2548 build system checks that the actual size does not
2551 Low Level (hardware related) configuration options:
2552 ---------------------------------------------------
2554 - CONFIG_SYS_CACHELINE_SIZE:
2555 Cache Line Size of the CPU.
2557 - CONFIG_SYS_CCSRBAR_DEFAULT:
2558 Default (power-on reset) physical address of CCSR on Freescale
2561 - CONFIG_SYS_CCSRBAR:
2562 Virtual address of CCSR. On a 32-bit build, this is typically
2563 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2565 - CONFIG_SYS_CCSRBAR_PHYS:
2566 Physical address of CCSR. CCSR can be relocated to a new
2567 physical address, if desired. In this case, this macro should
2568 be set to that address. Otherwise, it should be set to the
2569 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2570 is typically relocated on 36-bit builds. It is recommended
2571 that this macro be defined via the _HIGH and _LOW macros:
2573 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2574 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2576 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2577 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2578 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2579 used in assembly code, so it must not contain typecasts or
2580 integer size suffixes (e.g. "ULL").
2582 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2583 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2584 used in assembly code, so it must not contain typecasts or
2585 integer size suffixes (e.g. "ULL").
2587 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2588 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2589 forced to a value that ensures that CCSR is not relocated.
2592 Most IDE controllers were designed to be connected with PCI
2593 interface. Only few of them were designed for AHB interface.
2594 When software is doing ATA command and data transfer to
2595 IDE devices through IDE-AHB controller, some additional
2596 registers accessing to these kind of IDE-AHB controller
2599 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2600 DO NOT CHANGE unless you know exactly what you're
2601 doing! (11-4) [MPC8xx systems only]
2603 - CONFIG_SYS_INIT_RAM_ADDR:
2605 Start address of memory area that can be used for
2606 initial data and stack; please note that this must be
2607 writable memory that is working WITHOUT special
2608 initialization, i. e. you CANNOT use normal RAM which
2609 will become available only after programming the
2610 memory controller and running certain initialization
2613 U-Boot uses the following memory types:
2614 - MPC8xx: IMMR (internal memory of the CPU)
2616 - CONFIG_SYS_GBL_DATA_OFFSET:
2618 Offset of the initial data structure in the memory
2619 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2620 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2621 data is located at the end of the available space
2622 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2623 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2624 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2625 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2628 On the MPC824X (or other systems that use the data
2629 cache for initial memory) the address chosen for
2630 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2631 point to an otherwise UNUSED address space between
2632 the top of RAM and the start of the PCI space.
2634 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2636 - CONFIG_SYS_OR_TIMING_SDRAM:
2639 - CONFIG_SYS_MAMR_PTA:
2640 periodic timer for refresh
2642 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2643 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2644 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2645 CONFIG_SYS_BR1_PRELIM:
2646 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2648 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2649 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2650 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2651 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2653 - CONFIG_PCI_INDIRECT_BRIDGE:
2654 Enable support for indirect PCI bridges.
2657 Chip has SRIO or not
2660 Board has SRIO 1 port available
2663 Board has SRIO 2 port available
2665 - CONFIG_SRIO_PCIE_BOOT_MASTER
2666 Board can support master function for Boot from SRIO and PCIE
2668 - CONFIG_SYS_SRIOn_MEM_VIRT:
2669 Virtual Address of SRIO port 'n' memory region
2671 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2672 Physical Address of SRIO port 'n' memory region
2674 - CONFIG_SYS_SRIOn_MEM_SIZE:
2675 Size of SRIO port 'n' memory region
2677 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2678 Defined to tell the NAND controller that the NAND chip is using
2680 Not all NAND drivers use this symbol.
2681 Example of drivers that use it:
2682 - drivers/mtd/nand/raw/ndfc.c
2683 - drivers/mtd/nand/raw/mxc_nand.c
2685 - CONFIG_SYS_NDFC_EBC0_CFG
2686 Sets the EBC0_CFG register for the NDFC. If not defined
2687 a default value will be used.
2690 Get DDR timing information from an I2C EEPROM. Common
2691 with pluggable memory modules such as SODIMMs
2694 I2C address of the SPD EEPROM
2696 - CONFIG_SYS_SPD_BUS_NUM
2697 If SPD EEPROM is on an I2C bus other than the first
2698 one, specify here. Note that the value must resolve
2699 to something your driver can deal with.
2701 - CONFIG_SYS_DDR_RAW_TIMING
2702 Get DDR timing information from other than SPD. Common with
2703 soldered DDR chips onboard without SPD. DDR raw timing
2704 parameters are extracted from datasheet and hard-coded into
2705 header files or board specific files.
2707 - CONFIG_FSL_DDR_INTERACTIVE
2708 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2710 - CONFIG_FSL_DDR_SYNC_REFRESH
2711 Enable sync of refresh for multiple controllers.
2713 - CONFIG_FSL_DDR_BIST
2714 Enable built-in memory test for Freescale DDR controllers.
2716 - CONFIG_SYS_83XX_DDR_USES_CS0
2717 Only for 83xx systems. If specified, then DDR should
2718 be configured using CS0 and CS1 instead of CS2 and CS3.
2721 Enable RMII mode for all FECs.
2722 Note that this is a global option, we can't
2723 have one FEC in standard MII mode and another in RMII mode.
2725 - CONFIG_CRC32_VERIFY
2726 Add a verify option to the crc32 command.
2729 => crc32 -v <address> <count> <crc32>
2731 Where address/count indicate a memory area
2732 and crc32 is the correct crc32 which the
2736 Add the "loopw" memory command. This only takes effect if
2737 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2739 - CONFIG_CMD_MX_CYCLIC
2740 Add the "mdc" and "mwc" memory commands. These are cyclic
2745 This command will print 4 bytes (10,11,12,13) each 500 ms.
2747 => mwc.l 100 12345678 10
2748 This command will write 12345678 to address 100 all 10 ms.
2750 This only takes effect if the memory commands are activated
2751 globally (CONFIG_CMD_MEMORY).
2753 - CONFIG_SKIP_LOWLEVEL_INIT
2754 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
2755 low level initializations (like setting up the memory
2756 controller) are omitted and/or U-Boot does not
2757 relocate itself into RAM.
2759 Normally this variable MUST NOT be defined. The only
2760 exception is when U-Boot is loaded (to RAM) by some
2761 other boot loader or by a debugger which performs
2762 these initializations itself.
2764 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
2765 [ARM926EJ-S only] This allows just the call to lowlevel_init()
2766 to be skipped. The normal CP15 init (such as enabling the
2767 instruction cache) is still performed.
2770 Set when the currently-running compilation is for an artifact
2771 that will end up in the SPL (as opposed to the TPL or U-Boot
2772 proper). Code that needs stage-specific behavior should check
2776 Set when the currently-running compilation is for an artifact
2777 that will end up in the TPL (as opposed to the SPL or U-Boot
2778 proper). Code that needs stage-specific behavior should check
2781 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2782 Only for 85xx systems. If this variable is specified, the section
2783 .resetvec is not kept and the section .bootpg is placed in the
2784 previous 4k of the .text section.
2786 - CONFIG_ARCH_MAP_SYSMEM
2787 Generally U-Boot (and in particular the md command) uses
2788 effective address. It is therefore not necessary to regard
2789 U-Boot address as virtual addresses that need to be translated
2790 to physical addresses. However, sandbox requires this, since
2791 it maintains its own little RAM buffer which contains all
2792 addressable memory. This option causes some memory accesses
2793 to be mapped through map_sysmem() / unmap_sysmem().
