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_DWC2_REG_ADDR the physical CPU address of the DWC2
800 Define the below if you wish to use the USB console.
801 Once firmware is rebuilt from a serial console issue the
802 command "setenv stdin usbtty; setenv stdout usbtty" and
803 attach your USB cable. The Unix command "dmesg" should print
804 it has found a new device. The environment variable usbtty
805 can be set to gserial or cdc_acm to enable your device to
806 appear to a USB host as a Linux gserial device or a
807 Common Device Class Abstract Control Model serial device.
808 If you select usbtty = gserial you should be able to enumerate
810 # modprobe usbserial vendor=0xVendorID product=0xProductID
811 else if using cdc_acm, simply setting the environment
812 variable usbtty to be cdc_acm should suffice. The following
813 might be defined in YourBoardName.h
816 Define this to build a UDC device
819 Define this to have a tty type of device available to
820 talk to the UDC device
823 Define this to enable the high speed support for usb
824 device and usbtty. If this feature is enabled, a routine
825 int is_usbd_high_speed(void)
826 also needs to be defined by the driver to dynamically poll
827 whether the enumeration has succeded at high speed or full
830 If you have a USB-IF assigned VendorID then you may wish to
831 define your own vendor specific values either in BoardName.h
832 or directly in usbd_vendor_info.h. If you don't define
833 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
834 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
835 should pretend to be a Linux device to it's target host.
837 CONFIG_USBD_MANUFACTURER
838 Define this string as the name of your company for
839 - CONFIG_USBD_MANUFACTURER "my company"
841 CONFIG_USBD_PRODUCT_NAME
842 Define this string as the name of your product
843 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
846 Define this as your assigned Vendor ID from the USB
847 Implementors Forum. This *must* be a genuine Vendor ID
848 to avoid polluting the USB namespace.
849 - CONFIG_USBD_VENDORID 0xFFFF
851 CONFIG_USBD_PRODUCTID
852 Define this as the unique Product ID
854 - CONFIG_USBD_PRODUCTID 0xFFFF
856 - ULPI Layer Support:
857 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
858 the generic ULPI layer. The generic layer accesses the ULPI PHY
859 via the platform viewport, so you need both the genric layer and
860 the viewport enabled. Currently only Chipidea/ARC based
861 viewport is supported.
862 To enable the ULPI layer support, define CONFIG_USB_ULPI and
863 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
864 If your ULPI phy needs a different reference clock than the
865 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
866 the appropriate value in Hz.
869 The MMC controller on the Intel PXA is supported. To
870 enable this define CONFIG_MMC. The MMC can be
871 accessed from the boot prompt by mapping the device
872 to physical memory similar to flash. Command line is
873 enabled with CONFIG_CMD_MMC. The MMC driver also works with
874 the FAT fs. This is enabled with CONFIG_CMD_FAT.
877 Support for Renesas on-chip MMCIF controller
880 Define the base address of MMCIF registers
883 Define the clock frequency for MMCIF
885 - USB Device Firmware Update (DFU) class support:
887 This enables the USB portion of the DFU USB class
890 This enables support for exposing NAND devices via DFU.
893 This enables support for exposing RAM via DFU.
894 Note: DFU spec refer to non-volatile memory usage, but
895 allow usages beyond the scope of spec - here RAM usage,
896 one that would help mostly the developer.
898 CONFIG_SYS_DFU_DATA_BUF_SIZE
899 Dfu transfer uses a buffer before writing data to the
900 raw storage device. Make the size (in bytes) of this buffer
901 configurable. The size of this buffer is also configurable
902 through the "dfu_bufsiz" environment variable.
904 CONFIG_SYS_DFU_MAX_FILE_SIZE
905 When updating files rather than the raw storage device,
906 we use a static buffer to copy the file into and then write
907 the buffer once we've been given the whole file. Define
908 this to the maximum filesize (in bytes) for the buffer.
909 Default is 4 MiB if undefined.
911 DFU_DEFAULT_POLL_TIMEOUT
912 Poll timeout [ms], is the timeout a device can send to the
913 host. The host must wait for this timeout before sending
914 a subsequent DFU_GET_STATUS request to the device.
916 DFU_MANIFEST_POLL_TIMEOUT
917 Poll timeout [ms], which the device sends to the host when
918 entering dfuMANIFEST state. Host waits this timeout, before
919 sending again an USB request to the device.
921 - Journaling Flash filesystem support:
922 CONFIG_SYS_JFFS2_FIRST_SECTOR,
923 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
924 Define these for a default partition on a NOR device
927 See Kconfig help for available keyboard drivers.
929 - LCD Support: CONFIG_LCD
931 Define this to enable LCD support (for output to LCD
932 display); also select one of the supported displays
933 by defining one of these:
935 CONFIG_NEC_NL6448AC33:
937 NEC NL6448AC33-18. Active, color, single scan.
939 CONFIG_NEC_NL6448BC20
941 NEC NL6448BC20-08. 6.5", 640x480.
942 Active, color, single scan.
944 CONFIG_NEC_NL6448BC33_54
946 NEC NL6448BC33-54. 10.4", 640x480.
947 Active, color, single scan.
951 Sharp 320x240. Active, color, single scan.
952 It isn't 16x9, and I am not sure what it is.
954 CONFIG_SHARP_LQ64D341
956 Sharp LQ64D341 display, 640x480.
957 Active, color, single scan.
961 HLD1045 display, 640x480.
962 Active, color, single scan.
966 Optrex CBL50840-2 NF-FW 99 22 M5
968 Hitachi LMG6912RPFC-00T
972 320x240. Black & white.
976 Normally the LCD is page-aligned (typically 4KB). If this is
977 defined then the LCD will be aligned to this value instead.
978 For ARM it is sometimes useful to use MMU_SECTION_SIZE
979 here, since it is cheaper to change data cache settings on
985 Sometimes, for example if the display is mounted in portrait
986 mode or even if it's mounted landscape but rotated by 180degree,
987 we need to rotate our content of the display relative to the
988 framebuffer, so that user can read the messages which are
990 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
991 initialized with a given rotation from "vl_rot" out of
992 "vidinfo_t" which is provided by the board specific code.
993 The value for vl_rot is coded as following (matching to
994 fbcon=rotate:<n> linux-kernel commandline):
995 0 = no rotation respectively 0 degree
996 1 = 90 degree rotation
997 2 = 180 degree rotation
998 3 = 270 degree rotation
1000 If CONFIG_LCD_ROTATION is not defined, the console will be
1001 initialized with 0degree rotation.
1004 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1006 The clock frequency of the MII bus
1008 CONFIG_PHY_CMD_DELAY (ppc4xx)
1010 Some PHY like Intel LXT971A need extra delay after
1011 command issued before MII status register can be read
1016 Define a default value for the IP address to use for
1017 the default Ethernet interface, in case this is not
1018 determined through e.g. bootp.
1019 (Environment variable "ipaddr")
1021 - Server IP address:
1024 Defines a default value for the IP address of a TFTP
1025 server to contact when using the "tftboot" command.
1026 (Environment variable "serverip")
1028 - Gateway IP address:
1031 Defines a default value for the IP address of the
1032 default router where packets to other networks are
1034 (Environment variable "gatewayip")
1039 Defines a default value for the subnet mask (or
1040 routing prefix) which is used to determine if an IP
1041 address belongs to the local subnet or needs to be
1042 forwarded through a router.
1043 (Environment variable "netmask")
1045 - BOOTP Recovery Mode:
1046 CONFIG_BOOTP_RANDOM_DELAY
1048 If you have many targets in a network that try to
1049 boot using BOOTP, you may want to avoid that all
1050 systems send out BOOTP requests at precisely the same
1051 moment (which would happen for instance at recovery
1052 from a power failure, when all systems will try to
1053 boot, thus flooding the BOOTP server. Defining
1054 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1055 inserted before sending out BOOTP requests. The
1056 following delays are inserted then:
1058 1st BOOTP request: delay 0 ... 1 sec
1059 2nd BOOTP request: delay 0 ... 2 sec
1060 3rd BOOTP request: delay 0 ... 4 sec
1062 BOOTP requests: delay 0 ... 8 sec
1064 CONFIG_BOOTP_ID_CACHE_SIZE
1066 BOOTP packets are uniquely identified using a 32-bit ID. The
1067 server will copy the ID from client requests to responses and
1068 U-Boot will use this to determine if it is the destination of
1069 an incoming response. Some servers will check that addresses
1070 aren't in use before handing them out (usually using an ARP
1071 ping) and therefore take up to a few hundred milliseconds to
1072 respond. Network congestion may also influence the time it
1073 takes for a response to make it back to the client. If that
1074 time is too long, U-Boot will retransmit requests. In order
1075 to allow earlier responses to still be accepted after these
1076 retransmissions, U-Boot's BOOTP client keeps a small cache of
1077 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1078 cache. The default is to keep IDs for up to four outstanding
1079 requests. Increasing this will allow U-Boot to accept offers
1080 from a BOOTP client in networks with unusually high latency.
