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
303 Configuration Options:
304 ----------------------
306 Configuration depends on the combination of board and CPU type; all
307 such information is kept in a configuration file
308 "include/configs/<board_name>.h".
310 Example: For a TQM823L module, all configuration settings are in
311 "include/configs/TQM823L.h".
314 Many of the options are named exactly as the corresponding Linux
315 kernel configuration options. The intention is to make it easier to
316 build a config tool - later.
318 - ARM Platform Bus Type(CCI):
319 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
320 provides full cache coherency between two clusters of multi-core
321 CPUs and I/O coherency for devices and I/O masters
323 CONFIG_SYS_FSL_HAS_CCI400
325 Defined For SoC that has cache coherent interconnect
328 CONFIG_SYS_FSL_HAS_CCN504
330 Defined for SoC that has cache coherent interconnect CCN-504
332 The following options need to be configured:
334 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
336 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
341 Specifies that the core is a 64-bit PowerPC implementation (implements
342 the "64" category of the Power ISA). This is necessary for ePAPR
343 compliance, among other possible reasons.
345 CONFIG_SYS_FSL_TBCLK_DIV
347 Defines the core time base clock divider ratio compared to the
348 system clock. On most PQ3 devices this is 8, on newer QorIQ
349 devices it can be 16 or 32. The ratio varies from SoC to Soc.
351 CONFIG_SYS_FSL_PCIE_COMPAT
353 Defines the string to utilize when trying to match PCIe device
354 tree nodes for the given platform.
356 CONFIG_SYS_FSL_ERRATUM_A004510
358 Enables a workaround for erratum A004510. If set,
359 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
360 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
362 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
365 Defines one or two SoC revisions (low 8 bits of SVR)
366 for which the A004510 workaround should be applied.
368 The rest of SVR is either not relevant to the decision
369 of whether the erratum is present (e.g. p2040 versus
370 p2041) or is implied by the build target, which controls
371 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
373 See Freescale App Note 4493 for more information about
376 CONFIG_A003399_NOR_WORKAROUND
377 Enables a workaround for IFC erratum A003399. It is only
378 required during NOR boot.
380 CONFIG_A008044_WORKAROUND
381 Enables a workaround for T1040/T1042 erratum A008044. It is only
382 required during NAND boot and valid for Rev 1.0 SoC revision
384 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
386 This is the value to write into CCSR offset 0x18600
387 according to the A004510 workaround.
389 CONFIG_SYS_FSL_DSP_DDR_ADDR
390 This value denotes start offset of DDR memory which is
391 connected exclusively to the DSP cores.
393 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
394 This value denotes start offset of M2 memory
395 which is directly connected to the DSP core.
397 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
398 This value denotes start offset of M3 memory which is directly
399 connected to the DSP core.
401 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
402 This value denotes start offset of DSP CCSR space.
404 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
405 Single Source Clock is clocking mode present in some of FSL SoC's.
406 In this mode, a single differential clock is used to supply
407 clocks to the sysclock, ddrclock and usbclock.
409 CONFIG_SYS_CPC_REINIT_F
410 This CONFIG is defined when the CPC is configured as SRAM at the
411 time of U-Boot entry and is required to be re-initialized.
414 Indicates this SoC supports deep sleep feature. If deep sleep is
415 supported, core will start to execute uboot when wakes up.
417 - Generic CPU options:
418 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
420 Defines the endianess of the CPU. Implementation of those
421 values is arch specific.
424 Freescale DDR driver in use. This type of DDR controller is
425 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
427 CONFIG_SYS_FSL_DDR_ADDR
428 Freescale DDR memory-mapped register base.
430 CONFIG_SYS_FSL_DDR_EMU
431 Specify emulator support for DDR. Some DDR features such as
432 deskew training are not available.
434 CONFIG_SYS_FSL_DDRC_GEN1
435 Freescale DDR1 controller.
437 CONFIG_SYS_FSL_DDRC_GEN2
438 Freescale DDR2 controller.
440 CONFIG_SYS_FSL_DDRC_GEN3
441 Freescale DDR3 controller.
443 CONFIG_SYS_FSL_DDRC_GEN4
444 Freescale DDR4 controller.
446 CONFIG_SYS_FSL_DDRC_ARM_GEN3
447 Freescale DDR3 controller for ARM-based SoCs.
450 Board config to use DDR1. It can be enabled for SoCs with
451 Freescale DDR1 or DDR2 controllers, depending on the board
455 Board config to use DDR2. It can be enabled for SoCs with
456 Freescale DDR2 or DDR3 controllers, depending on the board
460 Board config to use DDR3. It can be enabled for SoCs with
461 Freescale DDR3 or DDR3L controllers.
464 Board config to use DDR3L. It can be enabled for SoCs with
467 CONFIG_SYS_FSL_IFC_BE
468 Defines the IFC controller register space as Big Endian
470 CONFIG_SYS_FSL_IFC_LE
471 Defines the IFC controller register space as Little Endian
473 CONFIG_SYS_FSL_IFC_CLK_DIV
474 Defines divider of platform clock(clock input to IFC controller).
476 CONFIG_SYS_FSL_LBC_CLK_DIV
477 Defines divider of platform clock(clock input to eLBC controller).
479 CONFIG_SYS_FSL_DDR_BE
480 Defines the DDR controller register space as Big Endian
482 CONFIG_SYS_FSL_DDR_LE
483 Defines the DDR controller register space as Little Endian
485 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
486 Physical address from the view of DDR controllers. It is the
487 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
488 it could be different for ARM SoCs.
490 CONFIG_SYS_FSL_DDR_INTLV_256B
491 DDR controller interleaving on 256-byte. This is a special
492 interleaving mode, handled by Dickens for Freescale layerscape
495 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
496 Number of controllers used as main memory.
498 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
499 Number of controllers used for other than main memory.
501 CONFIG_SYS_FSL_HAS_DP_DDR
502 Defines the SoC has DP-DDR used for DPAA.
504 CONFIG_SYS_FSL_SEC_BE
505 Defines the SEC controller register space as Big Endian
507 CONFIG_SYS_FSL_SEC_LE
508 Defines the SEC controller register space as Little Endian
511 CONFIG_SYS_INIT_SP_OFFSET
513 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
514 pointer. This is needed for the temporary stack before
517 CONFIG_XWAY_SWAP_BYTES
519 Enable compilation of tools/xway-swap-bytes needed for Lantiq
520 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
521 be swapped if a flash programmer is used.
524 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
526 Select high exception vectors of the ARM core, e.g., do not
527 clear the V bit of the c1 register of CP15.
530 Generic timer clock source frequency.
532 COUNTER_FREQUENCY_REAL
533 Generic timer clock source frequency if the real clock is
534 different from COUNTER_FREQUENCY, and can only be determined
538 CONFIG_TEGRA_SUPPORT_NON_SECURE
540 Support executing U-Boot in non-secure (NS) mode. Certain
541 impossible actions will be skipped if the CPU is in NS mode,
542 such as ARM architectural timer initialization.
544 - Linux Kernel Interface:
545 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
547 When transferring memsize parameter to Linux, some versions
548 expect it to be in bytes, others in MB.
549 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
553 New kernel versions are expecting firmware settings to be
554 passed using flattened device trees (based on open firmware
558 * New libfdt-based support
559 * Adds the "fdt" command
560 * The bootm command automatically updates the fdt
562 OF_TBCLK - The timebase frequency.
564 boards with QUICC Engines require OF_QE to set UCC MAC
567 CONFIG_OF_BOARD_SETUP
569 Board code has addition modification that it wants to make
570 to the flat device tree before handing it off to the kernel
572 CONFIG_OF_SYSTEM_SETUP
574 Other code has addition modification that it wants to make
575 to the flat device tree before handing it off to the kernel.
576 This causes ft_system_setup() to be called before booting
581 U-Boot can detect if an IDE device is present or not.
582 If not, and this new config option is activated, U-Boot
583 removes the ATA node from the DTS before booting Linux,
584 so the Linux IDE driver does not probe the device and
585 crash. This is needed for buggy hardware (uc101) where
586 no pull down resistor is connected to the signal IDE5V_DD7.
588 - vxWorks boot parameters:
590 bootvx constructs a valid bootline using the following
591 environments variables: bootdev, bootfile, ipaddr, netmask,
592 serverip, gatewayip, hostname, othbootargs.
593 It loads the vxWorks image pointed bootfile.
595 Note: If a "bootargs" environment is defined, it will override
596 the defaults discussed just above.
598 - Cache Configuration:
599 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
601 - Cache Configuration for ARM:
602 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
604 CONFIG_SYS_PL310_BASE - Physical base address of PL310
605 controller register space
610 Define this if you want support for Amba PrimeCell PL011 UARTs.
614 If you have Amba PrimeCell PL011 UARTs, set this variable to
615 the clock speed of the UARTs.
619 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
620 define this to a list of base addresses for each (supported)
621 port. See e.g. include/configs/versatile.h
623 CONFIG_SERIAL_HW_FLOW_CONTROL
625 Define this variable to enable hw flow control in serial driver.
626 Current user of this option is drivers/serial/nsl16550.c driver
630 Only needed when CONFIG_BOOTDELAY is enabled;
631 define a command string that is automatically executed
632 when no character is read on the console interface
633 within "Boot Delay" after reset.
635 CONFIG_RAMBOOT and CONFIG_NFSBOOT
636 The value of these goes into the environment as
637 "ramboot" and "nfsboot" respectively, and can be used
638 as a convenience, when switching between booting from
641 - Serial Download Echo Mode:
643 If defined to 1, all characters received during a
644 serial download (using the "loads" command) are
645 echoed back. This might be needed by some terminal
646 emulations (like "cu"), but may as well just take
647 time on others. This setting #define's the initial
648 value of the "loads_echo" environment variable.
650 - Removal of commands
651 If no commands are needed to boot, you can disable
652 CONFIG_CMDLINE to remove them. In this case, the command line
653 will not be available, and when U-Boot wants to execute the
654 boot command (on start-up) it will call board_run_command()
655 instead. This can reduce image size significantly for very
656 simple boot procedures.
658 - Regular expression support:
660 If this variable is defined, U-Boot is linked against
661 the SLRE (Super Light Regular Expression) library,
662 which adds regex support to some commands, as for
663 example "env grep" and "setexpr".
667 If this variable is defined, U-Boot will use a device tree
668 to configure its devices, instead of relying on statically
669 compiled #defines in the board file. This option is
670 experimental and only available on a few boards. The device
671 tree is available in the global data as gd->fdt_blob.
673 U-Boot needs to get its device tree from somewhere. This can
674 be done using one of the three options below:
677 If this variable is defined, U-Boot will build a device tree
678 binary. It will be called u-boot.dtb. Architecture-specific
679 code will locate it at run-time. Generally this works by:
681 cat u-boot.bin u-boot.dtb >image.bin
683 and in fact, U-Boot does this for you, creating a file called
684 u-boot-dtb.bin which is useful in the common case. You can
685 still use the individual files if you need something more
689 If this variable is defined, U-Boot will use the device tree
690 provided by the board at runtime instead of embedding one with
691 the image. Only boards defining board_fdt_blob_setup() support
692 this option (see include/fdtdec.h file).
696 If this variable is defined, it enables watchdog
697 support for the SoC. There must be support in the SoC
698 specific code for a watchdog. For the 8xx
699 CPUs, the SIU Watchdog feature is enabled in the SYPCR
700 register. When supported for a specific SoC is
701 available, then no further board specific code should
705 When using a watchdog circuitry external to the used
706 SoC, then define this variable and provide board
707 specific code for the "hw_watchdog_reset" function.
709 CONFIG_SYS_WATCHDOG_FREQ
710 Some platforms automatically call WATCHDOG_RESET()
711 from the timer interrupt handler every
712 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
713 board configuration file, a default of CONFIG_SYS_HZ/2
714 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
715 to 0 disables calling WATCHDOG_RESET() from the timer
720 When CONFIG_CMD_DATE is selected, the type of the RTC
721 has to be selected, too. Define exactly one of the
724 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
725 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
726 CONFIG_RTC_MC146818 - use MC146818 RTC
727 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
728 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
729 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
730 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
731 CONFIG_RTC_DS164x - use Dallas DS164x RTC
732 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
733 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
734 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
735 CONFIG_SYS_RV3029_TCR - enable trickle charger on
738 Note that if the RTC uses I2C, then the I2C interface
739 must also be configured. See I2C Support, below.
742 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
744 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
745 chip-ngpio pairs that tell the PCA953X driver the number of
746 pins supported by a particular chip.
748 Note that if the GPIO device uses I2C, then the I2C interface
749 must also be configured. See I2C Support, below.
752 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
753 accesses and can checksum them or write a list of them out
754 to memory. See the 'iotrace' command for details. This is
755 useful for testing device drivers since it can confirm that
756 the driver behaves the same way before and after a code
757 change. Currently this is supported on sandbox and arm. To
758 add support for your architecture, add '#include <iotrace.h>'
759 to the bottom of arch/<arch>/include/asm/io.h and test.
761 Example output from the 'iotrace stats' command is below.
762 Note that if the trace buffer is exhausted, the checksum will
763 still continue to operate.
766 Start: 10000000 (buffer start address)
767 Size: 00010000 (buffer size)
768 Offset: 00000120 (current buffer offset)
769 Output: 10000120 (start + offset)
770 Count: 00000018 (number of trace records)
771 CRC32: 9526fb66 (CRC32 of all trace records)
775 When CONFIG_TIMESTAMP is selected, the timestamp
776 (date and time) of an image is printed by image
777 commands like bootm or iminfo. This option is
778 automatically enabled when you select CONFIG_CMD_DATE .
780 - Partition Labels (disklabels) Supported:
781 Zero or more of the following:
782 CONFIG_MAC_PARTITION Apple's MacOS partition table.
783 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
784 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
785 bootloader. Note 2TB partition limit; see
787 CONFIG_SCSI) you must configure support for at
788 least one non-MTD partition type as well.
791 CONFIG_IDE_RESET_ROUTINE - this is defined in several
792 board configurations files but used nowhere!
794 CONFIG_IDE_RESET - is this is defined, IDE Reset will
795 be performed by calling the function
796 ide_set_reset(int reset)
797 which has to be defined in a board specific file
802 Set this to enable ATAPI support.
807 Set this to enable support for disks larger than 137GB
808 Also look at CONFIG_SYS_64BIT_LBA.
809 Whithout these , LBA48 support uses 32bit variables and will 'only'
810 support disks up to 2.1TB.
812 CONFIG_SYS_64BIT_LBA:
813 When enabled, makes the IDE subsystem use 64bit sector addresses.
817 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
818 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
819 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
820 maximum numbers of LUNs, SCSI ID's and target
823 The environment variable 'scsidevs' is set to the number of
824 SCSI devices found during the last scan.
826 - NETWORK Support (PCI):
828 Support for Intel 8254x/8257x gigabit chips.
831 Utility code for direct access to the SPI bus on Intel 8257x.
832 This does not do anything useful unless you set at least one
833 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
835 CONFIG_E1000_SPI_GENERIC
836 Allow generic access to the SPI bus on the Intel 8257x, for
837 example with the "sspi" command.