2795 - CONFIG_X86_RESET_VECTOR
2796 If defined, the x86 reset vector code is included. This is not
2797 needed when U-Boot is running from Coreboot.
2799 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2800 Option to disable subpage write in NAND driver
2801 driver that uses this:
2802 drivers/mtd/nand/raw/davinci_nand.c
2804 Freescale QE/FMAN Firmware Support:
2805 -----------------------------------
2807 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2808 loading of "firmware", which is encoded in the QE firmware binary format.
2809 This firmware often needs to be loaded during U-Boot booting, so macros
2810 are used to identify the storage device (NOR flash, SPI, etc) and the address
2813 - CONFIG_SYS_FMAN_FW_ADDR
2814 The address in the storage device where the FMAN microcode is located. The
2815 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2818 - CONFIG_SYS_QE_FW_ADDR
2819 The address in the storage device where the QE microcode is located. The
2820 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2823 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2824 The maximum possible size of the firmware. The firmware binary format
2825 has a field that specifies the actual size of the firmware, but it
2826 might not be possible to read any part of the firmware unless some
2827 local storage is allocated to hold the entire firmware first.
2829 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2830 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2831 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2832 virtual address in NOR flash.
2834 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2835 Specifies that QE/FMAN firmware is located in NAND flash.
2836 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2838 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2839 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2840 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2842 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2843 Specifies that QE/FMAN firmware is located in the remote (master)
2844 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2845 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2846 window->master inbound window->master LAW->the ucode address in
2847 master's memory space.
2849 Freescale Layerscape Management Complex Firmware Support:
2850 ---------------------------------------------------------
2851 The Freescale Layerscape Management Complex (MC) supports the loading of
2853 This firmware often needs to be loaded during U-Boot booting, so macros
2854 are used to identify the storage device (NOR flash, SPI, etc) and the address
2857 - CONFIG_FSL_MC_ENET
2858 Enable the MC driver for Layerscape SoCs.
2860 Freescale Layerscape Debug Server Support:
2861 -------------------------------------------
2862 The Freescale Layerscape Debug Server Support supports the loading of
2863 "Debug Server firmware" and triggering SP boot-rom.
2864 This firmware often needs to be loaded during U-Boot booting.
2866 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2867 Define alignment of reserved memory MC requires
2872 In order to achieve reproducible builds, timestamps used in the U-Boot build
2873 process have to be set to a fixed value.
2875 This is done using the SOURCE_DATE_EPOCH environment variable.
2876 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2877 option for U-Boot or an environment variable in U-Boot.
2879 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2881 Building the Software:
2882 ======================
2884 Building U-Boot has been tested in several native build environments
2885 and in many different cross environments. Of course we cannot support
2886 all possibly existing versions of cross development tools in all
2887 (potentially obsolete) versions. In case of tool chain problems we
2888 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2889 which is extensively used to build and test U-Boot.
2891 If you are not using a native environment, it is assumed that you
2892 have GNU cross compiling tools available in your path. In this case,
2893 you must set the environment variable CROSS_COMPILE in your shell.
2894 Note that no changes to the Makefile or any other source files are
2895 necessary. For example using the ELDK on a 4xx CPU, please enter:
2897 $ CROSS_COMPILE=ppc_4xx-
2898 $ export CROSS_COMPILE
2900 U-Boot is intended to be simple to build. After installing the
2901 sources you must configure U-Boot for one specific board type. This
2906 where "NAME_defconfig" is the name of one of the existing configu-
2907 rations; see configs/*_defconfig for supported names.
2909 Note: for some boards special configuration names may exist; check if
2910 additional information is available from the board vendor; for
2911 instance, the TQM823L systems are available without (standard)
2912 or with LCD support. You can select such additional "features"
2913 when choosing the configuration, i. e.
2915 make TQM823L_defconfig
2916 - will configure for a plain TQM823L, i. e. no LCD support
2918 make TQM823L_LCD_defconfig
2919 - will configure for a TQM823L with U-Boot console on LCD
2924 Finally, type "make all", and you should get some working U-Boot
2925 images ready for download to / installation on your system:
2927 - "u-boot.bin" is a raw binary image
2928 - "u-boot" is an image in ELF binary format
2929 - "u-boot.srec" is in Motorola S-Record format
2931 By default the build is performed locally and the objects are saved
2932 in the source directory. One of the two methods can be used to change
2933 this behavior and build U-Boot to some external directory:
2935 1. Add O= to the make command line invocations:
2937 make O=/tmp/build distclean
2938 make O=/tmp/build NAME_defconfig
2939 make O=/tmp/build all
2941 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2943 export KBUILD_OUTPUT=/tmp/build
2948 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2951 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2952 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2953 For example to treat all compiler warnings as errors:
2955 make KCFLAGS=-Werror
2957 Please be aware that the Makefiles assume you are using GNU make, so
2958 for instance on NetBSD you might need to use "gmake" instead of
2962 If the system board that you have is not listed, then you will need
2963 to port U-Boot to your hardware platform. To do this, follow these
2966 1. Create a new directory to hold your board specific code. Add any
2967 files you need. In your board directory, you will need at least
2968 the "Makefile" and a "<board>.c".
2969 2. Create a new configuration file "include/configs/<board>.h" for
2971 3. If you're porting U-Boot to a new CPU, then also create a new
2972 directory to hold your CPU specific code. Add any files you need.
2973 4. Run "make <board>_defconfig" with your new name.
2974 5. Type "make", and you should get a working "u-boot.srec" file
2975 to be installed on your target system.
2976 6. Debug and solve any problems that might arise.
2977 [Of course, this last step is much harder than it sounds.]
2980 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2981 ==============================================================
2983 If you have modified U-Boot sources (for instance added a new board
2984 or support for new devices, a new CPU, etc.) you are expected to
2985 provide feedback to the other developers. The feedback normally takes
2986 the form of a "patch", i.e. a context diff against a certain (latest
2987 official or latest in the git repository) version of U-Boot sources.
2989 But before you submit such a patch, please verify that your modifi-
2990 cation did not break existing code. At least make sure that *ALL* of
2991 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2992 just run the buildman script (tools/buildman/buildman), which will
2993 configure and build U-Boot for ALL supported system. Be warned, this
2994 will take a while. Please see the buildman README, or run 'buildman -H'