1082 - DHCP Advanced Options:
1084 - Link-local IP address negotiation:
1085 Negotiate with other link-local clients on the local network
1086 for an address that doesn't require explicit configuration.
1087 This is especially useful if a DHCP server cannot be guaranteed
1088 to exist in all environments that the device must operate.
1090 See doc/README.link-local for more information.
1092 - MAC address from environment variables
1094 FDT_SEQ_MACADDR_FROM_ENV
1096 Fix-up device tree with MAC addresses fetched sequentially from
1097 environment variables. This config work on assumption that
1098 non-usable ethernet node of device-tree are either not present
1099 or their status has been marked as "disabled".
1102 CONFIG_CDP_DEVICE_ID
1104 The device id used in CDP trigger frames.
1106 CONFIG_CDP_DEVICE_ID_PREFIX
1108 A two character string which is prefixed to the MAC address
1113 A printf format string which contains the ascii name of
1114 the port. Normally is set to "eth%d" which sets
1115 eth0 for the first Ethernet, eth1 for the second etc.
1117 CONFIG_CDP_CAPABILITIES
1119 A 32bit integer which indicates the device capabilities;
1120 0x00000010 for a normal host which does not forwards.
1124 An ascii string containing the version of the software.
1128 An ascii string containing the name of the platform.
1132 A 32bit integer sent on the trigger.
1134 CONFIG_CDP_POWER_CONSUMPTION
1136 A 16bit integer containing the power consumption of the
1137 device in .1 of milliwatts.
1139 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1141 A byte containing the id of the VLAN.
1143 - Status LED: CONFIG_LED_STATUS
1145 Several configurations allow to display the current
1146 status using a LED. For instance, the LED will blink
1147 fast while running U-Boot code, stop blinking as
1148 soon as a reply to a BOOTP request was received, and
1149 start blinking slow once the Linux kernel is running
1150 (supported by a status LED driver in the Linux
1151 kernel). Defining CONFIG_LED_STATUS enables this
1156 CONFIG_LED_STATUS_GPIO
1157 The status LED can be connected to a GPIO pin.
1158 In such cases, the gpio_led driver can be used as a
1159 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1160 to include the gpio_led driver in the U-Boot binary.
1162 CONFIG_GPIO_LED_INVERTED_TABLE
1163 Some GPIO connected LEDs may have inverted polarity in which
1164 case the GPIO high value corresponds to LED off state and
1165 GPIO low value corresponds to LED on state.
1166 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1167 with a list of GPIO LEDs that have inverted polarity.
1170 CONFIG_SYS_NUM_I2C_BUSES
1171 Hold the number of i2c buses you want to use.
1173 CONFIG_SYS_I2C_DIRECT_BUS
1174 define this, if you don't use i2c muxes on your hardware.
1175 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1178 CONFIG_SYS_I2C_MAX_HOPS
1179 define how many muxes are maximal consecutively connected
1180 on one i2c bus. If you not use i2c muxes, omit this
1183 CONFIG_SYS_I2C_BUSES
1184 hold a list of buses you want to use, only used if
1185 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1186 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1187 CONFIG_SYS_NUM_I2C_BUSES = 9:
1189 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1190 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1191 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1192 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1193 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1194 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1195 {1, {I2C_NULL_HOP}}, \
1196 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1197 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1201 bus 0 on adapter 0 without a mux
1202 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1203 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1204 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1205 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1206 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1207 bus 6 on adapter 1 without a mux
1208 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1209 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1211 If you do not have i2c muxes on your board, omit this define.
1213 - Legacy I2C Support:
1214 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1215 then the following macros need to be defined (examples are
1216 from include/configs/lwmon.h):
1220 (Optional). Any commands necessary to enable the I2C
1221 controller or configure ports.
1223 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1227 The code necessary to make the I2C data line active
1228 (driven). If the data line is open collector, this
1231 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1235 The code necessary to make the I2C data line tri-stated
1236 (inactive). If the data line is open collector, this
1239 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1243 Code that returns true if the I2C data line is high,
1246 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1250 If <bit> is true, sets the I2C data line high. If it
1251 is false, it clears it (low).
1253 eg: #define I2C_SDA(bit) \
1254 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1255 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1259 If <bit> is true, sets the I2C clock line high. If it
1260 is false, it clears it (low).
1262 eg: #define I2C_SCL(bit) \
1263 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1264 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1268 This delay is invoked four times per clock cycle so this
1269 controls the rate of data transfer. The data rate thus
1270 is 1 / (I2C_DELAY * 4). Often defined to be something
1273 #define I2C_DELAY udelay(2)
1275 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1277 If your arch supports the generic GPIO framework (asm/gpio.h),
1278 then you may alternatively define the two GPIOs that are to be
1279 used as SCL / SDA. Any of the previous I2C_xxx macros will
1280 have GPIO-based defaults assigned to them as appropriate.
1282 You should define these to the GPIO value as given directly to
1283 the generic GPIO functions.
1285 CONFIG_SYS_I2C_INIT_BOARD
1287 When a board is reset during an i2c bus transfer
1288 chips might think that the current transfer is still
1289 in progress. On some boards it is possible to access
1290 the i2c SCLK line directly, either by using the
1291 processor pin as a GPIO or by having a second pin
1292 connected to the bus. If this option is defined a
1293 custom i2c_init_board() routine in boards/xxx/board.c
1294 is run early in the boot sequence.
1296 CONFIG_I2C_MULTI_BUS
1298 This option allows the use of multiple I2C buses, each of which
1299 must have a controller. At any point in time, only one bus is
1300 active. To switch to a different bus, use the 'i2c dev' command.
1301 Note that bus numbering is zero-based.
1303 CONFIG_SYS_I2C_NOPROBES
1305 This option specifies a list of I2C devices that will be skipped
1306 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1307 is set, specify a list of bus-device pairs. Otherwise, specify
1308 a 1D array of device addresses
1311 #undef CONFIG_I2C_MULTI_BUS
1312 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1314 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1316 #define CONFIG_I2C_MULTI_BUS
1317 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1319 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1321 CONFIG_SYS_SPD_BUS_NUM
1323 If defined, then this indicates the I2C bus number for DDR SPD.
1324 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1326 CONFIG_SYS_RTC_BUS_NUM
1328 If defined, then this indicates the I2C bus number for the RTC.
1329 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1331 CONFIG_SOFT_I2C_READ_REPEATED_START
1333 defining this will force the i2c_read() function in
1334 the soft_i2c driver to perform an I2C repeated start
1335 between writing the address pointer and reading the
1336 data. If this define is omitted the default behaviour
1337 of doing a stop-start sequence will be used. Most I2C
1338 devices can use either method, but some require one or
1341 - SPI Support: CONFIG_SPI
1343 Enables SPI driver (so far only tested with
1344 SPI EEPROM, also an instance works with Crystal A/D and
1345 D/As on the SACSng board)
1347 CONFIG_SYS_SPI_MXC_WAIT
1348 Timeout for waiting until spi transfer completed.
1349 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1351 - FPGA Support: CONFIG_FPGA
1353 Enables FPGA subsystem.
1355 CONFIG_FPGA_<vendor>
1357 Enables support for specific chip vendors.
1360 CONFIG_FPGA_<family>
1362 Enables support for FPGA family.
1363 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1367 Specify the number of FPGA devices to support.
1369 CONFIG_SYS_FPGA_PROG_FEEDBACK
1371 Enable printing of hash marks during FPGA configuration.
1373 CONFIG_SYS_FPGA_CHECK_BUSY
1375 Enable checks on FPGA configuration interface busy
1376 status by the configuration function. This option
1377 will require a board or device specific function to
1382 If defined, a function that provides delays in the FPGA
1383 configuration driver.
1385 CONFIG_SYS_FPGA_CHECK_CTRLC
1386 Allow Control-C to interrupt FPGA configuration
1388 CONFIG_SYS_FPGA_CHECK_ERROR
1390 Check for configuration errors during FPGA bitfile
1391 loading. For example, abort during Virtex II
1392 configuration if the INIT_B line goes low (which
1393 indicated a CRC error).
