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.
670 Set this to enable support for disks larger than 137GB
671 Also look at CONFIG_SYS_64BIT_LBA.
672 Whithout these , LBA48 support uses 32bit variables and will 'only'
673 support disks up to 2.1TB.
675 CONFIG_SYS_64BIT_LBA:
676 When enabled, makes the IDE subsystem use 64bit sector addresses.
679 - NETWORK Support (PCI):
681 Utility code for direct access to the SPI bus on Intel 8257x.
682 This does not do anything useful unless you set at least one
683 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
686 Support for National dp83815 chips.
689 Support for National dp8382[01] gigabit chips.
691 - NETWORK Support (other):
693 Support for the Calxeda XGMAC device
696 Support for SMSC's LAN91C96 chips.
698 CONFIG_LAN91C96_USE_32_BIT
699 Define this to enable 32 bit addressing
702 Support for SMSC's LAN91C111 chip
705 Define this to hold the physical address
706 of the device (I/O space)
708 CONFIG_SMC_USE_32_BIT
709 Define this if data bus is 32 bits
711 CONFIG_SMC_USE_IOFUNCS
712 Define this to use i/o functions instead of macros
713 (some hardware wont work with macros)
715 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
716 Define this if you have more then 3 PHYs.
719 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
721 CONFIG_FTGMAC100_EGIGA
722 Define this to use GE link update with gigabit PHY.
723 Define this if FTGMAC100 is connected to gigabit PHY.
724 If your system has 10/100 PHY only, it might not occur
725 wrong behavior. Because PHY usually return timeout or
726 useless data when polling gigabit status and gigabit
727 control registers. This behavior won't affect the
728 correctnessof 10/100 link speed update.
731 Support for Renesas on-chip Ethernet controller
733 CONFIG_SH_ETHER_USE_PORT
734 Define the number of ports to be used
736 CONFIG_SH_ETHER_PHY_ADDR
737 Define the ETH PHY's address
739 CONFIG_SH_ETHER_CACHE_WRITEBACK
740 If this option is set, the driver enables cache flush.
746 CONFIG_TPM_TIS_INFINEON
747 Support for Infineon i2c bus TPM devices. Only one device
748 per system is supported at this time.
750 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
751 Define the burst count bytes upper limit
754 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
756 CONFIG_TPM_ST33ZP24_I2C
757 Support for STMicroelectronics ST33ZP24 I2C devices.
758 Requires TPM_ST33ZP24 and I2C.
760 CONFIG_TPM_ST33ZP24_SPI
761 Support for STMicroelectronics ST33ZP24 SPI devices.
762 Requires TPM_ST33ZP24 and SPI.
765 Support for Atmel TWI TPM device. Requires I2C support.
768 Support for generic parallel port TPM devices. Only one device
769 per system is supported at this time.
771 CONFIG_TPM_TIS_BASE_ADDRESS
772 Base address where the generic TPM device is mapped
773 to. Contemporary x86 systems usually map it at
777 Define this to enable the TPM support library which provides
778 functional interfaces to some TPM commands.
779 Requires support for a TPM device.
781 CONFIG_TPM_AUTH_SESSIONS
782 Define this to enable authorized functions in the TPM library.
783 Requires CONFIG_TPM and CONFIG_SHA1.
786 At the moment only the UHCI host controller is
787 supported (PIP405, MIP405); define
788 CONFIG_USB_UHCI to enable it.
789 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
790 and define CONFIG_USB_STORAGE to enable the USB
793 Supported are USB Keyboards and USB Floppy drives
796 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
797 txfilltuning field in the EHCI controller on reset.
799 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
803 Define the below if you wish to use the USB console.
804 Once firmware is rebuilt from a serial console issue the
805 command "setenv stdin usbtty; setenv stdout usbtty" and
806 attach your USB cable. The Unix command "dmesg" should print
807 it has found a new device. The environment variable usbtty
808 can be set to gserial or cdc_acm to enable your device to
809 appear to a USB host as a Linux gserial device or a
810 Common Device Class Abstract Control Model serial device.
811 If you select usbtty = gserial you should be able to enumerate
813 # modprobe usbserial vendor=0xVendorID product=0xProductID
814 else if using cdc_acm, simply setting the environment
815 variable usbtty to be cdc_acm should suffice. The following
816 might be defined in YourBoardName.h
819 Define this to build a UDC device
822 Define this to have a tty type of device available to
823 talk to the UDC device
826 Define this to enable the high speed support for usb
827 device and usbtty. If this feature is enabled, a routine
828 int is_usbd_high_speed(void)
829 also needs to be defined by the driver to dynamically poll
830 whether the enumeration has succeded at high speed or full
833 If you have a USB-IF assigned VendorID then you may wish to
834 define your own vendor specific values either in BoardName.h
835 or directly in usbd_vendor_info.h. If you don't define
836 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
837 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
838 should pretend to be a Linux device to it's target host.
840 CONFIG_USBD_MANUFACTURER
841 Define this string as the name of your company for
842 - CONFIG_USBD_MANUFACTURER "my company"
844 CONFIG_USBD_PRODUCT_NAME
845 Define this string as the name of your product
846 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
849 Define this as your assigned Vendor ID from the USB
850 Implementors Forum. This *must* be a genuine Vendor ID
851 to avoid polluting the USB namespace.
852 - CONFIG_USBD_VENDORID 0xFFFF
854 CONFIG_USBD_PRODUCTID
855 Define this as the unique Product ID
857 - CONFIG_USBD_PRODUCTID 0xFFFF
859 - ULPI Layer Support:
860 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
861 the generic ULPI layer. The generic layer accesses the ULPI PHY
862 via the platform viewport, so you need both the genric layer and
863 the viewport enabled. Currently only Chipidea/ARC based
864 viewport is supported.
865 To enable the ULPI layer support, define CONFIG_USB_ULPI and
866 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
867 If your ULPI phy needs a different reference clock than the
868 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
869 the appropriate value in Hz.
872 The MMC controller on the Intel PXA is supported. To
873 enable this define CONFIG_MMC. The MMC can be
874 accessed from the boot prompt by mapping the device
875 to physical memory similar to flash. Command line is
876 enabled with CONFIG_CMD_MMC. The MMC driver also works with
877 the FAT fs. This is enabled with CONFIG_CMD_FAT.
880 Support for Renesas on-chip MMCIF controller
883 Define the base address of MMCIF registers
886 Define the clock frequency for MMCIF
888 - USB Device Firmware Update (DFU) class support:
890 This enables the USB portion of the DFU USB class
893 This enables support for exposing NAND devices via DFU.
896 This enables support for exposing RAM via DFU.
897 Note: DFU spec refer to non-volatile memory usage, but
898 allow usages beyond the scope of spec - here RAM usage,
899 one that would help mostly the developer.
901 CONFIG_SYS_DFU_DATA_BUF_SIZE
902 Dfu transfer uses a buffer before writing data to the
903 raw storage device. Make the size (in bytes) of this buffer
904 configurable. The size of this buffer is also configurable
905 through the "dfu_bufsiz" environment variable.
907 CONFIG_SYS_DFU_MAX_FILE_SIZE
908 When updating files rather than the raw storage device,
909 we use a static buffer to copy the file into and then write
910 the buffer once we've been given the whole file. Define
911 this to the maximum filesize (in bytes) for the buffer.
912 Default is 4 MiB if undefined.
914 DFU_DEFAULT_POLL_TIMEOUT
915 Poll timeout [ms], is the timeout a device can send to the
916 host. The host must wait for this timeout before sending
917 a subsequent DFU_GET_STATUS request to the device.
919 DFU_MANIFEST_POLL_TIMEOUT
920 Poll timeout [ms], which the device sends to the host when
921 entering dfuMANIFEST state. Host waits this timeout, before
922 sending again an USB request to the device.
924 - Journaling Flash filesystem support:
925 CONFIG_SYS_JFFS2_FIRST_SECTOR,
926 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
927 Define these for a default partition on a NOR device
930 See Kconfig help for available keyboard drivers.
932 - LCD Support: CONFIG_LCD
934 Define this to enable LCD support (for output to LCD
935 display); also select one of the supported displays
936 by defining one of these:
938 CONFIG_NEC_NL6448AC33:
940 NEC NL6448AC33-18. Active, color, single scan.
942 CONFIG_NEC_NL6448BC20
944 NEC NL6448BC20-08. 6.5", 640x480.
945 Active, color, single scan.
947 CONFIG_NEC_NL6448BC33_54
949 NEC NL6448BC33-54. 10.4", 640x480.
950 Active, color, single scan.
954 Sharp 320x240. Active, color, single scan.
955 It isn't 16x9, and I am not sure what it is.
957 CONFIG_SHARP_LQ64D341
959 Sharp LQ64D341 display, 640x480.
960 Active, color, single scan.
964 HLD1045 display, 640x480.
965 Active, color, single scan.
969 Optrex CBL50840-2 NF-FW 99 22 M5
971 Hitachi LMG6912RPFC-00T
975 320x240. Black & white.
979 Normally the LCD is page-aligned (typically 4KB). If this is
980 defined then the LCD will be aligned to this value instead.
981 For ARM it is sometimes useful to use MMU_SECTION_SIZE
982 here, since it is cheaper to change data cache settings on
988 Sometimes, for example if the display is mounted in portrait
989 mode or even if it's mounted landscape but rotated by 180degree,
990 we need to rotate our content of the display relative to the
991 framebuffer, so that user can read the messages which are
993 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
994 initialized with a given rotation from "vl_rot" out of
995 "vidinfo_t" which is provided by the board specific code.
996 The value for vl_rot is coded as following (matching to
997 fbcon=rotate:<n> linux-kernel commandline):
998 0 = no rotation respectively 0 degree
999 1 = 90 degree rotation
1000 2 = 180 degree rotation
1001 3 = 270 degree rotation
1003 If CONFIG_LCD_ROTATION is not defined, the console will be
1004 initialized with 0degree rotation.
1007 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1009 The clock frequency of the MII bus
1011 CONFIG_PHY_CMD_DELAY (ppc4xx)
1013 Some PHY like Intel LXT971A need extra delay after
1014 command issued before MII status register can be read
1019 Define a default value for the IP address to use for
1020 the default Ethernet interface, in case this is not
1021 determined through e.g. bootp.
1022 (Environment variable "ipaddr")
1024 - Server IP address:
1027 Defines a default value for the IP address of a TFTP
1028 server to contact when using the "tftboot" command.
1029 (Environment variable "serverip")
1031 - Gateway IP address:
1034 Defines a default value for the IP address of the
1035 default router where packets to other networks are
1037 (Environment variable "gatewayip")
1042 Defines a default value for the subnet mask (or
1043 routing prefix) which is used to determine if an IP
1044 address belongs to the local subnet or needs to be
1045 forwarded through a router.