2998 See also "U-Boot Porting Guide" below.
3001 Monitor Commands - Overview:
3002 ============================
3004 go - start application at address 'addr'
3005 run - run commands in an environment variable
3006 bootm - boot application image from memory
3007 bootp - boot image via network using BootP/TFTP protocol
3008 bootz - boot zImage from memory
3009 tftpboot- boot image via network using TFTP protocol
3010 and env variables "ipaddr" and "serverip"
3011 (and eventually "gatewayip")
3012 tftpput - upload a file via network using TFTP protocol
3013 rarpboot- boot image via network using RARP/TFTP protocol
3014 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3015 loads - load S-Record file over serial line
3016 loadb - load binary file over serial line (kermit mode)
3018 mm - memory modify (auto-incrementing)
3019 nm - memory modify (constant address)
3020 mw - memory write (fill)
3023 cmp - memory compare
3024 crc32 - checksum calculation
3025 i2c - I2C sub-system
3026 sspi - SPI utility commands
3027 base - print or set address offset
3028 printenv- print environment variables
3029 pwm - control pwm channels
3030 setenv - set environment variables
3031 saveenv - save environment variables to persistent storage
3032 protect - enable or disable FLASH write protection
3033 erase - erase FLASH memory
3034 flinfo - print FLASH memory information
3035 nand - NAND memory operations (see doc/README.nand)
3036 bdinfo - print Board Info structure
3037 iminfo - print header information for application image
3038 coninfo - print console devices and informations
3039 ide - IDE sub-system
3040 loop - infinite loop on address range
3041 loopw - infinite write loop on address range
3042 mtest - simple RAM test
3043 icache - enable or disable instruction cache
3044 dcache - enable or disable data cache
3045 reset - Perform RESET of the CPU
3046 echo - echo args to console
3047 version - print monitor version
3048 help - print online help
3049 ? - alias for 'help'
3052 Monitor Commands - Detailed Description:
3053 ========================================
3057 For now: just type "help <command>".
3060 Environment Variables:
3061 ======================
3063 U-Boot supports user configuration using Environment Variables which
3064 can be made persistent by saving to Flash memory.
3066 Environment Variables are set using "setenv", printed using
3067 "printenv", and saved to Flash using "saveenv". Using "setenv"
3068 without a value can be used to delete a variable from the
3069 environment. As long as you don't save the environment you are
3070 working with an in-memory copy. In case the Flash area containing the
3071 environment is erased by accident, a default environment is provided.
3073 Some configuration options can be set using Environment Variables.
3075 List of environment variables (most likely not complete):
3077 baudrate - see CONFIG_BAUDRATE
3079 bootdelay - see CONFIG_BOOTDELAY
3081 bootcmd - see CONFIG_BOOTCOMMAND
3083 bootargs - Boot arguments when booting an RTOS image
3085 bootfile - Name of the image to load with TFTP
3087 bootm_low - Memory range available for image processing in the bootm
3088 command can be restricted. This variable is given as
3089 a hexadecimal number and defines lowest address allowed
3090 for use by the bootm command. See also "bootm_size"
3091 environment variable. Address defined by "bootm_low" is
3092 also the base of the initial memory mapping for the Linux
3093 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3096 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3097 This variable is given as a hexadecimal number and it
3098 defines the size of the memory region starting at base
3099 address bootm_low that is accessible by the Linux kernel
3100 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3101 as the default value if it is defined, and bootm_size is
3104 bootm_size - Memory range available for image processing in the bootm
3105 command can be restricted. This variable is given as
3106 a hexadecimal number and defines the size of the region
3107 allowed for use by the bootm command. See also "bootm_low"
3108 environment variable.
3110 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3112 updatefile - Location of the software update file on a TFTP server, used
3113 by the automatic software update feature. Please refer to
3114 documentation in doc/README.update for more details.
3116 autoload - if set to "no" (any string beginning with 'n'),
3117 "bootp" will just load perform a lookup of the
3118 configuration from the BOOTP server, but not try to
3119 load any image using TFTP
3121 autostart - if set to "yes", an image loaded using the "bootp",
3122 "rarpboot", "tftpboot" or "diskboot" commands will
3123 be automatically started (by internally calling
3126 If set to "no", a standalone image passed to the
3127 "bootm" command will be copied to the load address
3128 (and eventually uncompressed), but NOT be started.
3129 This can be used to load and uncompress arbitrary
3132 fdt_high - if set this restricts the maximum address that the
3133 flattened device tree will be copied into upon boot.
3134 For example, if you have a system with 1 GB memory
3135 at physical address 0x10000000, while Linux kernel
3136 only recognizes the first 704 MB as low memory, you
3137 may need to set fdt_high as 0x3C000000 to have the
3138 device tree blob be copied to the maximum address
3139 of the 704 MB low memory, so that Linux kernel can
3140 access it during the boot procedure.
3142 If this is set to the special value 0xFFFFFFFF then
3143 the fdt will not be copied at all on boot. For this
3144 to work it must reside in writable memory, have
3145 sufficient padding on the end of it for u-boot to
3146 add the information it needs into it, and the memory
3147 must be accessible by the kernel.
3149 fdtcontroladdr- if set this is the address of the control flattened
3150 device tree used by U-Boot when CONFIG_OF_CONTROL is
3153 i2cfast - (PPC405GP|PPC405EP only)
3154 if set to 'y' configures Linux I2C driver for fast
3155 mode (400kHZ). This environment variable is used in
3156 initialization code. So, for changes to be effective
3157 it must be saved and board must be reset.
3159 initrd_high - restrict positioning of initrd images:
3160 If this variable is not set, initrd images will be
3161 copied to the highest possible address in RAM; this
3162 is usually what you want since it allows for
3163 maximum initrd size. If for some reason you want to
3164 make sure that the initrd image is loaded below the
3165 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3166 variable to a value of "no" or "off" or "0".
3167 Alternatively, you can set it to a maximum upper
3168 address to use (U-Boot will still check that it
3169 does not overwrite the U-Boot stack and data).
3171 For instance, when you have a system with 16 MB
3172 RAM, and want to reserve 4 MB from use by Linux,
3173 you can do this by adding "mem=12M" to the value of
3174 the "bootargs" variable. However, now you must make
3175 sure that the initrd image is placed in the first
3176 12 MB as well - this can be done with
3178 setenv initrd_high 00c00000
3180 If you set initrd_high to 0xFFFFFFFF, this is an
3181 indication to U-Boot that all addresses are legal
3182 for the Linux kernel, including addresses in flash
3183 memory. In this case U-Boot will NOT COPY the
3184 ramdisk at all. This may be useful to reduce the
3185 boot time on your system, but requires that this
3186 feature is supported by your Linux kernel.
3188 ipaddr - IP address; needed for tftpboot command
3190 loadaddr - Default load address for commands like "bootp",
3191 "rarpboot", "tftpboot", "loadb" or "diskboot"
3193 loads_echo - see CONFIG_LOADS_ECHO
3195 serverip - TFTP server IP address; needed for tftpboot command
3197 bootretry - see CONFIG_BOOT_RETRY_TIME
3199 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3201 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3203 ethprime - controls which interface is used first.
3205 ethact - controls which interface is currently active.
3206 For example you can do the following
3208 => setenv ethact FEC
3209 => ping 192.168.0.1 # traffic sent on FEC
3210 => setenv ethact SCC
3211 => ping 10.0.0.1 # traffic sent on SCC
3213 ethrotate - When set to "no" U-Boot does not go through all
3214 available network interfaces.
3215 It just stays at the currently selected interface.
3217 netretry - When set to "no" each network operation will
3218 either succeed or fail without retrying.
3219 When set to "once" the network operation will
3220 fail when all the available network interfaces
3221 are tried once without success.
3222 Useful on scripts which control the retry operation
3225 npe_ucode - set load address for the NPE microcode
3227 silent_linux - If set then Linux will be told to boot silently, by
3228 changing the console to be empty. If "yes" it will be
3229 made silent. If "no" it will not be made silent. If
3230 unset, then it will be made silent if the U-Boot console
3233 tftpsrcp - If this is set, the value is used for TFTP's
3236 tftpdstp - If this is set, the value is used for TFTP's UDP
3237 destination port instead of the Well Know Port 69.
