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 /nios2 Files generic to Altera NIOS2 architecture
138 /powerpc Files generic to PowerPC architecture
139 /riscv Files generic to RISC-V architecture
140 /sandbox Files generic to HW-independent "sandbox"
141 /sh Files generic to SH architecture
142 /x86 Files generic to x86 architecture
143 /xtensa Files generic to Xtensa architecture
144 /api Machine/arch-independent API for external apps
145 /board Board-dependent files
146 /boot Support for images and booting
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_SYS_FSL_HAS_CCI400
298 Defined For SoC that has cache coherent interconnect
301 CONFIG_SYS_FSL_HAS_CCN504
303 Defined for SoC that has cache coherent interconnect CCN-504
305 The following options need to be configured:
307 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
309 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
314 Specifies that the core is a 64-bit PowerPC implementation (implements
315 the "64" category of the Power ISA). This is necessary for ePAPR
316 compliance, among other possible reasons.
318 CONFIG_SYS_FSL_TBCLK_DIV
320 Defines the core time base clock divider ratio compared to the
321 system clock. On most PQ3 devices this is 8, on newer QorIQ
322 devices it can be 16 or 32. The ratio varies from SoC to Soc.
324 CONFIG_SYS_FSL_PCIE_COMPAT
326 Defines the string to utilize when trying to match PCIe device
327 tree nodes for the given platform.
329 CONFIG_SYS_FSL_ERRATUM_A004510
331 Enables a workaround for erratum A004510. If set,
332 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
333 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
335 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
336 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
338 Defines one or two SoC revisions (low 8 bits of SVR)
339 for which the A004510 workaround should be applied.
341 The rest of SVR is either not relevant to the decision
342 of whether the erratum is present (e.g. p2040 versus
343 p2041) or is implied by the build target, which controls
344 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
346 See Freescale App Note 4493 for more information about
349 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
351 This is the value to write into CCSR offset 0x18600
352 according to the A004510 workaround.
354 CONFIG_SYS_FSL_DSP_DDR_ADDR
355 This value denotes start offset of DDR memory which is
356 connected exclusively to the DSP cores.
358 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
359 This value denotes start offset of M2 memory
360 which is directly connected to the DSP core.
362 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
363 This value denotes start offset of M3 memory which is directly
364 connected to the DSP core.
366 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
367 This value denotes start offset of DSP CCSR space.
369 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
370 Single Source Clock is clocking mode present in some of FSL SoC's.
371 In this mode, a single differential clock is used to supply
372 clocks to the sysclock, ddrclock and usbclock.
374 CONFIG_SYS_CPC_REINIT_F
375 This CONFIG is defined when the CPC is configured as SRAM at the
376 time of U-Boot entry and is required to be re-initialized.
378 - Generic CPU options:
379 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
381 Defines the endianess of the CPU. Implementation of those
382 values is arch specific.
385 Freescale DDR driver in use. This type of DDR controller is
386 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
388 CONFIG_SYS_FSL_DDR_ADDR
389 Freescale DDR memory-mapped register base.
391 CONFIG_SYS_FSL_DDR_EMU
392 Specify emulator support for DDR. Some DDR features such as
393 deskew training are not available.
395 CONFIG_SYS_FSL_DDRC_GEN1
396 Freescale DDR1 controller.
398 CONFIG_SYS_FSL_DDRC_GEN2
399 Freescale DDR2 controller.
401 CONFIG_SYS_FSL_DDRC_GEN3
402 Freescale DDR3 controller.
404 CONFIG_SYS_FSL_DDRC_GEN4
405 Freescale DDR4 controller.
407 CONFIG_SYS_FSL_DDRC_ARM_GEN3
408 Freescale DDR3 controller for ARM-based SoCs.
411 Board config to use DDR1. It can be enabled for SoCs with
412 Freescale DDR1 or DDR2 controllers, depending on the board
416 Board config to use DDR2. It can be enabled for SoCs with
417 Freescale DDR2 or DDR3 controllers, depending on the board
421 Board config to use DDR3. It can be enabled for SoCs with
422 Freescale DDR3 or DDR3L controllers.
425 Board config to use DDR3L. It can be enabled for SoCs with
428 CONFIG_SYS_FSL_IFC_BE
429 Defines the IFC controller register space as Big Endian
431 CONFIG_SYS_FSL_IFC_LE
432 Defines the IFC controller register space as Little Endian
434 CONFIG_SYS_FSL_IFC_CLK_DIV
435 Defines divider of platform clock(clock input to IFC controller).
437 CONFIG_SYS_FSL_LBC_CLK_DIV
438 Defines divider of platform clock(clock input to eLBC controller).
440 CONFIG_SYS_FSL_DDR_BE
441 Defines the DDR controller register space as Big Endian
443 CONFIG_SYS_FSL_DDR_LE
444 Defines the DDR controller register space as Little Endian
446 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
447 Physical address from the view of DDR controllers. It is the
448 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
449 it could be different for ARM SoCs.
451 CONFIG_SYS_FSL_DDR_INTLV_256B
452 DDR controller interleaving on 256-byte. This is a special
453 interleaving mode, handled by Dickens for Freescale layerscape
456 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
457 Number of controllers used as main memory.
459 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
460 Number of controllers used for other than main memory.
462 CONFIG_SYS_FSL_SEC_BE
463 Defines the SEC controller register space as Big Endian
465 CONFIG_SYS_FSL_SEC_LE
466 Defines the SEC controller register space as Little Endian
469 CONFIG_XWAY_SWAP_BYTES
471 Enable compilation of tools/xway-swap-bytes needed for Lantiq
472 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
473 be swapped if a flash programmer is used.
476 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
478 Select high exception vectors of the ARM core, e.g., do not
479 clear the V bit of the c1 register of CP15.
482 Generic timer clock source frequency.
484 COUNTER_FREQUENCY_REAL
485 Generic timer clock source frequency if the real clock is
486 different from COUNTER_FREQUENCY, and can only be determined
490 CONFIG_TEGRA_SUPPORT_NON_SECURE
492 Support executing U-Boot in non-secure (NS) mode. Certain
493 impossible actions will be skipped if the CPU is in NS mode,
494 such as ARM architectural timer initialization.
496 - Linux Kernel Interface:
497 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
499 When transferring memsize parameter to Linux, some versions
500 expect it to be in bytes, others in MB.
501 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
505 New kernel versions are expecting firmware settings to be
506 passed using flattened device trees (based on open firmware
510 * New libfdt-based support
511 * Adds the "fdt" command
512 * The bootm command automatically updates the fdt
514 OF_TBCLK - The timebase frequency.
516 boards with QUICC Engines require OF_QE to set UCC MAC
521 U-Boot can detect if an IDE device is present or not.
522 If not, and this new config option is activated, U-Boot
523 removes the ATA node from the DTS before booting Linux,
524 so the Linux IDE driver does not probe the device and
525 crash. This is needed for buggy hardware (uc101) where
526 no pull down resistor is connected to the signal IDE5V_DD7.
528 - vxWorks boot parameters:
530 bootvx constructs a valid bootline using the following
531 environments variables: bootdev, bootfile, ipaddr, netmask,
532 serverip, gatewayip, hostname, othbootargs.
533 It loads the vxWorks image pointed bootfile.
535 Note: If a "bootargs" environment is defined, it will override
536 the defaults discussed just above.
538 - Cache Configuration for ARM:
539 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
541 CONFIG_SYS_PL310_BASE - Physical base address of PL310
542 controller register space
547 If you have Amba PrimeCell PL011 UARTs, set this variable to
548 the clock speed of the UARTs.
552 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
553 define this to a list of base addresses for each (supported)
554 port. See e.g. include/configs/versatile.h
556 CONFIG_SERIAL_HW_FLOW_CONTROL
558 Define this variable to enable hw flow control in serial driver.
559 Current user of this option is drivers/serial/nsl16550.c driver
561 - Serial Download Echo Mode:
563 If defined to 1, all characters received during a
564 serial download (using the "loads" command) are
565 echoed back. This might be needed by some terminal
566 emulations (like "cu"), but may as well just take
567 time on others. This setting #define's the initial
568 value of the "loads_echo" environment variable.
570 - Removal of commands
571 If no commands are needed to boot, you can disable
572 CONFIG_CMDLINE to remove them. In this case, the command line
573 will not be available, and when U-Boot wants to execute the
574 boot command (on start-up) it will call board_run_command()
575 instead. This can reduce image size significantly for very
576 simple boot procedures.
578 - Regular expression support:
580 If this variable is defined, U-Boot is linked against
581 the SLRE (Super Light Regular Expression) library,
582 which adds regex support to some commands, as for
583 example "env grep" and "setexpr".
586 CONFIG_SYS_WATCHDOG_FREQ
587 Some platforms automatically call WATCHDOG_RESET()
588 from the timer interrupt handler every
589 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
590 board configuration file, a default of CONFIG_SYS_HZ/2
591 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
592 to 0 disables calling WATCHDOG_RESET() from the timer
597 When CONFIG_CMD_DATE is selected, the type of the RTC
598 has to be selected, too. Define exactly one of the
601 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
602 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
603 CONFIG_RTC_MC146818 - use MC146818 RTC
604 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
605 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
606 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
607 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
608 CONFIG_RTC_DS164x - use Dallas DS164x RTC
609 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
610 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
611 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
612 CONFIG_SYS_RV3029_TCR - enable trickle charger on
615 Note that if the RTC uses I2C, then the I2C interface
616 must also be configured. See I2C Support, below.
619 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
621 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
622 chip-ngpio pairs that tell the PCA953X driver the number of
623 pins supported by a particular chip.
625 Note that if the GPIO device uses I2C, then the I2C interface
626 must also be configured. See I2C Support, below.
629 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
630 accesses and can checksum them or write a list of them out
631 to memory. See the 'iotrace' command for details. This is
632 useful for testing device drivers since it can confirm that
633 the driver behaves the same way before and after a code
634 change. Currently this is supported on sandbox and arm. To
635 add support for your architecture, add '#include <iotrace.h>'
636 to the bottom of arch/<arch>/include/asm/io.h and test.
638 Example output from the 'iotrace stats' command is below.
639 Note that if the trace buffer is exhausted, the checksum will
640 still continue to operate.
643 Start: 10000000 (buffer start address)
644 Size: 00010000 (buffer size)
645 Offset: 00000120 (current buffer offset)
646 Output: 10000120 (start + offset)
647 Count: 00000018 (number of trace records)
648 CRC32: 9526fb66 (CRC32 of all trace records)
652 When CONFIG_TIMESTAMP is selected, the timestamp
653 (date and time) of an image is printed by image
654 commands like bootm or iminfo. This option is
655 automatically enabled when you select CONFIG_CMD_DATE .
657 - Partition Labels (disklabels) Supported:
658 Zero or more of the following:
659 CONFIG_MAC_PARTITION Apple's MacOS partition table.
660 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
661 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
662 bootloader. Note 2TB partition limit; see
664 CONFIG_SCSI) you must configure support for at
665 least one non-MTD partition type as well.
667 - NETWORK Support (PCI):
669 Utility code for direct access to the SPI bus on Intel 8257x.
670 This does not do anything useful unless you set at least one
671 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
674 Support for National dp83815 chips.
677 Support for National dp8382[01] gigabit chips.
679 - NETWORK Support (other):
681 Support for the Calxeda XGMAC device
684 Support for SMSC's LAN91C96 chips.
686 CONFIG_LAN91C96_USE_32_BIT
687 Define this to enable 32 bit addressing
690 Support for SMSC's LAN91C111 chip
693 Define this to hold the physical address
694 of the device (I/O space)
696 CONFIG_SMC_USE_32_BIT
697 Define this if data bus is 32 bits
699 CONFIG_SMC_USE_IOFUNCS
700 Define this to use i/o functions instead of macros
701 (some hardware wont work with macros)
703 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
704 Define this if you have more then 3 PHYs.
707 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
709 CONFIG_FTGMAC100_EGIGA
710 Define this to use GE link update with gigabit PHY.
711 Define this if FTGMAC100 is connected to gigabit PHY.
712 If your system has 10/100 PHY only, it might not occur
713 wrong behavior. Because PHY usually return timeout or
714 useless data when polling gigabit status and gigabit
715 control registers. This behavior won't affect the
716 correctnessof 10/100 link speed update.