1046 (Environment variable "netmask")
1048 - BOOTP Recovery Mode:
1049 CONFIG_BOOTP_RANDOM_DELAY
1051 If you have many targets in a network that try to
1052 boot using BOOTP, you may want to avoid that all
1053 systems send out BOOTP requests at precisely the same
1054 moment (which would happen for instance at recovery
1055 from a power failure, when all systems will try to
1056 boot, thus flooding the BOOTP server. Defining
1057 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1058 inserted before sending out BOOTP requests. The
1059 following delays are inserted then:
1061 1st BOOTP request: delay 0 ... 1 sec
1062 2nd BOOTP request: delay 0 ... 2 sec
1063 3rd BOOTP request: delay 0 ... 4 sec
1065 BOOTP requests: delay 0 ... 8 sec
1067 CONFIG_BOOTP_ID_CACHE_SIZE
1069 BOOTP packets are uniquely identified using a 32-bit ID. The
1070 server will copy the ID from client requests to responses and
1071 U-Boot will use this to determine if it is the destination of
1072 an incoming response. Some servers will check that addresses
1073 aren't in use before handing them out (usually using an ARP
1074 ping) and therefore take up to a few hundred milliseconds to
1075 respond. Network congestion may also influence the time it
1076 takes for a response to make it back to the client. If that
1077 time is too long, U-Boot will retransmit requests. In order
1078 to allow earlier responses to still be accepted after these
1079 retransmissions, U-Boot's BOOTP client keeps a small cache of
1080 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1081 cache. The default is to keep IDs for up to four outstanding
1082 requests. Increasing this will allow U-Boot to accept offers
1083 from a BOOTP client in networks with unusually high latency.
1085 - DHCP Advanced Options:
1087 - Link-local IP address negotiation:
1088 Negotiate with other link-local clients on the local network
1089 for an address that doesn't require explicit configuration.
1090 This is especially useful if a DHCP server cannot be guaranteed
1091 to exist in all environments that the device must operate.
1093 See doc/README.link-local for more information.
1095 - MAC address from environment variables
1097 FDT_SEQ_MACADDR_FROM_ENV
1099 Fix-up device tree with MAC addresses fetched sequentially from
1100 environment variables. This config work on assumption that
1101 non-usable ethernet node of device-tree are either not present
1102 or their status has been marked as "disabled".
1105 CONFIG_CDP_DEVICE_ID
1107 The device id used in CDP trigger frames.
1109 CONFIG_CDP_DEVICE_ID_PREFIX
1111 A two character string which is prefixed to the MAC address
1116 A printf format string which contains the ascii name of
1117 the port. Normally is set to "eth%d" which sets
1118 eth0 for the first Ethernet, eth1 for the second etc.
1120 CONFIG_CDP_CAPABILITIES
1122 A 32bit integer which indicates the device capabilities;
1123 0x00000010 for a normal host which does not forwards.
1127 An ascii string containing the version of the software.
1131 An ascii string containing the name of the platform.
1135 A 32bit integer sent on the trigger.
1137 CONFIG_CDP_POWER_CONSUMPTION
1139 A 16bit integer containing the power consumption of the
1140 device in .1 of milliwatts.
1142 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1144 A byte containing the id of the VLAN.
1146 - Status LED: CONFIG_LED_STATUS
1148 Several configurations allow to display the current
1149 status using a LED. For instance, the LED will blink
1150 fast while running U-Boot code, stop blinking as
1151 soon as a reply to a BOOTP request was received, and
1152 start blinking slow once the Linux kernel is running
1153 (supported by a status LED driver in the Linux
1154 kernel). Defining CONFIG_LED_STATUS enables this
1159 CONFIG_LED_STATUS_GPIO
1160 The status LED can be connected to a GPIO pin.
1161 In such cases, the gpio_led driver can be used as a
1162 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1163 to include the gpio_led driver in the U-Boot binary.
1165 CONFIG_GPIO_LED_INVERTED_TABLE
1166 Some GPIO connected LEDs may have inverted polarity in which
1167 case the GPIO high value corresponds to LED off state and
1168 GPIO low value corresponds to LED on state.
1169 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1170 with a list of GPIO LEDs that have inverted polarity.
1173 CONFIG_SYS_NUM_I2C_BUSES
1174 Hold the number of i2c buses you want to use.
1176 CONFIG_SYS_I2C_DIRECT_BUS
1177 define this, if you don't use i2c muxes on your hardware.
1178 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1181 CONFIG_SYS_I2C_MAX_HOPS
1182 define how many muxes are maximal consecutively connected
1183 on one i2c bus. If you not use i2c muxes, omit this
1186 CONFIG_SYS_I2C_BUSES
1187 hold a list of buses you want to use, only used if
1188 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1189 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1190 CONFIG_SYS_NUM_I2C_BUSES = 9:
1192 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1193 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1194 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1195 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1196 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1197 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1198 {1, {I2C_NULL_HOP}}, \
1199 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1200 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1204 bus 0 on adapter 0 without a mux
1205 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1206 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1207 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1208 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1209 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1210 bus 6 on adapter 1 without a mux
1211 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1212 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1214 If you do not have i2c muxes on your board, omit this define.
1216 - Legacy I2C Support:
1217 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1218 then the following macros need to be defined (examples are
1219 from include/configs/lwmon.h):
1223 (Optional). Any commands necessary to enable the I2C
1224 controller or configure ports.
1226 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1230 The code necessary to make the I2C data line active
1231 (driven). If the data line is open collector, this
1234 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1238 The code necessary to make the I2C data line tri-stated
1239 (inactive). If the data line is open collector, this
1242 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1246 Code that returns true if the I2C data line is high,
1249 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1253 If <bit> is true, sets the I2C data line high. If it
1254 is false, it clears it (low).
1256 eg: #define I2C_SDA(bit) \
1257 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1258 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1262 If <bit> is true, sets the I2C clock line high. If it
1263 is false, it clears it (low).
1265 eg: #define I2C_SCL(bit) \
1266 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1267 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1271 This delay is invoked four times per clock cycle so this
1272 controls the rate of data transfer. The data rate thus
1273 is 1 / (I2C_DELAY * 4). Often defined to be something
1276 #define I2C_DELAY udelay(2)
1278 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1280 If your arch supports the generic GPIO framework (asm/gpio.h),
1281 then you may alternatively define the two GPIOs that are to be
1282 used as SCL / SDA. Any of the previous I2C_xxx macros will
1283 have GPIO-based defaults assigned to them as appropriate.
1285 You should define these to the GPIO value as given directly to
1286 the generic GPIO functions.
1288 CONFIG_SYS_I2C_INIT_BOARD
1290 When a board is reset during an i2c bus transfer
1291 chips might think that the current transfer is still
1292 in progress. On some boards it is possible to access
1293 the i2c SCLK line directly, either by using the
1294 processor pin as a GPIO or by having a second pin
1295 connected to the bus. If this option is defined a
1296 custom i2c_init_board() routine in boards/xxx/board.c
1297 is run early in the boot sequence.
1299 CONFIG_I2C_MULTI_BUS
1301 This option allows the use of multiple I2C buses, each of which
1302 must have a controller. At any point in time, only one bus is
1303 active. To switch to a different bus, use the 'i2c dev' command.
1304 Note that bus numbering is zero-based.
1306 CONFIG_SYS_I2C_NOPROBES
1308 This option specifies a list of I2C devices that will be skipped
1309 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1310 is set, specify a list of bus-device pairs. Otherwise, specify
1311 a 1D array of device addresses
1314 #undef CONFIG_I2C_MULTI_BUS
1315 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1317 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1319 #define CONFIG_I2C_MULTI_BUS
1320 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1322 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1324 CONFIG_SYS_SPD_BUS_NUM
1326 If defined, then this indicates the I2C bus number for DDR SPD.
1327 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1329 CONFIG_SYS_RTC_BUS_NUM
1331 If defined, then this indicates the I2C bus number for the RTC.
1332 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1334 CONFIG_SOFT_I2C_READ_REPEATED_START
1336 defining this will force the i2c_read() function in
1337 the soft_i2c driver to perform an I2C repeated start
1338 between writing the address pointer and reading the
1339 data. If this define is omitted the default behaviour
1340 of doing a stop-start sequence will be used. Most I2C
1341 devices can use either method, but some require one or
1344 - SPI Support: CONFIG_SPI
1346 Enables SPI driver (so far only tested with
1347 SPI EEPROM, also an instance works with Crystal A/D and
1348 D/As on the SACSng board)
1350 CONFIG_SYS_SPI_MXC_WAIT
1351 Timeout for waiting until spi transfer completed.
1352 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1354 - FPGA Support: CONFIG_FPGA
1356 Enables FPGA subsystem.
1358 CONFIG_FPGA_<vendor>
1360 Enables support for specific chip vendors.
1363 CONFIG_FPGA_<family>
1365 Enables support for FPGA family.
1366 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1370 Specify the number of FPGA devices to support.
1372 CONFIG_SYS_FPGA_PROG_FEEDBACK
1374 Enable printing of hash marks during FPGA configuration.
1376 CONFIG_SYS_FPGA_CHECK_BUSY
1378 Enable checks on FPGA configuration interface busy
1379 status by the configuration function. This option
1380 will require a board or device specific function to
1385 If defined, a function that provides delays in the FPGA
1386 configuration driver.
1388 CONFIG_SYS_FPGA_CHECK_CTRLC
1389 Allow Control-C to interrupt FPGA configuration
1391 CONFIG_SYS_FPGA_CHECK_ERROR
1393 Check for configuration errors during FPGA bitfile
1394 loading. For example, abort during Virtex II
1395 configuration if the INIT_B line goes low (which
1396 indicated a CRC error).
1398 CONFIG_SYS_FPGA_WAIT_INIT
1400 Maximum time to wait for the INIT_B line to de-assert
1401 after PROB_B has been de-asserted during a Virtex II
1402 FPGA configuration sequence. The default time is 500
1405 CONFIG_SYS_FPGA_WAIT_BUSY
1407 Maximum time to wait for BUSY to de-assert during
1408 Virtex II FPGA configuration. The default is 5 ms.
1410 CONFIG_SYS_FPGA_WAIT_CONFIG
1412 Time to wait after FPGA configuration. The default is
1415 - Vendor Parameter Protection:
1417 U-Boot considers the values of the environment
1418 variables "serial#" (Board Serial Number) and
1419 "ethaddr" (Ethernet Address) to be parameters that
1420 are set once by the board vendor / manufacturer, and
1421 protects these variables from casual modification by
1422 the user. Once set, these variables are read-only,
1423 and write or delete attempts are rejected. You can
1424 change this behaviour:
1426 If CONFIG_ENV_OVERWRITE is #defined in your config
1427 file, the write protection for vendor parameters is
1428 completely disabled. Anybody can change or delete
1431 Alternatively, if you define _both_ an ethaddr in the
1432 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1433 Ethernet address is installed in the environment,
1434 which can be changed exactly ONCE by the user. [The
1435 serial# is unaffected by this, i. e. it remains
1438 The same can be accomplished in a more flexible way
1439 for any variable by configuring the type of access
1440 to allow for those variables in the ".flags" variable
1441 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1446 Define this variable to enable the reservation of
1447 "protected RAM", i. e. RAM which is not overwritten
1448 by U-Boot. Define CONFIG_PRAM to hold the number of
1449 kB you want to reserve for pRAM. You can overwrite
1450 this default value by defining an environment
1451 variable "pram" to the number of kB you want to
1452 reserve. Note that the board info structure will
1453 still show the full amount of RAM. If pRAM is
1454 reserved, a new environment variable "mem" will
1455 automatically be defined to hold the amount of
1456 remaining RAM in a form that can be passed as boot
1457 argument to Linux, for instance like that:
1459 setenv bootargs ... mem=\${mem}
1462 This way you can tell Linux not to use this memory,
1463 either, which results in a memory region that will
1464 not be affected by reboots.