3239 tftpblocksize - Block size to use for TFTP transfers; if not set,
3240 we use the TFTP server's default block size
3242 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3243 seconds, minimum value is 1000 = 1 second). Defines
3244 when a packet is considered to be lost so it has to
3245 be retransmitted. The default is 5000 = 5 seconds.
3246 Lowering this value may make downloads succeed
3247 faster in networks with high packet loss rates or
3248 with unreliable TFTP servers.
3250 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3251 unit, minimum value = 0). Defines how many timeouts
3252 can happen during a single file transfer before that
3253 transfer is aborted. The default is 10, and 0 means
3254 'no timeouts allowed'. Increasing this value may help
3255 downloads succeed with high packet loss rates, or with
3256 unreliable TFTP servers or client hardware.
3258 tftpwindowsize - if this is set, the value is used for TFTP's
3259 window size as described by RFC 7440.
3260 This means the count of blocks we can receive before
3261 sending ack to server.
3263 vlan - When set to a value < 4095 the traffic over
3264 Ethernet is encapsulated/received over 802.1q
3267 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3268 Unsigned value, in milliseconds. If not set, the period will
3269 be either the default (28000), or a value based on
3270 CONFIG_NET_RETRY_COUNT, if defined. This value has
3271 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3273 memmatches - Number of matches found by the last 'ms' command, in hex
3275 memaddr - Address of the last match found by the 'ms' command, in hex,
3278 mempos - Index position of the last match found by the 'ms' command,
3279 in units of the size (.b, .w, .l) of the search
3281 zbootbase - (x86 only) Base address of the bzImage 'setup' block
3283 zbootaddr - (x86 only) Address of the loaded bzImage, typically
3284 BZIMAGE_LOAD_ADDR which is 0x100000
3286 The following image location variables contain the location of images
3287 used in booting. The "Image" column gives the role of the image and is
3288 not an environment variable name. The other columns are environment
3289 variable names. "File Name" gives the name of the file on a TFTP
3290 server, "RAM Address" gives the location in RAM the image will be
3291 loaded to, and "Flash Location" gives the image's address in NOR
3292 flash or offset in NAND flash.
3294 *Note* - these variables don't have to be defined for all boards, some
3295 boards currently use other variables for these purposes, and some
3296 boards use these variables for other purposes.
3298 Image File Name RAM Address Flash Location
3299 ----- --------- ----------- --------------
3300 u-boot u-boot u-boot_addr_r u-boot_addr
3301 Linux kernel bootfile kernel_addr_r kernel_addr
3302 device tree blob fdtfile fdt_addr_r fdt_addr
3303 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3305 The following environment variables may be used and automatically
3306 updated by the network boot commands ("bootp" and "rarpboot"),
3307 depending the information provided by your boot server:
3309 bootfile - see above
3310 dnsip - IP address of your Domain Name Server
3311 dnsip2 - IP address of your secondary Domain Name Server
3312 gatewayip - IP address of the Gateway (Router) to use
3313 hostname - Target hostname
3315 netmask - Subnet Mask
3316 rootpath - Pathname of the root filesystem on the NFS server
3317 serverip - see above
3320 There are two special Environment Variables:
3322 serial# - contains hardware identification information such
3323 as type string and/or serial number
3324 ethaddr - Ethernet address
3326 These variables can be set only once (usually during manufacturing of
3327 the board). U-Boot refuses to delete or overwrite these variables
3328 once they have been set once.
3331 Further special Environment Variables:
3333 ver - Contains the U-Boot version string as printed
3334 with the "version" command. This variable is
3335 readonly (see CONFIG_VERSION_VARIABLE).
3338 Please note that changes to some configuration parameters may take
3339 only effect after the next boot (yes, that's just like Windoze :-).
3342 Callback functions for environment variables:
3343 ---------------------------------------------
3345 For some environment variables, the behavior of u-boot needs to change
3346 when their values are changed. This functionality allows functions to
3347 be associated with arbitrary variables. On creation, overwrite, or
3348 deletion, the callback will provide the opportunity for some side
3349 effect to happen or for the change to be rejected.
3351 The callbacks are named and associated with a function using the
3352 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3354 These callbacks are associated with variables in one of two ways. The
3355 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3356 in the board configuration to a string that defines a list of
3357 associations. The list must be in the following format:
3359 entry = variable_name[:callback_name]
3362 If the callback name is not specified, then the callback is deleted.
3363 Spaces are also allowed anywhere in the list.
3365 Callbacks can also be associated by defining the ".callbacks" variable
3366 with the same list format above. Any association in ".callbacks" will
3367 override any association in the static list. You can define
3368 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3369 ".callbacks" environment variable in the default or embedded environment.
3371 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3372 regular expression. This allows multiple variables to be connected to
3373 the same callback without explicitly listing them all out.
3375 The signature of the callback functions is:
3377 int callback(const char *name, const char *value, enum env_op op, int flags)
3379 * name - changed environment variable
3380 * value - new value of the environment variable
3381 * op - operation (create, overwrite, or delete)
3382 * flags - attributes of the environment variable change, see flags H_* in
3385 The return value is 0 if the variable change is accepted and 1 otherwise.
3388 Note for Redundant Ethernet Interfaces:
3389 =======================================
3391 Some boards come with redundant Ethernet interfaces; U-Boot supports
3392 such configurations and is capable of automatic selection of a
3393 "working" interface when needed. MAC assignment works as follows:
3395 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3396 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3397 "eth1addr" (=>eth1), "eth2addr", ...
3399 If the network interface stores some valid MAC address (for instance
3400 in SROM), this is used as default address if there is NO correspon-
3401 ding setting in the environment; if the corresponding environment
3402 variable is set, this overrides the settings in the card; that means:
3404 o If the SROM has a valid MAC address, and there is no address in the
3405 environment, the SROM's address is used.
3407 o If there is no valid address in the SROM, and a definition in the
3408 environment exists, then the value from the environment variable is
3411 o If both the SROM and the environment contain a MAC address, and
3412 both addresses are the same, this MAC address is used.
3414 o If both the SROM and the environment contain a MAC address, and the
3415 addresses differ, the value from the environment is used and a
3418 o If neither SROM nor the environment contain a MAC address, an error
3419 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3420 a random, locally-assigned MAC is used.
3422 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3423 will be programmed into hardware as part of the initialization process. This
3424 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3425 The naming convention is as follows:
3426 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3431 U-Boot is capable of booting (and performing other auxiliary operations on)
3432 images in two formats:
3434 New uImage format (FIT)
3435 -----------------------
3437 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3438 to Flattened Device Tree). It allows the use of images with multiple
3439 components (several kernels, ramdisks, etc.), with contents protected by
3440 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3446 Old image format is based on binary files which can be basically anything,
3447 preceded by a special header; see the definitions in include/image.h for
3448 details; basically, the header defines the following image properties:
3450 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3451 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3452 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3453 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3455 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3456 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3457 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3458 * Compression Type (uncompressed, gzip, bzip2)
3464 The header is marked by a special Magic Number, and both the header
3465 and the data portions of the image are secured against corruption by
3472 Although U-Boot should support any OS or standalone application
3473 easily, the main focus has always been on Linux during the design of
3476 U-Boot includes many features that so far have been part of some
3477 special "boot loader" code within the Linux kernel. Also, any
3478 "initrd" images to be used are no longer part of one big Linux image;
3479 instead, kernel and "initrd" are separate images. This implementation
3480 serves several purposes:
3482 - the same features can be used for other OS or standalone
3483 applications (for instance: using compressed images to reduce the
3484 Flash memory footprint)
3486 - it becomes much easier to port new Linux kernel versions because
3487 lots of low-level, hardware dependent stuff are done by U-Boot
3489 - the same Linux kernel image can now be used with different "initrd"
3490 images; of course this also means that different kernel images can
3491 be run with the same "initrd". This makes testing easier (you don't
3492 have to build a new "zImage.initrd" Linux image when you just
3493 change a file in your "initrd"). Also, a field-upgrade of the
3494 software is easier now.