840 Support for National dp83815 chips.
843 Support for National dp8382[01] gigabit chips.
845 - NETWORK Support (other):
847 Support for the Calxeda XGMAC device
850 Support for SMSC's LAN91C96 chips.
852 CONFIG_LAN91C96_USE_32_BIT
853 Define this to enable 32 bit addressing
856 Support for SMSC's LAN91C111 chip
859 Define this to hold the physical address
860 of the device (I/O space)
862 CONFIG_SMC_USE_32_BIT
863 Define this if data bus is 32 bits
865 CONFIG_SMC_USE_IOFUNCS
866 Define this to use i/o functions instead of macros
867 (some hardware wont work with macros)
869 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
870 Define this if you have more then 3 PHYs.
873 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
875 CONFIG_FTGMAC100_EGIGA
876 Define this to use GE link update with gigabit PHY.
877 Define this if FTGMAC100 is connected to gigabit PHY.
878 If your system has 10/100 PHY only, it might not occur
879 wrong behavior. Because PHY usually return timeout or
880 useless data when polling gigabit status and gigabit
881 control registers. This behavior won't affect the
882 correctnessof 10/100 link speed update.
885 Support for Renesas on-chip Ethernet controller
887 CONFIG_SH_ETHER_USE_PORT
888 Define the number of ports to be used
890 CONFIG_SH_ETHER_PHY_ADDR
891 Define the ETH PHY's address
893 CONFIG_SH_ETHER_CACHE_WRITEBACK
894 If this option is set, the driver enables cache flush.
900 CONFIG_TPM_TIS_INFINEON
901 Support for Infineon i2c bus TPM devices. Only one device
902 per system is supported at this time.
904 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
905 Define the burst count bytes upper limit
908 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
910 CONFIG_TPM_ST33ZP24_I2C
911 Support for STMicroelectronics ST33ZP24 I2C devices.
912 Requires TPM_ST33ZP24 and I2C.
914 CONFIG_TPM_ST33ZP24_SPI
915 Support for STMicroelectronics ST33ZP24 SPI devices.
916 Requires TPM_ST33ZP24 and SPI.
919 Support for Atmel TWI TPM device. Requires I2C support.
922 Support for generic parallel port TPM devices. Only one device
923 per system is supported at this time.
925 CONFIG_TPM_TIS_BASE_ADDRESS
926 Base address where the generic TPM device is mapped
927 to. Contemporary x86 systems usually map it at
931 Define this to enable the TPM support library which provides
932 functional interfaces to some TPM commands.
933 Requires support for a TPM device.
935 CONFIG_TPM_AUTH_SESSIONS
936 Define this to enable authorized functions in the TPM library.
937 Requires CONFIG_TPM and CONFIG_SHA1.
940 At the moment only the UHCI host controller is
941 supported (PIP405, MIP405); define
942 CONFIG_USB_UHCI to enable it.
943 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
944 and define CONFIG_USB_STORAGE to enable the USB
947 Supported are USB Keyboards and USB Floppy drives
950 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
951 txfilltuning field in the EHCI controller on reset.
953 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
957 Define the below if you wish to use the USB console.
958 Once firmware is rebuilt from a serial console issue the
959 command "setenv stdin usbtty; setenv stdout usbtty" and
960 attach your USB cable. The Unix command "dmesg" should print
961 it has found a new device. The environment variable usbtty
962 can be set to gserial or cdc_acm to enable your device to
963 appear to a USB host as a Linux gserial device or a
964 Common Device Class Abstract Control Model serial device.
965 If you select usbtty = gserial you should be able to enumerate
967 # modprobe usbserial vendor=0xVendorID product=0xProductID
968 else if using cdc_acm, simply setting the environment
969 variable usbtty to be cdc_acm should suffice. The following
970 might be defined in YourBoardName.h
973 Define this to build a UDC device
976 Define this to have a tty type of device available to
977 talk to the UDC device
980 Define this to enable the high speed support for usb
981 device and usbtty. If this feature is enabled, a routine
982 int is_usbd_high_speed(void)
983 also needs to be defined by the driver to dynamically poll
984 whether the enumeration has succeded at high speed or full
987 CONFIG_SYS_CONSOLE_IS_IN_ENV
988 Define this if you want stdin, stdout &/or stderr to
991 If you have a USB-IF assigned VendorID then you may wish to
992 define your own vendor specific values either in BoardName.h
993 or directly in usbd_vendor_info.h. If you don't define
994 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
995 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
996 should pretend to be a Linux device to it's target host.
998 CONFIG_USBD_MANUFACTURER
999 Define this string as the name of your company for
1000 - CONFIG_USBD_MANUFACTURER "my company"
1002 CONFIG_USBD_PRODUCT_NAME
1003 Define this string as the name of your product
1004 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1006 CONFIG_USBD_VENDORID
1007 Define this as your assigned Vendor ID from the USB
1008 Implementors Forum. This *must* be a genuine Vendor ID
1009 to avoid polluting the USB namespace.
1010 - CONFIG_USBD_VENDORID 0xFFFF
1012 CONFIG_USBD_PRODUCTID
1013 Define this as the unique Product ID
1015 - CONFIG_USBD_PRODUCTID 0xFFFF
1017 - ULPI Layer Support:
1018 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1019 the generic ULPI layer. The generic layer accesses the ULPI PHY
1020 via the platform viewport, so you need both the genric layer and
1021 the viewport enabled. Currently only Chipidea/ARC based
1022 viewport is supported.
1023 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1024 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1025 If your ULPI phy needs a different reference clock than the
1026 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1027 the appropriate value in Hz.
1030 The MMC controller on the Intel PXA is supported. To
1031 enable this define CONFIG_MMC. The MMC can be
1032 accessed from the boot prompt by mapping the device
1033 to physical memory similar to flash. Command line is
1034 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1035 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1038 Support for Renesas on-chip MMCIF controller
1040 CONFIG_SH_MMCIF_ADDR
1041 Define the base address of MMCIF registers
1044 Define the clock frequency for MMCIF
1046 - USB Device Firmware Update (DFU) class support:
1048 This enables the USB portion of the DFU USB class
1051 This enables support for exposing NAND devices via DFU.
1054 This enables support for exposing RAM via DFU.
1055 Note: DFU spec refer to non-volatile memory usage, but
1056 allow usages beyond the scope of spec - here RAM usage,
1057 one that would help mostly the developer.
1059 CONFIG_SYS_DFU_DATA_BUF_SIZE
1060 Dfu transfer uses a buffer before writing data to the
1061 raw storage device. Make the size (in bytes) of this buffer
1062 configurable. The size of this buffer is also configurable
1063 through the "dfu_bufsiz" environment variable.
1065 CONFIG_SYS_DFU_MAX_FILE_SIZE
1066 When updating files rather than the raw storage device,
1067 we use a static buffer to copy the file into and then write
1068 the buffer once we've been given the whole file. Define
1069 this to the maximum filesize (in bytes) for the buffer.
1070 Default is 4 MiB if undefined.
1072 DFU_DEFAULT_POLL_TIMEOUT
1073 Poll timeout [ms], is the timeout a device can send to the
1074 host. The host must wait for this timeout before sending
1075 a subsequent DFU_GET_STATUS request to the device.
1077 DFU_MANIFEST_POLL_TIMEOUT
1078 Poll timeout [ms], which the device sends to the host when
1079 entering dfuMANIFEST state. Host waits this timeout, before
1080 sending again an USB request to the device.
1082 - Journaling Flash filesystem support:
1084 Define these for a default partition on a NAND device
1086 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1087 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1088 Define these for a default partition on a NOR device
1091 See Kconfig help for available keyboard drivers.
1095 Define this to enable a custom keyboard support.
1096 This simply calls drv_keyboard_init() which must be
1097 defined in your board-specific files. This option is deprecated
1098 and is only used by novena. For new boards, use driver model
1103 Enable the Freescale DIU video driver. Reference boards for
1104 SOCs that have a DIU should define this macro to enable DIU
1105 support, and should also define these other macros:
1110 CONFIG_VIDEO_SW_CURSOR
1111 CONFIG_VGA_AS_SINGLE_DEVICE
1113 CONFIG_VIDEO_BMP_LOGO
1115 The DIU driver will look for the 'video-mode' environment
1116 variable, and if defined, enable the DIU as a console during
1117 boot. See the documentation file doc/README.video for a
1118 description of this variable.
1120 - LCD Support: CONFIG_LCD
1122 Define this to enable LCD support (for output to LCD
1123 display); also select one of the supported displays
1124 by defining one of these:
1128 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1130 CONFIG_NEC_NL6448AC33:
1132 NEC NL6448AC33-18. Active, color, single scan.
1134 CONFIG_NEC_NL6448BC20
1136 NEC NL6448BC20-08. 6.5", 640x480.
1137 Active, color, single scan.
1139 CONFIG_NEC_NL6448BC33_54
1141 NEC NL6448BC33-54. 10.4", 640x480.
1142 Active, color, single scan.
1146 Sharp 320x240. Active, color, single scan.
1147 It isn't 16x9, and I am not sure what it is.
1149 CONFIG_SHARP_LQ64D341
1151 Sharp LQ64D341 display, 640x480.
1152 Active, color, single scan.
1156 HLD1045 display, 640x480.
1157 Active, color, single scan.
1161 Optrex CBL50840-2 NF-FW 99 22 M5
1163 Hitachi LMG6912RPFC-00T
1167 320x240. Black & white.
1169 CONFIG_LCD_ALIGNMENT
1171 Normally the LCD is page-aligned (typically 4KB). If this is
1172 defined then the LCD will be aligned to this value instead.
1173 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1174 here, since it is cheaper to change data cache settings on
1175 a per-section basis.
1180 Sometimes, for example if the display is mounted in portrait
1181 mode or even if it's mounted landscape but rotated by 180degree,
1182 we need to rotate our content of the display relative to the
1183 framebuffer, so that user can read the messages which are
1185 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1186 initialized with a given rotation from "vl_rot" out of
1187 "vidinfo_t" which is provided by the board specific code.
1188 The value for vl_rot is coded as following (matching to
1189 fbcon=rotate:<n> linux-kernel commandline):
1190 0 = no rotation respectively 0 degree
1191 1 = 90 degree rotation
1192 2 = 180 degree rotation
1193 3 = 270 degree rotation
1195 If CONFIG_LCD_ROTATION is not defined, the console will be
1196 initialized with 0degree rotation.
1200 Support drawing of RLE8-compressed bitmaps on the LCD.
1204 Enables an 'i2c edid' command which can read EDID
1205 information over I2C from an attached LCD display.
1208 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1210 The clock frequency of the MII bus
1212 CONFIG_PHY_RESET_DELAY
1214 Some PHY like Intel LXT971A need extra delay after
1215 reset before any MII register access is possible.
1216 For such PHY, set this option to the usec delay
1217 required. (minimum 300usec for LXT971A)
1219 CONFIG_PHY_CMD_DELAY (ppc4xx)
1221 Some PHY like Intel LXT971A need extra delay after
1222 command issued before MII status register can be read
1227 Define a default value for the IP address to use for
1228 the default Ethernet interface, in case this is not
1229 determined through e.g. bootp.
1230 (Environment variable "ipaddr")
1232 - Server IP address:
1235 Defines a default value for the IP address of a TFTP
1236 server to contact when using the "tftboot" command.
1237 (Environment variable "serverip")
1239 CONFIG_KEEP_SERVERADDR
1241 Keeps the server's MAC address, in the env 'serveraddr'
1242 for passing to bootargs (like Linux's netconsole option)
1244 - Gateway IP address:
1247 Defines a default value for the IP address of the
1248 default router where packets to other networks are
1250 (Environment variable "gatewayip")
1255 Defines a default value for the subnet mask (or
1256 routing prefix) which is used to determine if an IP
1257 address belongs to the local subnet or needs to be
1258 forwarded through a router.
1259 (Environment variable "netmask")
1261 - BOOTP Recovery Mode:
1262 CONFIG_BOOTP_RANDOM_DELAY
1264 If you have many targets in a network that try to
1265 boot using BOOTP, you may want to avoid that all
1266 systems send out BOOTP requests at precisely the same
1267 moment (which would happen for instance at recovery
1268 from a power failure, when all systems will try to
1269 boot, thus flooding the BOOTP server. Defining
1270 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1271 inserted before sending out BOOTP requests. The
1272 following delays are inserted then:
1274 1st BOOTP request: delay 0 ... 1 sec
1275 2nd BOOTP request: delay 0 ... 2 sec
1276 3rd BOOTP request: delay 0 ... 4 sec
1278 BOOTP requests: delay 0 ... 8 sec
1280 CONFIG_BOOTP_ID_CACHE_SIZE
1282 BOOTP packets are uniquely identified using a 32-bit ID. The
1283 server will copy the ID from client requests to responses and
1284 U-Boot will use this to determine if it is the destination of
1285 an incoming response. Some servers will check that addresses
1286 aren't in use before handing them out (usually using an ARP
1287 ping) and therefore take up to a few hundred milliseconds to
1288 respond. Network congestion may also influence the time it
1289 takes for a response to make it back to the client. If that
1290 time is too long, U-Boot will retransmit requests. In order
1291 to allow earlier responses to still be accepted after these
1292 retransmissions, U-Boot's BOOTP client keeps a small cache of
1293 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1294 cache. The default is to keep IDs for up to four outstanding
1295 requests. Increasing this will allow U-Boot to accept offers
1296 from a BOOTP client in networks with unusually high latency.
1298 - DHCP Advanced Options:
1299 You can fine tune the DHCP functionality by defining
1300 CONFIG_BOOTP_* symbols:
1302 CONFIG_BOOTP_NISDOMAIN
1303 CONFIG_BOOTP_BOOTFILESIZE
1304 CONFIG_BOOTP_NTPSERVER
1305 CONFIG_BOOTP_TIMEOFFSET
1306 CONFIG_BOOTP_VENDOREX
1307 CONFIG_BOOTP_MAY_FAIL
1309 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1310 environment variable, not the BOOTP server.
1312 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1313 after the configured retry count, the call will fail
1314 instead of starting over. This can be used to fail over
1315 to Link-local IP address configuration if the DHCP server
1318 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1320 A 32bit value in microseconds for a delay between
1321 receiving a "DHCP Offer" and sending the "DHCP Request".
1322 This fixes a problem with certain DHCP servers that don't
1323 respond 100% of the time to a "DHCP request". E.g. On an
1324 AT91RM9200 processor running at 180MHz, this delay needed
1325 to be *at least* 15,000 usec before a Windows Server 2003
1326 DHCP server would reply 100% of the time. I recommend at
1327 least 50,000 usec to be safe. The alternative is to hope
1328 that one of the retries will be successful but note that
1329 the DHCP timeout and retry process takes a longer than
1332 - Link-local IP address negotiation:
1333 Negotiate with other link-local clients on the local network
1334 for an address that doesn't require explicit configuration.
1335 This is especially useful if a DHCP server cannot be guaranteed
1336 to exist in all environments that the device must operate.
1338 See doc/README.link-local for more information.
1340 - MAC address from environment variables
1342 FDT_SEQ_MACADDR_FROM_ENV
1344 Fix-up device tree with MAC addresses fetched sequentially from
1345 environment variables. This config work on assumption that
1346 non-usable ethernet node of device-tree are either not present
1347 or their status has been marked as "disabled".
1350 CONFIG_CDP_DEVICE_ID
1352 The device id used in CDP trigger frames.
1354 CONFIG_CDP_DEVICE_ID_PREFIX
1356 A two character string which is prefixed to the MAC address
1361 A printf format string which contains the ascii name of
1362 the port. Normally is set to "eth%d" which sets
1363 eth0 for the first Ethernet, eth1 for the second etc.
1365 CONFIG_CDP_CAPABILITIES
1367 A 32bit integer which indicates the device capabilities;
1368 0x00000010 for a normal host which does not forwards.