1395 CONFIG_SYS_FPGA_WAIT_INIT
1397 Maximum time to wait for the INIT_B line to de-assert
1398 after PROB_B has been de-asserted during a Virtex II
1399 FPGA configuration sequence. The default time is 500
1402 CONFIG_SYS_FPGA_WAIT_BUSY
1404 Maximum time to wait for BUSY to de-assert during
1405 Virtex II FPGA configuration. The default is 5 ms.
1407 CONFIG_SYS_FPGA_WAIT_CONFIG
1409 Time to wait after FPGA configuration. The default is
1412 - Vendor Parameter Protection:
1414 U-Boot considers the values of the environment
1415 variables "serial#" (Board Serial Number) and
1416 "ethaddr" (Ethernet Address) to be parameters that
1417 are set once by the board vendor / manufacturer, and
1418 protects these variables from casual modification by
1419 the user. Once set, these variables are read-only,
1420 and write or delete attempts are rejected. You can
1421 change this behaviour:
1423 If CONFIG_ENV_OVERWRITE is #defined in your config
1424 file, the write protection for vendor parameters is
1425 completely disabled. Anybody can change or delete
1428 Alternatively, if you define _both_ an ethaddr in the
1429 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1430 Ethernet address is installed in the environment,
1431 which can be changed exactly ONCE by the user. [The
1432 serial# is unaffected by this, i. e. it remains
1435 The same can be accomplished in a more flexible way
1436 for any variable by configuring the type of access
1437 to allow for those variables in the ".flags" variable
1438 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1443 Define this variable to enable the reservation of
1444 "protected RAM", i. e. RAM which is not overwritten
1445 by U-Boot. Define CONFIG_PRAM to hold the number of
1446 kB you want to reserve for pRAM. You can overwrite
1447 this default value by defining an environment
1448 variable "pram" to the number of kB you want to
1449 reserve. Note that the board info structure will
1450 still show the full amount of RAM. If pRAM is
1451 reserved, a new environment variable "mem" will
1452 automatically be defined to hold the amount of
1453 remaining RAM in a form that can be passed as boot
1454 argument to Linux, for instance like that:
1456 setenv bootargs ... mem=\${mem}
1459 This way you can tell Linux not to use this memory,
1460 either, which results in a memory region that will
1461 not be affected by reboots.
1463 *WARNING* If your board configuration uses automatic
1464 detection of the RAM size, you must make sure that
1465 this memory test is non-destructive. So far, the
1466 following board configurations are known to be
1469 IVMS8, IVML24, SPD8xx,
1470 HERMES, IP860, RPXlite, LWMON,
1476 In the current implementation, the local variables
1477 space and global environment variables space are
1478 separated. Local variables are those you define by
1479 simply typing `name=value'. To access a local
1480 variable later on, you have write `$name' or
1481 `${name}'; to execute the contents of a variable
1482 directly type `$name' at the command prompt.
1484 Global environment variables are those you use
1485 setenv/printenv to work with. To run a command stored
1486 in such a variable, you need to use the run command,
1487 and you must not use the '$' sign to access them.
1489 To store commands and special characters in a
1490 variable, please use double quotation marks
1491 surrounding the whole text of the variable, instead
1492 of the backslashes before semicolons and special
1495 - Default Environment:
1496 CONFIG_EXTRA_ENV_SETTINGS
1498 Define this to contain any number of null terminated
1499 strings (variable = value pairs) that will be part of
1500 the default environment compiled into the boot image.
1502 For example, place something like this in your
1503 board's config file:
1505 #define CONFIG_EXTRA_ENV_SETTINGS \
1509 Warning: This method is based on knowledge about the
1510 internal format how the environment is stored by the
1511 U-Boot code. This is NOT an official, exported
1512 interface! Although it is unlikely that this format
1513 will change soon, there is no guarantee either.
1514 You better know what you are doing here.
1516 Note: overly (ab)use of the default environment is
1517 discouraged. Make sure to check other ways to preset
1518 the environment like the "source" command or the
1521 CONFIG_DELAY_ENVIRONMENT
1523 Normally the environment is loaded when the board is
1524 initialised so that it is available to U-Boot. This inhibits
1525 that so that the environment is not available until
1526 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1527 this is instead controlled by the value of
1528 /config/load-environment.
1530 CONFIG_STANDALONE_LOAD_ADDR
1532 This option defines a board specific value for the
1533 address where standalone program gets loaded, thus
1534 overwriting the architecture dependent default
1537 - Frame Buffer Address:
1540 Define CONFIG_FB_ADDR if you want to use specific
1541 address for frame buffer. This is typically the case
1542 when using a graphics controller has separate video
1543 memory. U-Boot will then place the frame buffer at
1544 the given address instead of dynamically reserving it
1545 in system RAM by calling lcd_setmem(), which grabs
1546 the memory for the frame buffer depending on the
1547 configured panel size.
1549 Please see board_init_f function.
1551 - Automatic software updates via TFTP server
1553 CONFIG_UPDATE_TFTP_CNT_MAX
1554 CONFIG_UPDATE_TFTP_MSEC_MAX
1556 These options enable and control the auto-update feature;
1557 for a more detailed description refer to doc/README.update.
1559 - MTD Support (mtdparts command, UBI support)
1560 CONFIG_MTD_UBI_WL_THRESHOLD
1561 This parameter defines the maximum difference between the highest
1562 erase counter value and the lowest erase counter value of eraseblocks
1563 of UBI devices. When this threshold is exceeded, UBI starts performing
1564 wear leveling by means of moving data from eraseblock with low erase
1565 counter to eraseblocks with high erase counter.
1567 The default value should be OK for SLC NAND flashes, NOR flashes and
1568 other flashes which have eraseblock life-cycle 100000 or more.
1569 However, in case of MLC NAND flashes which typically have eraseblock
1570 life-cycle less than 10000, the threshold should be lessened (e.g.,
1571 to 128 or 256, although it does not have to be power of 2).
1575 CONFIG_MTD_UBI_BEB_LIMIT
1576 This option specifies the maximum bad physical eraseblocks UBI
1577 expects on the MTD device (per 1024 eraseblocks). If the
1578 underlying flash does not admit of bad eraseblocks (e.g. NOR
1579 flash), this value is ignored.
1581 NAND datasheets often specify the minimum and maximum NVM
1582 (Number of Valid Blocks) for the flashes' endurance lifetime.
1583 The maximum expected bad eraseblocks per 1024 eraseblocks
1584 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1585 which gives 20 for most NANDs (MaxNVB is basically the total
1586 count of eraseblocks on the chip).
1588 To put it differently, if this value is 20, UBI will try to
1589 reserve about 1.9% of physical eraseblocks for bad blocks
1590 handling. And that will be 1.9% of eraseblocks on the entire
1591 NAND chip, not just the MTD partition UBI attaches. This means
1592 that if you have, say, a NAND flash chip admits maximum 40 bad
1593 eraseblocks, and it is split on two MTD partitions of the same
1594 size, UBI will reserve 40 eraseblocks when attaching a
1599 CONFIG_MTD_UBI_FASTMAP
1600 Fastmap is a mechanism which allows attaching an UBI device
1601 in nearly constant time. Instead of scanning the whole MTD device it
1602 only has to locate a checkpoint (called fastmap) on the device.
1603 The on-flash fastmap contains all information needed to attach
1604 the device. Using fastmap makes only sense on large devices where
1605 attaching by scanning takes long. UBI will not automatically install
1606 a fastmap on old images, but you can set the UBI parameter
1607 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1608 that fastmap-enabled images are still usable with UBI implementations
1609 without fastmap support. On typical flash devices the whole fastmap
1610 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1612 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1613 Set this parameter to enable fastmap automatically on images
1617 CONFIG_MTD_UBI_FM_DEBUG
1618 Enable UBI fastmap debug
1623 Enable building of SPL globally.
1625 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1626 When defined, SPL will panic() if the image it has
1627 loaded does not have a signature.
1628 Defining this is useful when code which loads images
1629 in SPL cannot guarantee that absolutely all read errors
1631 An example is the LPC32XX MLC NAND driver, which will
1632 consider that a completely unreadable NAND block is bad,
1633 and thus should be skipped silently.
1635 CONFIG_SPL_DISPLAY_PRINT
1636 For ARM, enable an optional function to print more information
1637 about the running system.
1639 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1640 Set this for NAND SPL on PPC mpc83xx targets, so that
1641 start.S waits for the rest of the SPL to load before
1642 continuing (the hardware starts execution after just
1643 loading the first page rather than the full 4K).
1646 Support for a lightweight UBI (fastmap) scanner and
1649 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1650 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1651 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1652 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1653 CONFIG_SYS_NAND_ECCBYTES
1654 Defines the size and behavior of the NAND that SPL uses
1657 CONFIG_SYS_NAND_U_BOOT_DST
1658 Location in memory to load U-Boot to
1660 CONFIG_SYS_NAND_U_BOOT_SIZE
1661 Size of image to load
1663 CONFIG_SYS_NAND_U_BOOT_START
1664 Entry point in loaded image to jump to
1666 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1667 Define this if you need to first read the OOB and then the
1668 data. This is used, for example, on davinci platforms.