1466 *WARNING* If your board configuration uses automatic
1467 detection of the RAM size, you must make sure that
1468 this memory test is non-destructive. So far, the
1469 following board configurations are known to be
1472 IVMS8, IVML24, SPD8xx,
1473 HERMES, IP860, RPXlite, LWMON,
1479 In the current implementation, the local variables
1480 space and global environment variables space are
1481 separated. Local variables are those you define by
1482 simply typing `name=value'. To access a local
1483 variable later on, you have write `$name' or
1484 `${name}'; to execute the contents of a variable
1485 directly type `$name' at the command prompt.
1487 Global environment variables are those you use
1488 setenv/printenv to work with. To run a command stored
1489 in such a variable, you need to use the run command,
1490 and you must not use the '$' sign to access them.
1492 To store commands and special characters in a
1493 variable, please use double quotation marks
1494 surrounding the whole text of the variable, instead
1495 of the backslashes before semicolons and special
1498 - Default Environment:
1499 CONFIG_EXTRA_ENV_SETTINGS
1501 Define this to contain any number of null terminated
1502 strings (variable = value pairs) that will be part of
1503 the default environment compiled into the boot image.
1505 For example, place something like this in your
1506 board's config file:
1508 #define CONFIG_EXTRA_ENV_SETTINGS \
1512 Warning: This method is based on knowledge about the
1513 internal format how the environment is stored by the
1514 U-Boot code. This is NOT an official, exported
1515 interface! Although it is unlikely that this format
1516 will change soon, there is no guarantee either.
1517 You better know what you are doing here.
1519 Note: overly (ab)use of the default environment is
1520 discouraged. Make sure to check other ways to preset
1521 the environment like the "source" command or the
1524 CONFIG_DELAY_ENVIRONMENT
1526 Normally the environment is loaded when the board is
1527 initialised so that it is available to U-Boot. This inhibits
1528 that so that the environment is not available until
1529 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1530 this is instead controlled by the value of
1531 /config/load-environment.
1533 CONFIG_STANDALONE_LOAD_ADDR
1535 This option defines a board specific value for the
1536 address where standalone program gets loaded, thus
1537 overwriting the architecture dependent default
1540 - Frame Buffer Address:
1543 Define CONFIG_FB_ADDR if you want to use specific
1544 address for frame buffer. This is typically the case
1545 when using a graphics controller has separate video
1546 memory. U-Boot will then place the frame buffer at
1547 the given address instead of dynamically reserving it
1548 in system RAM by calling lcd_setmem(), which grabs
1549 the memory for the frame buffer depending on the
1550 configured panel size.
1552 Please see board_init_f function.
1554 - Automatic software updates via TFTP server
1556 CONFIG_UPDATE_TFTP_CNT_MAX
1557 CONFIG_UPDATE_TFTP_MSEC_MAX
1559 These options enable and control the auto-update feature;
1560 for a more detailed description refer to doc/README.update.
1562 - MTD Support (mtdparts command, UBI support)
1563 CONFIG_MTD_UBI_WL_THRESHOLD
1564 This parameter defines the maximum difference between the highest
1565 erase counter value and the lowest erase counter value of eraseblocks
1566 of UBI devices. When this threshold is exceeded, UBI starts performing
1567 wear leveling by means of moving data from eraseblock with low erase
1568 counter to eraseblocks with high erase counter.
1570 The default value should be OK for SLC NAND flashes, NOR flashes and
1571 other flashes which have eraseblock life-cycle 100000 or more.
1572 However, in case of MLC NAND flashes which typically have eraseblock
1573 life-cycle less than 10000, the threshold should be lessened (e.g.,
1574 to 128 or 256, although it does not have to be power of 2).
1578 CONFIG_MTD_UBI_BEB_LIMIT
1579 This option specifies the maximum bad physical eraseblocks UBI
1580 expects on the MTD device (per 1024 eraseblocks). If the
1581 underlying flash does not admit of bad eraseblocks (e.g. NOR
1582 flash), this value is ignored.
1584 NAND datasheets often specify the minimum and maximum NVM
1585 (Number of Valid Blocks) for the flashes' endurance lifetime.
1586 The maximum expected bad eraseblocks per 1024 eraseblocks
1587 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1588 which gives 20 for most NANDs (MaxNVB is basically the total
1589 count of eraseblocks on the chip).
1591 To put it differently, if this value is 20, UBI will try to
1592 reserve about 1.9% of physical eraseblocks for bad blocks
1593 handling. And that will be 1.9% of eraseblocks on the entire
1594 NAND chip, not just the MTD partition UBI attaches. This means
1595 that if you have, say, a NAND flash chip admits maximum 40 bad
1596 eraseblocks, and it is split on two MTD partitions of the same
1597 size, UBI will reserve 40 eraseblocks when attaching a
1602 CONFIG_MTD_UBI_FASTMAP
1603 Fastmap is a mechanism which allows attaching an UBI device
1604 in nearly constant time. Instead of scanning the whole MTD device it
1605 only has to locate a checkpoint (called fastmap) on the device.
1606 The on-flash fastmap contains all information needed to attach
1607 the device. Using fastmap makes only sense on large devices where
1608 attaching by scanning takes long. UBI will not automatically install
1609 a fastmap on old images, but you can set the UBI parameter
1610 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1611 that fastmap-enabled images are still usable with UBI implementations
1612 without fastmap support. On typical flash devices the whole fastmap
1613 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1615 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1616 Set this parameter to enable fastmap automatically on images
1620 CONFIG_MTD_UBI_FM_DEBUG
1621 Enable UBI fastmap debug
1626 Enable building of SPL globally.
1628 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1629 When defined, SPL will panic() if the image it has
1630 loaded does not have a signature.
1631 Defining this is useful when code which loads images
1632 in SPL cannot guarantee that absolutely all read errors
1634 An example is the LPC32XX MLC NAND driver, which will
1635 consider that a completely unreadable NAND block is bad,
1636 and thus should be skipped silently.
1638 CONFIG_SPL_DISPLAY_PRINT
1639 For ARM, enable an optional function to print more information
1640 about the running system.
1642 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1643 Set this for NAND SPL on PPC mpc83xx targets, so that
1644 start.S waits for the rest of the SPL to load before
1645 continuing (the hardware starts execution after just
1646 loading the first page rather than the full 4K).
1649 Support for a lightweight UBI (fastmap) scanner and
1652 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1653 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1654 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1655 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1656 CONFIG_SYS_NAND_ECCBYTES
1657 Defines the size and behavior of the NAND that SPL uses
1660 CONFIG_SYS_NAND_U_BOOT_DST
1661 Location in memory to load U-Boot to
1663 CONFIG_SYS_NAND_U_BOOT_SIZE
1664 Size of image to load
1666 CONFIG_SYS_NAND_U_BOOT_START
1667 Entry point in loaded image to jump to
1669 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1670 Define this if you need to first read the OOB and then the
1671 data. This is used, for example, on davinci platforms.
1673 CONFIG_SPL_RAM_DEVICE
1674 Support for running image already present in ram, in SPL binary
1676 CONFIG_SPL_FIT_PRINT
1677 Printing information about a FIT image adds quite a bit of
1678 code to SPL. So this is normally disabled in SPL. Use this
1679 option to re-enable it. This will affect the output of the
1680 bootm command when booting a FIT image.
1682 - Interrupt support (PPC):
1684 There are common interrupt_init() and timer_interrupt()
1685 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1686 for CPU specific initialization. interrupt_init_cpu()
1687 should set decrementer_count to appropriate value. If
1688 CPU resets decrementer automatically after interrupt
1689 (ppc4xx) it should set decrementer_count to zero.
1690 timer_interrupt() calls timer_interrupt_cpu() for CPU
1691 specific handling. If board has watchdog / status_led
1692 / other_activity_monitor it works automatically from
1693 general timer_interrupt().
1696 Board initialization settings:
1697 ------------------------------
1699 During Initialization u-boot calls a number of board specific functions
1700 to allow the preparation of board specific prerequisites, e.g. pin setup
1701 before drivers are initialized. To enable these callbacks the
1702 following configuration macros have to be defined. Currently this is
1703 architecture specific, so please check arch/your_architecture/lib/board.c
1704 typically in board_init_f() and board_init_r().
1706 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1707 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1708 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1710 Configuration Settings:
1711 -----------------------
1713 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1714 Optionally it can be defined to support 64-bit memory commands.
1716 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1717 undefine this when you're short of memory.
1719 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1720 width of the commands listed in the 'help' command output.
1722 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1723 prompt for user input.
1725 - CONFIG_SYS_BAUDRATE_TABLE:
1726 List of legal baudrate settings for this board.
1728 - CONFIG_SYS_MEM_RESERVE_SECURE
1729 Only implemented for ARMv8 for now.
1730 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1731 is substracted from total RAM and won't be reported to OS.
1732 This memory can be used as secure memory. A variable
1733 gd->arch.secure_ram is used to track the location. In systems
1734 the RAM base is not zero, or RAM is divided into banks,
1735 this variable needs to be recalcuated to get the address.
1737 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1738 Enable temporary baudrate change while serial download
1740 - CONFIG_SYS_SDRAM_BASE:
1741 Physical start address of SDRAM. _Must_ be 0 here.
1743 - CONFIG_SYS_FLASH_BASE:
1744 Physical start address of Flash memory.
1746 - CONFIG_SYS_MONITOR_LEN:
1747 Size of memory reserved for monitor code, used to
1748 determine _at_compile_time_ (!) if the environment is
1749 embedded within the U-Boot image, or in a separate
1752 - CONFIG_SYS_MALLOC_LEN:
1753 Size of DRAM reserved for malloc() use.
1755 - CONFIG_SYS_MALLOC_F_LEN
1756 Size of the malloc() pool for use before relocation. If
1757 this is defined, then a very simple malloc() implementation
1758 will become available before relocation. The address is just
1759 below the global data, and the stack is moved down to make
1762 This feature allocates regions with increasing addresses
1763 within the region. calloc() is supported, but realloc()
1764 is not available. free() is supported but does nothing.