3500 Porting Linux to U-Boot based systems:
3501 ---------------------------------------
3503 U-Boot cannot save you from doing all the necessary modifications to
3504 configure the Linux device drivers for use with your target hardware
3505 (no, we don't intend to provide a full virtual machine interface to
3508 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3510 Just make sure your machine specific header file (for instance
3511 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3512 Information structure as we define in include/asm-<arch>/u-boot.h,
3513 and make sure that your definition of IMAP_ADDR uses the same value
3514 as your U-Boot configuration in CONFIG_SYS_IMMR.
3516 Note that U-Boot now has a driver model, a unified model for drivers.
3517 If you are adding a new driver, plumb it into driver model. If there
3518 is no uclass available, you are encouraged to create one. See
3522 Configuring the Linux kernel:
3523 -----------------------------
3525 No specific requirements for U-Boot. Make sure you have some root
3526 device (initial ramdisk, NFS) for your target system.
3529 Building a Linux Image:
3530 -----------------------
3532 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3533 not used. If you use recent kernel source, a new build target
3534 "uImage" will exist which automatically builds an image usable by
3535 U-Boot. Most older kernels also have support for a "pImage" target,
3536 which was introduced for our predecessor project PPCBoot and uses a
3537 100% compatible format.
3541 make TQM850L_defconfig
3546 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3547 encapsulate a compressed Linux kernel image with header information,
3548 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3550 * build a standard "vmlinux" kernel image (in ELF binary format):
3552 * convert the kernel into a raw binary image:
3554 ${CROSS_COMPILE}-objcopy -O binary \
3555 -R .note -R .comment \
3556 -S vmlinux linux.bin
3558 * compress the binary image:
3562 * package compressed binary image for U-Boot:
3564 mkimage -A ppc -O linux -T kernel -C gzip \
3565 -a 0 -e 0 -n "Linux Kernel Image" \
3566 -d linux.bin.gz uImage
3569 The "mkimage" tool can also be used to create ramdisk images for use
3570 with U-Boot, either separated from the Linux kernel image, or
3571 combined into one file. "mkimage" encapsulates the images with a 64
3572 byte header containing information about target architecture,
3573 operating system, image type, compression method, entry points, time
3574 stamp, CRC32 checksums, etc.
3576 "mkimage" can be called in two ways: to verify existing images and
3577 print the header information, or to build new images.
3579 In the first form (with "-l" option) mkimage lists the information
3580 contained in the header of an existing U-Boot image; this includes
3581 checksum verification:
3583 tools/mkimage -l image
3584 -l ==> list image header information
3586 The second form (with "-d" option) is used to build a U-Boot image
3587 from a "data file" which is used as image payload:
3589 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3590 -n name -d data_file image
3591 -A ==> set architecture to 'arch'
3592 -O ==> set operating system to 'os'
3593 -T ==> set image type to 'type'
3594 -C ==> set compression type 'comp'
3595 -a ==> set load address to 'addr' (hex)
3596 -e ==> set entry point to 'ep' (hex)
3597 -n ==> set image name to 'name'
3598 -d ==> use image data from 'datafile'
3600 Right now, all Linux kernels for PowerPC systems use the same load
3601 address (0x00000000), but the entry point address depends on the
3604 - 2.2.x kernels have the entry point at 0x0000000C,
3605 - 2.3.x and later kernels have the entry point at 0x00000000.
3607 So a typical call to build a U-Boot image would read:
3609 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3610 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3611 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3612 > examples/uImage.TQM850L
3613 Image Name: 2.4.4 kernel for TQM850L
3614 Created: Wed Jul 19 02:34:59 2000
3615 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3616 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3617 Load Address: 0x00000000
3618 Entry Point: 0x00000000
3620 To verify the contents of the image (or check for corruption):
3622 -> tools/mkimage -l examples/uImage.TQM850L
3623 Image Name: 2.4.4 kernel for TQM850L
3624 Created: Wed Jul 19 02:34:59 2000
3625 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3626 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3627 Load Address: 0x00000000
3628 Entry Point: 0x00000000
3630 NOTE: for embedded systems where boot time is critical you can trade
3631 speed for memory and install an UNCOMPRESSED image instead: this
3632 needs more space in Flash, but boots much faster since it does not
3633 need to be uncompressed:
3635 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3636 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3637 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3638 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3639 > examples/uImage.TQM850L-uncompressed
3640 Image Name: 2.4.4 kernel for TQM850L
3641 Created: Wed Jul 19 02:34:59 2000
3642 Image Type: PowerPC Linux Kernel Image (uncompressed)
3643 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3644 Load Address: 0x00000000
3645 Entry Point: 0x00000000
3648 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3649 when your kernel is intended to use an initial ramdisk:
3651 -> tools/mkimage -n 'Simple Ramdisk Image' \
3652 > -A ppc -O linux -T ramdisk -C gzip \
3653 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3654 Image Name: Simple Ramdisk Image
3655 Created: Wed Jan 12 14:01:50 2000
3656 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3657 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3658 Load Address: 0x00000000
3659 Entry Point: 0x00000000
3661 The "dumpimage" tool can be used to disassemble or list the contents of images
3662 built by mkimage. See dumpimage's help output (-h) for details.
3664 Installing a Linux Image:
3665 -------------------------
3667 To downloading a U-Boot image over the serial (console) interface,
3668 you must convert the image to S-Record format:
3670 objcopy -I binary -O srec examples/image examples/image.srec
3672 The 'objcopy' does not understand the information in the U-Boot
3673 image header, so the resulting S-Record file will be relative to
3674 address 0x00000000. To load it to a given address, you need to
3675 specify the target address as 'offset' parameter with the 'loads'
3678 Example: install the image to address 0x40100000 (which on the
3679 TQM8xxL is in the first Flash bank):
3681 => erase 40100000 401FFFFF
3687 ## Ready for S-Record download ...
3688 ~>examples/image.srec
3689 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3691 15989 15990 15991 15992
3692 [file transfer complete]
3694 ## Start Addr = 0x00000000
3697 You can check the success of the download using the 'iminfo' command;
3698 this includes a checksum verification so you can be sure no data
3699 corruption happened:
3703 ## Checking Image at 40100000 ...
3704 Image Name: 2.2.13 for initrd on TQM850L
3705 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3706 Data Size: 335725 Bytes = 327 kB = 0 MB
3707 Load Address: 00000000
3708 Entry Point: 0000000c
3709 Verifying Checksum ... OK
3715 The "bootm" command is used to boot an application that is stored in
3716 memory (RAM or Flash). In case of a Linux kernel image, the contents
3717 of the "bootargs" environment variable is passed to the kernel as
3718 parameters. You can check and modify this variable using the
3719 "printenv" and "setenv" commands:
3722 => printenv bootargs
3723 bootargs=root=/dev/ram
3725 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3727 => printenv bootargs
3728 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3731 ## Booting Linux kernel at 40020000 ...