719 Support for Renesas on-chip Ethernet controller
721 CONFIG_SH_ETHER_USE_PORT
722 Define the number of ports to be used
724 CONFIG_SH_ETHER_PHY_ADDR
725 Define the ETH PHY's address
727 CONFIG_SH_ETHER_CACHE_WRITEBACK
728 If this option is set, the driver enables cache flush.
734 CONFIG_TPM_TIS_INFINEON
735 Support for Infineon i2c bus TPM devices. Only one device
736 per system is supported at this time.
738 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
739 Define the burst count bytes upper limit
742 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
744 CONFIG_TPM_ST33ZP24_I2C
745 Support for STMicroelectronics ST33ZP24 I2C devices.
746 Requires TPM_ST33ZP24 and I2C.
748 CONFIG_TPM_ST33ZP24_SPI
749 Support for STMicroelectronics ST33ZP24 SPI devices.
750 Requires TPM_ST33ZP24 and SPI.
753 Support for Atmel TWI TPM device. Requires I2C support.
756 Support for generic parallel port TPM devices. Only one device
757 per system is supported at this time.
759 CONFIG_TPM_TIS_BASE_ADDRESS
760 Base address where the generic TPM device is mapped
761 to. Contemporary x86 systems usually map it at
765 Define this to enable the TPM support library which provides
766 functional interfaces to some TPM commands.
767 Requires support for a TPM device.
769 CONFIG_TPM_AUTH_SESSIONS
770 Define this to enable authorized functions in the TPM library.
771 Requires CONFIG_TPM and CONFIG_SHA1.
774 At the moment only the UHCI host controller is
775 supported (PIP405, MIP405); define
776 CONFIG_USB_UHCI to enable it.
777 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
778 and define CONFIG_USB_STORAGE to enable the USB
781 Supported are USB Keyboards and USB Floppy drives
784 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
788 Define the below if you wish to use the USB console.
789 Once firmware is rebuilt from a serial console issue the
790 command "setenv stdin usbtty; setenv stdout usbtty" and
791 attach your USB cable. The Unix command "dmesg" should print
792 it has found a new device. The environment variable usbtty
793 can be set to gserial or cdc_acm to enable your device to
794 appear to a USB host as a Linux gserial device or a
795 Common Device Class Abstract Control Model serial device.
796 If you select usbtty = gserial you should be able to enumerate
798 # modprobe usbserial vendor=0xVendorID product=0xProductID
799 else if using cdc_acm, simply setting the environment
800 variable usbtty to be cdc_acm should suffice. The following
801 might be defined in YourBoardName.h
804 Define this to build a UDC device
807 Define this to have a tty type of device available to
808 talk to the UDC device
811 Define this to enable the high speed support for usb
812 device and usbtty. If this feature is enabled, a routine
813 int is_usbd_high_speed(void)
814 also needs to be defined by the driver to dynamically poll
815 whether the enumeration has succeded at high speed or full
818 If you have a USB-IF assigned VendorID then you may wish to
819 define your own vendor specific values either in BoardName.h
820 or directly in usbd_vendor_info.h. If you don't define
821 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
822 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
823 should pretend to be a Linux device to it's target host.
825 CONFIG_USBD_MANUFACTURER
826 Define this string as the name of your company for
827 - CONFIG_USBD_MANUFACTURER "my company"
829 CONFIG_USBD_PRODUCT_NAME
830 Define this string as the name of your product
831 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
834 Define this as your assigned Vendor ID from the USB
835 Implementors Forum. This *must* be a genuine Vendor ID
836 to avoid polluting the USB namespace.
837 - CONFIG_USBD_VENDORID 0xFFFF
839 CONFIG_USBD_PRODUCTID
840 Define this as the unique Product ID
842 - CONFIG_USBD_PRODUCTID 0xFFFF
844 - ULPI Layer Support:
845 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
846 the generic ULPI layer. The generic layer accesses the ULPI PHY
847 via the platform viewport, so you need both the genric layer and
848 the viewport enabled. Currently only Chipidea/ARC based
849 viewport is supported.
850 To enable the ULPI layer support, define CONFIG_USB_ULPI and
851 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
852 If your ULPI phy needs a different reference clock than the
853 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
854 the appropriate value in Hz.
857 The MMC controller on the Intel PXA is supported. To
858 enable this define CONFIG_MMC. The MMC can be
859 accessed from the boot prompt by mapping the device
860 to physical memory similar to flash. Command line is
861 enabled with CONFIG_CMD_MMC. The MMC driver also works with
862 the FAT fs. This is enabled with CONFIG_CMD_FAT.
865 Support for Renesas on-chip MMCIF controller
868 Define the base address of MMCIF registers
871 Define the clock frequency for MMCIF
873 - USB Device Firmware Update (DFU) class support:
875 This enables the USB portion of the DFU USB class
878 This enables support for exposing NAND devices via DFU.
881 This enables support for exposing RAM via DFU.
882 Note: DFU spec refer to non-volatile memory usage, but
883 allow usages beyond the scope of spec - here RAM usage,
884 one that would help mostly the developer.
886 CONFIG_SYS_DFU_DATA_BUF_SIZE
887 Dfu transfer uses a buffer before writing data to the
888 raw storage device. Make the size (in bytes) of this buffer
889 configurable. The size of this buffer is also configurable
890 through the "dfu_bufsiz" environment variable.
892 CONFIG_SYS_DFU_MAX_FILE_SIZE
893 When updating files rather than the raw storage device,
894 we use a static buffer to copy the file into and then write
895 the buffer once we've been given the whole file. Define
896 this to the maximum filesize (in bytes) for the buffer.
897 Default is 4 MiB if undefined.
899 DFU_DEFAULT_POLL_TIMEOUT
900 Poll timeout [ms], is the timeout a device can send to the
901 host. The host must wait for this timeout before sending
902 a subsequent DFU_GET_STATUS request to the device.
904 DFU_MANIFEST_POLL_TIMEOUT
905 Poll timeout [ms], which the device sends to the host when
906 entering dfuMANIFEST state. Host waits this timeout, before
907 sending again an USB request to the device.
909 - Journaling Flash filesystem support:
910 CONFIG_SYS_JFFS2_FIRST_SECTOR,
911 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
912 Define these for a default partition on a NOR device
915 See Kconfig help for available keyboard drivers.
917 - LCD Support: CONFIG_LCD
919 Define this to enable LCD support (for output to LCD
920 display); also select one of the supported displays
921 by defining one of these:
923 CONFIG_NEC_NL6448AC33:
925 NEC NL6448AC33-18. Active, color, single scan.
927 CONFIG_NEC_NL6448BC20
929 NEC NL6448BC20-08. 6.5", 640x480.
930 Active, color, single scan.
932 CONFIG_NEC_NL6448BC33_54
934 NEC NL6448BC33-54. 10.4", 640x480.
935 Active, color, single scan.
939 Sharp 320x240. Active, color, single scan.
940 It isn't 16x9, and I am not sure what it is.
942 CONFIG_SHARP_LQ64D341
944 Sharp LQ64D341 display, 640x480.
945 Active, color, single scan.
949 HLD1045 display, 640x480.
950 Active, color, single scan.
954 Optrex CBL50840-2 NF-FW 99 22 M5
956 Hitachi LMG6912RPFC-00T
960 320x240. Black & white.
964 Normally the LCD is page-aligned (typically 4KB). If this is
965 defined then the LCD will be aligned to this value instead.
966 For ARM it is sometimes useful to use MMU_SECTION_SIZE
967 here, since it is cheaper to change data cache settings on
973 Sometimes, for example if the display is mounted in portrait
974 mode or even if it's mounted landscape but rotated by 180degree,
975 we need to rotate our content of the display relative to the
976 framebuffer, so that user can read the messages which are
978 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
979 initialized with a given rotation from "vl_rot" out of
980 "vidinfo_t" which is provided by the board specific code.
981 The value for vl_rot is coded as following (matching to
982 fbcon=rotate:<n> linux-kernel commandline):
983 0 = no rotation respectively 0 degree
984 1 = 90 degree rotation
985 2 = 180 degree rotation
986 3 = 270 degree rotation
988 If CONFIG_LCD_ROTATION is not defined, the console will be
989 initialized with 0degree rotation.
992 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
994 The clock frequency of the MII bus
996 CONFIG_PHY_CMD_DELAY (ppc4xx)
998 Some PHY like Intel LXT971A need extra delay after
999 command issued before MII status register can be read
1004 Define a default value for the IP address to use for
1005 the default Ethernet interface, in case this is not
1006 determined through e.g. bootp.
1007 (Environment variable "ipaddr")
1009 - Server IP address:
1012 Defines a default value for the IP address of a TFTP
1013 server to contact when using the "tftboot" command.
1014 (Environment variable "serverip")
1016 - Gateway IP address:
1019 Defines a default value for the IP address of the
1020 default router where packets to other networks are
1022 (Environment variable "gatewayip")
1027 Defines a default value for the subnet mask (or
1028 routing prefix) which is used to determine if an IP
1029 address belongs to the local subnet or needs to be
1030 forwarded through a router.
1031 (Environment variable "netmask")
1033 - BOOTP Recovery Mode:
1034 CONFIG_BOOTP_RANDOM_DELAY
1036 If you have many targets in a network that try to
1037 boot using BOOTP, you may want to avoid that all
1038 systems send out BOOTP requests at precisely the same
1039 moment (which would happen for instance at recovery
1040 from a power failure, when all systems will try to
1041 boot, thus flooding the BOOTP server. Defining
1042 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1043 inserted before sending out BOOTP requests. The
1044 following delays are inserted then:
1046 1st BOOTP request: delay 0 ... 1 sec
1047 2nd BOOTP request: delay 0 ... 2 sec
1048 3rd BOOTP request: delay 0 ... 4 sec
1050 BOOTP requests: delay 0 ... 8 sec
1052 CONFIG_BOOTP_ID_CACHE_SIZE
1054 BOOTP packets are uniquely identified using a 32-bit ID. The
1055 server will copy the ID from client requests to responses and
1056 U-Boot will use this to determine if it is the destination of
1057 an incoming response. Some servers will check that addresses
1058 aren't in use before handing them out (usually using an ARP
1059 ping) and therefore take up to a few hundred milliseconds to
1060 respond. Network congestion may also influence the time it
1061 takes for a response to make it back to the client. If that
1062 time is too long, U-Boot will retransmit requests. In order
1063 to allow earlier responses to still be accepted after these
1064 retransmissions, U-Boot's BOOTP client keeps a small cache of
1065 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1066 cache. The default is to keep IDs for up to four outstanding
1067 requests. Increasing this will allow U-Boot to accept offers
1068 from a BOOTP client in networks with unusually high latency.
1070 - DHCP Advanced Options:
1072 - Link-local IP address negotiation:
1073 Negotiate with other link-local clients on the local network
1074 for an address that doesn't require explicit configuration.
1075 This is especially useful if a DHCP server cannot be guaranteed
1076 to exist in all environments that the device must operate.
1078 See doc/README.link-local for more information.
1080 - MAC address from environment variables
1082 FDT_SEQ_MACADDR_FROM_ENV
1084 Fix-up device tree with MAC addresses fetched sequentially from
1085 environment variables. This config work on assumption that
1086 non-usable ethernet node of device-tree are either not present
1087 or their status has been marked as "disabled".
1090 CONFIG_CDP_DEVICE_ID
1092 The device id used in CDP trigger frames.
1094 CONFIG_CDP_DEVICE_ID_PREFIX
1096 A two character string which is prefixed to the MAC address
1101 A printf format string which contains the ascii name of
1102 the port. Normally is set to "eth%d" which sets
1103 eth0 for the first Ethernet, eth1 for the second etc.
1105 CONFIG_CDP_CAPABILITIES
1107 A 32bit integer which indicates the device capabilities;
1108 0x00000010 for a normal host which does not forwards.
1112 An ascii string containing the version of the software.
1116 An ascii string containing the name of the platform.
1120 A 32bit integer sent on the trigger.
1122 CONFIG_CDP_POWER_CONSUMPTION
1124 A 16bit integer containing the power consumption of the
1125 device in .1 of milliwatts.