1765 The memory will be freed (or in fact just forgotten) when
1766 U-Boot relocates itself.
1768 - CONFIG_SYS_MALLOC_SIMPLE
1769 Provides a simple and small malloc() and calloc() for those
1770 boards which do not use the full malloc in SPL (which is
1771 enabled with CONFIG_SYS_SPL_MALLOC).
1773 - CONFIG_SYS_NONCACHED_MEMORY:
1774 Size of non-cached memory area. This area of memory will be
1775 typically located right below the malloc() area and mapped
1776 uncached in the MMU. This is useful for drivers that would
1777 otherwise require a lot of explicit cache maintenance. For
1778 some drivers it's also impossible to properly maintain the
1779 cache. For example if the regions that need to be flushed
1780 are not a multiple of the cache-line size, *and* padding
1781 cannot be allocated between the regions to align them (i.e.
1782 if the HW requires a contiguous array of regions, and the
1783 size of each region is not cache-aligned), then a flush of
1784 one region may result in overwriting data that hardware has
1785 written to another region in the same cache-line. This can
1786 happen for example in network drivers where descriptors for
1787 buffers are typically smaller than the CPU cache-line (e.g.
1788 16 bytes vs. 32 or 64 bytes).
1790 Non-cached memory is only supported on 32-bit ARM at present.
1792 - CONFIG_SYS_BOOTM_LEN:
1793 Normally compressed uImages are limited to an
1794 uncompressed size of 8 MBytes. If this is not enough,
1795 you can define CONFIG_SYS_BOOTM_LEN in your board config file
1796 to adjust this setting to your needs.
1798 - CONFIG_SYS_BOOTMAPSZ:
1799 Maximum size of memory mapped by the startup code of
1800 the Linux kernel; all data that must be processed by
1801 the Linux kernel (bd_info, boot arguments, FDT blob if
1802 used) must be put below this limit, unless "bootm_low"
1803 environment variable is defined and non-zero. In such case
1804 all data for the Linux kernel must be between "bootm_low"
1805 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
1806 variable "bootm_mapsize" will override the value of
1807 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
1808 then the value in "bootm_size" will be used instead.
1810 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
1811 Enable initrd_high functionality. If defined then the
1812 initrd_high feature is enabled and the bootm ramdisk subcommand
1815 - CONFIG_SYS_BOOT_GET_CMDLINE:
1816 Enables allocating and saving kernel cmdline in space between
1817 "bootm_low" and "bootm_low" + BOOTMAPSZ.
1819 - CONFIG_SYS_BOOT_GET_KBD:
1820 Enables allocating and saving a kernel copy of the bd_info in
1821 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
1823 - CONFIG_SYS_MAX_FLASH_SECT:
1824 Max number of sectors on a Flash chip
1826 - CONFIG_SYS_FLASH_ERASE_TOUT:
1827 Timeout for Flash erase operations (in ms)
1829 - CONFIG_SYS_FLASH_WRITE_TOUT:
1830 Timeout for Flash write operations (in ms)
1832 - CONFIG_SYS_FLASH_LOCK_TOUT
1833 Timeout for Flash set sector lock bit operation (in ms)
1835 - CONFIG_SYS_FLASH_UNLOCK_TOUT
1836 Timeout for Flash clear lock bits operation (in ms)
1838 - CONFIG_SYS_FLASH_PROTECTION
1839 If defined, hardware flash sectors protection is used
1840 instead of U-Boot software protection.
1842 - CONFIG_SYS_DIRECT_FLASH_TFTP:
1844 Enable TFTP transfers directly to flash memory;
1845 without this option such a download has to be
1846 performed in two steps: (1) download to RAM, and (2)
1847 copy from RAM to flash.
1849 The two-step approach is usually more reliable, since
1850 you can check if the download worked before you erase
1851 the flash, but in some situations (when system RAM is
1852 too limited to allow for a temporary copy of the
1853 downloaded image) this option may be very useful.
1855 - CONFIG_SYS_FLASH_CFI:
1856 Define if the flash driver uses extra elements in the
1857 common flash structure for storing flash geometry.
1859 - CONFIG_FLASH_CFI_DRIVER
1860 This option also enables the building of the cfi_flash driver
1861 in the drivers directory
1863 - CONFIG_FLASH_CFI_MTD
1864 This option enables the building of the cfi_mtd driver
1865 in the drivers directory. The driver exports CFI flash
1868 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
1869 Use buffered writes to flash.
1871 - CONFIG_FLASH_SPANSION_S29WS_N
1872 s29ws-n MirrorBit flash has non-standard addresses for buffered
1875 - CONFIG_SYS_FLASH_QUIET_TEST
1876 If this option is defined, the common CFI flash doesn't
1877 print it's warning upon not recognized FLASH banks. This
1878 is useful, if some of the configured banks are only
1879 optionally available.
1881 - CONFIG_FLASH_SHOW_PROGRESS
1882 If defined (must be an integer), print out countdown
1883 digits and dots. Recommended value: 45 (9..1) for 80
1884 column displays, 15 (3..1) for 40 column displays.
1886 - CONFIG_FLASH_VERIFY
1887 If defined, the content of the flash (destination) is compared
1888 against the source after the write operation. An error message
1889 will be printed when the contents are not identical.
1890 Please note that this option is useless in nearly all cases,
1891 since such flash programming errors usually are detected earlier
1892 while unprotecting/erasing/programming. Please only enable
1893 this option if you really know what you are doing.
1895 - CONFIG_ENV_MAX_ENTRIES
1897 Maximum number of entries in the hash table that is used
1898 internally to store the environment settings. The default
1899 setting is supposed to be generous and should work in most
1900 cases. This setting can be used to tune behaviour; see
1901 lib/hashtable.c for details.
1903 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1904 - CONFIG_ENV_FLAGS_LIST_STATIC
1905 Enable validation of the values given to environment variables when
1906 calling env set. Variables can be restricted to only decimal,
1907 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
1908 the variables can also be restricted to IP address or MAC address.
1910 The format of the list is:
1911 type_attribute = [s|d|x|b|i|m]
1912 access_attribute = [a|r|o|c]
1913 attributes = type_attribute[access_attribute]
1914 entry = variable_name[:attributes]
1917 The type attributes are:
1918 s - String (default)
1921 b - Boolean ([1yYtT|0nNfF])
1925 The access attributes are:
1931 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1932 Define this to a list (string) to define the ".flags"
1933 environment variable in the default or embedded environment.
1935 - CONFIG_ENV_FLAGS_LIST_STATIC
1936 Define this to a list (string) to define validation that
1937 should be done if an entry is not found in the ".flags"
1938 environment variable. To override a setting in the static
1939 list, simply add an entry for the same variable name to the
1942 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
1943 regular expression. This allows multiple variables to define the same
1944 flags without explicitly listing them for each variable.
1946 The following definitions that deal with the placement and management
1947 of environment data (variable area); in general, we support the
1948 following configurations:
1950 - CONFIG_BUILD_ENVCRC:
1952 Builds up envcrc with the target environment so that external utils
1953 may easily extract it and embed it in final U-Boot images.
1955 BE CAREFUL! The first access to the environment happens quite early
1956 in U-Boot initialization (when we try to get the setting of for the
1957 console baudrate). You *MUST* have mapped your NVRAM area then, or
1960 Please note that even with NVRAM we still use a copy of the
1961 environment in RAM: we could work on NVRAM directly, but we want to
1962 keep settings there always unmodified except somebody uses "saveenv"
1963 to save the current settings.
1965 BE CAREFUL! For some special cases, the local device can not use
1966 "saveenv" command. For example, the local device will get the
1967 environment stored in a remote NOR flash by SRIO or PCIE link,
1968 but it can not erase, write this NOR flash by SRIO or PCIE interface.
1970 - CONFIG_NAND_ENV_DST
1972 Defines address in RAM to which the nand_spl code should copy the
1973 environment. If redundant environment is used, it will be copied to
1974 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
1976 Please note that the environment is read-only until the monitor
1977 has been relocated to RAM and a RAM copy of the environment has been
1978 created; also, when using EEPROM you will have to use env_get_f()
1979 until then to read environment variables.
1981 The environment is protected by a CRC32 checksum. Before the monitor
1982 is relocated into RAM, as a result of a bad CRC you will be working
1983 with the compiled-in default environment - *silently*!!! [This is
1984 necessary, because the first environment variable we need is the
1985 "baudrate" setting for the console - if we have a bad CRC, we don't
1986 have any device yet where we could complain.]
1988 Note: once the monitor has been relocated, then it will complain if
1989 the default environment is used; a new CRC is computed as soon as you
1990 use the "saveenv" command to store a valid environment.
1992 - CONFIG_SYS_FAULT_MII_ADDR:
1993 MII address of the PHY to check for the Ethernet link state.
1995 - CONFIG_NS16550_MIN_FUNCTIONS:
1996 Define this if you desire to only have use of the NS16550_init
1997 and NS16550_putc functions for the serial driver located at
1998 drivers/serial/ns16550.c. This option is useful for saving
1999 space for already greatly restricted images, including but not
2000 limited to NAND_SPL configurations.
2002 - CONFIG_DISPLAY_BOARDINFO
2003 Display information about the board that U-Boot is running on
2004 when U-Boot starts up. The board function checkboard() is called
2007 - CONFIG_DISPLAY_BOARDINFO_LATE
2008 Similar to the previous option, but display this information
2009 later, once stdio is running and output goes to the LCD, if
2012 Low Level (hardware related) configuration options:
2013 ---------------------------------------------------
2015 - CONFIG_SYS_CACHELINE_SIZE:
2016 Cache Line Size of the CPU.
2018 - CONFIG_SYS_CCSRBAR_DEFAULT:
2019 Default (power-on reset) physical address of CCSR on Freescale
2022 - CONFIG_SYS_CCSRBAR:
2023 Virtual address of CCSR. On a 32-bit build, this is typically
2024 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2026 - CONFIG_SYS_CCSRBAR_PHYS:
2027 Physical address of CCSR. CCSR can be relocated to a new
2028 physical address, if desired. In this case, this macro should
2029 be set to that address. Otherwise, it should be set to the
2030 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2031 is typically relocated on 36-bit builds. It is recommended
2032 that this macro be defined via the _HIGH and _LOW macros:
2034 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2035 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2037 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2038 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2039 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2040 used in assembly code, so it must not contain typecasts or
2041 integer size suffixes (e.g. "ULL").
2043 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2044 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2045 used in assembly code, so it must not contain typecasts or
2046 integer size suffixes (e.g. "ULL").