3732 Image Name: 2.2.13 for NFS on TQM850L
3733 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3734 Data Size: 381681 Bytes = 372 kB = 0 MB
3735 Load Address: 00000000
3736 Entry Point: 0000000c
3737 Verifying Checksum ... OK
3738 Uncompressing Kernel Image ... OK
3739 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
3740 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3741 time_init: decrementer frequency = 187500000/60
3742 Calibrating delay loop... 49.77 BogoMIPS
3743 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3746 If you want to boot a Linux kernel with initial RAM disk, you pass
3747 the memory addresses of both the kernel and the initrd image (PPBCOOT
3748 format!) to the "bootm" command:
3750 => imi 40100000 40200000
3752 ## Checking Image at 40100000 ...
3753 Image Name: 2.2.13 for initrd on TQM850L
3754 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3755 Data Size: 335725 Bytes = 327 kB = 0 MB
3756 Load Address: 00000000
3757 Entry Point: 0000000c
3758 Verifying Checksum ... OK
3760 ## Checking Image at 40200000 ...
3761 Image Name: Simple Ramdisk Image
3762 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3763 Data Size: 566530 Bytes = 553 kB = 0 MB
3764 Load Address: 00000000
3765 Entry Point: 00000000
3766 Verifying Checksum ... OK
3768 => bootm 40100000 40200000
3769 ## Booting Linux kernel at 40100000 ...
3770 Image Name: 2.2.13 for initrd on TQM850L
3771 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3772 Data Size: 335725 Bytes = 327 kB = 0 MB
3773 Load Address: 00000000
3774 Entry Point: 0000000c
3775 Verifying Checksum ... OK
3776 Uncompressing Kernel Image ... OK
3777 ## Loading RAMDisk Image at 40200000 ...
3778 Image Name: Simple Ramdisk Image
3779 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3780 Data Size: 566530 Bytes = 553 kB = 0 MB
3781 Load Address: 00000000
3782 Entry Point: 00000000
3783 Verifying Checksum ... OK
3784 Loading Ramdisk ... OK
3785 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
3786 Boot arguments: root=/dev/ram
3787 time_init: decrementer frequency = 187500000/60
3788 Calibrating delay loop... 49.77 BogoMIPS
3790 RAMDISK: Compressed image found at block 0
3791 VFS: Mounted root (ext2 filesystem).
3795 Boot Linux and pass a flat device tree:
3798 First, U-Boot must be compiled with the appropriate defines. See the section
3799 titled "Linux Kernel Interface" above for a more in depth explanation. The
3800 following is an example of how to start a kernel and pass an updated
3806 oft=oftrees/mpc8540ads.dtb
3807 => tftp $oftaddr $oft
3808 Speed: 1000, full duplex
3810 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3811 Filename 'oftrees/mpc8540ads.dtb'.
3812 Load address: 0x300000
3815 Bytes transferred = 4106 (100a hex)
3816 => tftp $loadaddr $bootfile
3817 Speed: 1000, full duplex
3819 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3821 Load address: 0x200000
3822 Loading:############
3824 Bytes transferred = 1029407 (fb51f hex)
3829 => bootm $loadaddr - $oftaddr
3830 ## Booting image at 00200000 ...
3831 Image Name: Linux-2.6.17-dirty
3832 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3833 Data Size: 1029343 Bytes = 1005.2 kB
3834 Load Address: 00000000
3835 Entry Point: 00000000
3836 Verifying Checksum ... OK
3837 Uncompressing Kernel Image ... OK
3838 Booting using flat device tree at 0x300000
3839 Using MPC85xx ADS machine description
3840 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3844 More About U-Boot Image Types:
3845 ------------------------------
3847 U-Boot supports the following image types:
3849 "Standalone Programs" are directly runnable in the environment
3850 provided by U-Boot; it is expected that (if they behave
3851 well) you can continue to work in U-Boot after return from
3852 the Standalone Program.
3853 "OS Kernel Images" are usually images of some Embedded OS which
3854 will take over control completely. Usually these programs
3855 will install their own set of exception handlers, device
3856 drivers, set up the MMU, etc. - this means, that you cannot
3857 expect to re-enter U-Boot except by resetting the CPU.
3858 "RAMDisk Images" are more or less just data blocks, and their
3859 parameters (address, size) are passed to an OS kernel that is
3861 "Multi-File Images" contain several images, typically an OS
3862 (Linux) kernel image and one or more data images like
3863 RAMDisks. This construct is useful for instance when you want
3864 to boot over the network using BOOTP etc., where the boot
3865 server provides just a single image file, but you want to get
3866 for instance an OS kernel and a RAMDisk image.
3868 "Multi-File Images" start with a list of image sizes, each
3869 image size (in bytes) specified by an "uint32_t" in network
3870 byte order. This list is terminated by an "(uint32_t)0".
3871 Immediately after the terminating 0 follow the images, one by
3872 one, all aligned on "uint32_t" boundaries (size rounded up to
3873 a multiple of 4 bytes).
3875 "Firmware Images" are binary images containing firmware (like
3876 U-Boot or FPGA images) which usually will be programmed to
3879 "Script files" are command sequences that will be executed by
3880 U-Boot's command interpreter; this feature is especially
3881 useful when you configure U-Boot to use a real shell (hush)
3882 as command interpreter.
3884 Booting the Linux zImage:
3885 -------------------------
3887 On some platforms, it's possible to boot Linux zImage. This is done
3888 using the "bootz" command. The syntax of "bootz" command is the same
3889 as the syntax of "bootm" command.
3891 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3892 kernel with raw initrd images. The syntax is slightly different, the
3893 address of the initrd must be augmented by it's size, in the following
3894 format: "<initrd addres>:<initrd size>".
3900 One of the features of U-Boot is that you can dynamically load and
3901 run "standalone" applications, which can use some resources of
3902 U-Boot like console I/O functions or interrupt services.
3904 Two simple examples are included with the sources:
3909 'examples/hello_world.c' contains a small "Hello World" Demo
3910 application; it is automatically compiled when you build U-Boot.
3911 It's configured to run at address 0x00040004, so you can play with it
3915 ## Ready for S-Record download ...
3916 ~>examples/hello_world.srec
3917 1 2 3 4 5 6 7 8 9 10 11 ...
3918 [file transfer complete]
3920 ## Start Addr = 0x00040004
3922 => go 40004 Hello World! This is a test.
3923 ## Starting application at 0x00040004 ...
3934 Hit any key to exit ...
3936 ## Application terminated, rc = 0x0
3938 Another example, which demonstrates how to register a CPM interrupt
3939 handler with the U-Boot code, can be found in 'examples/timer.c'.
3940 Here, a CPM timer is set up to generate an interrupt every second.
3941 The interrupt service routine is trivial, just printing a '.'
3942 character, but this is just a demo program. The application can be
3943 controlled by the following keys:
3945 ? - print current values og the CPM Timer registers
3946 b - enable interrupts and start timer
3947 e - stop timer and disable interrupts
3948 q - quit application
3951 ## Ready for S-Record download ...
3952 ~>examples/timer.srec
3953 1 2 3 4 5 6 7 8 9 10 11 ...
3954 [file transfer complete]
3956 ## Start Addr = 0x00040004
3959 ## Starting application at 0x00040004 ...