1127 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1129 A byte containing the id of the VLAN.
1131 - Status LED: CONFIG_LED_STATUS
1133 Several configurations allow to display the current
1134 status using a LED. For instance, the LED will blink
1135 fast while running U-Boot code, stop blinking as
1136 soon as a reply to a BOOTP request was received, and
1137 start blinking slow once the Linux kernel is running
1138 (supported by a status LED driver in the Linux
1139 kernel). Defining CONFIG_LED_STATUS enables this
1144 CONFIG_LED_STATUS_GPIO
1145 The status LED can be connected to a GPIO pin.
1146 In such cases, the gpio_led driver can be used as a
1147 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1148 to include the gpio_led driver in the U-Boot binary.
1150 CONFIG_GPIO_LED_INVERTED_TABLE
1151 Some GPIO connected LEDs may have inverted polarity in which
1152 case the GPIO high value corresponds to LED off state and
1153 GPIO low value corresponds to LED on state.
1154 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1155 with a list of GPIO LEDs that have inverted polarity.
1158 CONFIG_SYS_NUM_I2C_BUSES
1159 Hold the number of i2c buses you want to use.
1161 CONFIG_SYS_I2C_DIRECT_BUS
1162 define this, if you don't use i2c muxes on your hardware.
1163 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1166 CONFIG_SYS_I2C_MAX_HOPS
1167 define how many muxes are maximal consecutively connected
1168 on one i2c bus. If you not use i2c muxes, omit this
1171 CONFIG_SYS_I2C_BUSES
1172 hold a list of buses you want to use, only used if
1173 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1174 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1175 CONFIG_SYS_NUM_I2C_BUSES = 9:
1177 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1178 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1179 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1180 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1181 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1182 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1183 {1, {I2C_NULL_HOP}}, \
1184 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1185 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1189 bus 0 on adapter 0 without a mux
1190 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1191 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1192 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1193 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1194 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1195 bus 6 on adapter 1 without a mux
1196 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1197 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1199 If you do not have i2c muxes on your board, omit this define.
1201 - Legacy I2C Support:
1202 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1203 then the following macros need to be defined (examples are
1204 from include/configs/lwmon.h):
1208 (Optional). Any commands necessary to enable the I2C
1209 controller or configure ports.
1211 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1215 The code necessary to make the I2C data line active
1216 (driven). If the data line is open collector, this
1219 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1223 The code necessary to make the I2C data line tri-stated
1224 (inactive). If the data line is open collector, this
1227 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1231 Code that returns true if the I2C data line is high,
1234 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1238 If <bit> is true, sets the I2C data line high. If it
1239 is false, it clears it (low).
1241 eg: #define I2C_SDA(bit) \
1242 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1243 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1247 If <bit> is true, sets the I2C clock line high. If it
1248 is false, it clears it (low).
1250 eg: #define I2C_SCL(bit) \
1251 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1252 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1256 This delay is invoked four times per clock cycle so this
1257 controls the rate of data transfer. The data rate thus
1258 is 1 / (I2C_DELAY * 4). Often defined to be something
1261 #define I2C_DELAY udelay(2)
1263 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1265 If your arch supports the generic GPIO framework (asm/gpio.h),
1266 then you may alternatively define the two GPIOs that are to be
1267 used as SCL / SDA. Any of the previous I2C_xxx macros will
1268 have GPIO-based defaults assigned to them as appropriate.
1270 You should define these to the GPIO value as given directly to
1271 the generic GPIO functions.
1273 CONFIG_SYS_I2C_INIT_BOARD
1275 When a board is reset during an i2c bus transfer
1276 chips might think that the current transfer is still
1277 in progress. On some boards it is possible to access
1278 the i2c SCLK line directly, either by using the
1279 processor pin as a GPIO or by having a second pin
1280 connected to the bus. If this option is defined a
1281 custom i2c_init_board() routine in boards/xxx/board.c
1282 is run early in the boot sequence.
1284 CONFIG_I2C_MULTI_BUS
1286 This option allows the use of multiple I2C buses, each of which
1287 must have a controller. At any point in time, only one bus is
1288 active. To switch to a different bus, use the 'i2c dev' command.
1289 Note that bus numbering is zero-based.
1291 CONFIG_SYS_I2C_NOPROBES
1293 This option specifies a list of I2C devices that will be skipped
1294 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1295 is set, specify a list of bus-device pairs. Otherwise, specify
1296 a 1D array of device addresses
1299 #undef CONFIG_I2C_MULTI_BUS
1300 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1302 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1304 #define CONFIG_I2C_MULTI_BUS
1305 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1307 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1309 CONFIG_SYS_SPD_BUS_NUM
1311 If defined, then this indicates the I2C bus number for DDR SPD.
1312 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1314 CONFIG_SYS_RTC_BUS_NUM
1316 If defined, then this indicates the I2C bus number for the RTC.
1317 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1319 CONFIG_SOFT_I2C_READ_REPEATED_START
1321 defining this will force the i2c_read() function in
1322 the soft_i2c driver to perform an I2C repeated start
1323 between writing the address pointer and reading the
1324 data. If this define is omitted the default behaviour
1325 of doing a stop-start sequence will be used. Most I2C
1326 devices can use either method, but some require one or
1329 - SPI Support: CONFIG_SPI
1331 Enables SPI driver (so far only tested with
1332 SPI EEPROM, also an instance works with Crystal A/D and
1333 D/As on the SACSng board)
1335 CONFIG_SYS_SPI_MXC_WAIT
1336 Timeout for waiting until spi transfer completed.
1337 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1339 - FPGA Support: CONFIG_FPGA
1341 Enables FPGA subsystem.
1343 CONFIG_FPGA_<vendor>
1345 Enables support for specific chip vendors.
1348 CONFIG_FPGA_<family>
1350 Enables support for FPGA family.
1351 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1353 CONFIG_SYS_FPGA_PROG_FEEDBACK
1355 Enable printing of hash marks during FPGA configuration.
1357 CONFIG_SYS_FPGA_CHECK_BUSY
1359 Enable checks on FPGA configuration interface busy
1360 status by the configuration function. This option
1361 will require a board or device specific function to
1366 If defined, a function that provides delays in the FPGA
1367 configuration driver.
1369 CONFIG_SYS_FPGA_CHECK_CTRLC
1370 Allow Control-C to interrupt FPGA configuration
1372 CONFIG_SYS_FPGA_CHECK_ERROR
1374 Check for configuration errors during FPGA bitfile
1375 loading. For example, abort during Virtex II
1376 configuration if the INIT_B line goes low (which
1377 indicated a CRC error).
1379 CONFIG_SYS_FPGA_WAIT_INIT
1381 Maximum time to wait for the INIT_B line to de-assert
1382 after PROB_B has been de-asserted during a Virtex II
1383 FPGA configuration sequence. The default time is 500
1386 CONFIG_SYS_FPGA_WAIT_BUSY
1388 Maximum time to wait for BUSY to de-assert during
1389 Virtex II FPGA configuration. The default is 5 ms.
1391 CONFIG_SYS_FPGA_WAIT_CONFIG
1393 Time to wait after FPGA configuration. The default is
1396 - Vendor Parameter Protection:
1398 U-Boot considers the values of the environment
1399 variables "serial#" (Board Serial Number) and
1400 "ethaddr" (Ethernet Address) to be parameters that
1401 are set once by the board vendor / manufacturer, and
1402 protects these variables from casual modification by
1403 the user. Once set, these variables are read-only,
1404 and write or delete attempts are rejected. You can
1405 change this behaviour:
1407 If CONFIG_ENV_OVERWRITE is #defined in your config
1408 file, the write protection for vendor parameters is
1409 completely disabled. Anybody can change or delete
1412 Alternatively, if you define _both_ an ethaddr in the
1413 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1414 Ethernet address is installed in the environment,
1415 which can be changed exactly ONCE by the user. [The
1416 serial# is unaffected by this, i. e. it remains
1419 The same can be accomplished in a more flexible way
1420 for any variable by configuring the type of access
1421 to allow for those variables in the ".flags" variable
1422 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1427 Define this variable to enable the reservation of
1428 "protected RAM", i. e. RAM which is not overwritten
1429 by U-Boot. Define CONFIG_PRAM to hold the number of
1430 kB you want to reserve for pRAM. You can overwrite
1431 this default value by defining an environment
1432 variable "pram" to the number of kB you want to
1433 reserve. Note that the board info structure will
1434 still show the full amount of RAM. If pRAM is
1435 reserved, a new environment variable "mem" will
1436 automatically be defined to hold the amount of
1437 remaining RAM in a form that can be passed as boot
1438 argument to Linux, for instance like that:
1440 setenv bootargs ... mem=\${mem}
1443 This way you can tell Linux not to use this memory,
1444 either, which results in a memory region that will
1445 not be affected by reboots.
1447 *WARNING* If your board configuration uses automatic
1448 detection of the RAM size, you must make sure that
1449 this memory test is non-destructive. So far, the
1450 following board configurations are known to be
1453 IVMS8, IVML24, SPD8xx,
1454 HERMES, IP860, RPXlite, LWMON,
1460 In the current implementation, the local variables
1461 space and global environment variables space are
1462 separated. Local variables are those you define by
1463 simply typing `name=value'. To access a local
1464 variable later on, you have write `$name' or
1465 `${name}'; to execute the contents of a variable
1466 directly type `$name' at the command prompt.
1468 Global environment variables are those you use
1469 setenv/printenv to work with. To run a command stored
1470 in such a variable, you need to use the run command,
1471 and you must not use the '$' sign to access them.
1473 To store commands and special characters in a
1474 variable, please use double quotation marks
1475 surrounding the whole text of the variable, instead
1476 of the backslashes before semicolons and special
1479 - Default Environment:
1480 CONFIG_EXTRA_ENV_SETTINGS
1482 Define this to contain any number of null terminated
1483 strings (variable = value pairs) that will be part of
1484 the default environment compiled into the boot image.
1486 For example, place something like this in your
1487 board's config file:
1489 #define CONFIG_EXTRA_ENV_SETTINGS \
1493 Warning: This method is based on knowledge about the
1494 internal format how the environment is stored by the
1495 U-Boot code. This is NOT an official, exported
1496 interface! Although it is unlikely that this format
1497 will change soon, there is no guarantee either.
1498 You better know what you are doing here.
1500 Note: overly (ab)use of the default environment is
1501 discouraged. Make sure to check other ways to preset
1502 the environment like the "source" command or the
1505 CONFIG_DELAY_ENVIRONMENT
1507 Normally the environment is loaded when the board is
1508 initialised so that it is available to U-Boot. This inhibits
1509 that so that the environment is not available until
1510 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1511 this is instead controlled by the value of
1512 /config/load-environment.
1514 CONFIG_STANDALONE_LOAD_ADDR
1516 This option defines a board specific value for the
1517 address where standalone program gets loaded, thus
1518 overwriting the architecture dependent default
1521 - Frame Buffer Address:
1524 Define CONFIG_FB_ADDR if you want to use specific
1525 address for frame buffer. This is typically the case
1526 when using a graphics controller has separate video
1527 memory. U-Boot will then place the frame buffer at
1528 the given address instead of dynamically reserving it
1529 in system RAM by calling lcd_setmem(), which grabs
1530 the memory for the frame buffer depending on the
1531 configured panel size.
1533 Please see board_init_f function.
1535 - Automatic software updates via TFTP server
1537 CONFIG_UPDATE_TFTP_CNT_MAX
1538 CONFIG_UPDATE_TFTP_MSEC_MAX
1540 These options enable and control the auto-update feature;
1541 for a more detailed description refer to doc/README.update.
1543 - MTD Support (mtdparts command, UBI support)
1544 CONFIG_MTD_UBI_WL_THRESHOLD
1545 This parameter defines the maximum difference between the highest
1546 erase counter value and the lowest erase counter value of eraseblocks
1547 of UBI devices. When this threshold is exceeded, UBI starts performing
1548 wear leveling by means of moving data from eraseblock with low erase
1549 counter to eraseblocks with high erase counter.