1670 CONFIG_SPL_RAM_DEVICE
1671 Support for running image already present in ram, in SPL binary
1673 CONFIG_SPL_FIT_PRINT
1674 Printing information about a FIT image adds quite a bit of
1675 code to SPL. So this is normally disabled in SPL. Use this
1676 option to re-enable it. This will affect the output of the
1677 bootm command when booting a FIT image.
1679 - Interrupt support (PPC):
1681 There are common interrupt_init() and timer_interrupt()
1682 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1683 for CPU specific initialization. interrupt_init_cpu()
1684 should set decrementer_count to appropriate value. If
1685 CPU resets decrementer automatically after interrupt
1686 (ppc4xx) it should set decrementer_count to zero.
1687 timer_interrupt() calls timer_interrupt_cpu() for CPU
1688 specific handling. If board has watchdog / status_led
1689 / other_activity_monitor it works automatically from
1690 general timer_interrupt().
1693 Board initialization settings:
1694 ------------------------------
1696 During Initialization u-boot calls a number of board specific functions
1697 to allow the preparation of board specific prerequisites, e.g. pin setup
1698 before drivers are initialized. To enable these callbacks the
1699 following configuration macros have to be defined. Currently this is
1700 architecture specific, so please check arch/your_architecture/lib/board.c
1701 typically in board_init_f() and board_init_r().
1703 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1704 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1705 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1707 Configuration Settings:
1708 -----------------------
1710 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1711 Optionally it can be defined to support 64-bit memory commands.
1713 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1714 undefine this when you're short of memory.
1716 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1717 width of the commands listed in the 'help' command output.
1719 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1720 prompt for user input.
1722 - CONFIG_SYS_BAUDRATE_TABLE:
1723 List of legal baudrate settings for this board.
1725 - CONFIG_SYS_MEM_RESERVE_SECURE
1726 Only implemented for ARMv8 for now.
1727 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1728 is substracted from total RAM and won't be reported to OS.
1729 This memory can be used as secure memory. A variable
1730 gd->arch.secure_ram is used to track the location. In systems
1731 the RAM base is not zero, or RAM is divided into banks,
1732 this variable needs to be recalcuated to get the address.
1734 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1735 Enable temporary baudrate change while serial download
1737 - CONFIG_SYS_SDRAM_BASE:
1738 Physical start address of SDRAM. _Must_ be 0 here.
1740 - CONFIG_SYS_FLASH_BASE:
1741 Physical start address of Flash memory.
1743 - CONFIG_SYS_MONITOR_LEN:
1744 Size of memory reserved for monitor code, used to
1745 determine _at_compile_time_ (!) if the environment is
1746 embedded within the U-Boot image, or in a separate
1749 - CONFIG_SYS_MALLOC_LEN:
1750 Size of DRAM reserved for malloc() use.
1752 - CONFIG_SYS_MALLOC_F_LEN
1753 Size of the malloc() pool for use before relocation. If
1754 this is defined, then a very simple malloc() implementation
1755 will become available before relocation. The address is just
1756 below the global data, and the stack is moved down to make
1759 This feature allocates regions with increasing addresses
1760 within the region. calloc() is supported, but realloc()
1761 is not available. free() is supported but does nothing.
1762 The memory will be freed (or in fact just forgotten) when
1763 U-Boot relocates itself.
1765 - CONFIG_SYS_MALLOC_SIMPLE
1766 Provides a simple and small malloc() and calloc() for those
1767 boards which do not use the full malloc in SPL (which is
1768 enabled with CONFIG_SYS_SPL_MALLOC).
1770 - CONFIG_SYS_NONCACHED_MEMORY:
1771 Size of non-cached memory area. This area of memory will be
1772 typically located right below the malloc() area and mapped
1773 uncached in the MMU. This is useful for drivers that would
1774 otherwise require a lot of explicit cache maintenance. For
1775 some drivers it's also impossible to properly maintain the
1776 cache. For example if the regions that need to be flushed
1777 are not a multiple of the cache-line size, *and* padding
1778 cannot be allocated between the regions to align them (i.e.
1779 if the HW requires a contiguous array of regions, and the
1780 size of each region is not cache-aligned), then a flush of
1781 one region may result in overwriting data that hardware has
1782 written to another region in the same cache-line. This can
1783 happen for example in network drivers where descriptors for
1784 buffers are typically smaller than the CPU cache-line (e.g.
1785 16 bytes vs. 32 or 64 bytes).
1787 Non-cached memory is only supported on 32-bit ARM at present.
1789 - CONFIG_SYS_BOOTM_LEN:
1790 Normally compressed uImages are limited to an
1791 uncompressed size of 8 MBytes. If this is not enough,
1792 you can define CONFIG_SYS_BOOTM_LEN in your board config file
1793 to adjust this setting to your needs.
1795 - CONFIG_SYS_BOOTMAPSZ:
1796 Maximum size of memory mapped by the startup code of
1797 the Linux kernel; all data that must be processed by
1798 the Linux kernel (bd_info, boot arguments, FDT blob if
1799 used) must be put below this limit, unless "bootm_low"
1800 environment variable is defined and non-zero. In such case
1801 all data for the Linux kernel must be between "bootm_low"
1802 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
1803 variable "bootm_mapsize" will override the value of
1804 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
1805 then the value in "bootm_size" will be used instead.
1807 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
1808 Enable initrd_high functionality. If defined then the
1809 initrd_high feature is enabled and the bootm ramdisk subcommand
1812 - CONFIG_SYS_BOOT_GET_CMDLINE:
1813 Enables allocating and saving kernel cmdline in space between
1814 "bootm_low" and "bootm_low" + BOOTMAPSZ.
1816 - CONFIG_SYS_BOOT_GET_KBD:
1817 Enables allocating and saving a kernel copy of the bd_info in
1818 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
1820 - CONFIG_SYS_MAX_FLASH_SECT:
1821 Max number of sectors on a Flash chip
1823 - CONFIG_SYS_FLASH_ERASE_TOUT:
1824 Timeout for Flash erase operations (in ms)
1826 - CONFIG_SYS_FLASH_WRITE_TOUT:
1827 Timeout for Flash write operations (in ms)
1829 - CONFIG_SYS_FLASH_LOCK_TOUT
1830 Timeout for Flash set sector lock bit operation (in ms)
1832 - CONFIG_SYS_FLASH_UNLOCK_TOUT
1833 Timeout for Flash clear lock bits operation (in ms)
1835 - CONFIG_SYS_FLASH_PROTECTION
1836 If defined, hardware flash sectors protection is used
1837 instead of U-Boot software protection.
1839 - CONFIG_SYS_DIRECT_FLASH_TFTP:
1841 Enable TFTP transfers directly to flash memory;
1842 without this option such a download has to be
1843 performed in two steps: (1) download to RAM, and (2)
1844 copy from RAM to flash.
1846 The two-step approach is usually more reliable, since
1847 you can check if the download worked before you erase
1848 the flash, but in some situations (when system RAM is
1849 too limited to allow for a temporary copy of the
1850 downloaded image) this option may be very useful.
1852 - CONFIG_SYS_FLASH_CFI:
1853 Define if the flash driver uses extra elements in the
1854 common flash structure for storing flash geometry.
1856 - CONFIG_FLASH_CFI_DRIVER
1857 This option also enables the building of the cfi_flash driver
1858 in the drivers directory
1860 - CONFIG_FLASH_CFI_MTD
1861 This option enables the building of the cfi_mtd driver
1862 in the drivers directory. The driver exports CFI flash
1865 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
1866 Use buffered writes to flash.
1868 - CONFIG_FLASH_SPANSION_S29WS_N
1869 s29ws-n MirrorBit flash has non-standard addresses for buffered
1872 - CONFIG_SYS_FLASH_QUIET_TEST
1873 If this option is defined, the common CFI flash doesn't
1874 print it's warning upon not recognized FLASH banks. This
1875 is useful, if some of the configured banks are only
1876 optionally available.
1878 - CONFIG_FLASH_SHOW_PROGRESS
1879 If defined (must be an integer), print out countdown
1880 digits and dots. Recommended value: 45 (9..1) for 80
1881 column displays, 15 (3..1) for 40 column displays.
1883 - CONFIG_FLASH_VERIFY
1884 If defined, the content of the flash (destination) is compared
1885 against the source after the write operation. An error message
1886 will be printed when the contents are not identical.
1887 Please note that this option is useless in nearly all cases,
1888 since such flash programming errors usually are detected earlier
1889 while unprotecting/erasing/programming. Please only enable
1890 this option if you really know what you are doing.