2048 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2049 DO NOT CHANGE unless you know exactly what you're
2050 doing! (11-4) [MPC8xx systems only]
2052 - CONFIG_SYS_INIT_RAM_ADDR:
2054 Start address of memory area that can be used for
2055 initial data and stack; please note that this must be
2056 writable memory that is working WITHOUT special
2057 initialization, i. e. you CANNOT use normal RAM which
2058 will become available only after programming the
2059 memory controller and running certain initialization
2062 U-Boot uses the following memory types:
2063 - MPC8xx: IMMR (internal memory of the CPU)
2065 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2067 - CONFIG_SYS_OR_TIMING_SDRAM:
2070 - CONFIG_SYS_MAMR_PTA:
2071 periodic timer for refresh
2074 Chip has SRIO or not
2077 Board has SRIO 1 port available
2080 Board has SRIO 2 port available
2082 - CONFIG_SRIO_PCIE_BOOT_MASTER
2083 Board can support master function for Boot from SRIO and PCIE
2085 - CONFIG_SYS_SRIOn_MEM_VIRT:
2086 Virtual Address of SRIO port 'n' memory region
2088 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2089 Physical Address of SRIO port 'n' memory region
2091 - CONFIG_SYS_SRIOn_MEM_SIZE:
2092 Size of SRIO port 'n' memory region
2094 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2095 Defined to tell the NAND controller that the NAND chip is using
2097 Not all NAND drivers use this symbol.
2098 Example of drivers that use it:
2099 - drivers/mtd/nand/raw/ndfc.c
2100 - drivers/mtd/nand/raw/mxc_nand.c
2102 - CONFIG_SYS_NDFC_EBC0_CFG
2103 Sets the EBC0_CFG register for the NDFC. If not defined
2104 a default value will be used.
2107 Get DDR timing information from an I2C EEPROM. Common
2108 with pluggable memory modules such as SODIMMs
2111 I2C address of the SPD EEPROM
2113 - CONFIG_SYS_SPD_BUS_NUM
2114 If SPD EEPROM is on an I2C bus other than the first
2115 one, specify here. Note that the value must resolve
2116 to something your driver can deal with.
2118 - CONFIG_SYS_DDR_RAW_TIMING
2119 Get DDR timing information from other than SPD. Common with
2120 soldered DDR chips onboard without SPD. DDR raw timing
2121 parameters are extracted from datasheet and hard-coded into
2122 header files or board specific files.
2124 - CONFIG_FSL_DDR_INTERACTIVE
2125 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2127 - CONFIG_FSL_DDR_SYNC_REFRESH
2128 Enable sync of refresh for multiple controllers.
2130 - CONFIG_FSL_DDR_BIST
2131 Enable built-in memory test for Freescale DDR controllers.
2133 - CONFIG_SYS_83XX_DDR_USES_CS0
2134 Only for 83xx systems. If specified, then DDR should
2135 be configured using CS0 and CS1 instead of CS2 and CS3.
2138 Enable RMII mode for all FECs.
2139 Note that this is a global option, we can't
2140 have one FEC in standard MII mode and another in RMII mode.
2142 - CONFIG_CRC32_VERIFY
2143 Add a verify option to the crc32 command.
2146 => crc32 -v <address> <count> <crc32>
2148 Where address/count indicate a memory area
2149 and crc32 is the correct crc32 which the
2153 Add the "loopw" memory command. This only takes effect if
2154 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2156 - CONFIG_CMD_MX_CYCLIC
2157 Add the "mdc" and "mwc" memory commands. These are cyclic
2162 This command will print 4 bytes (10,11,12,13) each 500 ms.
2164 => mwc.l 100 12345678 10
2165 This command will write 12345678 to address 100 all 10 ms.
2167 This only takes effect if the memory commands are activated
2168 globally (CONFIG_CMD_MEMORY).
2171 Set when the currently-running compilation is for an artifact
2172 that will end up in the SPL (as opposed to the TPL or U-Boot
2173 proper). Code that needs stage-specific behavior should check
2177 Set when the currently-running compilation is for an artifact
2178 that will end up in the TPL (as opposed to the SPL or U-Boot
2179 proper). Code that needs stage-specific behavior should check
2182 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2183 Only for 85xx systems. If this variable is specified, the section
2184 .resetvec is not kept and the section .bootpg is placed in the
2185 previous 4k of the .text section.
2187 - CONFIG_ARCH_MAP_SYSMEM
2188 Generally U-Boot (and in particular the md command) uses
2189 effective address. It is therefore not necessary to regard
2190 U-Boot address as virtual addresses that need to be translated
2191 to physical addresses. However, sandbox requires this, since
2192 it maintains its own little RAM buffer which contains all
2193 addressable memory. This option causes some memory accesses
2194 to be mapped through map_sysmem() / unmap_sysmem().
2196 - CONFIG_X86_RESET_VECTOR
2197 If defined, the x86 reset vector code is included. This is not
2198 needed when U-Boot is running from Coreboot.
2200 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2201 Option to disable subpage write in NAND driver
2202 driver that uses this:
2203 drivers/mtd/nand/raw/davinci_nand.c
2205 Freescale QE/FMAN Firmware Support:
2206 -----------------------------------
2208 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2209 loading of "firmware", which is encoded in the QE firmware binary format.
2210 This firmware often needs to be loaded during U-Boot booting, so macros
2211 are used to identify the storage device (NOR flash, SPI, etc) and the address
2214 - CONFIG_SYS_FMAN_FW_ADDR
2215 The address in the storage device where the FMAN microcode is located. The
2216 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2219 - CONFIG_SYS_QE_FW_ADDR
2220 The address in the storage device where the QE microcode is located. The
2221 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2224 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2225 The maximum possible size of the firmware. The firmware binary format
2226 has a field that specifies the actual size of the firmware, but it
2227 might not be possible to read any part of the firmware unless some
2228 local storage is allocated to hold the entire firmware first.
2230 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2231 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2232 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2233 virtual address in NOR flash.
2235 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2236 Specifies that QE/FMAN firmware is located in NAND flash.
2237 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2239 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2240 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2241 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2243 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2244 Specifies that QE/FMAN firmware is located in the remote (master)
2245 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2246 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2247 window->master inbound window->master LAW->the ucode address in
2248 master's memory space.
2250 Freescale Layerscape Management Complex Firmware Support:
2251 ---------------------------------------------------------
2252 The Freescale Layerscape Management Complex (MC) supports the loading of
2254 This firmware often needs to be loaded during U-Boot booting, so macros
2255 are used to identify the storage device (NOR flash, SPI, etc) and the address
2258 - CONFIG_FSL_MC_ENET
2259 Enable the MC driver for Layerscape SoCs.
2261 Freescale Layerscape Debug Server Support:
2262 -------------------------------------------
2263 The Freescale Layerscape Debug Server Support supports the loading of
2264 "Debug Server firmware" and triggering SP boot-rom.
2265 This firmware often needs to be loaded during U-Boot booting.
2267 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2268 Define alignment of reserved memory MC requires
2273 In order to achieve reproducible builds, timestamps used in the U-Boot build
2274 process have to be set to a fixed value.
2276 This is done using the SOURCE_DATE_EPOCH environment variable.
2277 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2278 option for U-Boot or an environment variable in U-Boot.
2280 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2282 Building the Software:
2283 ======================
2285 Building U-Boot has been tested in several native build environments
2286 and in many different cross environments. Of course we cannot support
2287 all possibly existing versions of cross development tools in all
2288 (potentially obsolete) versions. In case of tool chain problems we
2289 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2290 which is extensively used to build and test U-Boot.
2292 If you are not using a native environment, it is assumed that you
2293 have GNU cross compiling tools available in your path. In this case,
2294 you must set the environment variable CROSS_COMPILE in your shell.
2295 Note that no changes to the Makefile or any other source files are
2296 necessary. For example using the ELDK on a 4xx CPU, please enter:
2298 $ CROSS_COMPILE=ppc_4xx-
2299 $ export CROSS_COMPILE
2301 U-Boot is intended to be simple to build. After installing the
2302 sources you must configure U-Boot for one specific board type. This
2307 where "NAME_defconfig" is the name of one of the existing configu-
2308 rations; see configs/*_defconfig for supported names.
2310 Note: for some boards special configuration names may exist; check if
2311 additional information is available from the board vendor; for
2312 instance, the TQM823L systems are available without (standard)
2313 or with LCD support. You can select such additional "features"
2314 when choosing the configuration, i. e.
2316 make TQM823L_defconfig
2317 - will configure for a plain TQM823L, i. e. no LCD support
2319 make TQM823L_LCD_defconfig
2320 - will configure for a TQM823L with U-Boot console on LCD
2325 Finally, type "make all", and you should get some working U-Boot
2326 images ready for download to / installation on your system:
2328 - "u-boot.bin" is a raw binary image
2329 - "u-boot" is an image in ELF binary format
2330 - "u-boot.srec" is in Motorola S-Record format
2332 By default the build is performed locally and the objects are saved
2333 in the source directory. One of the two methods can be used to change
2334 this behavior and build U-Boot to some external directory:
2336 1. Add O= to the make command line invocations:
2338 make O=/tmp/build distclean
2339 make O=/tmp/build NAME_defconfig
2340 make O=/tmp/build all
2342 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2344 export KBUILD_OUTPUT=/tmp/build
2349 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2352 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2353 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2354 For example to treat all compiler warnings as errors:
2356 make KCFLAGS=-Werror
2358 Please be aware that the Makefiles assume you are using GNU make, so
2359 for instance on NetBSD you might need to use "gmake" instead of
2363 If the system board that you have is not listed, then you will need
2364 to port U-Boot to your hardware platform. To do this, follow these
2367 1. Create a new directory to hold your board specific code. Add any
2368 files you need. In your board directory, you will need at least
2369 the "Makefile" and a "<board>.c".
2370 2. Create a new configuration file "include/configs/<board>.h" for
2372 3. If you're porting U-Boot to a new CPU, then also create a new
2373 directory to hold your CPU specific code. Add any files you need.
2374 4. Run "make <board>_defconfig" with your new name.
2375 5. Type "make", and you should get a working "u-boot.srec" file
2376 to be installed on your target system.
2377 6. Debug and solve any problems that might arise.
2378 [Of course, this last step is much harder than it sounds.]
2381 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2382 ==============================================================
2384 If you have modified U-Boot sources (for instance added a new board
2385 or support for new devices, a new CPU, etc.) you are expected to
2386 provide feedback to the other developers. The feedback normally takes
2387 the form of a "patch", i.e. a context diff against a certain (latest
2388 official or latest in the git repository) version of U-Boot sources.