1372 An ascii string containing the version of the software.
1376 An ascii string containing the name of the platform.
1380 A 32bit integer sent on the trigger.
1382 CONFIG_CDP_POWER_CONSUMPTION
1384 A 16bit integer containing the power consumption of the
1385 device in .1 of milliwatts.
1387 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1389 A byte containing the id of the VLAN.
1391 - Status LED: CONFIG_LED_STATUS
1393 Several configurations allow to display the current
1394 status using a LED. For instance, the LED will blink
1395 fast while running U-Boot code, stop blinking as
1396 soon as a reply to a BOOTP request was received, and
1397 start blinking slow once the Linux kernel is running
1398 (supported by a status LED driver in the Linux
1399 kernel). Defining CONFIG_LED_STATUS enables this
1404 CONFIG_LED_STATUS_GPIO
1405 The status LED can be connected to a GPIO pin.
1406 In such cases, the gpio_led driver can be used as a
1407 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1408 to include the gpio_led driver in the U-Boot binary.
1410 CONFIG_GPIO_LED_INVERTED_TABLE
1411 Some GPIO connected LEDs may have inverted polarity in which
1412 case the GPIO high value corresponds to LED off state and
1413 GPIO low value corresponds to LED on state.
1414 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1415 with a list of GPIO LEDs that have inverted polarity.
1418 CONFIG_SYS_NUM_I2C_BUSES
1419 Hold the number of i2c buses you want to use.
1421 CONFIG_SYS_I2C_DIRECT_BUS
1422 define this, if you don't use i2c muxes on your hardware.
1423 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1426 CONFIG_SYS_I2C_MAX_HOPS
1427 define how many muxes are maximal consecutively connected
1428 on one i2c bus. If you not use i2c muxes, omit this
1431 CONFIG_SYS_I2C_BUSES
1432 hold a list of buses you want to use, only used if
1433 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1434 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1435 CONFIG_SYS_NUM_I2C_BUSES = 9:
1437 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1438 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1439 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1440 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1441 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1442 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1443 {1, {I2C_NULL_HOP}}, \
1444 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1445 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1449 bus 0 on adapter 0 without a mux
1450 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1451 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1452 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1453 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1454 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1455 bus 6 on adapter 1 without a mux
1456 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1457 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1459 If you do not have i2c muxes on your board, omit this define.
1461 - Legacy I2C Support:
1462 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1463 then the following macros need to be defined (examples are
1464 from include/configs/lwmon.h):
1468 (Optional). Any commands necessary to enable the I2C
1469 controller or configure ports.
1471 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1475 The code necessary to make the I2C data line active
1476 (driven). If the data line is open collector, this
1479 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1483 The code necessary to make the I2C data line tri-stated
1484 (inactive). If the data line is open collector, this
1487 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1491 Code that returns true if the I2C data line is high,
1494 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1498 If <bit> is true, sets the I2C data line high. If it
1499 is false, it clears it (low).
1501 eg: #define I2C_SDA(bit) \
1502 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1503 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1507 If <bit> is true, sets the I2C clock line high. If it
1508 is false, it clears it (low).
1510 eg: #define I2C_SCL(bit) \
1511 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1512 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1516 This delay is invoked four times per clock cycle so this
1517 controls the rate of data transfer. The data rate thus
1518 is 1 / (I2C_DELAY * 4). Often defined to be something
1521 #define I2C_DELAY udelay(2)
1523 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1525 If your arch supports the generic GPIO framework (asm/gpio.h),
1526 then you may alternatively define the two GPIOs that are to be
1527 used as SCL / SDA. Any of the previous I2C_xxx macros will
1528 have GPIO-based defaults assigned to them as appropriate.
1530 You should define these to the GPIO value as given directly to
1531 the generic GPIO functions.
1533 CONFIG_SYS_I2C_INIT_BOARD
1535 When a board is reset during an i2c bus transfer
1536 chips might think that the current transfer is still
1537 in progress. On some boards it is possible to access
1538 the i2c SCLK line directly, either by using the
1539 processor pin as a GPIO or by having a second pin
1540 connected to the bus. If this option is defined a
1541 custom i2c_init_board() routine in boards/xxx/board.c
1542 is run early in the boot sequence.
1544 CONFIG_I2C_MULTI_BUS
1546 This option allows the use of multiple I2C buses, each of which
1547 must have a controller. At any point in time, only one bus is
1548 active. To switch to a different bus, use the 'i2c dev' command.
1549 Note that bus numbering is zero-based.
1551 CONFIG_SYS_I2C_NOPROBES
1553 This option specifies a list of I2C devices that will be skipped
1554 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1555 is set, specify a list of bus-device pairs. Otherwise, specify
1556 a 1D array of device addresses
1559 #undef CONFIG_I2C_MULTI_BUS
1560 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1562 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1564 #define CONFIG_I2C_MULTI_BUS
1565 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1567 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1569 CONFIG_SYS_SPD_BUS_NUM
1571 If defined, then this indicates the I2C bus number for DDR SPD.
1572 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1574 CONFIG_SYS_RTC_BUS_NUM
1576 If defined, then this indicates the I2C bus number for the RTC.
1577 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1579 CONFIG_SOFT_I2C_READ_REPEATED_START
1581 defining this will force the i2c_read() function in
1582 the soft_i2c driver to perform an I2C repeated start
1583 between writing the address pointer and reading the
1584 data. If this define is omitted the default behaviour
1585 of doing a stop-start sequence will be used. Most I2C
1586 devices can use either method, but some require one or
1589 - SPI Support: CONFIG_SPI
1591 Enables SPI driver (so far only tested with
1592 SPI EEPROM, also an instance works with Crystal A/D and
1593 D/As on the SACSng board)
1597 Enables a software (bit-bang) SPI driver rather than
1598 using hardware support. This is a general purpose
1599 driver that only requires three general I/O port pins
1600 (two outputs, one input) to function. If this is
1601 defined, the board configuration must define several
1602 SPI configuration items (port pins to use, etc). For
1603 an example, see include/configs/sacsng.h.
1605 CONFIG_SYS_SPI_MXC_WAIT
1606 Timeout for waiting until spi transfer completed.
1607 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1609 - FPGA Support: CONFIG_FPGA
1611 Enables FPGA subsystem.
1613 CONFIG_FPGA_<vendor>
1615 Enables support for specific chip vendors.
1618 CONFIG_FPGA_<family>
1620 Enables support for FPGA family.
1621 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1625 Specify the number of FPGA devices to support.
1627 CONFIG_SYS_FPGA_PROG_FEEDBACK
1629 Enable printing of hash marks during FPGA configuration.
1631 CONFIG_SYS_FPGA_CHECK_BUSY
1633 Enable checks on FPGA configuration interface busy
1634 status by the configuration function. This option
1635 will require a board or device specific function to
1640 If defined, a function that provides delays in the FPGA
1641 configuration driver.
1643 CONFIG_SYS_FPGA_CHECK_CTRLC
1644 Allow Control-C to interrupt FPGA configuration
1646 CONFIG_SYS_FPGA_CHECK_ERROR
1648 Check for configuration errors during FPGA bitfile
1649 loading. For example, abort during Virtex II
1650 configuration if the INIT_B line goes low (which
1651 indicated a CRC error).
1653 CONFIG_SYS_FPGA_WAIT_INIT
1655 Maximum time to wait for the INIT_B line to de-assert
1656 after PROB_B has been de-asserted during a Virtex II
1657 FPGA configuration sequence. The default time is 500
1660 CONFIG_SYS_FPGA_WAIT_BUSY
1662 Maximum time to wait for BUSY to de-assert during
1663 Virtex II FPGA configuration. The default is 5 ms.
1665 CONFIG_SYS_FPGA_WAIT_CONFIG
1667 Time to wait after FPGA configuration. The default is
1670 - Configuration Management:
1674 If defined, this string will be added to the U-Boot
1675 version information (U_BOOT_VERSION)
1677 - Vendor Parameter Protection:
1679 U-Boot considers the values of the environment
1680 variables "serial#" (Board Serial Number) and
1681 "ethaddr" (Ethernet Address) to be parameters that
1682 are set once by the board vendor / manufacturer, and
1683 protects these variables from casual modification by
1684 the user. Once set, these variables are read-only,
1685 and write or delete attempts are rejected. You can
1686 change this behaviour:
1688 If CONFIG_ENV_OVERWRITE is #defined in your config
1689 file, the write protection for vendor parameters is
1690 completely disabled. Anybody can change or delete
1693 Alternatively, if you define _both_ an ethaddr in the
1694 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1695 Ethernet address is installed in the environment,
1696 which can be changed exactly ONCE by the user. [The
1697 serial# is unaffected by this, i. e. it remains
1700 The same can be accomplished in a more flexible way
1701 for any variable by configuring the type of access
1702 to allow for those variables in the ".flags" variable
1703 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1708 Define this variable to enable the reservation of
1709 "protected RAM", i. e. RAM which is not overwritten
1710 by U-Boot. Define CONFIG_PRAM to hold the number of
1711 kB you want to reserve for pRAM. You can overwrite
1712 this default value by defining an environment
1713 variable "pram" to the number of kB you want to
1714 reserve. Note that the board info structure will
1715 still show the full amount of RAM. If pRAM is
1716 reserved, a new environment variable "mem" will
1717 automatically be defined to hold the amount of
1718 remaining RAM in a form that can be passed as boot
1719 argument to Linux, for instance like that:
1721 setenv bootargs ... mem=\${mem}
1724 This way you can tell Linux not to use this memory,
1725 either, which results in a memory region that will
1726 not be affected by reboots.
1728 *WARNING* If your board configuration uses automatic
1729 detection of the RAM size, you must make sure that
1730 this memory test is non-destructive. So far, the
1731 following board configurations are known to be
1734 IVMS8, IVML24, SPD8xx,
1735 HERMES, IP860, RPXlite, LWMON,
1738 - Access to physical memory region (> 4GB)
1739 Some basic support is provided for operations on memory not
1740 normally accessible to U-Boot - e.g. some architectures
1741 support access to more than 4GB of memory on 32-bit
1742 machines using physical address extension or similar.
1743 Define CONFIG_PHYSMEM to access this basic support, which
1744 currently only supports clearing the memory.
1747 CONFIG_NET_RETRY_COUNT
1749 This variable defines the number of retries for
1750 network operations like ARP, RARP, TFTP, or BOOTP
1751 before giving up the operation. If not defined, a
1752 default value of 5 is used.
1756 Timeout waiting for an ARP reply in milliseconds.
1760 Timeout in milliseconds used in NFS protocol.
1761 If you encounter "ERROR: Cannot umount" in nfs command,
1762 try longer timeout such as
1763 #define CONFIG_NFS_TIMEOUT 10000UL
1767 In the current implementation, the local variables
1768 space and global environment variables space are
1769 separated. Local variables are those you define by
1770 simply typing `name=value'. To access a local
1771 variable later on, you have write `$name' or
1772 `${name}'; to execute the contents of a variable
1773 directly type `$name' at the command prompt.
1775 Global environment variables are those you use
1776 setenv/printenv to work with. To run a command stored
1777 in such a variable, you need to use the run command,
1778 and you must not use the '$' sign to access them.
1780 To store commands and special characters in a
1781 variable, please use double quotation marks
1782 surrounding the whole text of the variable, instead
1783 of the backslashes before semicolons and special
1786 - Command Line Editing and History:
1787 CONFIG_CMDLINE_PS_SUPPORT
1789 Enable support for changing the command prompt string
1790 at run-time. Only static string is supported so far.
1791 The string is obtained from environment variables PS1
1794 - Default Environment:
1795 CONFIG_EXTRA_ENV_SETTINGS
1797 Define this to contain any number of null terminated
1798 strings (variable = value pairs) that will be part of
1799 the default environment compiled into the boot image.
1801 For example, place something like this in your
1802 board's config file:
1804 #define CONFIG_EXTRA_ENV_SETTINGS \
1808 Warning: This method is based on knowledge about the
1809 internal format how the environment is stored by the
1810 U-Boot code. This is NOT an official, exported
1811 interface! Although it is unlikely that this format
1812 will change soon, there is no guarantee either.
1813 You better know what you are doing here.
1815 Note: overly (ab)use of the default environment is
1816 discouraged. Make sure to check other ways to preset
1817 the environment like the "source" command or the
1820 CONFIG_DELAY_ENVIRONMENT
1822 Normally the environment is loaded when the board is
1823 initialised so that it is available to U-Boot. This inhibits
1824 that so that the environment is not available until
1825 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1826 this is instead controlled by the value of
1827 /config/load-environment.
1829 - TFTP Fixed UDP Port:
1832 If this is defined, the environment variable tftpsrcp
1833 is used to supply the TFTP UDP source port value.
1834 If tftpsrcp isn't defined, the normal pseudo-random port
1835 number generator is used.
1837 Also, the environment variable tftpdstp is used to supply
1838 the TFTP UDP destination port value. If tftpdstp isn't
1839 defined, the normal port 69 is used.
1841 The purpose for tftpsrcp is to allow a TFTP server to
1842 blindly start the TFTP transfer using the pre-configured
1843 target IP address and UDP port. This has the effect of
1844 "punching through" the (Windows XP) firewall, allowing
1845 the remainder of the TFTP transfer to proceed normally.
1846 A better solution is to properly configure the firewall,
1847 but sometimes that is not allowed.
1849 CONFIG_STANDALONE_LOAD_ADDR
1851 This option defines a board specific value for the
1852 address where standalone program gets loaded, thus
1853 overwriting the architecture dependent default
1856 - Frame Buffer Address:
1859 Define CONFIG_FB_ADDR if you want to use specific
1860 address for frame buffer. This is typically the case
1861 when using a graphics controller has separate video
1862 memory. U-Boot will then place the frame buffer at
1863 the given address instead of dynamically reserving it
1864 in system RAM by calling lcd_setmem(), which grabs
1865 the memory for the frame buffer depending on the
1866 configured panel size.
1868 Please see board_init_f function.
1870 - Automatic software updates via TFTP server
1872 CONFIG_UPDATE_TFTP_CNT_MAX
1873 CONFIG_UPDATE_TFTP_MSEC_MAX
1875 These options enable and control the auto-update feature;
1876 for a more detailed description refer to doc/README.update.
1878 - MTD Support (mtdparts command, UBI support)
1879 CONFIG_MTD_UBI_WL_THRESHOLD
1880 This parameter defines the maximum difference between the highest
1881 erase counter value and the lowest erase counter value of eraseblocks
1882 of UBI devices. When this threshold is exceeded, UBI starts performing
1883 wear leveling by means of moving data from eraseblock with low erase
1884 counter to eraseblocks with high erase counter.
1886 The default value should be OK for SLC NAND flashes, NOR flashes and
1887 other flashes which have eraseblock life-cycle 100000 or more.
1888 However, in case of MLC NAND flashes which typically have eraseblock
1889 life-cycle less than 10000, the threshold should be lessened (e.g.,
1890 to 128 or 256, although it does not have to be power of 2).
1894 CONFIG_MTD_UBI_BEB_LIMIT
1895 This option specifies the maximum bad physical eraseblocks UBI
1896 expects on the MTD device (per 1024 eraseblocks). If the
1897 underlying flash does not admit of bad eraseblocks (e.g. NOR
1898 flash), this value is ignored.
1900 NAND datasheets often specify the minimum and maximum NVM
1901 (Number of Valid Blocks) for the flashes' endurance lifetime.