1892 - CONFIG_ENV_MAX_ENTRIES
1894 Maximum number of entries in the hash table that is used
1895 internally to store the environment settings. The default
1896 setting is supposed to be generous and should work in most
1897 cases. This setting can be used to tune behaviour; see
1898 lib/hashtable.c for details.
1900 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1901 - CONFIG_ENV_FLAGS_LIST_STATIC
1902 Enable validation of the values given to environment variables when
1903 calling env set. Variables can be restricted to only decimal,
1904 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
1905 the variables can also be restricted to IP address or MAC address.
1907 The format of the list is:
1908 type_attribute = [s|d|x|b|i|m]
1909 access_attribute = [a|r|o|c]
1910 attributes = type_attribute[access_attribute]
1911 entry = variable_name[:attributes]
1914 The type attributes are:
1915 s - String (default)
1918 b - Boolean ([1yYtT|0nNfF])
1922 The access attributes are:
1928 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1929 Define this to a list (string) to define the ".flags"
1930 environment variable in the default or embedded environment.
1932 - CONFIG_ENV_FLAGS_LIST_STATIC
1933 Define this to a list (string) to define validation that
1934 should be done if an entry is not found in the ".flags"
1935 environment variable. To override a setting in the static
1936 list, simply add an entry for the same variable name to the
1939 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
1940 regular expression. This allows multiple variables to define the same
1941 flags without explicitly listing them for each variable.
1943 The following definitions that deal with the placement and management
1944 of environment data (variable area); in general, we support the
1945 following configurations:
1947 - CONFIG_BUILD_ENVCRC:
1949 Builds up envcrc with the target environment so that external utils
1950 may easily extract it and embed it in final U-Boot images.
1952 BE CAREFUL! The first access to the environment happens quite early
1953 in U-Boot initialization (when we try to get the setting of for the
1954 console baudrate). You *MUST* have mapped your NVRAM area then, or
1957 Please note that even with NVRAM we still use a copy of the
1958 environment in RAM: we could work on NVRAM directly, but we want to
1959 keep settings there always unmodified except somebody uses "saveenv"
1960 to save the current settings.
1962 BE CAREFUL! For some special cases, the local device can not use
1963 "saveenv" command. For example, the local device will get the
1964 environment stored in a remote NOR flash by SRIO or PCIE link,
1965 but it can not erase, write this NOR flash by SRIO or PCIE interface.
1967 - CONFIG_NAND_ENV_DST
1969 Defines address in RAM to which the nand_spl code should copy the
1970 environment. If redundant environment is used, it will be copied to
1971 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
1973 Please note that the environment is read-only until the monitor
1974 has been relocated to RAM and a RAM copy of the environment has been
1975 created; also, when using EEPROM you will have to use env_get_f()
1976 until then to read environment variables.
1978 The environment is protected by a CRC32 checksum. Before the monitor
1979 is relocated into RAM, as a result of a bad CRC you will be working
1980 with the compiled-in default environment - *silently*!!! [This is
1981 necessary, because the first environment variable we need is the
1982 "baudrate" setting for the console - if we have a bad CRC, we don't
1983 have any device yet where we could complain.]
1985 Note: once the monitor has been relocated, then it will complain if
1986 the default environment is used; a new CRC is computed as soon as you
1987 use the "saveenv" command to store a valid environment.
1989 - CONFIG_SYS_FAULT_MII_ADDR:
1990 MII address of the PHY to check for the Ethernet link state.
1992 - CONFIG_NS16550_MIN_FUNCTIONS:
1993 Define this if you desire to only have use of the NS16550_init
1994 and NS16550_putc functions for the serial driver located at
1995 drivers/serial/ns16550.c. This option is useful for saving
1996 space for already greatly restricted images, including but not
1997 limited to NAND_SPL configurations.
1999 - CONFIG_DISPLAY_BOARDINFO
2000 Display information about the board that U-Boot is running on
2001 when U-Boot starts up. The board function checkboard() is called
2004 - CONFIG_DISPLAY_BOARDINFO_LATE
2005 Similar to the previous option, but display this information
2006 later, once stdio is running and output goes to the LCD, if
2009 Low Level (hardware related) configuration options:
2010 ---------------------------------------------------
2012 - CONFIG_SYS_CACHELINE_SIZE:
2013 Cache Line Size of the CPU.
2015 - CONFIG_SYS_CCSRBAR_DEFAULT:
2016 Default (power-on reset) physical address of CCSR on Freescale
2019 - CONFIG_SYS_CCSRBAR:
2020 Virtual address of CCSR. On a 32-bit build, this is typically
2021 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2023 - CONFIG_SYS_CCSRBAR_PHYS:
2024 Physical address of CCSR. CCSR can be relocated to a new
2025 physical address, if desired. In this case, this macro should
2026 be set to that address. Otherwise, it should be set to the
2027 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2028 is typically relocated on 36-bit builds. It is recommended
2029 that this macro be defined via the _HIGH and _LOW macros:
2031 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2032 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2034 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2035 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2036 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2037 used in assembly code, so it must not contain typecasts or
2038 integer size suffixes (e.g. "ULL").
2040 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2041 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2042 used in assembly code, so it must not contain typecasts or
2043 integer size suffixes (e.g. "ULL").
2045 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2046 DO NOT CHANGE unless you know exactly what you're
2047 doing! (11-4) [MPC8xx systems only]
2049 - CONFIG_SYS_INIT_RAM_ADDR:
2051 Start address of memory area that can be used for
2052 initial data and stack; please note that this must be
2053 writable memory that is working WITHOUT special
2054 initialization, i. e. you CANNOT use normal RAM which
2055 will become available only after programming the
2056 memory controller and running certain initialization
2059 U-Boot uses the following memory types:
2060 - MPC8xx: IMMR (internal memory of the CPU)
2062 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2064 - CONFIG_SYS_OR_TIMING_SDRAM:
2067 - CONFIG_SYS_MAMR_PTA:
2068 periodic timer for refresh
2071 Chip has SRIO or not
2074 Board has SRIO 1 port available
2077 Board has SRIO 2 port available
2079 - CONFIG_SRIO_PCIE_BOOT_MASTER
2080 Board can support master function for Boot from SRIO and PCIE
2082 - CONFIG_SYS_SRIOn_MEM_VIRT:
2083 Virtual Address of SRIO port 'n' memory region
2085 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2086 Physical Address of SRIO port 'n' memory region
2088 - CONFIG_SYS_SRIOn_MEM_SIZE:
2089 Size of SRIO port 'n' memory region
2091 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2092 Defined to tell the NAND controller that the NAND chip is using
2094 Not all NAND drivers use this symbol.
2095 Example of drivers that use it:
2096 - drivers/mtd/nand/raw/ndfc.c
2097 - drivers/mtd/nand/raw/mxc_nand.c
2099 - CONFIG_SYS_NDFC_EBC0_CFG
2100 Sets the EBC0_CFG register for the NDFC. If not defined
2101 a default value will be used.
2104 Get DDR timing information from an I2C EEPROM. Common
2105 with pluggable memory modules such as SODIMMs
2108 I2C address of the SPD EEPROM
2110 - CONFIG_SYS_SPD_BUS_NUM
2111 If SPD EEPROM is on an I2C bus other than the first
2112 one, specify here. Note that the value must resolve
2113 to something your driver can deal with.
2115 - CONFIG_SYS_DDR_RAW_TIMING
2116 Get DDR timing information from other than SPD. Common with
2117 soldered DDR chips onboard without SPD. DDR raw timing
2118 parameters are extracted from datasheet and hard-coded into
2119 header files or board specific files.
2121 - CONFIG_FSL_DDR_INTERACTIVE
2122 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2124 - CONFIG_FSL_DDR_SYNC_REFRESH
2125 Enable sync of refresh for multiple controllers.
2127 - CONFIG_FSL_DDR_BIST
2128 Enable built-in memory test for Freescale DDR controllers.
2130 - CONFIG_SYS_83XX_DDR_USES_CS0
2131 Only for 83xx systems. If specified, then DDR should
2132 be configured using CS0 and CS1 instead of CS2 and CS3.
2135 Enable RMII mode for all FECs.
2136 Note that this is a global option, we can't
2137 have one FEC in standard MII mode and another in RMII mode.
2139 - CONFIG_CRC32_VERIFY
2140 Add a verify option to the crc32 command.
2143 => crc32 -v <address> <count> <crc32>
2145 Where address/count indicate a memory area
2146 and crc32 is the correct crc32 which the
2150 Add the "loopw" memory command. This only takes effect if
2151 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2153 - CONFIG_CMD_MX_CYCLIC
2154 Add the "mdc" and "mwc" memory commands. These are cyclic
2159 This command will print 4 bytes (10,11,12,13) each 500 ms.
2161 => mwc.l 100 12345678 10
2162 This command will write 12345678 to address 100 all 10 ms.
2164 This only takes effect if the memory commands are activated
2165 globally (CONFIG_CMD_MEMORY).