1551 The default value should be OK for SLC NAND flashes, NOR flashes and
1552 other flashes which have eraseblock life-cycle 100000 or more.
1553 However, in case of MLC NAND flashes which typically have eraseblock
1554 life-cycle less than 10000, the threshold should be lessened (e.g.,
1555 to 128 or 256, although it does not have to be power of 2).
1559 CONFIG_MTD_UBI_BEB_LIMIT
1560 This option specifies the maximum bad physical eraseblocks UBI
1561 expects on the MTD device (per 1024 eraseblocks). If the
1562 underlying flash does not admit of bad eraseblocks (e.g. NOR
1563 flash), this value is ignored.
1565 NAND datasheets often specify the minimum and maximum NVM
1566 (Number of Valid Blocks) for the flashes' endurance lifetime.
1567 The maximum expected bad eraseblocks per 1024 eraseblocks
1568 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1569 which gives 20 for most NANDs (MaxNVB is basically the total
1570 count of eraseblocks on the chip).
1572 To put it differently, if this value is 20, UBI will try to
1573 reserve about 1.9% of physical eraseblocks for bad blocks
1574 handling. And that will be 1.9% of eraseblocks on the entire
1575 NAND chip, not just the MTD partition UBI attaches. This means
1576 that if you have, say, a NAND flash chip admits maximum 40 bad
1577 eraseblocks, and it is split on two MTD partitions of the same
1578 size, UBI will reserve 40 eraseblocks when attaching a
1583 CONFIG_MTD_UBI_FASTMAP
1584 Fastmap is a mechanism which allows attaching an UBI device
1585 in nearly constant time. Instead of scanning the whole MTD device it
1586 only has to locate a checkpoint (called fastmap) on the device.
1587 The on-flash fastmap contains all information needed to attach
1588 the device. Using fastmap makes only sense on large devices where
1589 attaching by scanning takes long. UBI will not automatically install
1590 a fastmap on old images, but you can set the UBI parameter
1591 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1592 that fastmap-enabled images are still usable with UBI implementations
1593 without fastmap support. On typical flash devices the whole fastmap
1594 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1596 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1597 Set this parameter to enable fastmap automatically on images
1601 CONFIG_MTD_UBI_FM_DEBUG
1602 Enable UBI fastmap debug
1607 Enable building of SPL globally.
1609 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1610 When defined, SPL will panic() if the image it has
1611 loaded does not have a signature.
1612 Defining this is useful when code which loads images
1613 in SPL cannot guarantee that absolutely all read errors
1615 An example is the LPC32XX MLC NAND driver, which will
1616 consider that a completely unreadable NAND block is bad,
1617 and thus should be skipped silently.
1619 CONFIG_SPL_DISPLAY_PRINT
1620 For ARM, enable an optional function to print more information
1621 about the running system.
1623 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1624 Set this for NAND SPL on PPC mpc83xx targets, so that
1625 start.S waits for the rest of the SPL to load before
1626 continuing (the hardware starts execution after just
1627 loading the first page rather than the full 4K).
1630 Support for a lightweight UBI (fastmap) scanner and
1633 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1634 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1635 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1636 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1637 CONFIG_SYS_NAND_ECCBYTES
1638 Defines the size and behavior of the NAND that SPL uses
1641 CONFIG_SYS_NAND_U_BOOT_DST
1642 Location in memory to load U-Boot to
1644 CONFIG_SYS_NAND_U_BOOT_SIZE
1645 Size of image to load
1647 CONFIG_SYS_NAND_U_BOOT_START
1648 Entry point in loaded image to jump to
1650 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1651 Define this if you need to first read the OOB and then the
1652 data. This is used, for example, on davinci platforms.
1654 CONFIG_SPL_RAM_DEVICE
1655 Support for running image already present in ram, in SPL binary
1657 CONFIG_SPL_FIT_PRINT
1658 Printing information about a FIT image adds quite a bit of
1659 code to SPL. So this is normally disabled in SPL. Use this
1660 option to re-enable it. This will affect the output of the
1661 bootm command when booting a FIT image.
1663 - Interrupt support (PPC):
1665 There are common interrupt_init() and timer_interrupt()
1666 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1667 for CPU specific initialization. interrupt_init_cpu()
1668 should set decrementer_count to appropriate value. If
1669 CPU resets decrementer automatically after interrupt
1670 (ppc4xx) it should set decrementer_count to zero.
1671 timer_interrupt() calls timer_interrupt_cpu() for CPU
1672 specific handling. If board has watchdog / status_led
1673 / other_activity_monitor it works automatically from
1674 general timer_interrupt().
1677 Board initialization settings:
1678 ------------------------------
1680 During Initialization u-boot calls a number of board specific functions
1681 to allow the preparation of board specific prerequisites, e.g. pin setup
1682 before drivers are initialized. To enable these callbacks the
1683 following configuration macros have to be defined. Currently this is
1684 architecture specific, so please check arch/your_architecture/lib/board.c
1685 typically in board_init_f() and board_init_r().
1687 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1688 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1689 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1691 Configuration Settings:
1692 -----------------------
1694 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1695 Optionally it can be defined to support 64-bit memory commands.
1697 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1698 undefine this when you're short of memory.
1700 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1701 width of the commands listed in the 'help' command output.
1703 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1704 prompt for user input.
1706 - CONFIG_SYS_BAUDRATE_TABLE:
1707 List of legal baudrate settings for this board.
1709 - CONFIG_SYS_MEM_RESERVE_SECURE
1710 Only implemented for ARMv8 for now.
1711 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1712 is substracted from total RAM and won't be reported to OS.
1713 This memory can be used as secure memory. A variable
1714 gd->arch.secure_ram is used to track the location. In systems
1715 the RAM base is not zero, or RAM is divided into banks,
1716 this variable needs to be recalcuated to get the address.
1718 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1719 Enable temporary baudrate change while serial download
1721 - CONFIG_SYS_SDRAM_BASE:
1722 Physical start address of SDRAM. _Must_ be 0 here.
1724 - CONFIG_SYS_FLASH_BASE:
1725 Physical start address of Flash memory.
1727 - CONFIG_SYS_MONITOR_LEN:
1728 Size of memory reserved for monitor code, used to
1729 determine _at_compile_time_ (!) if the environment is
1730 embedded within the U-Boot image, or in a separate
1733 - CONFIG_SYS_MALLOC_LEN:
1734 Size of DRAM reserved for malloc() use.
1736 - CONFIG_SYS_MALLOC_F_LEN
1737 Size of the malloc() pool for use before relocation. If
1738 this is defined, then a very simple malloc() implementation
1739 will become available before relocation. The address is just
1740 below the global data, and the stack is moved down to make
1743 This feature allocates regions with increasing addresses
1744 within the region. calloc() is supported, but realloc()
1745 is not available. free() is supported but does nothing.
1746 The memory will be freed (or in fact just forgotten) when
1747 U-Boot relocates itself.
1749 - CONFIG_SYS_MALLOC_SIMPLE
1750 Provides a simple and small malloc() and calloc() for those
1751 boards which do not use the full malloc in SPL (which is
1752 enabled with CONFIG_SYS_SPL_MALLOC).
1754 - CONFIG_SYS_NONCACHED_MEMORY:
1755 Size of non-cached memory area. This area of memory will be
1756 typically located right below the malloc() area and mapped
1757 uncached in the MMU. This is useful for drivers that would
1758 otherwise require a lot of explicit cache maintenance. For
1759 some drivers it's also impossible to properly maintain the
1760 cache. For example if the regions that need to be flushed
1761 are not a multiple of the cache-line size, *and* padding
1762 cannot be allocated between the regions to align them (i.e.
1763 if the HW requires a contiguous array of regions, and the
1764 size of each region is not cache-aligned), then a flush of
1765 one region may result in overwriting data that hardware has
1766 written to another region in the same cache-line. This can
1767 happen for example in network drivers where descriptors for
1768 buffers are typically smaller than the CPU cache-line (e.g.
1769 16 bytes vs. 32 or 64 bytes).
1771 Non-cached memory is only supported on 32-bit ARM at present.
1773 - CONFIG_SYS_BOOTM_LEN:
1774 Normally compressed uImages are limited to an
1775 uncompressed size of 8 MBytes. If this is not enough,
1776 you can define CONFIG_SYS_BOOTM_LEN in your board config file
1777 to adjust this setting to your needs.
1779 - CONFIG_SYS_BOOTMAPSZ:
1780 Maximum size of memory mapped by the startup code of
1781 the Linux kernel; all data that must be processed by
1782 the Linux kernel (bd_info, boot arguments, FDT blob if
1783 used) must be put below this limit, unless "bootm_low"
1784 environment variable is defined and non-zero. In such case
1785 all data for the Linux kernel must be between "bootm_low"
1786 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
1787 variable "bootm_mapsize" will override the value of
1788 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
1789 then the value in "bootm_size" will be used instead.
1791 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
1792 Enable initrd_high functionality. If defined then the
1793 initrd_high feature is enabled and the bootm ramdisk subcommand
1796 - CONFIG_SYS_BOOT_GET_CMDLINE:
1797 Enables allocating and saving kernel cmdline in space between
1798 "bootm_low" and "bootm_low" + BOOTMAPSZ.
1800 - CONFIG_SYS_BOOT_GET_KBD:
1801 Enables allocating and saving a kernel copy of the bd_info in
1802 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
1804 - CONFIG_SYS_MAX_FLASH_SECT:
1805 Max number of sectors on a Flash chip
1807 - CONFIG_SYS_FLASH_ERASE_TOUT:
1808 Timeout for Flash erase operations (in ms)
1810 - CONFIG_SYS_FLASH_WRITE_TOUT:
1811 Timeout for Flash write operations (in ms)
1813 - CONFIG_SYS_FLASH_LOCK_TOUT
1814 Timeout for Flash set sector lock bit operation (in ms)
1816 - CONFIG_SYS_FLASH_UNLOCK_TOUT
1817 Timeout for Flash clear lock bits operation (in ms)
1819 - CONFIG_SYS_FLASH_PROTECTION
1820 If defined, hardware flash sectors protection is used
1821 instead of U-Boot software protection.
1823 - CONFIG_SYS_DIRECT_FLASH_TFTP:
1825 Enable TFTP transfers directly to flash memory;
1826 without this option such a download has to be
1827 performed in two steps: (1) download to RAM, and (2)
1828 copy from RAM to flash.
1830 The two-step approach is usually more reliable, since
1831 you can check if the download worked before you erase
1832 the flash, but in some situations (when system RAM is
1833 too limited to allow for a temporary copy of the
1834 downloaded image) this option may be very useful.
1836 - CONFIG_SYS_FLASH_CFI:
1837 Define if the flash driver uses extra elements in the
1838 common flash structure for storing flash geometry.
1840 - CONFIG_FLASH_CFI_DRIVER
1841 This option also enables the building of the cfi_flash driver
1842 in the drivers directory
1844 - CONFIG_FLASH_CFI_MTD
1845 This option enables the building of the cfi_mtd driver
1846 in the drivers directory. The driver exports CFI flash
1849 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
1850 Use buffered writes to flash.
1852 - CONFIG_FLASH_SPANSION_S29WS_N
1853 s29ws-n MirrorBit flash has non-standard addresses for buffered
1856 - CONFIG_SYS_FLASH_QUIET_TEST
1857 If this option is defined, the common CFI flash doesn't
1858 print it's warning upon not recognized FLASH banks. This
1859 is useful, if some of the configured banks are only
1860 optionally available.
1862 - CONFIG_FLASH_SHOW_PROGRESS
1863 If defined (must be an integer), print out countdown
1864 digits and dots. Recommended value: 45 (9..1) for 80
1865 column displays, 15 (3..1) for 40 column displays.
1867 - CONFIG_FLASH_VERIFY
1868 If defined, the content of the flash (destination) is compared
1869 against the source after the write operation. An error message
1870 will be printed when the contents are not identical.
1871 Please note that this option is useless in nearly all cases,
1872 since such flash programming errors usually are detected earlier
1873 while unprotecting/erasing/programming. Please only enable
1874 this option if you really know what you are doing.