1902 The maximum expected bad eraseblocks per 1024 eraseblocks
1903 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1904 which gives 20 for most NANDs (MaxNVB is basically the total
1905 count of eraseblocks on the chip).
1907 To put it differently, if this value is 20, UBI will try to
1908 reserve about 1.9% of physical eraseblocks for bad blocks
1909 handling. And that will be 1.9% of eraseblocks on the entire
1910 NAND chip, not just the MTD partition UBI attaches. This means
1911 that if you have, say, a NAND flash chip admits maximum 40 bad
1912 eraseblocks, and it is split on two MTD partitions of the same
1913 size, UBI will reserve 40 eraseblocks when attaching a
1918 CONFIG_MTD_UBI_FASTMAP
1919 Fastmap is a mechanism which allows attaching an UBI device
1920 in nearly constant time. Instead of scanning the whole MTD device it
1921 only has to locate a checkpoint (called fastmap) on the device.
1922 The on-flash fastmap contains all information needed to attach
1923 the device. Using fastmap makes only sense on large devices where
1924 attaching by scanning takes long. UBI will not automatically install
1925 a fastmap on old images, but you can set the UBI parameter
1926 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1927 that fastmap-enabled images are still usable with UBI implementations
1928 without fastmap support. On typical flash devices the whole fastmap
1929 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1931 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1932 Set this parameter to enable fastmap automatically on images
1936 CONFIG_MTD_UBI_FM_DEBUG
1937 Enable UBI fastmap debug
1942 Enable building of SPL globally.
1945 LDSCRIPT for linking the SPL binary.
1947 CONFIG_SPL_MAX_FOOTPRINT
1948 Maximum size in memory allocated to the SPL, BSS included.
1949 When defined, the linker checks that the actual memory
1950 used by SPL from _start to __bss_end does not exceed it.
1951 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1952 must not be both defined at the same time.
1955 Maximum size of the SPL image (text, data, rodata, and
1956 linker lists sections), BSS excluded.
1957 When defined, the linker checks that the actual size does
1960 CONFIG_SPL_RELOC_TEXT_BASE
1961 Address to relocate to. If unspecified, this is equal to
1962 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1964 CONFIG_SPL_BSS_START_ADDR
1965 Link address for the BSS within the SPL binary.
1967 CONFIG_SPL_BSS_MAX_SIZE
1968 Maximum size in memory allocated to the SPL BSS.
1969 When defined, the linker checks that the actual memory used
1970 by SPL from __bss_start to __bss_end does not exceed it.
1971 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1972 must not be both defined at the same time.
1975 Adress of the start of the stack SPL will use
1977 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1978 When defined, SPL will panic() if the image it has
1979 loaded does not have a signature.
1980 Defining this is useful when code which loads images
1981 in SPL cannot guarantee that absolutely all read errors
1983 An example is the LPC32XX MLC NAND driver, which will
1984 consider that a completely unreadable NAND block is bad,
1985 and thus should be skipped silently.
1987 CONFIG_SPL_RELOC_STACK
1988 Adress of the start of the stack SPL will use after
1989 relocation. If unspecified, this is equal to
1992 CONFIG_SYS_SPL_MALLOC_START
1993 Starting address of the malloc pool used in SPL.
1994 When this option is set the full malloc is used in SPL and
1995 it is set up by spl_init() and before that, the simple malloc()
1996 can be used if CONFIG_SYS_MALLOC_F is defined.
1998 CONFIG_SYS_SPL_MALLOC_SIZE
1999 The size of the malloc pool used in SPL.
2002 Enable booting directly to an OS from SPL.
2003 See also: doc/README.falcon
2005 CONFIG_SPL_DISPLAY_PRINT
2006 For ARM, enable an optional function to print more information
2007 about the running system.
2009 CONFIG_SPL_INIT_MINIMAL
2010 Arch init code should be built for a very small image
2012 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2013 Partition on the MMC to load U-Boot from when the MMC is being
2016 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2017 Sector to load kernel uImage from when MMC is being
2018 used in raw mode (for Falcon mode)
2020 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2021 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2022 Sector and number of sectors to load kernel argument
2023 parameters from when MMC is being used in raw mode
2026 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2027 Filename to read to load U-Boot when reading from filesystem
2029 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2030 Filename to read to load kernel uImage when reading
2031 from filesystem (for Falcon mode)
2033 CONFIG_SPL_FS_LOAD_ARGS_NAME
2034 Filename to read to load kernel argument parameters
2035 when reading from filesystem (for Falcon mode)
2037 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2038 Set this for NAND SPL on PPC mpc83xx targets, so that
2039 start.S waits for the rest of the SPL to load before
2040 continuing (the hardware starts execution after just
2041 loading the first page rather than the full 4K).
2043 CONFIG_SPL_SKIP_RELOCATE
2044 Avoid SPL relocation
2046 CONFIG_SPL_NAND_IDENT
2047 SPL uses the chip ID list to identify the NAND flash.
2048 Requires CONFIG_SPL_NAND_BASE.
2051 Support for a lightweight UBI (fastmap) scanner and
2054 CONFIG_SPL_NAND_RAW_ONLY
2055 Support to boot only raw u-boot.bin images. Use this only
2056 if you need to save space.
2058 CONFIG_SPL_COMMON_INIT_DDR
2059 Set for common ddr init with serial presence detect in
2062 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2063 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2064 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2065 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2066 CONFIG_SYS_NAND_ECCBYTES
2067 Defines the size and behavior of the NAND that SPL uses
2070 CONFIG_SYS_NAND_U_BOOT_DST
2071 Location in memory to load U-Boot to
2073 CONFIG_SYS_NAND_U_BOOT_SIZE
2074 Size of image to load
2076 CONFIG_SYS_NAND_U_BOOT_START
2077 Entry point in loaded image to jump to
2079 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2080 Define this if you need to first read the OOB and then the
2081 data. This is used, for example, on davinci platforms.
2083 CONFIG_SPL_RAM_DEVICE
2084 Support for running image already present in ram, in SPL binary
2087 Image offset to which the SPL should be padded before appending
2088 the SPL payload. By default, this is defined as
2089 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2090 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2091 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2094 Final target image containing SPL and payload. Some SPLs
2095 use an arch-specific makefile fragment instead, for
2096 example if more than one image needs to be produced.
2098 CONFIG_SPL_FIT_PRINT
2099 Printing information about a FIT image adds quite a bit of
2100 code to SPL. So this is normally disabled in SPL. Use this
2101 option to re-enable it. This will affect the output of the
2102 bootm command when booting a FIT image.
2106 Enable building of TPL globally.
2109 Image offset to which the TPL should be padded before appending
2110 the TPL payload. By default, this is defined as
2111 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2112 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2113 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2115 - Interrupt support (PPC):
2117 There are common interrupt_init() and timer_interrupt()
2118 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2119 for CPU specific initialization. interrupt_init_cpu()
2120 should set decrementer_count to appropriate value. If
2121 CPU resets decrementer automatically after interrupt
2122 (ppc4xx) it should set decrementer_count to zero.
2123 timer_interrupt() calls timer_interrupt_cpu() for CPU
2124 specific handling. If board has watchdog / status_led
2125 / other_activity_monitor it works automatically from
2126 general timer_interrupt().
2129 Board initialization settings:
2130 ------------------------------
2132 During Initialization u-boot calls a number of board specific functions
2133 to allow the preparation of board specific prerequisites, e.g. pin setup
2134 before drivers are initialized. To enable these callbacks the
2135 following configuration macros have to be defined. Currently this is
2136 architecture specific, so please check arch/your_architecture/lib/board.c
2137 typically in board_init_f() and board_init_r().
2139 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2140 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2141 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2142 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2144 Configuration Settings:
2145 -----------------------
2147 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2148 Optionally it can be defined to support 64-bit memory commands.
2150 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2151 undefine this when you're short of memory.
2153 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2154 width of the commands listed in the 'help' command output.
2156 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2157 prompt for user input.
2159 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2161 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2163 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2165 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2166 the application (usually a Linux kernel) when it is
2169 - CONFIG_SYS_BAUDRATE_TABLE:
2170 List of legal baudrate settings for this board.
2172 - CONFIG_SYS_MEM_RESERVE_SECURE
2173 Only implemented for ARMv8 for now.
2174 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2175 is substracted from total RAM and won't be reported to OS.
2176 This memory can be used as secure memory. A variable
2177 gd->arch.secure_ram is used to track the location. In systems
2178 the RAM base is not zero, or RAM is divided into banks,
2179 this variable needs to be recalcuated to get the address.
2181 - CONFIG_SYS_MEM_TOP_HIDE:
2182 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2183 this specified memory area will get subtracted from the top
2184 (end) of RAM and won't get "touched" at all by U-Boot. By
2185 fixing up gd->ram_size the Linux kernel should gets passed
2186 the now "corrected" memory size and won't touch it either.
2187 This should work for arch/ppc and arch/powerpc. Only Linux
2188 board ports in arch/powerpc with bootwrapper support that
2189 recalculate the memory size from the SDRAM controller setup
2190 will have to get fixed in Linux additionally.
2192 This option can be used as a workaround for the 440EPx/GRx
2193 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2196 WARNING: Please make sure that this value is a multiple of
2197 the Linux page size (normally 4k). If this is not the case,
2198 then the end address of the Linux memory will be located at a
2199 non page size aligned address and this could cause major
2202 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2203 Enable temporary baudrate change while serial download
2205 - CONFIG_SYS_SDRAM_BASE:
2206 Physical start address of SDRAM. _Must_ be 0 here.
2208 - CONFIG_SYS_FLASH_BASE:
2209 Physical start address of Flash memory.
2211 - CONFIG_SYS_MONITOR_BASE:
2212 Physical start address of boot monitor code (set by
2213 make config files to be same as the text base address
2214 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2215 CONFIG_SYS_FLASH_BASE when booting from flash.
2217 - CONFIG_SYS_MONITOR_LEN:
2218 Size of memory reserved for monitor code, used to
2219 determine _at_compile_time_ (!) if the environment is
2220 embedded within the U-Boot image, or in a separate
2223 - CONFIG_SYS_MALLOC_LEN:
2224 Size of DRAM reserved for malloc() use.
2226 - CONFIG_SYS_MALLOC_F_LEN
2227 Size of the malloc() pool for use before relocation. If
2228 this is defined, then a very simple malloc() implementation
2229 will become available before relocation. The address is just
2230 below the global data, and the stack is moved down to make
2233 This feature allocates regions with increasing addresses
2234 within the region. calloc() is supported, but realloc()
2235 is not available. free() is supported but does nothing.
2236 The memory will be freed (or in fact just forgotten) when
2237 U-Boot relocates itself.
2239 - CONFIG_SYS_MALLOC_SIMPLE
2240 Provides a simple and small malloc() and calloc() for those
2241 boards which do not use the full malloc in SPL (which is
2242 enabled with CONFIG_SYS_SPL_MALLOC_START).
2244 - CONFIG_SYS_NONCACHED_MEMORY:
2245 Size of non-cached memory area. This area of memory will be
2246 typically located right below the malloc() area and mapped
2247 uncached in the MMU. This is useful for drivers that would
2248 otherwise require a lot of explicit cache maintenance. For
2249 some drivers it's also impossible to properly maintain the
2250 cache. For example if the regions that need to be flushed
2251 are not a multiple of the cache-line size, *and* padding
2252 cannot be allocated between the regions to align them (i.e.
2253 if the HW requires a contiguous array of regions, and the
2254 size of each region is not cache-aligned), then a flush of
2255 one region may result in overwriting data that hardware has
2256 written to another region in the same cache-line. This can
2257 happen for example in network drivers where descriptors for
2258 buffers are typically smaller than the CPU cache-line (e.g.
2259 16 bytes vs. 32 or 64 bytes).
2261 Non-cached memory is only supported on 32-bit ARM at present.
2263 - CONFIG_SYS_BOOTM_LEN:
2264 Normally compressed uImages are limited to an
2265 uncompressed size of 8 MBytes. If this is not enough,
2266 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2267 to adjust this setting to your needs.
2269 - CONFIG_SYS_BOOTMAPSZ:
2270 Maximum size of memory mapped by the startup code of
2271 the Linux kernel; all data that must be processed by
2272 the Linux kernel (bd_info, boot arguments, FDT blob if
2273 used) must be put below this limit, unless "bootm_low"
2274 environment variable is defined and non-zero. In such case
2275 all data for the Linux kernel must be between "bootm_low"
2276 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2277 variable "bootm_mapsize" will override the value of
2278 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2279 then the value in "bootm_size" will be used instead.
2281 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2282 Enable initrd_high functionality. If defined then the
2283 initrd_high feature is enabled and the bootm ramdisk subcommand
2286 - CONFIG_SYS_BOOT_GET_CMDLINE:
2287 Enables allocating and saving kernel cmdline in space between
2288 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2290 - CONFIG_SYS_BOOT_GET_KBD:
2291 Enables allocating and saving a kernel copy of the bd_info in
2292 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2294 - CONFIG_SYS_MAX_FLASH_BANKS:
2295 Max number of Flash memory banks
2297 - CONFIG_SYS_MAX_FLASH_SECT:
2298 Max number of sectors on a Flash chip
2300 - CONFIG_SYS_FLASH_ERASE_TOUT:
2301 Timeout for Flash erase operations (in ms)
2303 - CONFIG_SYS_FLASH_WRITE_TOUT:
2304 Timeout for Flash write operations (in ms)
2306 - CONFIG_SYS_FLASH_LOCK_TOUT
2307 Timeout for Flash set sector lock bit operation (in ms)
2309 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2310 Timeout for Flash clear lock bits operation (in ms)
2312 - CONFIG_SYS_FLASH_PROTECTION
2313 If defined, hardware flash sectors protection is used
2314 instead of U-Boot software protection.
2316 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2318 Enable TFTP transfers directly to flash memory;
2319 without this option such a download has to be
2320 performed in two steps: (1) download to RAM, and (2)
2321 copy from RAM to flash.
2323 The two-step approach is usually more reliable, since
2324 you can check if the download worked before you erase
2325 the flash, but in some situations (when system RAM is
2326 too limited to allow for a temporary copy of the
2327 downloaded image) this option may be very useful.
2329 - CONFIG_SYS_FLASH_CFI:
2330 Define if the flash driver uses extra elements in the
2331 common flash structure for storing flash geometry.
2333 - CONFIG_FLASH_CFI_DRIVER
2334 This option also enables the building of the cfi_flash driver
2335 in the drivers directory
2337 - CONFIG_FLASH_CFI_MTD
2338 This option enables the building of the cfi_mtd driver
2339 in the drivers directory. The driver exports CFI flash
2342 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2343 Use buffered writes to flash.
2345 - CONFIG_FLASH_SPANSION_S29WS_N
2346 s29ws-n MirrorBit flash has non-standard addresses for buffered
2349 - CONFIG_SYS_FLASH_QUIET_TEST
2350 If this option is defined, the common CFI flash doesn't
2351 print it's warning upon not recognized FLASH banks. This
2352 is useful, if some of the configured banks are only
2353 optionally available.
2355 - CONFIG_FLASH_SHOW_PROGRESS
2356 If defined (must be an integer), print out countdown
2357 digits and dots. Recommended value: 45 (9..1) for 80
2358 column displays, 15 (3..1) for 40 column displays.
2360 - CONFIG_FLASH_VERIFY
2361 If defined, the content of the flash (destination) is compared
2362 against the source after the write operation. An error message
2363 will be printed when the contents are not identical.