2168 Set when the currently-running compilation is for an artifact
2169 that will end up in the SPL (as opposed to the TPL or U-Boot
2170 proper). Code that needs stage-specific behavior should check
2174 Set when the currently-running compilation is for an artifact
2175 that will end up in the TPL (as opposed to the SPL or U-Boot
2176 proper). Code that needs stage-specific behavior should check
2179 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2180 Only for 85xx systems. If this variable is specified, the section
2181 .resetvec is not kept and the section .bootpg is placed in the
2182 previous 4k of the .text section.
2184 - CONFIG_ARCH_MAP_SYSMEM
2185 Generally U-Boot (and in particular the md command) uses
2186 effective address. It is therefore not necessary to regard
2187 U-Boot address as virtual addresses that need to be translated
2188 to physical addresses. However, sandbox requires this, since
2189 it maintains its own little RAM buffer which contains all
2190 addressable memory. This option causes some memory accesses
2191 to be mapped through map_sysmem() / unmap_sysmem().
2193 - CONFIG_X86_RESET_VECTOR
2194 If defined, the x86 reset vector code is included. This is not
2195 needed when U-Boot is running from Coreboot.
2197 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2198 Option to disable subpage write in NAND driver
2199 driver that uses this:
2200 drivers/mtd/nand/raw/davinci_nand.c
2202 Freescale QE/FMAN Firmware Support:
2203 -----------------------------------
2205 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2206 loading of "firmware", which is encoded in the QE firmware binary format.
2207 This firmware often needs to be loaded during U-Boot booting, so macros
2208 are used to identify the storage device (NOR flash, SPI, etc) and the address
2211 - CONFIG_SYS_FMAN_FW_ADDR
2212 The address in the storage device where the FMAN microcode is located. The
2213 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2216 - CONFIG_SYS_QE_FW_ADDR
2217 The address in the storage device where the QE microcode is located. The
2218 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2221 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2222 The maximum possible size of the firmware. The firmware binary format
2223 has a field that specifies the actual size of the firmware, but it
2224 might not be possible to read any part of the firmware unless some
2225 local storage is allocated to hold the entire firmware first.
2227 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2228 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2229 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2230 virtual address in NOR flash.
2232 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2233 Specifies that QE/FMAN firmware is located in NAND flash.
2234 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2236 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2237 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2238 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2240 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2241 Specifies that QE/FMAN firmware is located in the remote (master)
2242 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2243 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2244 window->master inbound window->master LAW->the ucode address in
2245 master's memory space.
2247 Freescale Layerscape Management Complex Firmware Support:
2248 ---------------------------------------------------------
2249 The Freescale Layerscape Management Complex (MC) supports the loading of
2251 This firmware often needs to be loaded during U-Boot booting, so macros
2252 are used to identify the storage device (NOR flash, SPI, etc) and the address
2255 - CONFIG_FSL_MC_ENET
2256 Enable the MC driver for Layerscape SoCs.
2258 Freescale Layerscape Debug Server Support:
2259 -------------------------------------------
2260 The Freescale Layerscape Debug Server Support supports the loading of
2261 "Debug Server firmware" and triggering SP boot-rom.
2262 This firmware often needs to be loaded during U-Boot booting.
2264 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2265 Define alignment of reserved memory MC requires
2270 In order to achieve reproducible builds, timestamps used in the U-Boot build
2271 process have to be set to a fixed value.
2273 This is done using the SOURCE_DATE_EPOCH environment variable.
2274 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2275 option for U-Boot or an environment variable in U-Boot.
2277 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2279 Building the Software:
2280 ======================
2282 Building U-Boot has been tested in several native build environments
2283 and in many different cross environments. Of course we cannot support
2284 all possibly existing versions of cross development tools in all
2285 (potentially obsolete) versions. In case of tool chain problems we
2286 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2287 which is extensively used to build and test U-Boot.
2289 If you are not using a native environment, it is assumed that you
2290 have GNU cross compiling tools available in your path. In this case,
2291 you must set the environment variable CROSS_COMPILE in your shell.
2292 Note that no changes to the Makefile or any other source files are
2293 necessary. For example using the ELDK on a 4xx CPU, please enter:
2295 $ CROSS_COMPILE=ppc_4xx-
2296 $ export CROSS_COMPILE
2298 U-Boot is intended to be simple to build. After installing the
2299 sources you must configure U-Boot for one specific board type. This
2304 where "NAME_defconfig" is the name of one of the existing configu-
2305 rations; see configs/*_defconfig for supported names.
2307 Note: for some boards special configuration names may exist; check if
2308 additional information is available from the board vendor; for
2309 instance, the TQM823L systems are available without (standard)
2310 or with LCD support. You can select such additional "features"
2311 when choosing the configuration, i. e.
2313 make TQM823L_defconfig
2314 - will configure for a plain TQM823L, i. e. no LCD support
2316 make TQM823L_LCD_defconfig
2317 - will configure for a TQM823L with U-Boot console on LCD
2322 Finally, type "make all", and you should get some working U-Boot
2323 images ready for download to / installation on your system:
2325 - "u-boot.bin" is a raw binary image
2326 - "u-boot" is an image in ELF binary format
2327 - "u-boot.srec" is in Motorola S-Record format
2329 By default the build is performed locally and the objects are saved
2330 in the source directory. One of the two methods can be used to change
2331 this behavior and build U-Boot to some external directory:
2333 1. Add O= to the make command line invocations:
2335 make O=/tmp/build distclean
2336 make O=/tmp/build NAME_defconfig
2337 make O=/tmp/build all
2339 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2341 export KBUILD_OUTPUT=/tmp/build
2346 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2349 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2350 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2351 For example to treat all compiler warnings as errors:
2353 make KCFLAGS=-Werror
2355 Please be aware that the Makefiles assume you are using GNU make, so
2356 for instance on NetBSD you might need to use "gmake" instead of
2360 If the system board that you have is not listed, then you will need
2361 to port U-Boot to your hardware platform. To do this, follow these
2364 1. Create a new directory to hold your board specific code. Add any
2365 files you need. In your board directory, you will need at least
2366 the "Makefile" and a "<board>.c".
2367 2. Create a new configuration file "include/configs/<board>.h" for
2369 3. If you're porting U-Boot to a new CPU, then also create a new
2370 directory to hold your CPU specific code. Add any files you need.
2371 4. Run "make <board>_defconfig" with your new name.
2372 5. Type "make", and you should get a working "u-boot.srec" file
2373 to be installed on your target system.
2374 6. Debug and solve any problems that might arise.
2375 [Of course, this last step is much harder than it sounds.]
2378 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2379 ==============================================================
2381 If you have modified U-Boot sources (for instance added a new board
2382 or support for new devices, a new CPU, etc.) you are expected to
2383 provide feedback to the other developers. The feedback normally takes
2384 the form of a "patch", i.e. a context diff against a certain (latest
2385 official or latest in the git repository) version of U-Boot sources.
2387 But before you submit such a patch, please verify that your modifi-
2388 cation did not break existing code. At least make sure that *ALL* of
2389 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2390 just run the buildman script (tools/buildman/buildman), which will
2391 configure and build U-Boot for ALL supported system. Be warned, this
2392 will take a while. Please see the buildman README, or run 'buildman -H'
2396 See also "U-Boot Porting Guide" below.
2399 Monitor Commands - Overview:
2400 ============================
2402 go - start application at address 'addr'
2403 run - run commands in an environment variable
2404 bootm - boot application image from memory
2405 bootp - boot image via network using BootP/TFTP protocol
2406 bootz - boot zImage from memory
2407 tftpboot- boot image via network using TFTP protocol
2408 and env variables "ipaddr" and "serverip"
2409 (and eventually "gatewayip")
2410 tftpput - upload a file via network using TFTP protocol
2411 rarpboot- boot image via network using RARP/TFTP protocol
2412 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2413 loads - load S-Record file over serial line
2414 loadb - load binary file over serial line (kermit mode)
2415 loadm - load binary blob from source address to destination address
2417 mm - memory modify (auto-incrementing)
2418 nm - memory modify (constant address)
2419 mw - memory write (fill)
2422 cmp - memory compare
2423 crc32 - checksum calculation
2424 i2c - I2C sub-system
2425 sspi - SPI utility commands
2426 base - print or set address offset
2427 printenv- print environment variables
2428 pwm - control pwm channels
2429 setenv - set environment variables
2430 saveenv - save environment variables to persistent storage
2431 protect - enable or disable FLASH write protection
2432 erase - erase FLASH memory
2433 flinfo - print FLASH memory information
2434 nand - NAND memory operations (see doc/README.nand)
2435 bdinfo - print Board Info structure
2436 iminfo - print header information for application image
2437 coninfo - print console devices and informations
2438 ide - IDE sub-system
2439 loop - infinite loop on address range
2440 loopw - infinite write loop on address range
2441 mtest - simple RAM test
2442 icache - enable or disable instruction cache
2443 dcache - enable or disable data cache
2444 reset - Perform RESET of the CPU
2445 echo - echo args to console
2446 version - print monitor version
2447 help - print online help
2448 ? - alias for 'help'
2451 Monitor Commands - Detailed Description:
2452 ========================================
2456 For now: just type "help <command>".
2459 Note for Redundant Ethernet Interfaces:
2460 =======================================
2462 Some boards come with redundant Ethernet interfaces; U-Boot supports
2463 such configurations and is capable of automatic selection of a
2464 "working" interface when needed. MAC assignment works as follows:
2466 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2467 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2468 "eth1addr" (=>eth1), "eth2addr", ...