2390 But before you submit such a patch, please verify that your modifi-
2391 cation did not break existing code. At least make sure that *ALL* of
2392 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2393 just run the buildman script (tools/buildman/buildman), which will
2394 configure and build U-Boot for ALL supported system. Be warned, this
2395 will take a while. Please see the buildman README, or run 'buildman -H'
2399 See also "U-Boot Porting Guide" below.
2402 Monitor Commands - Overview:
2403 ============================
2405 go - start application at address 'addr'
2406 run - run commands in an environment variable
2407 bootm - boot application image from memory
2408 bootp - boot image via network using BootP/TFTP protocol
2409 bootz - boot zImage from memory
2410 tftpboot- boot image via network using TFTP protocol
2411 and env variables "ipaddr" and "serverip"
2412 (and eventually "gatewayip")
2413 tftpput - upload a file via network using TFTP protocol
2414 rarpboot- boot image via network using RARP/TFTP protocol
2415 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2416 loads - load S-Record file over serial line
2417 loadb - load binary file over serial line (kermit mode)
2419 mm - memory modify (auto-incrementing)
2420 nm - memory modify (constant address)
2421 mw - memory write (fill)
2424 cmp - memory compare
2425 crc32 - checksum calculation
2426 i2c - I2C sub-system
2427 sspi - SPI utility commands
2428 base - print or set address offset
2429 printenv- print environment variables
2430 pwm - control pwm channels
2431 setenv - set environment variables
2432 saveenv - save environment variables to persistent storage
2433 protect - enable or disable FLASH write protection
2434 erase - erase FLASH memory
2435 flinfo - print FLASH memory information
2436 nand - NAND memory operations (see doc/README.nand)
2437 bdinfo - print Board Info structure
2438 iminfo - print header information for application image
2439 coninfo - print console devices and informations
2440 ide - IDE sub-system
2441 loop - infinite loop on address range
2442 loopw - infinite write loop on address range
2443 mtest - simple RAM test
2444 icache - enable or disable instruction cache
2445 dcache - enable or disable data cache
2446 reset - Perform RESET of the CPU
2447 echo - echo args to console
2448 version - print monitor version
2449 help - print online help
2450 ? - alias for 'help'
2453 Monitor Commands - Detailed Description:
2454 ========================================
2458 For now: just type "help <command>".
2461 Note for Redundant Ethernet Interfaces:
2462 =======================================
2464 Some boards come with redundant Ethernet interfaces; U-Boot supports
2465 such configurations and is capable of automatic selection of a
2466 "working" interface when needed. MAC assignment works as follows:
2468 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2469 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2470 "eth1addr" (=>eth1), "eth2addr", ...
2472 If the network interface stores some valid MAC address (for instance
2473 in SROM), this is used as default address if there is NO correspon-
2474 ding setting in the environment; if the corresponding environment
2475 variable is set, this overrides the settings in the card; that means:
2477 o If the SROM has a valid MAC address, and there is no address in the
2478 environment, the SROM's address is used.
2480 o If there is no valid address in the SROM, and a definition in the
2481 environment exists, then the value from the environment variable is
2484 o If both the SROM and the environment contain a MAC address, and
2485 both addresses are the same, this MAC address is used.
2487 o If both the SROM and the environment contain a MAC address, and the
2488 addresses differ, the value from the environment is used and a
2491 o If neither SROM nor the environment contain a MAC address, an error
2492 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2493 a random, locally-assigned MAC is used.
2495 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2496 will be programmed into hardware as part of the initialization process. This
2497 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2498 The naming convention is as follows:
2499 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2504 U-Boot is capable of booting (and performing other auxiliary operations on)
2505 images in two formats:
2507 New uImage format (FIT)
2508 -----------------------
2510 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2511 to Flattened Device Tree). It allows the use of images with multiple
2512 components (several kernels, ramdisks, etc.), with contents protected by
2513 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2519 Old image format is based on binary files which can be basically anything,
2520 preceded by a special header; see the definitions in include/image.h for
2521 details; basically, the header defines the following image properties:
2523 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2524 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2525 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2526 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2527 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2528 IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2529 Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
2530 * Compression Type (uncompressed, gzip, bzip2)
2536 The header is marked by a special Magic Number, and both the header
2537 and the data portions of the image are secured against corruption by
2544 Although U-Boot should support any OS or standalone application
2545 easily, the main focus has always been on Linux during the design of
2548 U-Boot includes many features that so far have been part of some
2549 special "boot loader" code within the Linux kernel. Also, any
2550 "initrd" images to be used are no longer part of one big Linux image;
2551 instead, kernel and "initrd" are separate images. This implementation
2552 serves several purposes:
2554 - the same features can be used for other OS or standalone
2555 applications (for instance: using compressed images to reduce the
2556 Flash memory footprint)
2558 - it becomes much easier to port new Linux kernel versions because
2559 lots of low-level, hardware dependent stuff are done by U-Boot
2561 - the same Linux kernel image can now be used with different "initrd"
2562 images; of course this also means that different kernel images can
2563 be run with the same "initrd". This makes testing easier (you don't
2564 have to build a new "zImage.initrd" Linux image when you just
2565 change a file in your "initrd"). Also, a field-upgrade of the
2566 software is easier now.
2572 Porting Linux to U-Boot based systems:
2573 ---------------------------------------
2575 U-Boot cannot save you from doing all the necessary modifications to
2576 configure the Linux device drivers for use with your target hardware
2577 (no, we don't intend to provide a full virtual machine interface to
2580 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2582 Just make sure your machine specific header file (for instance
2583 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2584 Information structure as we define in include/asm-<arch>/u-boot.h,
2585 and make sure that your definition of IMAP_ADDR uses the same value
2586 as your U-Boot configuration in CONFIG_SYS_IMMR.
2588 Note that U-Boot now has a driver model, a unified model for drivers.
2589 If you are adding a new driver, plumb it into driver model. If there
2590 is no uclass available, you are encouraged to create one. See
2594 Configuring the Linux kernel:
2595 -----------------------------
2597 No specific requirements for U-Boot. Make sure you have some root
2598 device (initial ramdisk, NFS) for your target system.
2601 Building a Linux Image:
2602 -----------------------
2604 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2605 not used. If you use recent kernel source, a new build target
2606 "uImage" will exist which automatically builds an image usable by
2607 U-Boot. Most older kernels also have support for a "pImage" target,
2608 which was introduced for our predecessor project PPCBoot and uses a
2609 100% compatible format.
2613 make TQM850L_defconfig
2618 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2619 encapsulate a compressed Linux kernel image with header information,
2620 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2622 * build a standard "vmlinux" kernel image (in ELF binary format):
2624 * convert the kernel into a raw binary image:
2626 ${CROSS_COMPILE}-objcopy -O binary \
2627 -R .note -R .comment \
2628 -S vmlinux linux.bin
2630 * compress the binary image:
2634 * package compressed binary image for U-Boot:
2636 mkimage -A ppc -O linux -T kernel -C gzip \
2637 -a 0 -e 0 -n "Linux Kernel Image" \
2638 -d linux.bin.gz uImage
2641 The "mkimage" tool can also be used to create ramdisk images for use
2642 with U-Boot, either separated from the Linux kernel image, or
2643 combined into one file. "mkimage" encapsulates the images with a 64
2644 byte header containing information about target architecture,
2645 operating system, image type, compression method, entry points, time
2646 stamp, CRC32 checksums, etc.
2648 "mkimage" can be called in two ways: to verify existing images and
2649 print the header information, or to build new images.
2651 In the first form (with "-l" option) mkimage lists the information
2652 contained in the header of an existing U-Boot image; this includes
2653 checksum verification:
2655 tools/mkimage -l image
2656 -l ==> list image header information
2658 The second form (with "-d" option) is used to build a U-Boot image
2659 from a "data file" which is used as image payload:
2661 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2662 -n name -d data_file image
2663 -A ==> set architecture to 'arch'
2664 -O ==> set operating system to 'os'
2665 -T ==> set image type to 'type'
2666 -C ==> set compression type 'comp'
2667 -a ==> set load address to 'addr' (hex)
2668 -e ==> set entry point to 'ep' (hex)
2669 -n ==> set image name to 'name'
2670 -d ==> use image data from 'datafile'
2672 Right now, all Linux kernels for PowerPC systems use the same load
2673 address (0x00000000), but the entry point address depends on the
2676 - 2.2.x kernels have the entry point at 0x0000000C,
2677 - 2.3.x and later kernels have the entry point at 0x00000000.
2679 So a typical call to build a U-Boot image would read:
2681 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2682 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2683 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2684 > examples/uImage.TQM850L
2685 Image Name: 2.4.4 kernel for TQM850L
2686 Created: Wed Jul 19 02:34:59 2000
2687 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2688 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2689 Load Address: 0x00000000
2690 Entry Point: 0x00000000
2692 To verify the contents of the image (or check for corruption):
2694 -> tools/mkimage -l examples/uImage.TQM850L
2695 Image Name: 2.4.4 kernel for TQM850L
2696 Created: Wed Jul 19 02:34:59 2000
2697 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2698 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2699 Load Address: 0x00000000
2700 Entry Point: 0x00000000
2702 NOTE: for embedded systems where boot time is critical you can trade
2703 speed for memory and install an UNCOMPRESSED image instead: this
2704 needs more space in Flash, but boots much faster since it does not
2705 need to be uncompressed:
2707 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2708 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2709 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2710 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2711 > examples/uImage.TQM850L-uncompressed
2712 Image Name: 2.4.4 kernel for TQM850L
2713 Created: Wed Jul 19 02:34:59 2000
2714 Image Type: PowerPC Linux Kernel Image (uncompressed)
2715 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2716 Load Address: 0x00000000
2717 Entry Point: 0x00000000
2720 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2721 when your kernel is intended to use an initial ramdisk:
2723 -> tools/mkimage -n 'Simple Ramdisk Image' \
2724 > -A ppc -O linux -T ramdisk -C gzip \
2725 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2726 Image Name: Simple Ramdisk Image
2727 Created: Wed Jan 12 14:01:50 2000
2728 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2729 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2730 Load Address: 0x00000000
2731 Entry Point: 0x00000000
2733 The "dumpimage" tool can be used to disassemble or list the contents of images
2734 built by mkimage. See dumpimage's help output (-h) for details.
2736 Installing a Linux Image:
2737 -------------------------
2739 To downloading a U-Boot image over the serial (console) interface,
2740 you must convert the image to S-Record format:
2742 objcopy -I binary -O srec examples/image examples/image.srec
2744 The 'objcopy' does not understand the information in the U-Boot
2745 image header, so the resulting S-Record file will be relative to
2746 address 0x00000000. To load it to a given address, you need to
2747 specify the target address as 'offset' parameter with the 'loads'
2750 Example: install the image to address 0x40100000 (which on the
2751 TQM8xxL is in the first Flash bank):
2753 => erase 40100000 401FFFFF
2759 ## Ready for S-Record download ...
2760 ~>examples/image.srec
2761 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2763 15989 15990 15991 15992
2764 [file transfer complete]
2766 ## Start Addr = 0x00000000
2769 You can check the success of the download using the 'iminfo' command;
2770 this includes a checksum verification so you can be sure no data
2771 corruption happened:
2775 ## Checking Image at 40100000 ...