2364 Please note that this option is useless in nearly all cases,
2365 since such flash programming errors usually are detected earlier
2366 while unprotecting/erasing/programming. Please only enable
2367 this option if you really know what you are doing.
2369 - CONFIG_SYS_RX_ETH_BUFFER:
2370 Defines the number of Ethernet receive buffers. On some
2371 Ethernet controllers it is recommended to set this value
2372 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2373 buffers can be full shortly after enabling the interface
2374 on high Ethernet traffic.
2375 Defaults to 4 if not defined.
2377 - CONFIG_ENV_MAX_ENTRIES
2379 Maximum number of entries in the hash table that is used
2380 internally to store the environment settings. The default
2381 setting is supposed to be generous and should work in most
2382 cases. This setting can be used to tune behaviour; see
2383 lib/hashtable.c for details.
2385 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2386 - CONFIG_ENV_FLAGS_LIST_STATIC
2387 Enable validation of the values given to environment variables when
2388 calling env set. Variables can be restricted to only decimal,
2389 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2390 the variables can also be restricted to IP address or MAC address.
2392 The format of the list is:
2393 type_attribute = [s|d|x|b|i|m]
2394 access_attribute = [a|r|o|c]
2395 attributes = type_attribute[access_attribute]
2396 entry = variable_name[:attributes]
2399 The type attributes are:
2400 s - String (default)
2403 b - Boolean ([1yYtT|0nNfF])
2407 The access attributes are:
2413 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2414 Define this to a list (string) to define the ".flags"
2415 environment variable in the default or embedded environment.
2417 - CONFIG_ENV_FLAGS_LIST_STATIC
2418 Define this to a list (string) to define validation that
2419 should be done if an entry is not found in the ".flags"
2420 environment variable. To override a setting in the static
2421 list, simply add an entry for the same variable name to the
2424 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2425 regular expression. This allows multiple variables to define the same
2426 flags without explicitly listing them for each variable.
2428 The following definitions that deal with the placement and management
2429 of environment data (variable area); in general, we support the
2430 following configurations:
2432 - CONFIG_BUILD_ENVCRC:
2434 Builds up envcrc with the target environment so that external utils
2435 may easily extract it and embed it in final U-Boot images.
2437 BE CAREFUL! The first access to the environment happens quite early
2438 in U-Boot initialization (when we try to get the setting of for the
2439 console baudrate). You *MUST* have mapped your NVRAM area then, or
2442 Please note that even with NVRAM we still use a copy of the
2443 environment in RAM: we could work on NVRAM directly, but we want to
2444 keep settings there always unmodified except somebody uses "saveenv"
2445 to save the current settings.
2447 BE CAREFUL! For some special cases, the local device can not use
2448 "saveenv" command. For example, the local device will get the
2449 environment stored in a remote NOR flash by SRIO or PCIE link,
2450 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2452 - CONFIG_NAND_ENV_DST
2454 Defines address in RAM to which the nand_spl code should copy the
2455 environment. If redundant environment is used, it will be copied to
2456 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2458 Please note that the environment is read-only until the monitor
2459 has been relocated to RAM and a RAM copy of the environment has been
2460 created; also, when using EEPROM you will have to use env_get_f()
2461 until then to read environment variables.
2463 The environment is protected by a CRC32 checksum. Before the monitor
2464 is relocated into RAM, as a result of a bad CRC you will be working
2465 with the compiled-in default environment - *silently*!!! [This is
2466 necessary, because the first environment variable we need is the
2467 "baudrate" setting for the console - if we have a bad CRC, we don't
2468 have any device yet where we could complain.]
2470 Note: once the monitor has been relocated, then it will complain if
2471 the default environment is used; a new CRC is computed as soon as you
2472 use the "saveenv" command to store a valid environment.
2474 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2475 Echo the inverted Ethernet link state to the fault LED.
2477 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2478 also needs to be defined.
2480 - CONFIG_SYS_FAULT_MII_ADDR:
2481 MII address of the PHY to check for the Ethernet link state.
2483 - CONFIG_NS16550_MIN_FUNCTIONS:
2484 Define this if you desire to only have use of the NS16550_init
2485 and NS16550_putc functions for the serial driver located at
2486 drivers/serial/ns16550.c. This option is useful for saving
2487 space for already greatly restricted images, including but not
2488 limited to NAND_SPL configurations.
2490 - CONFIG_DISPLAY_BOARDINFO
2491 Display information about the board that U-Boot is running on
2492 when U-Boot starts up. The board function checkboard() is called
2495 - CONFIG_DISPLAY_BOARDINFO_LATE
2496 Similar to the previous option, but display this information
2497 later, once stdio is running and output goes to the LCD, if
2500 - CONFIG_BOARD_SIZE_LIMIT:
2501 Maximum size of the U-Boot image. When defined, the
2502 build system checks that the actual size does not
2505 Low Level (hardware related) configuration options:
2506 ---------------------------------------------------
2508 - CONFIG_SYS_CACHELINE_SIZE:
2509 Cache Line Size of the CPU.
2511 - CONFIG_SYS_CCSRBAR_DEFAULT:
2512 Default (power-on reset) physical address of CCSR on Freescale
2515 - CONFIG_SYS_CCSRBAR:
2516 Virtual address of CCSR. On a 32-bit build, this is typically
2517 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2519 - CONFIG_SYS_CCSRBAR_PHYS:
2520 Physical address of CCSR. CCSR can be relocated to a new
2521 physical address, if desired. In this case, this macro should
2522 be set to that address. Otherwise, it should be set to the
2523 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2524 is typically relocated on 36-bit builds. It is recommended
2525 that this macro be defined via the _HIGH and _LOW macros:
2527 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2528 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2530 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2531 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2532 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2533 used in assembly code, so it must not contain typecasts or
2534 integer size suffixes (e.g. "ULL").
2536 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2537 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2538 used in assembly code, so it must not contain typecasts or
2539 integer size suffixes (e.g. "ULL").
2541 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2542 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2543 forced to a value that ensures that CCSR is not relocated.
2546 Most IDE controllers were designed to be connected with PCI
2547 interface. Only few of them were designed for AHB interface.
2548 When software is doing ATA command and data transfer to
2549 IDE devices through IDE-AHB controller, some additional
2550 registers accessing to these kind of IDE-AHB controller
2553 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2554 DO NOT CHANGE unless you know exactly what you're
2555 doing! (11-4) [MPC8xx systems only]
2557 - CONFIG_SYS_INIT_RAM_ADDR:
2559 Start address of memory area that can be used for
2560 initial data and stack; please note that this must be
2561 writable memory that is working WITHOUT special
2562 initialization, i. e. you CANNOT use normal RAM which
2563 will become available only after programming the
2564 memory controller and running certain initialization
2567 U-Boot uses the following memory types:
2568 - MPC8xx: IMMR (internal memory of the CPU)
2570 - CONFIG_SYS_GBL_DATA_OFFSET:
2572 Offset of the initial data structure in the memory
2573 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2574 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2575 data is located at the end of the available space
2576 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2577 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2578 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2579 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2582 On the MPC824X (or other systems that use the data
2583 cache for initial memory) the address chosen for
2584 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2585 point to an otherwise UNUSED address space between
2586 the top of RAM and the start of the PCI space.
2588 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2590 - CONFIG_SYS_OR_TIMING_SDRAM:
2593 - CONFIG_SYS_MAMR_PTA:
2594 periodic timer for refresh
2596 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2597 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2598 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2599 CONFIG_SYS_BR1_PRELIM:
2600 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2602 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2603 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2604 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2605 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2608 Chip has SRIO or not
2611 Board has SRIO 1 port available
2614 Board has SRIO 2 port available
2616 - CONFIG_SRIO_PCIE_BOOT_MASTER
2617 Board can support master function for Boot from SRIO and PCIE
2619 - CONFIG_SYS_SRIOn_MEM_VIRT:
2620 Virtual Address of SRIO port 'n' memory region
2622 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2623 Physical Address of SRIO port 'n' memory region
2625 - CONFIG_SYS_SRIOn_MEM_SIZE:
2626 Size of SRIO port 'n' memory region
2628 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2629 Defined to tell the NAND controller that the NAND chip is using
2631 Not all NAND drivers use this symbol.
2632 Example of drivers that use it:
2633 - drivers/mtd/nand/raw/ndfc.c
2634 - drivers/mtd/nand/raw/mxc_nand.c
2636 - CONFIG_SYS_NDFC_EBC0_CFG
2637 Sets the EBC0_CFG register for the NDFC. If not defined
2638 a default value will be used.
2641 Get DDR timing information from an I2C EEPROM. Common
2642 with pluggable memory modules such as SODIMMs
2645 I2C address of the SPD EEPROM
2647 - CONFIG_SYS_SPD_BUS_NUM
2648 If SPD EEPROM is on an I2C bus other than the first
2649 one, specify here. Note that the value must resolve
2650 to something your driver can deal with.
2652 - CONFIG_SYS_DDR_RAW_TIMING
2653 Get DDR timing information from other than SPD. Common with
2654 soldered DDR chips onboard without SPD. DDR raw timing
2655 parameters are extracted from datasheet and hard-coded into
2656 header files or board specific files.
2658 - CONFIG_FSL_DDR_INTERACTIVE
2659 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2661 - CONFIG_FSL_DDR_SYNC_REFRESH
2662 Enable sync of refresh for multiple controllers.
2664 - CONFIG_FSL_DDR_BIST
2665 Enable built-in memory test for Freescale DDR controllers.
2667 - CONFIG_SYS_83XX_DDR_USES_CS0
2668 Only for 83xx systems. If specified, then DDR should
2669 be configured using CS0 and CS1 instead of CS2 and CS3.
2672 Enable RMII mode for all FECs.
2673 Note that this is a global option, we can't
2674 have one FEC in standard MII mode and another in RMII mode.
2676 - CONFIG_CRC32_VERIFY
2677 Add a verify option to the crc32 command.
2680 => crc32 -v <address> <count> <crc32>
2682 Where address/count indicate a memory area
2683 and crc32 is the correct crc32 which the
2687 Add the "loopw" memory command. This only takes effect if
2688 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2690 - CONFIG_CMD_MX_CYCLIC
2691 Add the "mdc" and "mwc" memory commands. These are cyclic
2696 This command will print 4 bytes (10,11,12,13) each 500 ms.
2698 => mwc.l 100 12345678 10
2699 This command will write 12345678 to address 100 all 10 ms.
2701 This only takes effect if the memory commands are activated
2702 globally (CONFIG_CMD_MEMORY).
2705 Set when the currently-running compilation is for an artifact
2706 that will end up in the SPL (as opposed to the TPL or U-Boot
2707 proper). Code that needs stage-specific behavior should check
2711 Set when the currently-running compilation is for an artifact
2712 that will end up in the TPL (as opposed to the SPL or U-Boot
2713 proper). Code that needs stage-specific behavior should check
2716 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2717 Only for 85xx systems. If this variable is specified, the section
2718 .resetvec is not kept and the section .bootpg is placed in the
2719 previous 4k of the .text section.
2721 - CONFIG_ARCH_MAP_SYSMEM
2722 Generally U-Boot (and in particular the md command) uses
2723 effective address. It is therefore not necessary to regard
2724 U-Boot address as virtual addresses that need to be translated
2725 to physical addresses. However, sandbox requires this, since
2726 it maintains its own little RAM buffer which contains all
2727 addressable memory. This option causes some memory accesses
2728 to be mapped through map_sysmem() / unmap_sysmem().
2730 - CONFIG_X86_RESET_VECTOR
2731 If defined, the x86 reset vector code is included. This is not
2732 needed when U-Boot is running from Coreboot.
2734 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2735 Option to disable subpage write in NAND driver
2736 driver that uses this:
2737 drivers/mtd/nand/raw/davinci_nand.c
2739 Freescale QE/FMAN Firmware Support:
2740 -----------------------------------
2742 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2743 loading of "firmware", which is encoded in the QE firmware binary format.
2744 This firmware often needs to be loaded during U-Boot booting, so macros
2745 are used to identify the storage device (NOR flash, SPI, etc) and the address
2748 - CONFIG_SYS_FMAN_FW_ADDR
2749 The address in the storage device where the FMAN microcode is located. The
2750 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2753 - CONFIG_SYS_QE_FW_ADDR
2754 The address in the storage device where the QE microcode is located. The
2755 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2758 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2759 The maximum possible size of the firmware. The firmware binary format
2760 has a field that specifies the actual size of the firmware, but it
2761 might not be possible to read any part of the firmware unless some
2762 local storage is allocated to hold the entire firmware first.
2764 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2765 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2766 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2767 virtual address in NOR flash.
2769 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2770 Specifies that QE/FMAN firmware is located in NAND flash.
2771 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2773 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2774 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2775 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2777 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2778 Specifies that QE/FMAN firmware is located in the remote (master)
2779 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2780 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2781 window->master inbound window->master LAW->the ucode address in
2782 master's memory space.
2784 Freescale Layerscape Management Complex Firmware Support:
2785 ---------------------------------------------------------
2786 The Freescale Layerscape Management Complex (MC) supports the loading of
2788 This firmware often needs to be loaded during U-Boot booting, so macros
2789 are used to identify the storage device (NOR flash, SPI, etc) and the address
2792 - CONFIG_FSL_MC_ENET
2793 Enable the MC driver for Layerscape SoCs.
2795 Freescale Layerscape Debug Server Support:
2796 -------------------------------------------
2797 The Freescale Layerscape Debug Server Support supports the loading of
2798 "Debug Server firmware" and triggering SP boot-rom.
2799 This firmware often needs to be loaded during U-Boot booting.
2801 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2802 Define alignment of reserved memory MC requires
2807 In order to achieve reproducible builds, timestamps used in the U-Boot build
2808 process have to be set to a fixed value.
2810 This is done using the SOURCE_DATE_EPOCH environment variable.
2811 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2812 option for U-Boot or an environment variable in U-Boot.
2814 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2816 Building the Software:
2817 ======================
2819 Building U-Boot has been tested in several native build environments
2820 and in many different cross environments. Of course we cannot support
2821 all possibly existing versions of cross development tools in all
2822 (potentially obsolete) versions. In case of tool chain problems we
2823 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2824 which is extensively used to build and test U-Boot.
2826 If you are not using a native environment, it is assumed that you
2827 have GNU cross compiling tools available in your path. In this case,
2828 you must set the environment variable CROSS_COMPILE in your shell.
2829 Note that no changes to the Makefile or any other source files are
2830 necessary. For example using the ELDK on a 4xx CPU, please enter:
2832 $ CROSS_COMPILE=ppc_4xx-
2833 $ export CROSS_COMPILE
2835 U-Boot is intended to be simple to build. After installing the
2836 sources you must configure U-Boot for one specific board type. This
2841 where "NAME_defconfig" is the name of one of the existing configu-
2842 rations; see configs/*_defconfig for supported names.
2844 Note: for some boards special configuration names may exist; check if
2845 additional information is available from the board vendor; for
2846 instance, the TQM823L systems are available without (standard)
2847 or with LCD support. You can select such additional "features"
2848 when choosing the configuration, i. e.