1876 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1877 - CONFIG_ENV_FLAGS_LIST_STATIC
1878 Enable validation of the values given to environment variables when
1879 calling env set. Variables can be restricted to only decimal,
1880 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
1881 the variables can also be restricted to IP address or MAC address.
1883 The format of the list is:
1884 type_attribute = [s|d|x|b|i|m]
1885 access_attribute = [a|r|o|c]
1886 attributes = type_attribute[access_attribute]
1887 entry = variable_name[:attributes]
1890 The type attributes are:
1891 s - String (default)
1894 b - Boolean ([1yYtT|0nNfF])
1898 The access attributes are:
1904 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1905 Define this to a list (string) to define the ".flags"
1906 environment variable in the default or embedded environment.
1908 - CONFIG_ENV_FLAGS_LIST_STATIC
1909 Define this to a list (string) to define validation that
1910 should be done if an entry is not found in the ".flags"
1911 environment variable. To override a setting in the static
1912 list, simply add an entry for the same variable name to the
1915 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
1916 regular expression. This allows multiple variables to define the same
1917 flags without explicitly listing them for each variable.
1919 The following definitions that deal with the placement and management
1920 of environment data (variable area); in general, we support the
1921 following configurations:
1923 - CONFIG_BUILD_ENVCRC:
1925 Builds up envcrc with the target environment so that external utils
1926 may easily extract it and embed it in final U-Boot images.
1928 BE CAREFUL! The first access to the environment happens quite early
1929 in U-Boot initialization (when we try to get the setting of for the
1930 console baudrate). You *MUST* have mapped your NVRAM area then, or
1933 Please note that even with NVRAM we still use a copy of the
1934 environment in RAM: we could work on NVRAM directly, but we want to
1935 keep settings there always unmodified except somebody uses "saveenv"
1936 to save the current settings.
1938 BE CAREFUL! For some special cases, the local device can not use
1939 "saveenv" command. For example, the local device will get the
1940 environment stored in a remote NOR flash by SRIO or PCIE link,
1941 but it can not erase, write this NOR flash by SRIO or PCIE interface.
1943 - CONFIG_NAND_ENV_DST
1945 Defines address in RAM to which the nand_spl code should copy the
1946 environment. If redundant environment is used, it will be copied to
1947 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
1949 Please note that the environment is read-only until the monitor
1950 has been relocated to RAM and a RAM copy of the environment has been
1951 created; also, when using EEPROM you will have to use env_get_f()
1952 until then to read environment variables.
1954 The environment is protected by a CRC32 checksum. Before the monitor
1955 is relocated into RAM, as a result of a bad CRC you will be working
1956 with the compiled-in default environment - *silently*!!! [This is
1957 necessary, because the first environment variable we need is the
1958 "baudrate" setting for the console - if we have a bad CRC, we don't
1959 have any device yet where we could complain.]
1961 Note: once the monitor has been relocated, then it will complain if
1962 the default environment is used; a new CRC is computed as soon as you
1963 use the "saveenv" command to store a valid environment.
1965 - CONFIG_SYS_FAULT_MII_ADDR:
1966 MII address of the PHY to check for the Ethernet link state.
1968 - CONFIG_NS16550_MIN_FUNCTIONS:
1969 Define this if you desire to only have use of the NS16550_init
1970 and NS16550_putc functions for the serial driver located at
1971 drivers/serial/ns16550.c. This option is useful for saving
1972 space for already greatly restricted images, including but not
1973 limited to NAND_SPL configurations.
1975 - CONFIG_DISPLAY_BOARDINFO
1976 Display information about the board that U-Boot is running on
1977 when U-Boot starts up. The board function checkboard() is called
1980 - CONFIG_DISPLAY_BOARDINFO_LATE
1981 Similar to the previous option, but display this information
1982 later, once stdio is running and output goes to the LCD, if
1985 Low Level (hardware related) configuration options:
1986 ---------------------------------------------------
1988 - CONFIG_SYS_CACHELINE_SIZE:
1989 Cache Line Size of the CPU.
1991 - CONFIG_SYS_CCSRBAR_DEFAULT:
1992 Default (power-on reset) physical address of CCSR on Freescale
1995 - CONFIG_SYS_CCSRBAR:
1996 Virtual address of CCSR. On a 32-bit build, this is typically
1997 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
1999 - CONFIG_SYS_CCSRBAR_PHYS:
2000 Physical address of CCSR. CCSR can be relocated to a new
2001 physical address, if desired. In this case, this macro should
2002 be set to that address. Otherwise, it should be set to the
2003 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2004 is typically relocated on 36-bit builds. It is recommended
2005 that this macro be defined via the _HIGH and _LOW macros:
2007 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2008 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2010 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2011 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2012 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2013 used in assembly code, so it must not contain typecasts or
2014 integer size suffixes (e.g. "ULL").
2016 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2017 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2018 used in assembly code, so it must not contain typecasts or
2019 integer size suffixes (e.g. "ULL").
2021 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2022 DO NOT CHANGE unless you know exactly what you're
2023 doing! (11-4) [MPC8xx systems only]
2025 - CONFIG_SYS_INIT_RAM_ADDR:
2027 Start address of memory area that can be used for
2028 initial data and stack; please note that this must be
2029 writable memory that is working WITHOUT special
2030 initialization, i. e. you CANNOT use normal RAM which
2031 will become available only after programming the
2032 memory controller and running certain initialization
2035 U-Boot uses the following memory types:
2036 - MPC8xx: IMMR (internal memory of the CPU)
2038 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2040 - CONFIG_SYS_OR_TIMING_SDRAM:
2043 - CONFIG_SYS_MAMR_PTA:
2044 periodic timer for refresh
2047 Chip has SRIO or not
2050 Board has SRIO 1 port available
2053 Board has SRIO 2 port available
2055 - CONFIG_SRIO_PCIE_BOOT_MASTER
2056 Board can support master function for Boot from SRIO and PCIE
2058 - CONFIG_SYS_SRIOn_MEM_VIRT:
2059 Virtual Address of SRIO port 'n' memory region
2061 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2062 Physical Address of SRIO port 'n' memory region
2064 - CONFIG_SYS_SRIOn_MEM_SIZE:
2065 Size of SRIO port 'n' memory region
2067 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2068 Defined to tell the NAND controller that the NAND chip is using
2070 Not all NAND drivers use this symbol.
2071 Example of drivers that use it:
2072 - drivers/mtd/nand/raw/ndfc.c
2073 - drivers/mtd/nand/raw/mxc_nand.c
2075 - CONFIG_SYS_NDFC_EBC0_CFG
2076 Sets the EBC0_CFG register for the NDFC. If not defined
2077 a default value will be used.
2080 Get DDR timing information from an I2C EEPROM. Common
2081 with pluggable memory modules such as SODIMMs
2084 I2C address of the SPD EEPROM
2086 - CONFIG_SYS_SPD_BUS_NUM
2087 If SPD EEPROM is on an I2C bus other than the first
2088 one, specify here. Note that the value must resolve
2089 to something your driver can deal with.
2091 - CONFIG_SYS_DDR_RAW_TIMING
2092 Get DDR timing information from other than SPD. Common with
2093 soldered DDR chips onboard without SPD. DDR raw timing
2094 parameters are extracted from datasheet and hard-coded into
2095 header files or board specific files.
2097 - CONFIG_FSL_DDR_INTERACTIVE
2098 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2100 - CONFIG_FSL_DDR_SYNC_REFRESH
2101 Enable sync of refresh for multiple controllers.
2103 - CONFIG_FSL_DDR_BIST
2104 Enable built-in memory test for Freescale DDR controllers.
2106 - CONFIG_SYS_83XX_DDR_USES_CS0
2107 Only for 83xx systems. If specified, then DDR should
2108 be configured using CS0 and CS1 instead of CS2 and CS3.
2111 Enable RMII mode for all FECs.
2112 Note that this is a global option, we can't
2113 have one FEC in standard MII mode and another in RMII mode.
2115 - CONFIG_CRC32_VERIFY
2116 Add a verify option to the crc32 command.
2119 => crc32 -v <address> <count> <crc32>
2121 Where address/count indicate a memory area
2122 and crc32 is the correct crc32 which the
2126 Add the "loopw" memory command. This only takes effect if
2127 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2129 - CONFIG_CMD_MX_CYCLIC
2130 Add the "mdc" and "mwc" memory commands. These are cyclic
2135 This command will print 4 bytes (10,11,12,13) each 500 ms.
2137 => mwc.l 100 12345678 10
2138 This command will write 12345678 to address 100 all 10 ms.
2140 This only takes effect if the memory commands are activated
2141 globally (CONFIG_CMD_MEMORY).
2144 Set when the currently-running compilation is for an artifact
2145 that will end up in the SPL (as opposed to the TPL or U-Boot
2146 proper). Code that needs stage-specific behavior should check
2150 Set when the currently-running compilation is for an artifact
2151 that will end up in the TPL (as opposed to the SPL or U-Boot
2152 proper). Code that needs stage-specific behavior should check
2155 - CONFIG_ARCH_MAP_SYSMEM
2156 Generally U-Boot (and in particular the md command) uses
2157 effective address. It is therefore not necessary to regard
2158 U-Boot address as virtual addresses that need to be translated
2159 to physical addresses. However, sandbox requires this, since
2160 it maintains its own little RAM buffer which contains all
2161 addressable memory. This option causes some memory accesses
2162 to be mapped through map_sysmem() / unmap_sysmem().
2164 - CONFIG_X86_RESET_VECTOR
2165 If defined, the x86 reset vector code is included. This is not
2166 needed when U-Boot is running from Coreboot.
2168 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2169 Option to disable subpage write in NAND driver
2170 driver that uses this:
2171 drivers/mtd/nand/raw/davinci_nand.c
2173 Freescale QE/FMAN Firmware Support:
2174 -----------------------------------
2176 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2177 loading of "firmware", which is encoded in the QE firmware binary format.
2178 This firmware often needs to be loaded during U-Boot booting, so macros
2179 are used to identify the storage device (NOR flash, SPI, etc) and the address
2182 - CONFIG_SYS_FMAN_FW_ADDR
2183 The address in the storage device where the FMAN microcode is located. The
2184 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2187 - CONFIG_SYS_QE_FW_ADDR
2188 The address in the storage device where the QE microcode is located. The
2189 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2192 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2193 The maximum possible size of the firmware. The firmware binary format
2194 has a field that specifies the actual size of the firmware, but it
2195 might not be possible to read any part of the firmware unless some
2196 local storage is allocated to hold the entire firmware first.
2198 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2199 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2200 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2201 virtual address in NOR flash.
2203 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2204 Specifies that QE/FMAN firmware is located in NAND flash.
2205 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2207 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2208 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2209 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2211 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2212 Specifies that QE/FMAN firmware is located in the remote (master)
2213 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2214 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2215 window->master inbound window->master LAW->the ucode address in
2216 master's memory space.
2218 Freescale Layerscape Management Complex Firmware Support:
2219 ---------------------------------------------------------
2220 The Freescale Layerscape Management Complex (MC) supports the loading of
2222 This firmware often needs to be loaded during U-Boot booting, so macros
2223 are used to identify the storage device (NOR flash, SPI, etc) and the address
2226 - CONFIG_FSL_MC_ENET
2227 Enable the MC driver for Layerscape SoCs.
2229 Freescale Layerscape Debug Server Support:
2230 -------------------------------------------
2231 The Freescale Layerscape Debug Server Support supports the loading of
2232 "Debug Server firmware" and triggering SP boot-rom.
2233 This firmware often needs to be loaded during U-Boot booting.
2235 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2236 Define alignment of reserved memory MC requires
2241 In order to achieve reproducible builds, timestamps used in the U-Boot build
2242 process have to be set to a fixed value.
2244 This is done using the SOURCE_DATE_EPOCH environment variable.
2245 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2246 option for U-Boot or an environment variable in U-Boot.
2248 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2250 Building the Software:
2251 ======================
2253 Building U-Boot has been tested in several native build environments
2254 and in many different cross environments. Of course we cannot support
2255 all possibly existing versions of cross development tools in all
2256 (potentially obsolete) versions. In case of tool chain problems we
2257 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2258 which is extensively used to build and test U-Boot.