2470 If the network interface stores some valid MAC address (for instance
2471 in SROM), this is used as default address if there is NO correspon-
2472 ding setting in the environment; if the corresponding environment
2473 variable is set, this overrides the settings in the card; that means:
2475 o If the SROM has a valid MAC address, and there is no address in the
2476 environment, the SROM's address is used.
2478 o If there is no valid address in the SROM, and a definition in the
2479 environment exists, then the value from the environment variable is
2482 o If both the SROM and the environment contain a MAC address, and
2483 both addresses are the same, this MAC address is used.
2485 o If both the SROM and the environment contain a MAC address, and the
2486 addresses differ, the value from the environment is used and a
2489 o If neither SROM nor the environment contain a MAC address, an error
2490 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2491 a random, locally-assigned MAC is used.
2493 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2494 will be programmed into hardware as part of the initialization process. This
2495 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2496 The naming convention is as follows:
2497 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2502 U-Boot is capable of booting (and performing other auxiliary operations on)
2503 images in two formats:
2505 New uImage format (FIT)
2506 -----------------------
2508 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2509 to Flattened Device Tree). It allows the use of images with multiple
2510 components (several kernels, ramdisks, etc.), with contents protected by
2511 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2517 Old image format is based on binary files which can be basically anything,
2518 preceded by a special header; see the definitions in include/image.h for
2519 details; basically, the header defines the following image properties:
2521 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2522 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2523 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2524 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2525 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2526 IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2527 Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
2528 * Compression Type (uncompressed, gzip, bzip2)
2534 The header is marked by a special Magic Number, and both the header
2535 and the data portions of the image are secured against corruption by
2542 Although U-Boot should support any OS or standalone application
2543 easily, the main focus has always been on Linux during the design of
2546 U-Boot includes many features that so far have been part of some
2547 special "boot loader" code within the Linux kernel. Also, any
2548 "initrd" images to be used are no longer part of one big Linux image;
2549 instead, kernel and "initrd" are separate images. This implementation
2550 serves several purposes:
2552 - the same features can be used for other OS or standalone
2553 applications (for instance: using compressed images to reduce the
2554 Flash memory footprint)
2556 - it becomes much easier to port new Linux kernel versions because
2557 lots of low-level, hardware dependent stuff are done by U-Boot
2559 - the same Linux kernel image can now be used with different "initrd"
2560 images; of course this also means that different kernel images can
2561 be run with the same "initrd". This makes testing easier (you don't
2562 have to build a new "zImage.initrd" Linux image when you just
2563 change a file in your "initrd"). Also, a field-upgrade of the
2564 software is easier now.
2570 Porting Linux to U-Boot based systems:
2571 ---------------------------------------
2573 U-Boot cannot save you from doing all the necessary modifications to
2574 configure the Linux device drivers for use with your target hardware
2575 (no, we don't intend to provide a full virtual machine interface to
2578 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2580 Just make sure your machine specific header file (for instance
2581 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2582 Information structure as we define in include/asm-<arch>/u-boot.h,
2583 and make sure that your definition of IMAP_ADDR uses the same value
2584 as your U-Boot configuration in CONFIG_SYS_IMMR.
2586 Note that U-Boot now has a driver model, a unified model for drivers.
2587 If you are adding a new driver, plumb it into driver model. If there
2588 is no uclass available, you are encouraged to create one. See
2592 Configuring the Linux kernel:
2593 -----------------------------
2595 No specific requirements for U-Boot. Make sure you have some root
2596 device (initial ramdisk, NFS) for your target system.
2599 Building a Linux Image:
2600 -----------------------
2602 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2603 not used. If you use recent kernel source, a new build target
2604 "uImage" will exist which automatically builds an image usable by
2605 U-Boot. Most older kernels also have support for a "pImage" target,
2606 which was introduced for our predecessor project PPCBoot and uses a
2607 100% compatible format.
2611 make TQM850L_defconfig
2616 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2617 encapsulate a compressed Linux kernel image with header information,
2618 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2620 * build a standard "vmlinux" kernel image (in ELF binary format):
2622 * convert the kernel into a raw binary image:
2624 ${CROSS_COMPILE}-objcopy -O binary \
2625 -R .note -R .comment \
2626 -S vmlinux linux.bin
2628 * compress the binary image:
2632 * package compressed binary image for U-Boot:
2634 mkimage -A ppc -O linux -T kernel -C gzip \
2635 -a 0 -e 0 -n "Linux Kernel Image" \
2636 -d linux.bin.gz uImage
2639 The "mkimage" tool can also be used to create ramdisk images for use
2640 with U-Boot, either separated from the Linux kernel image, or
2641 combined into one file. "mkimage" encapsulates the images with a 64
2642 byte header containing information about target architecture,
2643 operating system, image type, compression method, entry points, time
2644 stamp, CRC32 checksums, etc.
2646 "mkimage" can be called in two ways: to verify existing images and
2647 print the header information, or to build new images.
2649 In the first form (with "-l" option) mkimage lists the information
2650 contained in the header of an existing U-Boot image; this includes
2651 checksum verification:
2653 tools/mkimage -l image
2654 -l ==> list image header information
2656 The second form (with "-d" option) is used to build a U-Boot image
2657 from a "data file" which is used as image payload:
2659 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2660 -n name -d data_file image
2661 -A ==> set architecture to 'arch'
2662 -O ==> set operating system to 'os'
2663 -T ==> set image type to 'type'
2664 -C ==> set compression type 'comp'
2665 -a ==> set load address to 'addr' (hex)
2666 -e ==> set entry point to 'ep' (hex)
2667 -n ==> set image name to 'name'
2668 -d ==> use image data from 'datafile'
2670 Right now, all Linux kernels for PowerPC systems use the same load
2671 address (0x00000000), but the entry point address depends on the
2674 - 2.2.x kernels have the entry point at 0x0000000C,
2675 - 2.3.x and later kernels have the entry point at 0x00000000.
2677 So a typical call to build a U-Boot image would read:
2679 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2680 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2681 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2682 > examples/uImage.TQM850L
2683 Image Name: 2.4.4 kernel for TQM850L
2684 Created: Wed Jul 19 02:34:59 2000
2685 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2686 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2687 Load Address: 0x00000000
2688 Entry Point: 0x00000000
2690 To verify the contents of the image (or check for corruption):
2692 -> tools/mkimage -l examples/uImage.TQM850L
2693 Image Name: 2.4.4 kernel for TQM850L
2694 Created: Wed Jul 19 02:34:59 2000
2695 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2696 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2697 Load Address: 0x00000000
2698 Entry Point: 0x00000000
2700 NOTE: for embedded systems where boot time is critical you can trade
2701 speed for memory and install an UNCOMPRESSED image instead: this
2702 needs more space in Flash, but boots much faster since it does not
2703 need to be uncompressed:
2705 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2706 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2707 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2708 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2709 > examples/uImage.TQM850L-uncompressed
2710 Image Name: 2.4.4 kernel for TQM850L
2711 Created: Wed Jul 19 02:34:59 2000
2712 Image Type: PowerPC Linux Kernel Image (uncompressed)
2713 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2714 Load Address: 0x00000000
2715 Entry Point: 0x00000000
2718 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2719 when your kernel is intended to use an initial ramdisk:
2721 -> tools/mkimage -n 'Simple Ramdisk Image' \
2722 > -A ppc -O linux -T ramdisk -C gzip \
2723 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2724 Image Name: Simple Ramdisk Image
2725 Created: Wed Jan 12 14:01:50 2000
2726 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2727 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2728 Load Address: 0x00000000
2729 Entry Point: 0x00000000
2731 The "dumpimage" tool can be used to disassemble or list the contents of images
2732 built by mkimage. See dumpimage's help output (-h) for details.