2850 make TQM823L_defconfig
2851 - will configure for a plain TQM823L, i. e. no LCD support
2853 make TQM823L_LCD_defconfig
2854 - will configure for a TQM823L with U-Boot console on LCD
2859 Finally, type "make all", and you should get some working U-Boot
2860 images ready for download to / installation on your system:
2862 - "u-boot.bin" is a raw binary image
2863 - "u-boot" is an image in ELF binary format
2864 - "u-boot.srec" is in Motorola S-Record format
2866 By default the build is performed locally and the objects are saved
2867 in the source directory. One of the two methods can be used to change
2868 this behavior and build U-Boot to some external directory:
2870 1. Add O= to the make command line invocations:
2872 make O=/tmp/build distclean
2873 make O=/tmp/build NAME_defconfig
2874 make O=/tmp/build all
2876 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2878 export KBUILD_OUTPUT=/tmp/build
2883 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2886 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2887 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2888 For example to treat all compiler warnings as errors:
2890 make KCFLAGS=-Werror
2892 Please be aware that the Makefiles assume you are using GNU make, so
2893 for instance on NetBSD you might need to use "gmake" instead of
2897 If the system board that you have is not listed, then you will need
2898 to port U-Boot to your hardware platform. To do this, follow these
2901 1. Create a new directory to hold your board specific code. Add any
2902 files you need. In your board directory, you will need at least
2903 the "Makefile" and a "<board>.c".
2904 2. Create a new configuration file "include/configs/<board>.h" for
2906 3. If you're porting U-Boot to a new CPU, then also create a new
2907 directory to hold your CPU specific code. Add any files you need.
2908 4. Run "make <board>_defconfig" with your new name.
2909 5. Type "make", and you should get a working "u-boot.srec" file
2910 to be installed on your target system.
2911 6. Debug and solve any problems that might arise.
2912 [Of course, this last step is much harder than it sounds.]
2915 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2916 ==============================================================
2918 If you have modified U-Boot sources (for instance added a new board
2919 or support for new devices, a new CPU, etc.) you are expected to
2920 provide feedback to the other developers. The feedback normally takes
2921 the form of a "patch", i.e. a context diff against a certain (latest
2922 official or latest in the git repository) version of U-Boot sources.
2924 But before you submit such a patch, please verify that your modifi-
2925 cation did not break existing code. At least make sure that *ALL* of
2926 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2927 just run the buildman script (tools/buildman/buildman), which will
2928 configure and build U-Boot for ALL supported system. Be warned, this
2929 will take a while. Please see the buildman README, or run 'buildman -H'
2933 See also "U-Boot Porting Guide" below.
2936 Monitor Commands - Overview:
2937 ============================
2939 go - start application at address 'addr'
2940 run - run commands in an environment variable
2941 bootm - boot application image from memory
2942 bootp - boot image via network using BootP/TFTP protocol
2943 bootz - boot zImage from memory
2944 tftpboot- boot image via network using TFTP protocol
2945 and env variables "ipaddr" and "serverip"
2946 (and eventually "gatewayip")
2947 tftpput - upload a file via network using TFTP protocol
2948 rarpboot- boot image via network using RARP/TFTP protocol
2949 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2950 loads - load S-Record file over serial line
2951 loadb - load binary file over serial line (kermit mode)
2953 mm - memory modify (auto-incrementing)
2954 nm - memory modify (constant address)
2955 mw - memory write (fill)
2958 cmp - memory compare
2959 crc32 - checksum calculation
2960 i2c - I2C sub-system
2961 sspi - SPI utility commands
2962 base - print or set address offset
2963 printenv- print environment variables
2964 pwm - control pwm channels
2965 setenv - set environment variables
2966 saveenv - save environment variables to persistent storage
2967 protect - enable or disable FLASH write protection
2968 erase - erase FLASH memory
2969 flinfo - print FLASH memory information
2970 nand - NAND memory operations (see doc/README.nand)
2971 bdinfo - print Board Info structure
2972 iminfo - print header information for application image
2973 coninfo - print console devices and informations
2974 ide - IDE sub-system
2975 loop - infinite loop on address range
2976 loopw - infinite write loop on address range
2977 mtest - simple RAM test
2978 icache - enable or disable instruction cache
2979 dcache - enable or disable data cache
2980 reset - Perform RESET of the CPU
2981 echo - echo args to console
2982 version - print monitor version
2983 help - print online help
2984 ? - alias for 'help'
2987 Monitor Commands - Detailed Description:
2988 ========================================
2992 For now: just type "help <command>".
2995 Environment Variables:
2996 ======================
2998 U-Boot supports user configuration using Environment Variables which
2999 can be made persistent by saving to Flash memory.
3001 Environment Variables are set using "setenv", printed using
3002 "printenv", and saved to Flash using "saveenv". Using "setenv"
3003 without a value can be used to delete a variable from the
3004 environment. As long as you don't save the environment you are
3005 working with an in-memory copy. In case the Flash area containing the
3006 environment is erased by accident, a default environment is provided.
3008 Some configuration options can be set using Environment Variables.
3010 List of environment variables (most likely not complete):
3012 baudrate - see CONFIG_BAUDRATE
3014 bootdelay - see CONFIG_BOOTDELAY
3016 bootcmd - see CONFIG_BOOTCOMMAND
3018 bootargs - Boot arguments when booting an RTOS image
3020 bootfile - Name of the image to load with TFTP
3022 bootm_low - Memory range available for image processing in the bootm
3023 command can be restricted. This variable is given as
3024 a hexadecimal number and defines lowest address allowed
3025 for use by the bootm command. See also "bootm_size"
3026 environment variable. Address defined by "bootm_low" is
3027 also the base of the initial memory mapping for the Linux
3028 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3031 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3032 This variable is given as a hexadecimal number and it
3033 defines the size of the memory region starting at base
3034 address bootm_low that is accessible by the Linux kernel
3035 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3036 as the default value if it is defined, and bootm_size is
3039 bootm_size - Memory range available for image processing in the bootm
3040 command can be restricted. This variable is given as
3041 a hexadecimal number and defines the size of the region
3042 allowed for use by the bootm command. See also "bootm_low"
3043 environment variable.
3045 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3047 updatefile - Location of the software update file on a TFTP server, used
3048 by the automatic software update feature. Please refer to
3049 documentation in doc/README.update for more details.
3051 autoload - if set to "no" (any string beginning with 'n'),
3052 "bootp" will just load perform a lookup of the
3053 configuration from the BOOTP server, but not try to
3054 load any image using TFTP
3056 autostart - if set to "yes", an image loaded using the "bootp",
3057 "rarpboot", "tftpboot" or "diskboot" commands will
3058 be automatically started (by internally calling
3061 If set to "no", a standalone image passed to the
3062 "bootm" command will be copied to the load address
3063 (and eventually uncompressed), but NOT be started.
3064 This can be used to load and uncompress arbitrary
3067 fdt_high - if set this restricts the maximum address that the
3068 flattened device tree will be copied into upon boot.
3069 For example, if you have a system with 1 GB memory
3070 at physical address 0x10000000, while Linux kernel
3071 only recognizes the first 704 MB as low memory, you
3072 may need to set fdt_high as 0x3C000000 to have the
3073 device tree blob be copied to the maximum address
3074 of the 704 MB low memory, so that Linux kernel can
3075 access it during the boot procedure.
3077 If this is set to the special value 0xFFFFFFFF then
3078 the fdt will not be copied at all on boot. For this
3079 to work it must reside in writable memory, have
3080 sufficient padding on the end of it for u-boot to
3081 add the information it needs into it, and the memory
3082 must be accessible by the kernel.
3084 fdtcontroladdr- if set this is the address of the control flattened
3085 device tree used by U-Boot when CONFIG_OF_CONTROL is
3088 i2cfast - (PPC405GP|PPC405EP only)
3089 if set to 'y' configures Linux I2C driver for fast
3090 mode (400kHZ). This environment variable is used in
3091 initialization code. So, for changes to be effective
3092 it must be saved and board must be reset.
3094 initrd_high - restrict positioning of initrd images:
3095 If this variable is not set, initrd images will be
3096 copied to the highest possible address in RAM; this
3097 is usually what you want since it allows for
3098 maximum initrd size. If for some reason you want to
3099 make sure that the initrd image is loaded below the
3100 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3101 variable to a value of "no" or "off" or "0".
3102 Alternatively, you can set it to a maximum upper
3103 address to use (U-Boot will still check that it
3104 does not overwrite the U-Boot stack and data).
3106 For instance, when you have a system with 16 MB
3107 RAM, and want to reserve 4 MB from use by Linux,
3108 you can do this by adding "mem=12M" to the value of
3109 the "bootargs" variable. However, now you must make
3110 sure that the initrd image is placed in the first
3111 12 MB as well - this can be done with
3113 setenv initrd_high 00c00000
3115 If you set initrd_high to 0xFFFFFFFF, this is an
3116 indication to U-Boot that all addresses are legal
3117 for the Linux kernel, including addresses in flash
3118 memory. In this case U-Boot will NOT COPY the
3119 ramdisk at all. This may be useful to reduce the
3120 boot time on your system, but requires that this
3121 feature is supported by your Linux kernel.
3123 ipaddr - IP address; needed for tftpboot command
3125 loadaddr - Default load address for commands like "bootp",
3126 "rarpboot", "tftpboot", "loadb" or "diskboot"
3128 loads_echo - see CONFIG_LOADS_ECHO
3130 serverip - TFTP server IP address; needed for tftpboot command
3132 bootretry - see CONFIG_BOOT_RETRY_TIME
3134 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3136 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3138 ethprime - controls which interface is used first.
3140 ethact - controls which interface is currently active.
3141 For example you can do the following
3143 => setenv ethact FEC
3144 => ping 192.168.0.1 # traffic sent on FEC
3145 => setenv ethact SCC
3146 => ping 10.0.0.1 # traffic sent on SCC
3148 ethrotate - When set to "no" U-Boot does not go through all
3149 available network interfaces.
3150 It just stays at the currently selected interface.
3152 netretry - When set to "no" each network operation will
3153 either succeed or fail without retrying.
3154 When set to "once" the network operation will
3155 fail when all the available network interfaces
3156 are tried once without success.
3157 Useful on scripts which control the retry operation
3160 npe_ucode - set load address for the NPE microcode
3162 silent_linux - If set then Linux will be told to boot silently, by
3163 changing the console to be empty. If "yes" it will be
3164 made silent. If "no" it will not be made silent. If
3165 unset, then it will be made silent if the U-Boot console
3168 tftpsrcp - If this is set, the value is used for TFTP's
3171 tftpdstp - If this is set, the value is used for TFTP's UDP
3172 destination port instead of the Well Know Port 69.
3174 tftpblocksize - Block size to use for TFTP transfers; if not set,
3175 we use the TFTP server's default block size
3177 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3178 seconds, minimum value is 1000 = 1 second). Defines
3179 when a packet is considered to be lost so it has to
3180 be retransmitted. The default is 5000 = 5 seconds.
3181 Lowering this value may make downloads succeed
3182 faster in networks with high packet loss rates or
3183 with unreliable TFTP servers.
3185 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3186 unit, minimum value = 0). Defines how many timeouts
3187 can happen during a single file transfer before that
3188 transfer is aborted. The default is 10, and 0 means
3189 'no timeouts allowed'. Increasing this value may help
3190 downloads succeed with high packet loss rates, or with
3191 unreliable TFTP servers or client hardware.
3193 tftpwindowsize - if this is set, the value is used for TFTP's
3194 window size as described by RFC 7440.
3195 This means the count of blocks we can receive before
3196 sending ack to server.
3198 vlan - When set to a value < 4095 the traffic over
3199 Ethernet is encapsulated/received over 802.1q
3202 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3203 Unsigned value, in milliseconds. If not set, the period will
3204 be either the default (28000), or a value based on
3205 CONFIG_NET_RETRY_COUNT, if defined. This value has
3206 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3208 memmatches - Number of matches found by the last 'ms' command, in hex
3210 memaddr - Address of the last match found by the 'ms' command, in hex,
3213 mempos - Index position of the last match found by the 'ms' command,
3214 in units of the size (.b, .w, .l) of the search
3216 zbootbase - (x86 only) Base address of the bzImage 'setup' block
3218 zbootaddr - (x86 only) Address of the loaded bzImage, typically
3219 BZIMAGE_LOAD_ADDR which is 0x100000
3221 The following image location variables contain the location of images
3222 used in booting. The "Image" column gives the role of the image and is
3223 not an environment variable name. The other columns are environment
3224 variable names. "File Name" gives the name of the file on a TFTP
3225 server, "RAM Address" gives the location in RAM the image will be
3226 loaded to, and "Flash Location" gives the image's address in NOR
3227 flash or offset in NAND flash.
3229 *Note* - these variables don't have to be defined for all boards, some
3230 boards currently use other variables for these purposes, and some
3231 boards use these variables for other purposes.
3233 Image File Name RAM Address Flash Location
3234 ----- --------- ----------- --------------
3235 u-boot u-boot u-boot_addr_r u-boot_addr
3236 Linux kernel bootfile kernel_addr_r kernel_addr
3237 device tree blob fdtfile fdt_addr_r fdt_addr
3238 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3240 The following environment variables may be used and automatically
3241 updated by the network boot commands ("bootp" and "rarpboot"),
3242 depending the information provided by your boot server:
3244 bootfile - see above
3245 dnsip - IP address of your Domain Name Server
3246 dnsip2 - IP address of your secondary Domain Name Server
3247 gatewayip - IP address of the Gateway (Router) to use
3248 hostname - Target hostname
3250 netmask - Subnet Mask
3251 rootpath - Pathname of the root filesystem on the NFS server
3252 serverip - see above
3255 There are two special Environment Variables:
3257 serial# - contains hardware identification information such
3258 as type string and/or serial number
3259 ethaddr - Ethernet address
3261 These variables can be set only once (usually during manufacturing of
3262 the board). U-Boot refuses to delete or overwrite these variables
3263 once they have been set once.
3266 Further special Environment Variables:
3268 ver - Contains the U-Boot version string as printed
3269 with the "version" command. This variable is
3270 readonly (see CONFIG_VERSION_VARIABLE).
3273 Please note that changes to some configuration parameters may take
3274 only effect after the next boot (yes, that's just like Windoze :-).
3277 Callback functions for environment variables:
3278 ---------------------------------------------
3280 For some environment variables, the behavior of u-boot needs to change
3281 when their values are changed. This functionality allows functions to
3282 be associated with arbitrary variables. On creation, overwrite, or
3283 deletion, the callback will provide the opportunity for some side
3284 effect to happen or for the change to be rejected.
3286 The callbacks are named and associated with a function using the
3287 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3289 These callbacks are associated with variables in one of two ways. The
3290 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3291 in the board configuration to a string that defines a list of
3292 associations. The list must be in the following format:
3294 entry = variable_name[:callback_name]
3297 If the callback name is not specified, then the callback is deleted.
3298 Spaces are also allowed anywhere in the list.
3300 Callbacks can also be associated by defining the ".callbacks" variable
3301 with the same list format above. Any association in ".callbacks" will
3302 override any association in the static list. You can define
3303 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3304 ".callbacks" environment variable in the default or embedded environment.
3306 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3307 regular expression. This allows multiple variables to be connected to
3308 the same callback without explicitly listing them all out.
3310 The signature of the callback functions is:
3312 int callback(const char *name, const char *value, enum env_op op, int flags)
3314 * name - changed environment variable
3315 * value - new value of the environment variable
3316 * op - operation (create, overwrite, or delete)
3317 * flags - attributes of the environment variable change, see flags H_* in
3320 The return value is 0 if the variable change is accepted and 1 otherwise.
3323 Note for Redundant Ethernet Interfaces:
3324 =======================================
3326 Some boards come with redundant Ethernet interfaces; U-Boot supports
3327 such configurations and is capable of automatic selection of a
3328 "working" interface when needed. MAC assignment works as follows:
3330 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3331 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3332 "eth1addr" (=>eth1), "eth2addr", ...