2260 If you are not using a native environment, it is assumed that you
2261 have GNU cross compiling tools available in your path. In this case,
2262 you must set the environment variable CROSS_COMPILE in your shell.
2263 Note that no changes to the Makefile or any other source files are
2264 necessary. For example using the ELDK on a 4xx CPU, please enter:
2266 $ CROSS_COMPILE=ppc_4xx-
2267 $ export CROSS_COMPILE
2269 U-Boot is intended to be simple to build. After installing the
2270 sources you must configure U-Boot for one specific board type. This
2275 where "NAME_defconfig" is the name of one of the existing configu-
2276 rations; see configs/*_defconfig for supported names.
2278 Note: for some boards special configuration names may exist; check if
2279 additional information is available from the board vendor; for
2280 instance, the TQM823L systems are available without (standard)
2281 or with LCD support. You can select such additional "features"
2282 when choosing the configuration, i. e.
2284 make TQM823L_defconfig
2285 - will configure for a plain TQM823L, i. e. no LCD support
2287 make TQM823L_LCD_defconfig
2288 - will configure for a TQM823L with U-Boot console on LCD
2293 Finally, type "make all", and you should get some working U-Boot
2294 images ready for download to / installation on your system:
2296 - "u-boot.bin" is a raw binary image
2297 - "u-boot" is an image in ELF binary format
2298 - "u-boot.srec" is in Motorola S-Record format
2300 By default the build is performed locally and the objects are saved
2301 in the source directory. One of the two methods can be used to change
2302 this behavior and build U-Boot to some external directory:
2304 1. Add O= to the make command line invocations:
2306 make O=/tmp/build distclean
2307 make O=/tmp/build NAME_defconfig
2308 make O=/tmp/build all
2310 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2312 export KBUILD_OUTPUT=/tmp/build
2317 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2320 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2321 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2322 For example to treat all compiler warnings as errors:
2324 make KCFLAGS=-Werror
2326 Please be aware that the Makefiles assume you are using GNU make, so
2327 for instance on NetBSD you might need to use "gmake" instead of
2331 If the system board that you have is not listed, then you will need
2332 to port U-Boot to your hardware platform. To do this, follow these
2335 1. Create a new directory to hold your board specific code. Add any
2336 files you need. In your board directory, you will need at least
2337 the "Makefile" and a "<board>.c".
2338 2. Create a new configuration file "include/configs/<board>.h" for
2340 3. If you're porting U-Boot to a new CPU, then also create a new
2341 directory to hold your CPU specific code. Add any files you need.
2342 4. Run "make <board>_defconfig" with your new name.
2343 5. Type "make", and you should get a working "u-boot.srec" file
2344 to be installed on your target system.
2345 6. Debug and solve any problems that might arise.
2346 [Of course, this last step is much harder than it sounds.]
2349 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2350 ==============================================================
2352 If you have modified U-Boot sources (for instance added a new board
2353 or support for new devices, a new CPU, etc.) you are expected to
2354 provide feedback to the other developers. The feedback normally takes
2355 the form of a "patch", i.e. a context diff against a certain (latest
2356 official or latest in the git repository) version of U-Boot sources.
2358 But before you submit such a patch, please verify that your modifi-
2359 cation did not break existing code. At least make sure that *ALL* of
2360 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2361 just run the buildman script (tools/buildman/buildman), which will
2362 configure and build U-Boot for ALL supported system. Be warned, this
2363 will take a while. Please see the buildman README, or run 'buildman -H'
2367 See also "U-Boot Porting Guide" below.
2370 Monitor Commands - Overview:
2371 ============================
2373 go - start application at address 'addr'
2374 run - run commands in an environment variable
2375 bootm - boot application image from memory
2376 bootp - boot image via network using BootP/TFTP protocol
2377 bootz - boot zImage from memory
2378 tftpboot- boot image via network using TFTP protocol
2379 and env variables "ipaddr" and "serverip"
2380 (and eventually "gatewayip")
2381 tftpput - upload a file via network using TFTP protocol
2382 rarpboot- boot image via network using RARP/TFTP protocol
2383 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2384 loads - load S-Record file over serial line
2385 loadb - load binary file over serial line (kermit mode)
2386 loadm - load binary blob from source address to destination address
2388 mm - memory modify (auto-incrementing)
2389 nm - memory modify (constant address)
2390 mw - memory write (fill)
2393 cmp - memory compare
2394 crc32 - checksum calculation
2395 i2c - I2C sub-system
2396 sspi - SPI utility commands
2397 base - print or set address offset
2398 printenv- print environment variables
2399 pwm - control pwm channels
2400 setenv - set environment variables
2401 saveenv - save environment variables to persistent storage
2402 protect - enable or disable FLASH write protection
2403 erase - erase FLASH memory
2404 flinfo - print FLASH memory information
2405 nand - NAND memory operations (see doc/README.nand)
2406 bdinfo - print Board Info structure
2407 iminfo - print header information for application image
2408 coninfo - print console devices and informations
2409 ide - IDE sub-system
2410 loop - infinite loop on address range
2411 loopw - infinite write loop on address range
2412 mtest - simple RAM test
2413 icache - enable or disable instruction cache
2414 dcache - enable or disable data cache
2415 reset - Perform RESET of the CPU
2416 echo - echo args to console
2417 version - print monitor version
2418 help - print online help
2419 ? - alias for 'help'
2422 Monitor Commands - Detailed Description:
2423 ========================================
2427 For now: just type "help <command>".
2430 Note for Redundant Ethernet Interfaces:
2431 =======================================
2433 Some boards come with redundant Ethernet interfaces; U-Boot supports
2434 such configurations and is capable of automatic selection of a
2435 "working" interface when needed. MAC assignment works as follows:
2437 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2438 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2439 "eth1addr" (=>eth1), "eth2addr", ...
2441 If the network interface stores some valid MAC address (for instance
2442 in SROM), this is used as default address if there is NO correspon-
2443 ding setting in the environment; if the corresponding environment
2444 variable is set, this overrides the settings in the card; that means:
2446 o If the SROM has a valid MAC address, and there is no address in the
2447 environment, the SROM's address is used.
2449 o If there is no valid address in the SROM, and a definition in the
2450 environment exists, then the value from the environment variable is
2453 o If both the SROM and the environment contain a MAC address, and
2454 both addresses are the same, this MAC address is used.
2456 o If both the SROM and the environment contain a MAC address, and the
2457 addresses differ, the value from the environment is used and a
2460 o If neither SROM nor the environment contain a MAC address, an error
2461 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2462 a random, locally-assigned MAC is used.
2464 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2465 will be programmed into hardware as part of the initialization process. This
2466 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2467 The naming convention is as follows:
2468 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2473 U-Boot is capable of booting (and performing other auxiliary operations on)
2474 images in two formats:
2476 New uImage format (FIT)
2477 -----------------------
2479 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2480 to Flattened Device Tree). It allows the use of images with multiple
2481 components (several kernels, ramdisks, etc.), with contents protected by
2482 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2488 Old image format is based on binary files which can be basically anything,
2489 preceded by a special header; see the definitions in include/image.h for
2490 details; basically, the header defines the following image properties:
2492 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2493 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2494 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2495 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2496 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2497 IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2498 Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
2499 * Compression Type (uncompressed, gzip, bzip2)
2505 The header is marked by a special Magic Number, and both the header
2506 and the data portions of the image are secured against corruption by
2513 Although U-Boot should support any OS or standalone application
2514 easily, the main focus has always been on Linux during the design of
2517 U-Boot includes many features that so far have been part of some
2518 special "boot loader" code within the Linux kernel. Also, any
2519 "initrd" images to be used are no longer part of one big Linux image;
2520 instead, kernel and "initrd" are separate images. This implementation
2521 serves several purposes:
2523 - the same features can be used for other OS or standalone
2524 applications (for instance: using compressed images to reduce the
2525 Flash memory footprint)
2527 - it becomes much easier to port new Linux kernel versions because
2528 lots of low-level, hardware dependent stuff are done by U-Boot
2530 - the same Linux kernel image can now be used with different "initrd"
2531 images; of course this also means that different kernel images can
2532 be run with the same "initrd". This makes testing easier (you don't
2533 have to build a new "zImage.initrd" Linux image when you just
2534 change a file in your "initrd"). Also, a field-upgrade of the
2535 software is easier now.
2541 Porting Linux to U-Boot based systems:
2542 ---------------------------------------
2544 U-Boot cannot save you from doing all the necessary modifications to
2545 configure the Linux device drivers for use with your target hardware
2546 (no, we don't intend to provide a full virtual machine interface to
2549 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2551 Just make sure your machine specific header file (for instance
2552 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2553 Information structure as we define in include/asm-<arch>/u-boot.h,
2554 and make sure that your definition of IMAP_ADDR uses the same value
2555 as your U-Boot configuration in CONFIG_SYS_IMMR.
2557 Note that U-Boot now has a driver model, a unified model for drivers.
2558 If you are adding a new driver, plumb it into driver model. If there
2559 is no uclass available, you are encouraged to create one. See
2563 Configuring the Linux kernel:
2564 -----------------------------
2566 No specific requirements for U-Boot. Make sure you have some root
2567 device (initial ramdisk, NFS) for your target system.
2570 Building a Linux Image:
2571 -----------------------
2573 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2574 not used. If you use recent kernel source, a new build target
2575 "uImage" will exist which automatically builds an image usable by
2576 U-Boot. Most older kernels also have support for a "pImage" target,
2577 which was introduced for our predecessor project PPCBoot and uses a
2578 100% compatible format.
2582 make TQM850L_defconfig
2587 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2588 encapsulate a compressed Linux kernel image with header information,
2589 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2591 * build a standard "vmlinux" kernel image (in ELF binary format):
2593 * convert the kernel into a raw binary image:
2595 ${CROSS_COMPILE}-objcopy -O binary \
2596 -R .note -R .comment \
2597 -S vmlinux linux.bin
2599 * compress the binary image:
2603 * package compressed binary image for U-Boot:
2605 mkimage -A ppc -O linux -T kernel -C gzip \
2606 -a 0 -e 0 -n "Linux Kernel Image" \
2607 -d linux.bin.gz uImage
2610 The "mkimage" tool can also be used to create ramdisk images for use
2611 with U-Boot, either separated from the Linux kernel image, or
2612 combined into one file. "mkimage" encapsulates the images with a 64
2613 byte header containing information about target architecture,
2614 operating system, image type, compression method, entry points, time
2615 stamp, CRC32 checksums, etc.
2617 "mkimage" can be called in two ways: to verify existing images and
2618 print the header information, or to build new images.
2620 In the first form (with "-l" option) mkimage lists the information
2621 contained in the header of an existing U-Boot image; this includes
2622 checksum verification:
2624 tools/mkimage -l image
2625 -l ==> list image header information
2627 The second form (with "-d" option) is used to build a U-Boot image
2628 from a "data file" which is used as image payload:
2630 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2631 -n name -d data_file image
2632 -A ==> set architecture to 'arch'
2633 -O ==> set operating system to 'os'
2634 -T ==> set image type to 'type'
2635 -C ==> set compression type 'comp'
2636 -a ==> set load address to 'addr' (hex)
2637 -e ==> set entry point to 'ep' (hex)
2638 -n ==> set image name to 'name'
2639 -d ==> use image data from 'datafile'
2641 Right now, all Linux kernels for PowerPC systems use the same load
2642 address (0x00000000), but the entry point address depends on the
2645 - 2.2.x kernels have the entry point at 0x0000000C,
2646 - 2.3.x and later kernels have the entry point at 0x00000000.