2776 Image Name: 2.2.13 for initrd on TQM850L
2777 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2778 Data Size: 335725 Bytes = 327 kB = 0 MB
2779 Load Address: 00000000
2780 Entry Point: 0000000c
2781 Verifying Checksum ... OK
2787 The "bootm" command is used to boot an application that is stored in
2788 memory (RAM or Flash). In case of a Linux kernel image, the contents
2789 of the "bootargs" environment variable is passed to the kernel as
2790 parameters. You can check and modify this variable using the
2791 "printenv" and "setenv" commands:
2794 => printenv bootargs
2795 bootargs=root=/dev/ram
2797 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2799 => printenv bootargs
2800 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2803 ## Booting Linux kernel at 40020000 ...
2804 Image Name: 2.2.13 for NFS on TQM850L
2805 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2806 Data Size: 381681 Bytes = 372 kB = 0 MB
2807 Load Address: 00000000
2808 Entry Point: 0000000c
2809 Verifying Checksum ... OK
2810 Uncompressing Kernel Image ... OK
2811 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
2812 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2813 time_init: decrementer frequency = 187500000/60
2814 Calibrating delay loop... 49.77 BogoMIPS
2815 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2818 If you want to boot a Linux kernel with initial RAM disk, you pass
2819 the memory addresses of both the kernel and the initrd image (PPBCOOT
2820 format!) to the "bootm" command:
2822 => imi 40100000 40200000
2824 ## Checking Image at 40100000 ...
2825 Image Name: 2.2.13 for initrd on TQM850L
2826 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2827 Data Size: 335725 Bytes = 327 kB = 0 MB
2828 Load Address: 00000000
2829 Entry Point: 0000000c
2830 Verifying Checksum ... OK
2832 ## Checking Image at 40200000 ...
2833 Image Name: Simple Ramdisk Image
2834 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2835 Data Size: 566530 Bytes = 553 kB = 0 MB
2836 Load Address: 00000000
2837 Entry Point: 00000000
2838 Verifying Checksum ... OK
2840 => bootm 40100000 40200000
2841 ## Booting Linux kernel at 40100000 ...
2842 Image Name: 2.2.13 for initrd on TQM850L
2843 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2844 Data Size: 335725 Bytes = 327 kB = 0 MB
2845 Load Address: 00000000
2846 Entry Point: 0000000c
2847 Verifying Checksum ... OK
2848 Uncompressing Kernel Image ... OK
2849 ## Loading RAMDisk Image at 40200000 ...
2850 Image Name: Simple Ramdisk Image
2851 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2852 Data Size: 566530 Bytes = 553 kB = 0 MB
2853 Load Address: 00000000
2854 Entry Point: 00000000
2855 Verifying Checksum ... OK
2856 Loading Ramdisk ... OK
2857 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
2858 Boot arguments: root=/dev/ram
2859 time_init: decrementer frequency = 187500000/60
2860 Calibrating delay loop... 49.77 BogoMIPS
2862 RAMDISK: Compressed image found at block 0
2863 VFS: Mounted root (ext2 filesystem).
2867 Boot Linux and pass a flat device tree:
2870 First, U-Boot must be compiled with the appropriate defines. See the section
2871 titled "Linux Kernel Interface" above for a more in depth explanation. The
2872 following is an example of how to start a kernel and pass an updated
2878 oft=oftrees/mpc8540ads.dtb
2879 => tftp $oftaddr $oft
2880 Speed: 1000, full duplex
2882 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
2883 Filename 'oftrees/mpc8540ads.dtb'.
2884 Load address: 0x300000
2887 Bytes transferred = 4106 (100a hex)
2888 => tftp $loadaddr $bootfile
2889 Speed: 1000, full duplex
2891 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
2893 Load address: 0x200000
2894 Loading:############
2896 Bytes transferred = 1029407 (fb51f hex)
2901 => bootm $loadaddr - $oftaddr
2902 ## Booting image at 00200000 ...
2903 Image Name: Linux-2.6.17-dirty
2904 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2905 Data Size: 1029343 Bytes = 1005.2 kB
2906 Load Address: 00000000
2907 Entry Point: 00000000
2908 Verifying Checksum ... OK
2909 Uncompressing Kernel Image ... OK
2910 Booting using flat device tree at 0x300000
2911 Using MPC85xx ADS machine description
2912 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
2916 More About U-Boot Image Types:
2917 ------------------------------
2919 U-Boot supports the following image types:
2921 "Standalone Programs" are directly runnable in the environment
2922 provided by U-Boot; it is expected that (if they behave
2923 well) you can continue to work in U-Boot after return from
2924 the Standalone Program.
2925 "OS Kernel Images" are usually images of some Embedded OS which
2926 will take over control completely. Usually these programs
2927 will install their own set of exception handlers, device
2928 drivers, set up the MMU, etc. - this means, that you cannot
2929 expect to re-enter U-Boot except by resetting the CPU.
2930 "RAMDisk Images" are more or less just data blocks, and their
2931 parameters (address, size) are passed to an OS kernel that is
2933 "Multi-File Images" contain several images, typically an OS
2934 (Linux) kernel image and one or more data images like
2935 RAMDisks. This construct is useful for instance when you want
2936 to boot over the network using BOOTP etc., where the boot
2937 server provides just a single image file, but you want to get
2938 for instance an OS kernel and a RAMDisk image.
2940 "Multi-File Images" start with a list of image sizes, each
2941 image size (in bytes) specified by an "uint32_t" in network
2942 byte order. This list is terminated by an "(uint32_t)0".
2943 Immediately after the terminating 0 follow the images, one by
2944 one, all aligned on "uint32_t" boundaries (size rounded up to
2945 a multiple of 4 bytes).
2947 "Firmware Images" are binary images containing firmware (like
2948 U-Boot or FPGA images) which usually will be programmed to
2951 "Script files" are command sequences that will be executed by
2952 U-Boot's command interpreter; this feature is especially
2953 useful when you configure U-Boot to use a real shell (hush)
2954 as command interpreter.
2956 Booting the Linux zImage:
2957 -------------------------
2959 On some platforms, it's possible to boot Linux zImage. This is done
2960 using the "bootz" command. The syntax of "bootz" command is the same
2961 as the syntax of "bootm" command.
2963 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
2964 kernel with raw initrd images. The syntax is slightly different, the
2965 address of the initrd must be augmented by it's size, in the following
2966 format: "<initrd addres>:<initrd size>".
2972 One of the features of U-Boot is that you can dynamically load and
2973 run "standalone" applications, which can use some resources of
2974 U-Boot like console I/O functions or interrupt services.
2976 Two simple examples are included with the sources:
2981 'examples/hello_world.c' contains a small "Hello World" Demo
2982 application; it is automatically compiled when you build U-Boot.
2983 It's configured to run at address 0x00040004, so you can play with it
2987 ## Ready for S-Record download ...
2988 ~>examples/hello_world.srec
2989 1 2 3 4 5 6 7 8 9 10 11 ...
2990 [file transfer complete]
2992 ## Start Addr = 0x00040004
2994 => go 40004 Hello World! This is a test.
2995 ## Starting application at 0x00040004 ...
3006 Hit any key to exit ...
3008 ## Application terminated, rc = 0x0
3010 Another example, which demonstrates how to register a CPM interrupt
3011 handler with the U-Boot code, can be found in 'examples/timer.c'.
3012 Here, a CPM timer is set up to generate an interrupt every second.
3013 The interrupt service routine is trivial, just printing a '.'
3014 character, but this is just a demo program. The application can be
3015 controlled by the following keys:
3017 ? - print current values og the CPM Timer registers
3018 b - enable interrupts and start timer
3019 e - stop timer and disable interrupts
3020 q - quit application
3023 ## Ready for S-Record download ...
3024 ~>examples/timer.srec
3025 1 2 3 4 5 6 7 8 9 10 11 ...
3026 [file transfer complete]
3028 ## Start Addr = 0x00040004
3031 ## Starting application at 0x00040004 ...
3034 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3037 [q, b, e, ?] Set interval 1000000 us
3040 [q, b, e, ?] ........
3041 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3044 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3047 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3050 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3052 [q, b, e, ?] ...Stopping timer
3054 [q, b, e, ?] ## Application terminated, rc = 0x0
3060 Over time, many people have reported problems when trying to use the
3061 "minicom" terminal emulation program for serial download. I (wd)
3062 consider minicom to be broken, and recommend not to use it. Under
3063 Unix, I recommend to use C-Kermit for general purpose use (and
3064 especially for kermit binary protocol download ("loadb" command), and
3065 use "cu" for S-Record download ("loads" command). See
3066 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3067 for help with kermit.
3070 Nevertheless, if you absolutely want to use it try adding this
3071 configuration to your "File transfer protocols" section:
3073 Name Program Name U/D FullScr IO-Red. Multi
3074 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3075 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3081 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3082 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3084 Building requires a cross environment; it is known to work on
3085 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3086 need gmake since the Makefiles are not compatible with BSD make).
3087 Note that the cross-powerpc package does not install include files;
3088 attempting to build U-Boot will fail because <machine/ansi.h> is
3089 missing. This file has to be installed and patched manually:
3091 # cd /usr/pkg/cross/powerpc-netbsd/include
3093 # ln -s powerpc machine
3094 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3095 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3097 Native builds *don't* work due to incompatibilities between native
3098 and U-Boot include files.
3100 Booting assumes that (the first part of) the image booted is a
3101 stage-2 loader which in turn loads and then invokes the kernel
3102 proper. Loader sources will eventually appear in the NetBSD source
3103 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3104 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3107 Implementation Internals:
3108 =========================
3110 The following is not intended to be a complete description of every
3111 implementation detail. However, it should help to understand the
3112 inner workings of U-Boot and make it easier to port it to custom
3116 Initial Stack, Global Data:
3117 ---------------------------
3119 The implementation of U-Boot is complicated by the fact that U-Boot
3120 starts running out of ROM (flash memory), usually without access to
3121 system RAM (because the memory controller is not initialized yet).
3122 This means that we don't have writable Data or BSS segments, and BSS
3123 is not initialized as zero. To be able to get a C environment working
3124 at all, we have to allocate at least a minimal stack. Implementation
3125 options for this are defined and restricted by the CPU used: Some CPU
3126 models provide on-chip memory (like the IMMR area on MPC8xx and
3127 MPC826x processors), on others (parts of) the data cache can be
3128 locked as (mis-) used as memory, etc.
3130 Chris Hallinan posted a good summary of these issues to the
3131 U-Boot mailing list:
3133 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3134 From: "Chris Hallinan" <clh@net1plus.com>
3135 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3138 Correct me if I'm wrong, folks, but the way I understand it
3139 is this: Using DCACHE as initial RAM for Stack, etc, does not
3140 require any physical RAM backing up the cache. The cleverness
3141 is that the cache is being used as a temporary supply of
3142 necessary storage before the SDRAM controller is setup. It's
3143 beyond the scope of this list to explain the details, but you
3144 can see how this works by studying the cache architecture and
3145 operation in the architecture and processor-specific manuals.