3334 If the network interface stores some valid MAC address (for instance
3335 in SROM), this is used as default address if there is NO correspon-
3336 ding setting in the environment; if the corresponding environment
3337 variable is set, this overrides the settings in the card; that means:
3339 o If the SROM has a valid MAC address, and there is no address in the
3340 environment, the SROM's address is used.
3342 o If there is no valid address in the SROM, and a definition in the
3343 environment exists, then the value from the environment variable is
3346 o If both the SROM and the environment contain a MAC address, and
3347 both addresses are the same, this MAC address is used.
3349 o If both the SROM and the environment contain a MAC address, and the
3350 addresses differ, the value from the environment is used and a
3353 o If neither SROM nor the environment contain a MAC address, an error
3354 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3355 a random, locally-assigned MAC is used.
3357 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3358 will be programmed into hardware as part of the initialization process. This
3359 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3360 The naming convention is as follows:
3361 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3366 U-Boot is capable of booting (and performing other auxiliary operations on)
3367 images in two formats:
3369 New uImage format (FIT)
3370 -----------------------
3372 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3373 to Flattened Device Tree). It allows the use of images with multiple
3374 components (several kernels, ramdisks, etc.), with contents protected by
3375 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3381 Old image format is based on binary files which can be basically anything,
3382 preceded by a special header; see the definitions in include/image.h for
3383 details; basically, the header defines the following image properties:
3385 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3386 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3387 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3388 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3390 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3391 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3392 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3393 * Compression Type (uncompressed, gzip, bzip2)
3399 The header is marked by a special Magic Number, and both the header
3400 and the data portions of the image are secured against corruption by
3407 Although U-Boot should support any OS or standalone application
3408 easily, the main focus has always been on Linux during the design of
3411 U-Boot includes many features that so far have been part of some
3412 special "boot loader" code within the Linux kernel. Also, any
3413 "initrd" images to be used are no longer part of one big Linux image;
3414 instead, kernel and "initrd" are separate images. This implementation
3415 serves several purposes:
3417 - the same features can be used for other OS or standalone
3418 applications (for instance: using compressed images to reduce the
3419 Flash memory footprint)
3421 - it becomes much easier to port new Linux kernel versions because
3422 lots of low-level, hardware dependent stuff are done by U-Boot
3424 - the same Linux kernel image can now be used with different "initrd"
3425 images; of course this also means that different kernel images can
3426 be run with the same "initrd". This makes testing easier (you don't
3427 have to build a new "zImage.initrd" Linux image when you just
3428 change a file in your "initrd"). Also, a field-upgrade of the
3429 software is easier now.
3435 Porting Linux to U-Boot based systems:
3436 ---------------------------------------
3438 U-Boot cannot save you from doing all the necessary modifications to
3439 configure the Linux device drivers for use with your target hardware
3440 (no, we don't intend to provide a full virtual machine interface to
3443 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3445 Just make sure your machine specific header file (for instance
3446 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3447 Information structure as we define in include/asm-<arch>/u-boot.h,
3448 and make sure that your definition of IMAP_ADDR uses the same value
3449 as your U-Boot configuration in CONFIG_SYS_IMMR.
3451 Note that U-Boot now has a driver model, a unified model for drivers.
3452 If you are adding a new driver, plumb it into driver model. If there
3453 is no uclass available, you are encouraged to create one. See
3457 Configuring the Linux kernel:
3458 -----------------------------
3460 No specific requirements for U-Boot. Make sure you have some root
3461 device (initial ramdisk, NFS) for your target system.
3464 Building a Linux Image:
3465 -----------------------
3467 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3468 not used. If you use recent kernel source, a new build target
3469 "uImage" will exist which automatically builds an image usable by
3470 U-Boot. Most older kernels also have support for a "pImage" target,
3471 which was introduced for our predecessor project PPCBoot and uses a
3472 100% compatible format.
3476 make TQM850L_defconfig
3481 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3482 encapsulate a compressed Linux kernel image with header information,
3483 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3485 * build a standard "vmlinux" kernel image (in ELF binary format):
3487 * convert the kernel into a raw binary image:
3489 ${CROSS_COMPILE}-objcopy -O binary \
3490 -R .note -R .comment \
3491 -S vmlinux linux.bin
3493 * compress the binary image:
3497 * package compressed binary image for U-Boot:
3499 mkimage -A ppc -O linux -T kernel -C gzip \
3500 -a 0 -e 0 -n "Linux Kernel Image" \
3501 -d linux.bin.gz uImage
3504 The "mkimage" tool can also be used to create ramdisk images for use
3505 with U-Boot, either separated from the Linux kernel image, or
3506 combined into one file. "mkimage" encapsulates the images with a 64
3507 byte header containing information about target architecture,
3508 operating system, image type, compression method, entry points, time
3509 stamp, CRC32 checksums, etc.
3511 "mkimage" can be called in two ways: to verify existing images and
3512 print the header information, or to build new images.
3514 In the first form (with "-l" option) mkimage lists the information
3515 contained in the header of an existing U-Boot image; this includes
3516 checksum verification:
3518 tools/mkimage -l image
3519 -l ==> list image header information
3521 The second form (with "-d" option) is used to build a U-Boot image
3522 from a "data file" which is used as image payload:
3524 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3525 -n name -d data_file image
3526 -A ==> set architecture to 'arch'
3527 -O ==> set operating system to 'os'
3528 -T ==> set image type to 'type'
3529 -C ==> set compression type 'comp'
3530 -a ==> set load address to 'addr' (hex)
3531 -e ==> set entry point to 'ep' (hex)
3532 -n ==> set image name to 'name'
3533 -d ==> use image data from 'datafile'
3535 Right now, all Linux kernels for PowerPC systems use the same load
3536 address (0x00000000), but the entry point address depends on the
3539 - 2.2.x kernels have the entry point at 0x0000000C,
3540 - 2.3.x and later kernels have the entry point at 0x00000000.
3542 So a typical call to build a U-Boot image would read:
3544 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3545 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3546 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3547 > examples/uImage.TQM850L
3548 Image Name: 2.4.4 kernel for TQM850L
3549 Created: Wed Jul 19 02:34:59 2000
3550 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3551 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3552 Load Address: 0x00000000
3553 Entry Point: 0x00000000
3555 To verify the contents of the image (or check for corruption):
3557 -> tools/mkimage -l examples/uImage.TQM850L
3558 Image Name: 2.4.4 kernel for TQM850L
3559 Created: Wed Jul 19 02:34:59 2000
3560 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3561 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3562 Load Address: 0x00000000
3563 Entry Point: 0x00000000
3565 NOTE: for embedded systems where boot time is critical you can trade
3566 speed for memory and install an UNCOMPRESSED image instead: this
3567 needs more space in Flash, but boots much faster since it does not
3568 need to be uncompressed:
3570 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3571 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3572 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3573 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3574 > examples/uImage.TQM850L-uncompressed
3575 Image Name: 2.4.4 kernel for TQM850L
3576 Created: Wed Jul 19 02:34:59 2000
3577 Image Type: PowerPC Linux Kernel Image (uncompressed)
3578 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3579 Load Address: 0x00000000
3580 Entry Point: 0x00000000
3583 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3584 when your kernel is intended to use an initial ramdisk:
3586 -> tools/mkimage -n 'Simple Ramdisk Image' \
3587 > -A ppc -O linux -T ramdisk -C gzip \
3588 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3589 Image Name: Simple Ramdisk Image
3590 Created: Wed Jan 12 14:01:50 2000
3591 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3592 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3593 Load Address: 0x00000000
3594 Entry Point: 0x00000000
3596 The "dumpimage" tool can be used to disassemble or list the contents of images
3597 built by mkimage. See dumpimage's help output (-h) for details.
3599 Installing a Linux Image:
3600 -------------------------
3602 To downloading a U-Boot image over the serial (console) interface,
3603 you must convert the image to S-Record format:
3605 objcopy -I binary -O srec examples/image examples/image.srec
3607 The 'objcopy' does not understand the information in the U-Boot
3608 image header, so the resulting S-Record file will be relative to
3609 address 0x00000000. To load it to a given address, you need to
3610 specify the target address as 'offset' parameter with the 'loads'
3613 Example: install the image to address 0x40100000 (which on the
3614 TQM8xxL is in the first Flash bank):
3616 => erase 40100000 401FFFFF
3622 ## Ready for S-Record download ...
3623 ~>examples/image.srec
3624 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3626 15989 15990 15991 15992
3627 [file transfer complete]
3629 ## Start Addr = 0x00000000
3632 You can check the success of the download using the 'iminfo' command;
3633 this includes a checksum verification so you can be sure no data
3634 corruption happened:
3638 ## Checking Image at 40100000 ...
3639 Image Name: 2.2.13 for initrd on TQM850L
3640 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3641 Data Size: 335725 Bytes = 327 kB = 0 MB
3642 Load Address: 00000000
3643 Entry Point: 0000000c
3644 Verifying Checksum ... OK
3650 The "bootm" command is used to boot an application that is stored in
3651 memory (RAM or Flash). In case of a Linux kernel image, the contents
3652 of the "bootargs" environment variable is passed to the kernel as
3653 parameters. You can check and modify this variable using the
3654 "printenv" and "setenv" commands:
3657 => printenv bootargs
3658 bootargs=root=/dev/ram
3660 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3662 => printenv bootargs
3663 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3666 ## Booting Linux kernel at 40020000 ...
3667 Image Name: 2.2.13 for NFS on TQM850L
3668 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3669 Data Size: 381681 Bytes = 372 kB = 0 MB
3670 Load Address: 00000000
3671 Entry Point: 0000000c
3672 Verifying Checksum ... OK
3673 Uncompressing Kernel Image ... OK
3674 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
3675 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3676 time_init: decrementer frequency = 187500000/60
3677 Calibrating delay loop... 49.77 BogoMIPS
3678 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3681 If you want to boot a Linux kernel with initial RAM disk, you pass
3682 the memory addresses of both the kernel and the initrd image (PPBCOOT
3683 format!) to the "bootm" command:
3685 => imi 40100000 40200000
3687 ## Checking Image at 40100000 ...
3688 Image Name: 2.2.13 for initrd on TQM850L
3689 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3690 Data Size: 335725 Bytes = 327 kB = 0 MB
3691 Load Address: 00000000
3692 Entry Point: 0000000c
3693 Verifying Checksum ... OK
3695 ## Checking Image at 40200000 ...
3696 Image Name: Simple Ramdisk Image
3697 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3698 Data Size: 566530 Bytes = 553 kB = 0 MB
3699 Load Address: 00000000
3700 Entry Point: 00000000
3701 Verifying Checksum ... OK
3703 => bootm 40100000 40200000
3704 ## Booting Linux kernel at 40100000 ...
3705 Image Name: 2.2.13 for initrd on TQM850L
3706 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3707 Data Size: 335725 Bytes = 327 kB = 0 MB
3708 Load Address: 00000000
3709 Entry Point: 0000000c
3710 Verifying Checksum ... OK
3711 Uncompressing Kernel Image ... OK
3712 ## Loading RAMDisk Image at 40200000 ...
3713 Image Name: Simple Ramdisk Image
3714 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3715 Data Size: 566530 Bytes = 553 kB = 0 MB
3716 Load Address: 00000000
3717 Entry Point: 00000000
3718 Verifying Checksum ... OK
3719 Loading Ramdisk ... OK
3720 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
3721 Boot arguments: root=/dev/ram
3722 time_init: decrementer frequency = 187500000/60
3723 Calibrating delay loop... 49.77 BogoMIPS
3725 RAMDISK: Compressed image found at block 0
3726 VFS: Mounted root (ext2 filesystem).
3730 Boot Linux and pass a flat device tree:
3733 First, U-Boot must be compiled with the appropriate defines. See the section
3734 titled "Linux Kernel Interface" above for a more in depth explanation. The
3735 following is an example of how to start a kernel and pass an updated
3741 oft=oftrees/mpc8540ads.dtb
3742 => tftp $oftaddr $oft
3743 Speed: 1000, full duplex
3745 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3746 Filename 'oftrees/mpc8540ads.dtb'.
3747 Load address: 0x300000
3750 Bytes transferred = 4106 (100a hex)
3751 => tftp $loadaddr $bootfile
3752 Speed: 1000, full duplex
3754 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3756 Load address: 0x200000
3757 Loading:############
3759 Bytes transferred = 1029407 (fb51f hex)
3764 => bootm $loadaddr - $oftaddr
3765 ## Booting image at 00200000 ...
3766 Image Name: Linux-2.6.17-dirty
3767 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3768 Data Size: 1029343 Bytes = 1005.2 kB
3769 Load Address: 00000000
3770 Entry Point: 00000000
3771 Verifying Checksum ... OK
3772 Uncompressing Kernel Image ... OK
3773 Booting using flat device tree at 0x300000
3774 Using MPC85xx ADS machine description
3775 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3779 More About U-Boot Image Types:
3780 ------------------------------
3782 U-Boot supports the following image types:
3784 "Standalone Programs" are directly runnable in the environment
3785 provided by U-Boot; it is expected that (if they behave
3786 well) you can continue to work in U-Boot after return from
3787 the Standalone Program.
3788 "OS Kernel Images" are usually images of some Embedded OS which
3789 will take over control completely. Usually these programs
3790 will install their own set of exception handlers, device
3791 drivers, set up the MMU, etc. - this means, that you cannot
3792 expect to re-enter U-Boot except by resetting the CPU.
3793 "RAMDisk Images" are more or less just data blocks, and their
3794 parameters (address, size) are passed to an OS kernel that is
3796 "Multi-File Images" contain several images, typically an OS
3797 (Linux) kernel image and one or more data images like
3798 RAMDisks. This construct is useful for instance when you want
3799 to boot over the network using BOOTP etc., where the boot
3800 server provides just a single image file, but you want to get
3801 for instance an OS kernel and a RAMDisk image.
3803 "Multi-File Images" start with a list of image sizes, each
3804 image size (in bytes) specified by an "uint32_t" in network
3805 byte order. This list is terminated by an "(uint32_t)0".
3806 Immediately after the terminating 0 follow the images, one by
3807 one, all aligned on "uint32_t" boundaries (size rounded up to
3808 a multiple of 4 bytes).
3810 "Firmware Images" are binary images containing firmware (like
3811 U-Boot or FPGA images) which usually will be programmed to
3814 "Script files" are command sequences that will be executed by
3815 U-Boot's command interpreter; this feature is especially
3816 useful when you configure U-Boot to use a real shell (hush)
3817 as command interpreter.
3819 Booting the Linux zImage:
3820 -------------------------
3822 On some platforms, it's possible to boot Linux zImage. This is done
3823 using the "bootz" command. The syntax of "bootz" command is the same
3824 as the syntax of "bootm" command.
3826 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3827 kernel with raw initrd images. The syntax is slightly different, the
3828 address of the initrd must be augmented by it's size, in the following
3829 format: "<initrd addres>:<initrd size>".
3835 One of the features of U-Boot is that you can dynamically load and
3836 run "standalone" applications, which can use some resources of
3837 U-Boot like console I/O functions or interrupt services.
3839 Two simple examples are included with the sources:
3844 'examples/hello_world.c' contains a small "Hello World" Demo
3845 application; it is automatically compiled when you build U-Boot.
3846 It's configured to run at address 0x00040004, so you can play with it
3850 ## Ready for S-Record download ...
3851 ~>examples/hello_world.srec
3852 1 2 3 4 5 6 7 8 9 10 11 ...