3962 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3965 [q, b, e, ?] Set interval 1000000 us
3968 [q, b, e, ?] ........
3969 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3972 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3975 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3978 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3980 [q, b, e, ?] ...Stopping timer
3982 [q, b, e, ?] ## Application terminated, rc = 0x0
3988 Over time, many people have reported problems when trying to use the
3989 "minicom" terminal emulation program for serial download. I (wd)
3990 consider minicom to be broken, and recommend not to use it. Under
3991 Unix, I recommend to use C-Kermit for general purpose use (and
3992 especially for kermit binary protocol download ("loadb" command), and
3993 use "cu" for S-Record download ("loads" command). See
3994 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3995 for help with kermit.
3998 Nevertheless, if you absolutely want to use it try adding this
3999 configuration to your "File transfer protocols" section:
4001 Name Program Name U/D FullScr IO-Red. Multi
4002 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4003 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4009 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4010 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4012 Building requires a cross environment; it is known to work on
4013 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4014 need gmake since the Makefiles are not compatible with BSD make).
4015 Note that the cross-powerpc package does not install include files;
4016 attempting to build U-Boot will fail because <machine/ansi.h> is
4017 missing. This file has to be installed and patched manually:
4019 # cd /usr/pkg/cross/powerpc-netbsd/include
4021 # ln -s powerpc machine
4022 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4023 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4025 Native builds *don't* work due to incompatibilities between native
4026 and U-Boot include files.
4028 Booting assumes that (the first part of) the image booted is a
4029 stage-2 loader which in turn loads and then invokes the kernel
4030 proper. Loader sources will eventually appear in the NetBSD source
4031 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4032 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4035 Implementation Internals:
4036 =========================
4038 The following is not intended to be a complete description of every
4039 implementation detail. However, it should help to understand the
4040 inner workings of U-Boot and make it easier to port it to custom
4044 Initial Stack, Global Data:
4045 ---------------------------
4047 The implementation of U-Boot is complicated by the fact that U-Boot
4048 starts running out of ROM (flash memory), usually without access to
4049 system RAM (because the memory controller is not initialized yet).
4050 This means that we don't have writable Data or BSS segments, and BSS
4051 is not initialized as zero. To be able to get a C environment working
4052 at all, we have to allocate at least a minimal stack. Implementation
4053 options for this are defined and restricted by the CPU used: Some CPU
4054 models provide on-chip memory (like the IMMR area on MPC8xx and
4055 MPC826x processors), on others (parts of) the data cache can be
4056 locked as (mis-) used as memory, etc.
4058 Chris Hallinan posted a good summary of these issues to the
4059 U-Boot mailing list:
4061 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4062 From: "Chris Hallinan" <clh@net1plus.com>
4063 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4066 Correct me if I'm wrong, folks, but the way I understand it
4067 is this: Using DCACHE as initial RAM for Stack, etc, does not
4068 require any physical RAM backing up the cache. The cleverness
4069 is that the cache is being used as a temporary supply of
4070 necessary storage before the SDRAM controller is setup. It's
4071 beyond the scope of this list to explain the details, but you
4072 can see how this works by studying the cache architecture and
4073 operation in the architecture and processor-specific manuals.
4075 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4076 is another option for the system designer to use as an
4077 initial stack/RAM area prior to SDRAM being available. Either
4078 option should work for you. Using CS 4 should be fine if your
4079 board designers haven't used it for something that would
4080 cause you grief during the initial boot! It is frequently not
4083 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4084 with your processor/board/system design. The default value
4085 you will find in any recent u-boot distribution in
4086 walnut.h should work for you. I'd set it to a value larger
4087 than your SDRAM module. If you have a 64MB SDRAM module, set
4088 it above 400_0000. Just make sure your board has no resources
4089 that are supposed to respond to that address! That code in
4090 start.S has been around a while and should work as is when
4091 you get the config right.
4096 It is essential to remember this, since it has some impact on the C
4097 code for the initialization procedures:
4099 * Initialized global data (data segment) is read-only. Do not attempt
4102 * Do not use any uninitialized global data (or implicitly initialized
4103 as zero data - BSS segment) at all - this is undefined, initiali-
4104 zation is performed later (when relocating to RAM).
4106 * Stack space is very limited. Avoid big data buffers or things like
4109 Having only the stack as writable memory limits means we cannot use
4110 normal global data to share information between the code. But it
4111 turned out that the implementation of U-Boot can be greatly
4112 simplified by making a global data structure (gd_t) available to all
4113 functions. We could pass a pointer to this data as argument to _all_
4114 functions, but this would bloat the code. Instead we use a feature of
4115 the GCC compiler (Global Register Variables) to share the data: we
4116 place a pointer (gd) to the global data into a register which we
4117 reserve for this purpose.
4119 When choosing a register for such a purpose we are restricted by the
4120 relevant (E)ABI specifications for the current architecture, and by
4121 GCC's implementation.
4123 For PowerPC, the following registers have specific use:
4125 R2: reserved for system use
4126 R3-R4: parameter passing and return values
4127 R5-R10: parameter passing
4128 R13: small data area pointer
4132 (U-Boot also uses R12 as internal GOT pointer. r12
4133 is a volatile register so r12 needs to be reset when
4134 going back and forth between asm and C)
4136 ==> U-Boot will use R2 to hold a pointer to the global data
4138 Note: on PPC, we could use a static initializer (since the
4139 address of the global data structure is known at compile time),
4140 but it turned out that reserving a register results in somewhat
4141 smaller code - although the code savings are not that big (on
4142 average for all boards 752 bytes for the whole U-Boot image,
4143 624 text + 127 data).
4145 On ARM, the following registers are used:
4147 R0: function argument word/integer result
4148 R1-R3: function argument word
4149 R9: platform specific
4150 R10: stack limit (used only if stack checking is enabled)
4151 R11: argument (frame) pointer
4152 R12: temporary workspace
4155 R15: program counter
4157 ==> U-Boot will use R9 to hold a pointer to the global data
4159 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4161 On Nios II, the ABI is documented here:
4162 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4164 ==> U-Boot will use gp to hold a pointer to the global data
4166 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4167 to access small data sections, so gp is free.
4169 On NDS32, the following registers are used:
4171 R0-R1: argument/return
4173 R15: temporary register for assembler
4174 R16: trampoline register
4175 R28: frame pointer (FP)
4176 R29: global pointer (GP)
4177 R30: link register (LP)
4178 R31: stack pointer (SP)
4179 PC: program counter (PC)
4181 ==> U-Boot will use R10 to hold a pointer to the global data
4183 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4184 or current versions of GCC may "optimize" the code too much.
4186 On RISC-V, the following registers are used:
4188 x0: hard-wired zero (zero)
4189 x1: return address (ra)
4190 x2: stack pointer (sp)
4191 x3: global pointer (gp)
4192 x4: thread pointer (tp)
4193 x5: link register (t0)
4194 x8: frame pointer (fp)
4195 x10-x11: arguments/return values (a0-1)
4196 x12-x17: arguments (a2-7)
4197 x28-31: temporaries (t3-6)
4198 pc: program counter (pc)
4200 ==> U-Boot will use gp to hold a pointer to the global data
4205 U-Boot runs in system state and uses physical addresses, i.e. the
4206 MMU is not used either for address mapping nor for memory protection.
4208 The available memory is mapped to fixed addresses using the memory
4209 controller. In this process, a contiguous block is formed for each
4210 memory type (Flash, SDRAM, SRAM), even when it consists of several
4211 physical memory banks.