3147 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3148 is another option for the system designer to use as an
3149 initial stack/RAM area prior to SDRAM being available. Either
3150 option should work for you. Using CS 4 should be fine if your
3151 board designers haven't used it for something that would
3152 cause you grief during the initial boot! It is frequently not
3155 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3156 with your processor/board/system design. The default value
3157 you will find in any recent u-boot distribution in
3158 walnut.h should work for you. I'd set it to a value larger
3159 than your SDRAM module. If you have a 64MB SDRAM module, set
3160 it above 400_0000. Just make sure your board has no resources
3161 that are supposed to respond to that address! That code in
3162 start.S has been around a while and should work as is when
3163 you get the config right.
3168 It is essential to remember this, since it has some impact on the C
3169 code for the initialization procedures:
3171 * Initialized global data (data segment) is read-only. Do not attempt
3174 * Do not use any uninitialized global data (or implicitly initialized
3175 as zero data - BSS segment) at all - this is undefined, initiali-
3176 zation is performed later (when relocating to RAM).
3178 * Stack space is very limited. Avoid big data buffers or things like
3181 Having only the stack as writable memory limits means we cannot use
3182 normal global data to share information between the code. But it
3183 turned out that the implementation of U-Boot can be greatly
3184 simplified by making a global data structure (gd_t) available to all
3185 functions. We could pass a pointer to this data as argument to _all_
3186 functions, but this would bloat the code. Instead we use a feature of
3187 the GCC compiler (Global Register Variables) to share the data: we
3188 place a pointer (gd) to the global data into a register which we
3189 reserve for this purpose.
3191 When choosing a register for such a purpose we are restricted by the
3192 relevant (E)ABI specifications for the current architecture, and by
3193 GCC's implementation.
3195 For PowerPC, the following registers have specific use:
3197 R2: reserved for system use
3198 R3-R4: parameter passing and return values
3199 R5-R10: parameter passing
3200 R13: small data area pointer
3204 (U-Boot also uses R12 as internal GOT pointer. r12
3205 is a volatile register so r12 needs to be reset when
3206 going back and forth between asm and C)
3208 ==> U-Boot will use R2 to hold a pointer to the global data
3210 Note: on PPC, we could use a static initializer (since the
3211 address of the global data structure is known at compile time),
3212 but it turned out that reserving a register results in somewhat
3213 smaller code - although the code savings are not that big (on
3214 average for all boards 752 bytes for the whole U-Boot image,
3215 624 text + 127 data).
3217 On ARM, the following registers are used:
3219 R0: function argument word/integer result
3220 R1-R3: function argument word
3221 R9: platform specific
3222 R10: stack limit (used only if stack checking is enabled)
3223 R11: argument (frame) pointer
3224 R12: temporary workspace
3227 R15: program counter
3229 ==> U-Boot will use R9 to hold a pointer to the global data
3231 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3233 On Nios II, the ABI is documented here:
3234 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3236 ==> U-Boot will use gp to hold a pointer to the global data
3238 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3239 to access small data sections, so gp is free.
3241 On RISC-V, the following registers are used:
3243 x0: hard-wired zero (zero)
3244 x1: return address (ra)
3245 x2: stack pointer (sp)
3246 x3: global pointer (gp)
3247 x4: thread pointer (tp)
3248 x5: link register (t0)
3249 x8: frame pointer (fp)
3250 x10-x11: arguments/return values (a0-1)
3251 x12-x17: arguments (a2-7)
3252 x28-31: temporaries (t3-6)
3253 pc: program counter (pc)
3255 ==> U-Boot will use gp to hold a pointer to the global data
3260 U-Boot runs in system state and uses physical addresses, i.e. the
3261 MMU is not used either for address mapping nor for memory protection.
3263 The available memory is mapped to fixed addresses using the memory
3264 controller. In this process, a contiguous block is formed for each
3265 memory type (Flash, SDRAM, SRAM), even when it consists of several
3266 physical memory banks.
3268 U-Boot is installed in the first 128 kB of the first Flash bank (on
3269 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3270 booting and sizing and initializing DRAM, the code relocates itself
3271 to the upper end of DRAM. Immediately below the U-Boot code some
3272 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3273 configuration setting]. Below that, a structure with global Board
3274 Info data is placed, followed by the stack (growing downward).
3276 Additionally, some exception handler code is copied to the low 8 kB
3277 of DRAM (0x00000000 ... 0x00001FFF).
3279 So a typical memory configuration with 16 MB of DRAM could look like
3282 0x0000 0000 Exception Vector code
3285 0x0000 2000 Free for Application Use
3291 0x00FB FF20 Monitor Stack (Growing downward)
3292 0x00FB FFAC Board Info Data and permanent copy of global data
3293 0x00FC 0000 Malloc Arena
3296 0x00FE 0000 RAM Copy of Monitor Code
3297 ... eventually: LCD or video framebuffer
3298 ... eventually: pRAM (Protected RAM - unchanged by reset)
3299 0x00FF FFFF [End of RAM]
3302 System Initialization:
3303 ----------------------
3305 In the reset configuration, U-Boot starts at the reset entry point
3306 (on most PowerPC systems at address 0x00000100). Because of the reset
3307 configuration for CS0# this is a mirror of the on board Flash memory.
3308 To be able to re-map memory U-Boot then jumps to its link address.
3309 To be able to implement the initialization code in C, a (small!)
3310 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3311 which provide such a feature like), or in a locked part of the data
3312 cache. After that, U-Boot initializes the CPU core, the caches and
3315 Next, all (potentially) available memory banks are mapped using a
3316 preliminary mapping. For example, we put them on 512 MB boundaries
3317 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3318 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3319 programmed for SDRAM access. Using the temporary configuration, a
3320 simple memory test is run that determines the size of the SDRAM
3323 When there is more than one SDRAM bank, and the banks are of
3324 different size, the largest is mapped first. For equal size, the first
3325 bank (CS2#) is mapped first. The first mapping is always for address
3326 0x00000000, with any additional banks following immediately to create
3327 contiguous memory starting from 0.
3329 Then, the monitor installs itself at the upper end of the SDRAM area
3330 and allocates memory for use by malloc() and for the global Board
3331 Info data; also, the exception vector code is copied to the low RAM
3332 pages, and the final stack is set up.
3334 Only after this relocation will you have a "normal" C environment;
3335 until that you are restricted in several ways, mostly because you are
3336 running from ROM, and because the code will have to be relocated to a
3340 U-Boot Porting Guide:
3341 ----------------------
3343 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3347 int main(int argc, char *argv[])
3349 sighandler_t no_more_time;
3351 signal(SIGALRM, no_more_time);
3352 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3354 if (available_money > available_manpower) {
3355 Pay consultant to port U-Boot;
3359 Download latest U-Boot source;
3361 Subscribe to u-boot mailing list;
3364 email("Hi, I am new to U-Boot, how do I get started?");
3367 Read the README file in the top level directory;
3368 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3369 Read applicable doc/README.*;
3370 Read the source, Luke;
3371 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3374 if (available_money > toLocalCurrency ($2500))
3377 Add a lot of aggravation and time;
3379 if (a similar board exists) { /* hopefully... */
3380 cp -a board/<similar> board/<myboard>
3381 cp include/configs/<similar>.h include/configs/<myboard>.h
3383 Create your own board support subdirectory;
3384 Create your own board include/configs/<myboard>.h file;
3386 Edit new board/<myboard> files
3387 Edit new include/configs/<myboard>.h
3392 Add / modify source code;
3396 email("Hi, I am having problems...");
3398 Send patch file to the U-Boot email list;
3399 if (reasonable critiques)
3400 Incorporate improvements from email list code review;
3402 Defend code as written;
3408 void no_more_time (int sig)
3417 All contributions to U-Boot should conform to the Linux kernel
3418 coding style; see the kernel coding style guide at
3419 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3420 script "scripts/Lindent" in your Linux kernel source directory.
3422 Source files originating from a different project (for example the
3423 MTD subsystem) are generally exempt from these guidelines and are not
3424 reformatted to ease subsequent migration to newer versions of those
3427 Please note that U-Boot is implemented in C (and to some small parts in
3428 Assembler); no C++ is used, so please do not use C++ style comments (//)
3431 Please also stick to the following formatting rules:
3432 - remove any trailing white space
3433 - use TAB characters for indentation and vertical alignment, not spaces
3434 - make sure NOT to use DOS '\r\n' line feeds
3435 - do not add more than 2 consecutive empty lines to source files
3436 - do not add trailing empty lines to source files
3438 Submissions which do not conform to the standards may be returned
3439 with a request to reformat the changes.
3445 Since the number of patches for U-Boot is growing, we need to
3446 establish some rules. Submissions which do not conform to these rules
3447 may be rejected, even when they contain important and valuable stuff.
3449 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3451 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3452 see https://lists.denx.de/listinfo/u-boot
3454 When you send a patch, please include the following information with
3457 * For bug fixes: a description of the bug and how your patch fixes
3458 this bug. Please try to include a way of demonstrating that the
3459 patch actually fixes something.
3461 * For new features: a description of the feature and your
3464 * For major contributions, add a MAINTAINERS file with your
3465 information and associated file and directory references.
3467 * When you add support for a new board, don't forget to add a
3468 maintainer e-mail address to the boards.cfg file, too.
3470 * If your patch adds new configuration options, don't forget to
3471 document these in the README file.
3473 * The patch itself. If you are using git (which is *strongly*
3474 recommended) you can easily generate the patch using the
3475 "git format-patch". If you then use "git send-email" to send it to
3476 the U-Boot mailing list, you will avoid most of the common problems
3477 with some other mail clients.
3479 If you cannot use git, use "diff -purN OLD NEW". If your version of
3480 diff does not support these options, then get the latest version of
3483 The current directory when running this command shall be the parent
3484 directory of the U-Boot source tree (i. e. please make sure that
3485 your patch includes sufficient directory information for the
3488 We prefer patches as plain text. MIME attachments are discouraged,
3489 and compressed attachments must not be used.
3491 * If one logical set of modifications affects or creates several
3492 files, all these changes shall be submitted in a SINGLE patch file.
3494 * Changesets that contain different, unrelated modifications shall be
3495 submitted as SEPARATE patches, one patch per changeset.
3500 * Before sending the patch, run the buildman script on your patched
3501 source tree and make sure that no errors or warnings are reported
3502 for any of the boards.
3504 * Keep your modifications to the necessary minimum: A patch
3505 containing several unrelated changes or arbitrary reformats will be
3506 returned with a request to re-formatting / split it.
3508 * If you modify existing code, make sure that your new code does not
3509 add to the memory footprint of the code ;-) Small is beautiful!
3510 When adding new features, these should compile conditionally only
3511 (using #ifdef), and the resulting code with the new feature
3512 disabled must not need more memory than the old code without your
3515 * Remember that there is a size limit of 100 kB per message on the
3516 u-boot mailing list. Bigger patches will be moderated. If they are
3517 reasonable and not too big, they will be acknowledged. But patches
3518 bigger than the size limit should be avoided.
projects / platform / kernel / u-boot.git / blob