3853 [file transfer complete]
3855 ## Start Addr = 0x00040004
3857 => go 40004 Hello World! This is a test.
3858 ## Starting application at 0x00040004 ...
3869 Hit any key to exit ...
3871 ## Application terminated, rc = 0x0
3873 Another example, which demonstrates how to register a CPM interrupt
3874 handler with the U-Boot code, can be found in 'examples/timer.c'.
3875 Here, a CPM timer is set up to generate an interrupt every second.
3876 The interrupt service routine is trivial, just printing a '.'
3877 character, but this is just a demo program. The application can be
3878 controlled by the following keys:
3880 ? - print current values og the CPM Timer registers
3881 b - enable interrupts and start timer
3882 e - stop timer and disable interrupts
3883 q - quit application
3886 ## Ready for S-Record download ...
3887 ~>examples/timer.srec
3888 1 2 3 4 5 6 7 8 9 10 11 ...
3889 [file transfer complete]
3891 ## Start Addr = 0x00040004
3894 ## Starting application at 0x00040004 ...
3897 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3900 [q, b, e, ?] Set interval 1000000 us
3903 [q, b, e, ?] ........
3904 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3907 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3910 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3913 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3915 [q, b, e, ?] ...Stopping timer
3917 [q, b, e, ?] ## Application terminated, rc = 0x0
3923 Over time, many people have reported problems when trying to use the
3924 "minicom" terminal emulation program for serial download. I (wd)
3925 consider minicom to be broken, and recommend not to use it. Under
3926 Unix, I recommend to use C-Kermit for general purpose use (and
3927 especially for kermit binary protocol download ("loadb" command), and
3928 use "cu" for S-Record download ("loads" command). See
3929 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3930 for help with kermit.
3933 Nevertheless, if you absolutely want to use it try adding this
3934 configuration to your "File transfer protocols" section:
3936 Name Program Name U/D FullScr IO-Red. Multi
3937 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3938 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3944 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3945 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3947 Building requires a cross environment; it is known to work on
3948 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3949 need gmake since the Makefiles are not compatible with BSD make).
3950 Note that the cross-powerpc package does not install include files;
3951 attempting to build U-Boot will fail because <machine/ansi.h> is
3952 missing. This file has to be installed and patched manually:
3954 # cd /usr/pkg/cross/powerpc-netbsd/include
3956 # ln -s powerpc machine
3957 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3958 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3960 Native builds *don't* work due to incompatibilities between native
3961 and U-Boot include files.
3963 Booting assumes that (the first part of) the image booted is a
3964 stage-2 loader which in turn loads and then invokes the kernel
3965 proper. Loader sources will eventually appear in the NetBSD source
3966 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3967 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3970 Implementation Internals:
3971 =========================
3973 The following is not intended to be a complete description of every
3974 implementation detail. However, it should help to understand the
3975 inner workings of U-Boot and make it easier to port it to custom
3979 Initial Stack, Global Data:
3980 ---------------------------
3982 The implementation of U-Boot is complicated by the fact that U-Boot
3983 starts running out of ROM (flash memory), usually without access to
3984 system RAM (because the memory controller is not initialized yet).
3985 This means that we don't have writable Data or BSS segments, and BSS
3986 is not initialized as zero. To be able to get a C environment working
3987 at all, we have to allocate at least a minimal stack. Implementation
3988 options for this are defined and restricted by the CPU used: Some CPU
3989 models provide on-chip memory (like the IMMR area on MPC8xx and
3990 MPC826x processors), on others (parts of) the data cache can be
3991 locked as (mis-) used as memory, etc.
3993 Chris Hallinan posted a good summary of these issues to the
3994 U-Boot mailing list:
3996 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3997 From: "Chris Hallinan" <clh@net1plus.com>
3998 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4001 Correct me if I'm wrong, folks, but the way I understand it
4002 is this: Using DCACHE as initial RAM for Stack, etc, does not
4003 require any physical RAM backing up the cache. The cleverness
4004 is that the cache is being used as a temporary supply of
4005 necessary storage before the SDRAM controller is setup. It's
4006 beyond the scope of this list to explain the details, but you
4007 can see how this works by studying the cache architecture and
4008 operation in the architecture and processor-specific manuals.
4010 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4011 is another option for the system designer to use as an
4012 initial stack/RAM area prior to SDRAM being available. Either
4013 option should work for you. Using CS 4 should be fine if your
4014 board designers haven't used it for something that would
4015 cause you grief during the initial boot! It is frequently not
4018 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4019 with your processor/board/system design. The default value
4020 you will find in any recent u-boot distribution in
4021 walnut.h should work for you. I'd set it to a value larger
4022 than your SDRAM module. If you have a 64MB SDRAM module, set
4023 it above 400_0000. Just make sure your board has no resources
4024 that are supposed to respond to that address! That code in
4025 start.S has been around a while and should work as is when
4026 you get the config right.
4031 It is essential to remember this, since it has some impact on the C
4032 code for the initialization procedures:
4034 * Initialized global data (data segment) is read-only. Do not attempt
4037 * Do not use any uninitialized global data (or implicitly initialized
4038 as zero data - BSS segment) at all - this is undefined, initiali-
4039 zation is performed later (when relocating to RAM).
4041 * Stack space is very limited. Avoid big data buffers or things like
4044 Having only the stack as writable memory limits means we cannot use
4045 normal global data to share information between the code. But it
4046 turned out that the implementation of U-Boot can be greatly
4047 simplified by making a global data structure (gd_t) available to all
4048 functions. We could pass a pointer to this data as argument to _all_
4049 functions, but this would bloat the code. Instead we use a feature of
4050 the GCC compiler (Global Register Variables) to share the data: we
4051 place a pointer (gd) to the global data into a register which we
4052 reserve for this purpose.
4054 When choosing a register for such a purpose we are restricted by the
4055 relevant (E)ABI specifications for the current architecture, and by
4056 GCC's implementation.
4058 For PowerPC, the following registers have specific use:
4060 R2: reserved for system use
4061 R3-R4: parameter passing and return values
4062 R5-R10: parameter passing
4063 R13: small data area pointer
4067 (U-Boot also uses R12 as internal GOT pointer. r12
4068 is a volatile register so r12 needs to be reset when
4069 going back and forth between asm and C)
4071 ==> U-Boot will use R2 to hold a pointer to the global data
4073 Note: on PPC, we could use a static initializer (since the
4074 address of the global data structure is known at compile time),
4075 but it turned out that reserving a register results in somewhat
4076 smaller code - although the code savings are not that big (on
4077 average for all boards 752 bytes for the whole U-Boot image,
4078 624 text + 127 data).
4080 On ARM, the following registers are used:
4082 R0: function argument word/integer result
4083 R1-R3: function argument word
4084 R9: platform specific
4085 R10: stack limit (used only if stack checking is enabled)
4086 R11: argument (frame) pointer
4087 R12: temporary workspace
4090 R15: program counter
4092 ==> U-Boot will use R9 to hold a pointer to the global data
4094 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4096 On Nios II, the ABI is documented here:
4097 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4099 ==> U-Boot will use gp to hold a pointer to the global data
4101 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4102 to access small data sections, so gp is free.
4104 On NDS32, the following registers are used:
4106 R0-R1: argument/return
4108 R15: temporary register for assembler
4109 R16: trampoline register
4110 R28: frame pointer (FP)
4111 R29: global pointer (GP)
4112 R30: link register (LP)
4113 R31: stack pointer (SP)
4114 PC: program counter (PC)
4116 ==> U-Boot will use R10 to hold a pointer to the global data
4118 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4119 or current versions of GCC may "optimize" the code too much.
4121 On RISC-V, the following registers are used:
4123 x0: hard-wired zero (zero)
4124 x1: return address (ra)
4125 x2: stack pointer (sp)
4126 x3: global pointer (gp)
4127 x4: thread pointer (tp)
4128 x5: link register (t0)
4129 x8: frame pointer (fp)
4130 x10-x11: arguments/return values (a0-1)
4131 x12-x17: arguments (a2-7)
4132 x28-31: temporaries (t3-6)
4133 pc: program counter (pc)
4135 ==> U-Boot will use gp to hold a pointer to the global data
4140 U-Boot runs in system state and uses physical addresses, i.e. the
4141 MMU is not used either for address mapping nor for memory protection.
4143 The available memory is mapped to fixed addresses using the memory
4144 controller. In this process, a contiguous block is formed for each
4145 memory type (Flash, SDRAM, SRAM), even when it consists of several
4146 physical memory banks.
4148 U-Boot is installed in the first 128 kB of the first Flash bank (on
4149 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4150 booting and sizing and initializing DRAM, the code relocates itself
4151 to the upper end of DRAM. Immediately below the U-Boot code some
4152 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4153 configuration setting]. Below that, a structure with global Board
4154 Info data is placed, followed by the stack (growing downward).
4156 Additionally, some exception handler code is copied to the low 8 kB
4157 of DRAM (0x00000000 ... 0x00001FFF).
4159 So a typical memory configuration with 16 MB of DRAM could look like
4162 0x0000 0000 Exception Vector code
4165 0x0000 2000 Free for Application Use
4171 0x00FB FF20 Monitor Stack (Growing downward)
4172 0x00FB FFAC Board Info Data and permanent copy of global data
4173 0x00FC 0000 Malloc Arena
4176 0x00FE 0000 RAM Copy of Monitor Code
4177 ... eventually: LCD or video framebuffer
4178 ... eventually: pRAM (Protected RAM - unchanged by reset)
4179 0x00FF FFFF [End of RAM]
4182 System Initialization:
4183 ----------------------
4185 In the reset configuration, U-Boot starts at the reset entry point
4186 (on most PowerPC systems at address 0x00000100). Because of the reset
4187 configuration for CS0# this is a mirror of the on board Flash memory.
4188 To be able to re-map memory U-Boot then jumps to its link address.
4189 To be able to implement the initialization code in C, a (small!)
4190 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4191 which provide such a feature like), or in a locked part of the data
4192 cache. After that, U-Boot initializes the CPU core, the caches and
4195 Next, all (potentially) available memory banks are mapped using a
4196 preliminary mapping. For example, we put them on 512 MB boundaries
4197 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4198 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4199 programmed for SDRAM access. Using the temporary configuration, a
4200 simple memory test is run that determines the size of the SDRAM
4203 When there is more than one SDRAM bank, and the banks are of
4204 different size, the largest is mapped first. For equal size, the first
4205 bank (CS2#) is mapped first. The first mapping is always for address
4206 0x00000000, with any additional banks following immediately to create
4207 contiguous memory starting from 0.
4209 Then, the monitor installs itself at the upper end of the SDRAM area
4210 and allocates memory for use by malloc() and for the global Board
4211 Info data; also, the exception vector code is copied to the low RAM
4212 pages, and the final stack is set up.
4214 Only after this relocation will you have a "normal" C environment;
4215 until that you are restricted in several ways, mostly because you are
4216 running from ROM, and because the code will have to be relocated to a
4220 U-Boot Porting Guide:
4221 ----------------------
4223 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4227 int main(int argc, char *argv[])
4229 sighandler_t no_more_time;
4231 signal(SIGALRM, no_more_time);
4232 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4234 if (available_money > available_manpower) {
4235 Pay consultant to port U-Boot;
4239 Download latest U-Boot source;
4241 Subscribe to u-boot mailing list;
4244 email("Hi, I am new to U-Boot, how do I get started?");
4247 Read the README file in the top level directory;
4248 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
4249 Read applicable doc/README.*;
4250 Read the source, Luke;
4251 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4254 if (available_money > toLocalCurrency ($2500))
4257 Add a lot of aggravation and time;
4259 if (a similar board exists) { /* hopefully... */
4260 cp -a board/<similar> board/<myboard>
4261 cp include/configs/<similar>.h include/configs/<myboard>.h
4263 Create your own board support subdirectory;
4264 Create your own board include/configs/<myboard>.h file;
4266 Edit new board/<myboard> files
4267 Edit new include/configs/<myboard>.h
4272 Add / modify source code;
4276 email("Hi, I am having problems...");
4278 Send patch file to the U-Boot email list;
4279 if (reasonable critiques)
4280 Incorporate improvements from email list code review;
4282 Defend code as written;
4288 void no_more_time (int sig)
4297 All contributions to U-Boot should conform to the Linux kernel
4298 coding style; see the kernel coding style guide at
4299 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4300 script "scripts/Lindent" in your Linux kernel source directory.
4302 Source files originating from a different project (for example the
4303 MTD subsystem) are generally exempt from these guidelines and are not
4304 reformatted to ease subsequent migration to newer versions of those
4307 Please note that U-Boot is implemented in C (and to some small parts in
4308 Assembler); no C++ is used, so please do not use C++ style comments (//)
4311 Please also stick to the following formatting rules:
4312 - remove any trailing white space
4313 - use TAB characters for indentation and vertical alignment, not spaces
4314 - make sure NOT to use DOS '\r\n' line feeds
4315 - do not add more than 2 consecutive empty lines to source files
4316 - do not add trailing empty lines to source files
4318 Submissions which do not conform to the standards may be returned
4319 with a request to reformat the changes.
4325 Since the number of patches for U-Boot is growing, we need to
4326 establish some rules. Submissions which do not conform to these rules
4327 may be rejected, even when they contain important and valuable stuff.
4329 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
4331 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4332 see https://lists.denx.de/listinfo/u-boot
4334 When you send a patch, please include the following information with
4337 * For bug fixes: a description of the bug and how your patch fixes
4338 this bug. Please try to include a way of demonstrating that the
4339 patch actually fixes something.
4341 * For new features: a description of the feature and your
4344 * For major contributions, add a MAINTAINERS file with your
4345 information and associated file and directory references.
4347 * When you add support for a new board, don't forget to add a
4348 maintainer e-mail address to the boards.cfg file, too.
4350 * If your patch adds new configuration options, don't forget to
4351 document these in the README file.
4353 * The patch itself. If you are using git (which is *strongly*
4354 recommended) you can easily generate the patch using the
4355 "git format-patch". If you then use "git send-email" to send it to
4356 the U-Boot mailing list, you will avoid most of the common problems
4357 with some other mail clients.
4359 If you cannot use git, use "diff -purN OLD NEW". If your version of
4360 diff does not support these options, then get the latest version of
4363 The current directory when running this command shall be the parent
4364 directory of the U-Boot source tree (i. e. please make sure that
4365 your patch includes sufficient directory information for the
4368 We prefer patches as plain text. MIME attachments are discouraged,
4369 and compressed attachments must not be used.
4371 * If one logical set of modifications affects or creates several
4372 files, all these changes shall be submitted in a SINGLE patch file.
4374 * Changesets that contain different, unrelated modifications shall be
4375 submitted as SEPARATE patches, one patch per changeset.
4380 * Before sending the patch, run the buildman script on your patched
4381 source tree and make sure that no errors or warnings are reported
4382 for any of the boards.
4384 * Keep your modifications to the necessary minimum: A patch
4385 containing several unrelated changes or arbitrary reformats will be
4386 returned with a request to re-formatting / split it.
4388 * If you modify existing code, make sure that your new code does not
4389 add to the memory footprint of the code ;-) Small is beautiful!
4390 When adding new features, these should compile conditionally only
4391 (using #ifdef), and the resulting code with the new feature
4392 disabled must not need more memory than the old code without your
4395 * Remember that there is a size limit of 100 kB per message on the
4396 u-boot mailing list. Bigger patches will be moderated. If they are
4397 reasonable and not too big, they will be acknowledged. But patches
4398 bigger than the size limit should be avoided.