2648 So a typical call to build a U-Boot image would read:
2650 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2651 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2652 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2653 > examples/uImage.TQM850L
2654 Image Name: 2.4.4 kernel for TQM850L
2655 Created: Wed Jul 19 02:34:59 2000
2656 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2657 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2658 Load Address: 0x00000000
2659 Entry Point: 0x00000000
2661 To verify the contents of the image (or check for corruption):
2663 -> tools/mkimage -l examples/uImage.TQM850L
2664 Image Name: 2.4.4 kernel for TQM850L
2665 Created: Wed Jul 19 02:34:59 2000
2666 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2667 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2668 Load Address: 0x00000000
2669 Entry Point: 0x00000000
2671 NOTE: for embedded systems where boot time is critical you can trade
2672 speed for memory and install an UNCOMPRESSED image instead: this
2673 needs more space in Flash, but boots much faster since it does not
2674 need to be uncompressed:
2676 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2677 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2678 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2679 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2680 > examples/uImage.TQM850L-uncompressed
2681 Image Name: 2.4.4 kernel for TQM850L
2682 Created: Wed Jul 19 02:34:59 2000
2683 Image Type: PowerPC Linux Kernel Image (uncompressed)
2684 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2685 Load Address: 0x00000000
2686 Entry Point: 0x00000000
2689 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2690 when your kernel is intended to use an initial ramdisk:
2692 -> tools/mkimage -n 'Simple Ramdisk Image' \
2693 > -A ppc -O linux -T ramdisk -C gzip \
2694 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2695 Image Name: Simple Ramdisk Image
2696 Created: Wed Jan 12 14:01:50 2000
2697 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2698 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2699 Load Address: 0x00000000
2700 Entry Point: 0x00000000
2702 The "dumpimage" tool can be used to disassemble or list the contents of images
2703 built by mkimage. See dumpimage's help output (-h) for details.
2705 Installing a Linux Image:
2706 -------------------------
2708 To downloading a U-Boot image over the serial (console) interface,
2709 you must convert the image to S-Record format:
2711 objcopy -I binary -O srec examples/image examples/image.srec
2713 The 'objcopy' does not understand the information in the U-Boot
2714 image header, so the resulting S-Record file will be relative to
2715 address 0x00000000. To load it to a given address, you need to
2716 specify the target address as 'offset' parameter with the 'loads'
2719 Example: install the image to address 0x40100000 (which on the
2720 TQM8xxL is in the first Flash bank):
2722 => erase 40100000 401FFFFF
2728 ## Ready for S-Record download ...
2729 ~>examples/image.srec
2730 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2732 15989 15990 15991 15992
2733 [file transfer complete]
2735 ## Start Addr = 0x00000000
2738 You can check the success of the download using the 'iminfo' command;
2739 this includes a checksum verification so you can be sure no data
2740 corruption happened:
2744 ## Checking Image at 40100000 ...
2745 Image Name: 2.2.13 for initrd on TQM850L
2746 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2747 Data Size: 335725 Bytes = 327 kB = 0 MB
2748 Load Address: 00000000
2749 Entry Point: 0000000c
2750 Verifying Checksum ... OK
2756 The "bootm" command is used to boot an application that is stored in
2757 memory (RAM or Flash). In case of a Linux kernel image, the contents
2758 of the "bootargs" environment variable is passed to the kernel as
2759 parameters. You can check and modify this variable using the
2760 "printenv" and "setenv" commands:
2763 => printenv bootargs
2764 bootargs=root=/dev/ram
2766 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2768 => printenv bootargs
2769 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2772 ## Booting Linux kernel at 40020000 ...
2773 Image Name: 2.2.13 for NFS on TQM850L
2774 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2775 Data Size: 381681 Bytes = 372 kB = 0 MB
2776 Load Address: 00000000
2777 Entry Point: 0000000c
2778 Verifying Checksum ... OK
2779 Uncompressing Kernel Image ... OK
2780 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
2781 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2782 time_init: decrementer frequency = 187500000/60
2783 Calibrating delay loop... 49.77 BogoMIPS
2784 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2787 If you want to boot a Linux kernel with initial RAM disk, you pass
2788 the memory addresses of both the kernel and the initrd image (PPBCOOT
2789 format!) to the "bootm" command:
2791 => imi 40100000 40200000
2793 ## Checking Image at 40100000 ...
2794 Image Name: 2.2.13 for initrd on TQM850L
2795 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2796 Data Size: 335725 Bytes = 327 kB = 0 MB
2797 Load Address: 00000000
2798 Entry Point: 0000000c
2799 Verifying Checksum ... OK
2801 ## Checking Image at 40200000 ...
2802 Image Name: Simple Ramdisk Image
2803 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2804 Data Size: 566530 Bytes = 553 kB = 0 MB
2805 Load Address: 00000000
2806 Entry Point: 00000000
2807 Verifying Checksum ... OK
2809 => bootm 40100000 40200000
2810 ## Booting Linux kernel at 40100000 ...
2811 Image Name: 2.2.13 for initrd on TQM850L
2812 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2813 Data Size: 335725 Bytes = 327 kB = 0 MB
2814 Load Address: 00000000
2815 Entry Point: 0000000c
2816 Verifying Checksum ... OK
2817 Uncompressing Kernel Image ... OK
2818 ## Loading RAMDisk Image at 40200000 ...
2819 Image Name: Simple Ramdisk Image
2820 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2821 Data Size: 566530 Bytes = 553 kB = 0 MB
2822 Load Address: 00000000
2823 Entry Point: 00000000
2824 Verifying Checksum ... OK
2825 Loading Ramdisk ... OK
2826 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
2827 Boot arguments: root=/dev/ram
2828 time_init: decrementer frequency = 187500000/60
2829 Calibrating delay loop... 49.77 BogoMIPS
2831 RAMDISK: Compressed image found at block 0
2832 VFS: Mounted root (ext2 filesystem).
2836 Boot Linux and pass a flat device tree:
2839 First, U-Boot must be compiled with the appropriate defines. See the section
2840 titled "Linux Kernel Interface" above for a more in depth explanation. The
2841 following is an example of how to start a kernel and pass an updated
2847 oft=oftrees/mpc8540ads.dtb
2848 => tftp $oftaddr $oft
2849 Speed: 1000, full duplex
2851 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
2852 Filename 'oftrees/mpc8540ads.dtb'.
2853 Load address: 0x300000
2856 Bytes transferred = 4106 (100a hex)
2857 => tftp $loadaddr $bootfile
2858 Speed: 1000, full duplex
2860 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
2862 Load address: 0x200000
2863 Loading:############
2865 Bytes transferred = 1029407 (fb51f hex)
2870 => bootm $loadaddr - $oftaddr
2871 ## Booting image at 00200000 ...
2872 Image Name: Linux-2.6.17-dirty
2873 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2874 Data Size: 1029343 Bytes = 1005.2 kB
2875 Load Address: 00000000
2876 Entry Point: 00000000
2877 Verifying Checksum ... OK
2878 Uncompressing Kernel Image ... OK
2879 Booting using flat device tree at 0x300000
2880 Using MPC85xx ADS machine description
2881 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
2885 More About U-Boot Image Types:
2886 ------------------------------
2888 U-Boot supports the following image types:
2890 "Standalone Programs" are directly runnable in the environment
2891 provided by U-Boot; it is expected that (if they behave
2892 well) you can continue to work in U-Boot after return from
2893 the Standalone Program.
2894 "OS Kernel Images" are usually images of some Embedded OS which
2895 will take over control completely. Usually these programs
2896 will install their own set of exception handlers, device
2897 drivers, set up the MMU, etc. - this means, that you cannot
2898 expect to re-enter U-Boot except by resetting the CPU.
2899 "RAMDisk Images" are more or less just data blocks, and their
2900 parameters (address, size) are passed to an OS kernel that is
2902 "Multi-File Images" contain several images, typically an OS
2903 (Linux) kernel image and one or more data images like
2904 RAMDisks. This construct is useful for instance when you want
2905 to boot over the network using BOOTP etc., where the boot
2906 server provides just a single image file, but you want to get
2907 for instance an OS kernel and a RAMDisk image.
2909 "Multi-File Images" start with a list of image sizes, each
2910 image size (in bytes) specified by an "uint32_t" in network
2911 byte order. This list is terminated by an "(uint32_t)0".
2912 Immediately after the terminating 0 follow the images, one by
2913 one, all aligned on "uint32_t" boundaries (size rounded up to
2914 a multiple of 4 bytes).
2916 "Firmware Images" are binary images containing firmware (like
2917 U-Boot or FPGA images) which usually will be programmed to
2920 "Script files" are command sequences that will be executed by
2921 U-Boot's command interpreter; this feature is especially
2922 useful when you configure U-Boot to use a real shell (hush)
2923 as command interpreter.
2925 Booting the Linux zImage:
2926 -------------------------
2928 On some platforms, it's possible to boot Linux zImage. This is done
2929 using the "bootz" command. The syntax of "bootz" command is the same
2930 as the syntax of "bootm" command.
2932 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
2933 kernel with raw initrd images. The syntax is slightly different, the
2934 address of the initrd must be augmented by it's size, in the following
2935 format: "<initrd addres>:<initrd size>".
2941 One of the features of U-Boot is that you can dynamically load and
2942 run "standalone" applications, which can use some resources of
2943 U-Boot like console I/O functions or interrupt services.
2945 Two simple examples are included with the sources:
2950 'examples/hello_world.c' contains a small "Hello World" Demo
2951 application; it is automatically compiled when you build U-Boot.
2952 It's configured to run at address 0x00040004, so you can play with it
2956 ## Ready for S-Record download ...
2957 ~>examples/hello_world.srec
2958 1 2 3 4 5 6 7 8 9 10 11 ...
2959 [file transfer complete]
2961 ## Start Addr = 0x00040004
2963 => go 40004 Hello World! This is a test.
2964 ## Starting application at 0x00040004 ...
2975 Hit any key to exit ...
2977 ## Application terminated, rc = 0x0
2979 Another example, which demonstrates how to register a CPM interrupt
2980 handler with the U-Boot code, can be found in 'examples/timer.c'.
2981 Here, a CPM timer is set up to generate an interrupt every second.
2982 The interrupt service routine is trivial, just printing a '.'
2983 character, but this is just a demo program. The application can be
2984 controlled by the following keys:
2986 ? - print current values og the CPM Timer registers
2987 b - enable interrupts and start timer
2988 e - stop timer and disable interrupts
2989 q - quit application
2992 ## Ready for S-Record download ...
2993 ~>examples/timer.srec
2994 1 2 3 4 5 6 7 8 9 10 11 ...
2995 [file transfer complete]
2997 ## Start Addr = 0x00040004
3000 ## Starting application at 0x00040004 ...
3003 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3006 [q, b, e, ?] Set interval 1000000 us
3009 [q, b, e, ?] ........
3010 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3013 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3016 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3019 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3021 [q, b, e, ?] ...Stopping timer
3023 [q, b, e, ?] ## Application terminated, rc = 0x0
3029 Over time, many people have reported problems when trying to use the
3030 "minicom" terminal emulation program for serial download. I (wd)
3031 consider minicom to be broken, and recommend not to use it. Under
3032 Unix, I recommend to use C-Kermit for general purpose use (and
3033 especially for kermit binary protocol download ("loadb" command), and
3034 use "cu" for S-Record download ("loads" command). See
3035 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3036 for help with kermit.
3039 Nevertheless, if you absolutely want to use it try adding this
3040 configuration to your "File transfer protocols" section:
3042 Name Program Name U/D FullScr IO-Red. Multi
3043 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3044 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3050 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3051 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3053 Building requires a cross environment; it is known to work on
3054 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3055 need gmake since the Makefiles are not compatible with BSD make).
3056 Note that the cross-powerpc package does not install include files;
3057 attempting to build U-Boot will fail because <machine/ansi.h> is
3058 missing. This file has to be installed and patched manually:
3060 # cd /usr/pkg/cross/powerpc-netbsd/include
3062 # ln -s powerpc machine
3063 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3064 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3066 Native builds *don't* work due to incompatibilities between native
3067 and U-Boot include files.
3069 Booting assumes that (the first part of) the image booted is a
3070 stage-2 loader which in turn loads and then invokes the kernel
3071 proper. Loader sources will eventually appear in the NetBSD source
3072 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3073 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3076 Implementation Internals:
3077 =========================
3079 The following is not intended to be a complete description of every
3080 implementation detail. However, it should help to understand the
3081 inner workings of U-Boot and make it easier to port it to custom
3085 Initial Stack, Global Data:
3086 ---------------------------
3088 The implementation of U-Boot is complicated by the fact that U-Boot
3089 starts running out of ROM (flash memory), usually without access to
3090 system RAM (because the memory controller is not initialized yet).