4213 U-Boot is installed in the first 128 kB of the first Flash bank (on
4214 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4215 booting and sizing and initializing DRAM, the code relocates itself
4216 to the upper end of DRAM. Immediately below the U-Boot code some
4217 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4218 configuration setting]. Below that, a structure with global Board
4219 Info data is placed, followed by the stack (growing downward).
4221 Additionally, some exception handler code is copied to the low 8 kB
4222 of DRAM (0x00000000 ... 0x00001FFF).
4224 So a typical memory configuration with 16 MB of DRAM could look like
4227 0x0000 0000 Exception Vector code
4230 0x0000 2000 Free for Application Use
4236 0x00FB FF20 Monitor Stack (Growing downward)
4237 0x00FB FFAC Board Info Data and permanent copy of global data
4238 0x00FC 0000 Malloc Arena
4241 0x00FE 0000 RAM Copy of Monitor Code
4242 ... eventually: LCD or video framebuffer
4243 ... eventually: pRAM (Protected RAM - unchanged by reset)
4244 0x00FF FFFF [End of RAM]
4247 System Initialization:
4248 ----------------------
4250 In the reset configuration, U-Boot starts at the reset entry point
4251 (on most PowerPC systems at address 0x00000100). Because of the reset
4252 configuration for CS0# this is a mirror of the on board Flash memory.
4253 To be able to re-map memory U-Boot then jumps to its link address.
4254 To be able to implement the initialization code in C, a (small!)
4255 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4256 which provide such a feature like), or in a locked part of the data
4257 cache. After that, U-Boot initializes the CPU core, the caches and
4260 Next, all (potentially) available memory banks are mapped using a
4261 preliminary mapping. For example, we put them on 512 MB boundaries
4262 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4263 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4264 programmed for SDRAM access. Using the temporary configuration, a
4265 simple memory test is run that determines the size of the SDRAM
4268 When there is more than one SDRAM bank, and the banks are of
4269 different size, the largest is mapped first. For equal size, the first
4270 bank (CS2#) is mapped first. The first mapping is always for address
4271 0x00000000, with any additional banks following immediately to create
4272 contiguous memory starting from 0.
4274 Then, the monitor installs itself at the upper end of the SDRAM area
4275 and allocates memory for use by malloc() and for the global Board
4276 Info data; also, the exception vector code is copied to the low RAM
4277 pages, and the final stack is set up.
4279 Only after this relocation will you have a "normal" C environment;
4280 until that you are restricted in several ways, mostly because you are
4281 running from ROM, and because the code will have to be relocated to a
4285 U-Boot Porting Guide:
4286 ----------------------
4288 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4292 int main(int argc, char *argv[])
4294 sighandler_t no_more_time;
4296 signal(SIGALRM, no_more_time);
4297 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4299 if (available_money > available_manpower) {
4300 Pay consultant to port U-Boot;
4304 Download latest U-Boot source;
4306 Subscribe to u-boot mailing list;
4309 email("Hi, I am new to U-Boot, how do I get started?");
4312 Read the README file in the top level directory;
4313 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
4314 Read applicable doc/README.*;
4315 Read the source, Luke;
4316 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4319 if (available_money > toLocalCurrency ($2500))
4322 Add a lot of aggravation and time;
4324 if (a similar board exists) { /* hopefully... */
4325 cp -a board/<similar> board/<myboard>
4326 cp include/configs/<similar>.h include/configs/<myboard>.h
4328 Create your own board support subdirectory;
4329 Create your own board include/configs/<myboard>.h file;
4331 Edit new board/<myboard> files
4332 Edit new include/configs/<myboard>.h
4337 Add / modify source code;
4341 email("Hi, I am having problems...");
4343 Send patch file to the U-Boot email list;
4344 if (reasonable critiques)
4345 Incorporate improvements from email list code review;
4347 Defend code as written;
4353 void no_more_time (int sig)
4362 All contributions to U-Boot should conform to the Linux kernel
4363 coding style; see the kernel coding style guide at
4364 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4365 script "scripts/Lindent" in your Linux kernel source directory.
4367 Source files originating from a different project (for example the
4368 MTD subsystem) are generally exempt from these guidelines and are not
4369 reformatted to ease subsequent migration to newer versions of those
4372 Please note that U-Boot is implemented in C (and to some small parts in
4373 Assembler); no C++ is used, so please do not use C++ style comments (//)
4376 Please also stick to the following formatting rules:
4377 - remove any trailing white space
4378 - use TAB characters for indentation and vertical alignment, not spaces
4379 - make sure NOT to use DOS '\r\n' line feeds
4380 - do not add more than 2 consecutive empty lines to source files
4381 - do not add trailing empty lines to source files
4383 Submissions which do not conform to the standards may be returned
4384 with a request to reformat the changes.
4390 Since the number of patches for U-Boot is growing, we need to
4391 establish some rules. Submissions which do not conform to these rules
4392 may be rejected, even when they contain important and valuable stuff.
4394 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
4396 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4397 see https://lists.denx.de/listinfo/u-boot
4399 When you send a patch, please include the following information with
4402 * For bug fixes: a description of the bug and how your patch fixes
4403 this bug. Please try to include a way of demonstrating that the
4404 patch actually fixes something.
4406 * For new features: a description of the feature and your
4409 * For major contributions, add a MAINTAINERS file with your
4410 information and associated file and directory references.
4412 * When you add support for a new board, don't forget to add a
4413 maintainer e-mail address to the boards.cfg file, too.
4415 * If your patch adds new configuration options, don't forget to
4416 document these in the README file.
4418 * The patch itself. If you are using git (which is *strongly*
4419 recommended) you can easily generate the patch using the
4420 "git format-patch". If you then use "git send-email" to send it to
4421 the U-Boot mailing list, you will avoid most of the common problems
4422 with some other mail clients.
4424 If you cannot use git, use "diff -purN OLD NEW". If your version of
4425 diff does not support these options, then get the latest version of
4428 The current directory when running this command shall be the parent
4429 directory of the U-Boot source tree (i. e. please make sure that
4430 your patch includes sufficient directory information for the
4433 We prefer patches as plain text. MIME attachments are discouraged,
4434 and compressed attachments must not be used.
4436 * If one logical set of modifications affects or creates several
4437 files, all these changes shall be submitted in a SINGLE patch file.
4439 * Changesets that contain different, unrelated modifications shall be
4440 submitted as SEPARATE patches, one patch per changeset.
4445 * Before sending the patch, run the buildman script on your patched
4446 source tree and make sure that no errors or warnings are reported
4447 for any of the boards.
4449 * Keep your modifications to the necessary minimum: A patch
4450 containing several unrelated changes or arbitrary reformats will be
4451 returned with a request to re-formatting / split it.
4453 * If you modify existing code, make sure that your new code does not
4454 add to the memory footprint of the code ;-) Small is beautiful!
4455 When adding new features, these should compile conditionally only
4456 (using #ifdef), and the resulting code with the new feature
4457 disabled must not need more memory than the old code without your
4460 * Remember that there is a size limit of 100 kB per message on the
4461 u-boot mailing list. Bigger patches will be moderated. If they are
4462 reasonable and not too big, they will be acknowledged. But patches
4463 bigger than the size limit should be avoided.
projects / platform / kernel / u-boot.git / blob