3091 This means that we don't have writable Data or BSS segments, and BSS
3092 is not initialized as zero. To be able to get a C environment working
3093 at all, we have to allocate at least a minimal stack. Implementation
3094 options for this are defined and restricted by the CPU used: Some CPU
3095 models provide on-chip memory (like the IMMR area on MPC8xx and
3096 MPC826x processors), on others (parts of) the data cache can be
3097 locked as (mis-) used as memory, etc.
3099 Chris Hallinan posted a good summary of these issues to the
3100 U-Boot mailing list:
3102 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3103 From: "Chris Hallinan" <clh@net1plus.com>
3104 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3107 Correct me if I'm wrong, folks, but the way I understand it
3108 is this: Using DCACHE as initial RAM for Stack, etc, does not
3109 require any physical RAM backing up the cache. The cleverness
3110 is that the cache is being used as a temporary supply of
3111 necessary storage before the SDRAM controller is setup. It's
3112 beyond the scope of this list to explain the details, but you
3113 can see how this works by studying the cache architecture and
3114 operation in the architecture and processor-specific manuals.
3116 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3117 is another option for the system designer to use as an
3118 initial stack/RAM area prior to SDRAM being available. Either
3119 option should work for you. Using CS 4 should be fine if your
3120 board designers haven't used it for something that would
3121 cause you grief during the initial boot! It is frequently not
3124 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3125 with your processor/board/system design. The default value
3126 you will find in any recent u-boot distribution in
3127 walnut.h should work for you. I'd set it to a value larger
3128 than your SDRAM module. If you have a 64MB SDRAM module, set
3129 it above 400_0000. Just make sure your board has no resources
3130 that are supposed to respond to that address! That code in
3131 start.S has been around a while and should work as is when
3132 you get the config right.
3137 It is essential to remember this, since it has some impact on the C
3138 code for the initialization procedures:
3140 * Initialized global data (data segment) is read-only. Do not attempt
3143 * Do not use any uninitialized global data (or implicitly initialized
3144 as zero data - BSS segment) at all - this is undefined, initiali-
3145 zation is performed later (when relocating to RAM).
3147 * Stack space is very limited. Avoid big data buffers or things like
3150 Having only the stack as writable memory limits means we cannot use
3151 normal global data to share information between the code. But it
3152 turned out that the implementation of U-Boot can be greatly
3153 simplified by making a global data structure (gd_t) available to all
3154 functions. We could pass a pointer to this data as argument to _all_
3155 functions, but this would bloat the code. Instead we use a feature of
3156 the GCC compiler (Global Register Variables) to share the data: we
3157 place a pointer (gd) to the global data into a register which we
3158 reserve for this purpose.
3160 When choosing a register for such a purpose we are restricted by the
3161 relevant (E)ABI specifications for the current architecture, and by
3162 GCC's implementation.
3164 For PowerPC, the following registers have specific use:
3166 R2: reserved for system use
3167 R3-R4: parameter passing and return values
3168 R5-R10: parameter passing
3169 R13: small data area pointer
3173 (U-Boot also uses R12 as internal GOT pointer. r12
3174 is a volatile register so r12 needs to be reset when
3175 going back and forth between asm and C)
3177 ==> U-Boot will use R2 to hold a pointer to the global data
3179 Note: on PPC, we could use a static initializer (since the
3180 address of the global data structure is known at compile time),
3181 but it turned out that reserving a register results in somewhat
3182 smaller code - although the code savings are not that big (on
3183 average for all boards 752 bytes for the whole U-Boot image,
3184 624 text + 127 data).
3186 On ARM, the following registers are used:
3188 R0: function argument word/integer result
3189 R1-R3: function argument word
3190 R9: platform specific
3191 R10: stack limit (used only if stack checking is enabled)
3192 R11: argument (frame) pointer
3193 R12: temporary workspace
3196 R15: program counter
3198 ==> U-Boot will use R9 to hold a pointer to the global data
3200 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3202 On Nios II, the ABI is documented here:
3203 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3205 ==> U-Boot will use gp to hold a pointer to the global data
3207 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3208 to access small data sections, so gp is free.
3210 On RISC-V, the following registers are used:
3212 x0: hard-wired zero (zero)
3213 x1: return address (ra)
3214 x2: stack pointer (sp)
3215 x3: global pointer (gp)
3216 x4: thread pointer (tp)
3217 x5: link register (t0)
3218 x8: frame pointer (fp)
3219 x10-x11: arguments/return values (a0-1)
3220 x12-x17: arguments (a2-7)
3221 x28-31: temporaries (t3-6)
3222 pc: program counter (pc)
3224 ==> U-Boot will use gp to hold a pointer to the global data
3229 U-Boot runs in system state and uses physical addresses, i.e. the
3230 MMU is not used either for address mapping nor for memory protection.
3232 The available memory is mapped to fixed addresses using the memory
3233 controller. In this process, a contiguous block is formed for each
3234 memory type (Flash, SDRAM, SRAM), even when it consists of several
3235 physical memory banks.
3237 U-Boot is installed in the first 128 kB of the first Flash bank (on
3238 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3239 booting and sizing and initializing DRAM, the code relocates itself
3240 to the upper end of DRAM. Immediately below the U-Boot code some
3241 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3242 configuration setting]. Below that, a structure with global Board
3243 Info data is placed, followed by the stack (growing downward).
3245 Additionally, some exception handler code is copied to the low 8 kB
3246 of DRAM (0x00000000 ... 0x00001FFF).
3248 So a typical memory configuration with 16 MB of DRAM could look like
3251 0x0000 0000 Exception Vector code
3254 0x0000 2000 Free for Application Use
3260 0x00FB FF20 Monitor Stack (Growing downward)
3261 0x00FB FFAC Board Info Data and permanent copy of global data
3262 0x00FC 0000 Malloc Arena
3265 0x00FE 0000 RAM Copy of Monitor Code
3266 ... eventually: LCD or video framebuffer
3267 ... eventually: pRAM (Protected RAM - unchanged by reset)
3268 0x00FF FFFF [End of RAM]
3271 System Initialization:
3272 ----------------------
3274 In the reset configuration, U-Boot starts at the reset entry point
3275 (on most PowerPC systems at address 0x00000100). Because of the reset
3276 configuration for CS0# this is a mirror of the on board Flash memory.
3277 To be able to re-map memory U-Boot then jumps to its link address.
3278 To be able to implement the initialization code in C, a (small!)
3279 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3280 which provide such a feature like), or in a locked part of the data
3281 cache. After that, U-Boot initializes the CPU core, the caches and
3284 Next, all (potentially) available memory banks are mapped using a
3285 preliminary mapping. For example, we put them on 512 MB boundaries
3286 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3287 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3288 programmed for SDRAM access. Using the temporary configuration, a
3289 simple memory test is run that determines the size of the SDRAM
3292 When there is more than one SDRAM bank, and the banks are of
3293 different size, the largest is mapped first. For equal size, the first
3294 bank (CS2#) is mapped first. The first mapping is always for address
3295 0x00000000, with any additional banks following immediately to create
3296 contiguous memory starting from 0.
3298 Then, the monitor installs itself at the upper end of the SDRAM area
3299 and allocates memory for use by malloc() and for the global Board
3300 Info data; also, the exception vector code is copied to the low RAM
3301 pages, and the final stack is set up.
3303 Only after this relocation will you have a "normal" C environment;
3304 until that you are restricted in several ways, mostly because you are
3305 running from ROM, and because the code will have to be relocated to a
3309 U-Boot Porting Guide:
3310 ----------------------
3312 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3316 int main(int argc, char *argv[])
3318 sighandler_t no_more_time;
3320 signal(SIGALRM, no_more_time);
3321 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3323 if (available_money > available_manpower) {
3324 Pay consultant to port U-Boot;
3328 Download latest U-Boot source;
3330 Subscribe to u-boot mailing list;
3333 email("Hi, I am new to U-Boot, how do I get started?");
3336 Read the README file in the top level directory;
3337 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3338 Read applicable doc/README.*;
3339 Read the source, Luke;
3340 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3343 if (available_money > toLocalCurrency ($2500))
3346 Add a lot of aggravation and time;
3348 if (a similar board exists) { /* hopefully... */
3349 cp -a board/<similar> board/<myboard>
3350 cp include/configs/<similar>.h include/configs/<myboard>.h
3352 Create your own board support subdirectory;
3353 Create your own board include/configs/<myboard>.h file;
3355 Edit new board/<myboard> files
3356 Edit new include/configs/<myboard>.h
3361 Add / modify source code;
3365 email("Hi, I am having problems...");
3367 Send patch file to the U-Boot email list;
3368 if (reasonable critiques)
3369 Incorporate improvements from email list code review;
3371 Defend code as written;
3377 void no_more_time (int sig)
3386 All contributions to U-Boot should conform to the Linux kernel
3387 coding style; see the kernel coding style guide at
3388 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3389 script "scripts/Lindent" in your Linux kernel source directory.
3391 Source files originating from a different project (for example the
3392 MTD subsystem) are generally exempt from these guidelines and are not
3393 reformatted to ease subsequent migration to newer versions of those
3396 Please note that U-Boot is implemented in C (and to some small parts in
3397 Assembler); no C++ is used, so please do not use C++ style comments (//)
3400 Please also stick to the following formatting rules:
3401 - remove any trailing white space
3402 - use TAB characters for indentation and vertical alignment, not spaces
3403 - make sure NOT to use DOS '\r\n' line feeds
3404 - do not add more than 2 consecutive empty lines to source files
3405 - do not add trailing empty lines to source files
3407 Submissions which do not conform to the standards may be returned
3408 with a request to reformat the changes.
3414 Since the number of patches for U-Boot is growing, we need to
3415 establish some rules. Submissions which do not conform to these rules
3416 may be rejected, even when they contain important and valuable stuff.
3418 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3420 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3421 see https://lists.denx.de/listinfo/u-boot
3423 When you send a patch, please include the following information with
3426 * For bug fixes: a description of the bug and how your patch fixes
3427 this bug. Please try to include a way of demonstrating that the
3428 patch actually fixes something.
3430 * For new features: a description of the feature and your
3433 * For major contributions, add a MAINTAINERS file with your
3434 information and associated file and directory references.
3436 * When you add support for a new board, don't forget to add a
3437 maintainer e-mail address to the boards.cfg file, too.
3439 * If your patch adds new configuration options, don't forget to
3440 document these in the README file.
3442 * The patch itself. If you are using git (which is *strongly*
3443 recommended) you can easily generate the patch using the
3444 "git format-patch". If you then use "git send-email" to send it to
3445 the U-Boot mailing list, you will avoid most of the common problems
3446 with some other mail clients.
3448 If you cannot use git, use "diff -purN OLD NEW". If your version of
3449 diff does not support these options, then get the latest version of
3452 The current directory when running this command shall be the parent
3453 directory of the U-Boot source tree (i. e. please make sure that
3454 your patch includes sufficient directory information for the
3457 We prefer patches as plain text. MIME attachments are discouraged,
3458 and compressed attachments must not be used.
3460 * If one logical set of modifications affects or creates several
3461 files, all these changes shall be submitted in a SINGLE patch file.
3463 * Changesets that contain different, unrelated modifications shall be
3464 submitted as SEPARATE patches, one patch per changeset.
3469 * Before sending the patch, run the buildman script on your patched
3470 source tree and make sure that no errors or warnings are reported
3471 for any of the boards.
3473 * Keep your modifications to the necessary minimum: A patch
3474 containing several unrelated changes or arbitrary reformats will be
3475 returned with a request to re-formatting / split it.
3477 * If you modify existing code, make sure that your new code does not
3478 add to the memory footprint of the code ;-) Small is beautiful!
3479 When adding new features, these should compile conditionally only
3480 (using #ifdef), and the resulting code with the new feature
3481 disabled must not need more memory than the old code without your
3484 * Remember that there is a size limit of 100 kB per message on the
3485 u-boot mailing list. Bigger patches will be moderated. If they are
3486 reasonable and not too big, they will be acknowledged. But patches
3487 bigger than the size limit should be avoided.
projects / platform / kernel / u-boot.git / blob