2734 Installing a Linux Image:
2735 -------------------------
2737 To downloading a U-Boot image over the serial (console) interface,
2738 you must convert the image to S-Record format:
2740 objcopy -I binary -O srec examples/image examples/image.srec
2742 The 'objcopy' does not understand the information in the U-Boot
2743 image header, so the resulting S-Record file will be relative to
2744 address 0x00000000. To load it to a given address, you need to
2745 specify the target address as 'offset' parameter with the 'loads'
2748 Example: install the image to address 0x40100000 (which on the
2749 TQM8xxL is in the first Flash bank):
2751 => erase 40100000 401FFFFF
2757 ## Ready for S-Record download ...
2758 ~>examples/image.srec
2759 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2761 15989 15990 15991 15992
2762 [file transfer complete]
2764 ## Start Addr = 0x00000000
2767 You can check the success of the download using the 'iminfo' command;
2768 this includes a checksum verification so you can be sure no data
2769 corruption happened:
2773 ## Checking Image at 40100000 ...
2774 Image Name: 2.2.13 for initrd on TQM850L
2775 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2776 Data Size: 335725 Bytes = 327 kB = 0 MB
2777 Load Address: 00000000
2778 Entry Point: 0000000c
2779 Verifying Checksum ... OK
2785 The "bootm" command is used to boot an application that is stored in
2786 memory (RAM or Flash). In case of a Linux kernel image, the contents
2787 of the "bootargs" environment variable is passed to the kernel as
2788 parameters. You can check and modify this variable using the
2789 "printenv" and "setenv" commands:
2792 => printenv bootargs
2793 bootargs=root=/dev/ram
2795 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2797 => printenv bootargs
2798 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2801 ## Booting Linux kernel at 40020000 ...
2802 Image Name: 2.2.13 for NFS on TQM850L
2803 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2804 Data Size: 381681 Bytes = 372 kB = 0 MB
2805 Load Address: 00000000
2806 Entry Point: 0000000c
2807 Verifying Checksum ... OK
2808 Uncompressing Kernel Image ... OK
2809 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
2810 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2811 time_init: decrementer frequency = 187500000/60
2812 Calibrating delay loop... 49.77 BogoMIPS
2813 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2816 If you want to boot a Linux kernel with initial RAM disk, you pass
2817 the memory addresses of both the kernel and the initrd image (PPBCOOT
2818 format!) to the "bootm" command:
2820 => imi 40100000 40200000
2822 ## Checking Image at 40100000 ...
2823 Image Name: 2.2.13 for initrd on TQM850L
2824 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2825 Data Size: 335725 Bytes = 327 kB = 0 MB
2826 Load Address: 00000000
2827 Entry Point: 0000000c
2828 Verifying Checksum ... OK
2830 ## Checking Image at 40200000 ...
2831 Image Name: Simple Ramdisk Image
2832 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2833 Data Size: 566530 Bytes = 553 kB = 0 MB
2834 Load Address: 00000000
2835 Entry Point: 00000000
2836 Verifying Checksum ... OK
2838 => bootm 40100000 40200000
2839 ## Booting Linux kernel at 40100000 ...
2840 Image Name: 2.2.13 for initrd on TQM850L
2841 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2842 Data Size: 335725 Bytes = 327 kB = 0 MB
2843 Load Address: 00000000
2844 Entry Point: 0000000c
2845 Verifying Checksum ... OK
2846 Uncompressing Kernel Image ... OK
2847 ## Loading RAMDisk Image at 40200000 ...
2848 Image Name: Simple Ramdisk Image
2849 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2850 Data Size: 566530 Bytes = 553 kB = 0 MB
2851 Load Address: 00000000
2852 Entry Point: 00000000
2853 Verifying Checksum ... OK
2854 Loading Ramdisk ... OK
2855 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
2856 Boot arguments: root=/dev/ram
2857 time_init: decrementer frequency = 187500000/60
2858 Calibrating delay loop... 49.77 BogoMIPS
2860 RAMDISK: Compressed image found at block 0
2861 VFS: Mounted root (ext2 filesystem).
2865 Boot Linux and pass a flat device tree:
2868 First, U-Boot must be compiled with the appropriate defines. See the section
2869 titled "Linux Kernel Interface" above for a more in depth explanation. The
2870 following is an example of how to start a kernel and pass an updated
2876 oft=oftrees/mpc8540ads.dtb
2877 => tftp $oftaddr $oft
2878 Speed: 1000, full duplex
2880 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
2881 Filename 'oftrees/mpc8540ads.dtb'.
2882 Load address: 0x300000
2885 Bytes transferred = 4106 (100a hex)
2886 => tftp $loadaddr $bootfile
2887 Speed: 1000, full duplex
2889 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
2891 Load address: 0x200000
2892 Loading:############
2894 Bytes transferred = 1029407 (fb51f hex)
2899 => bootm $loadaddr - $oftaddr
2900 ## Booting image at 00200000 ...
2901 Image Name: Linux-2.6.17-dirty
2902 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2903 Data Size: 1029343 Bytes = 1005.2 kB
2904 Load Address: 00000000
2905 Entry Point: 00000000
2906 Verifying Checksum ... OK
2907 Uncompressing Kernel Image ... OK
2908 Booting using flat device tree at 0x300000
2909 Using MPC85xx ADS machine description
2910 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
2914 More About U-Boot Image Types:
2915 ------------------------------
2917 U-Boot supports the following image types:
2919 "Standalone Programs" are directly runnable in the environment
2920 provided by U-Boot; it is expected that (if they behave
2921 well) you can continue to work in U-Boot after return from
2922 the Standalone Program.
2923 "OS Kernel Images" are usually images of some Embedded OS which
2924 will take over control completely. Usually these programs
2925 will install their own set of exception handlers, device
2926 drivers, set up the MMU, etc. - this means, that you cannot
2927 expect to re-enter U-Boot except by resetting the CPU.
2928 "RAMDisk Images" are more or less just data blocks, and their
2929 parameters (address, size) are passed to an OS kernel that is
2931 "Multi-File Images" contain several images, typically an OS
2932 (Linux) kernel image and one or more data images like
2933 RAMDisks. This construct is useful for instance when you want
2934 to boot over the network using BOOTP etc., where the boot
2935 server provides just a single image file, but you want to get
2936 for instance an OS kernel and a RAMDisk image.
2938 "Multi-File Images" start with a list of image sizes, each
2939 image size (in bytes) specified by an "uint32_t" in network
2940 byte order. This list is terminated by an "(uint32_t)0".
2941 Immediately after the terminating 0 follow the images, one by
2942 one, all aligned on "uint32_t" boundaries (size rounded up to
2943 a multiple of 4 bytes).
2945 "Firmware Images" are binary images containing firmware (like
2946 U-Boot or FPGA images) which usually will be programmed to
2949 "Script files" are command sequences that will be executed by
2950 U-Boot's command interpreter; this feature is especially
2951 useful when you configure U-Boot to use a real shell (hush)
2952 as command interpreter.
2954 Booting the Linux zImage:
2955 -------------------------
2957 On some platforms, it's possible to boot Linux zImage. This is done
2958 using the "bootz" command. The syntax of "bootz" command is the same
2959 as the syntax of "bootm" command.
2961 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
2962 kernel with raw initrd images. The syntax is slightly different, the
2963 address of the initrd must be augmented by it's size, in the following
2964 format: "<initrd addres>:<initrd size>".
2970 One of the features of U-Boot is that you can dynamically load and
2971 run "standalone" applications, which can use some resources of
2972 U-Boot like console I/O functions or interrupt services.
2974 Two simple examples are included with the sources:
2979 'examples/hello_world.c' contains a small "Hello World" Demo
2980 application; it is automatically compiled when you build U-Boot.
2981 It's configured to run at address 0x00040004, so you can play with it
2985 ## Ready for S-Record download ...
2986 ~>examples/hello_world.srec
2987 1 2 3 4 5 6 7 8 9 10 11 ...
2988 [file transfer complete]
2990 ## Start Addr = 0x00040004
2992 => go 40004 Hello World! This is a test.
2993 ## Starting application at 0x00040004 ...
3004 Hit any key to exit ...
3006 ## Application terminated, rc = 0x0
3008 Another example, which demonstrates how to register a CPM interrupt
3009 handler with the U-Boot code, can be found in 'examples/timer.c'.
3010 Here, a CPM timer is set up to generate an interrupt every second.
3011 The interrupt service routine is trivial, just printing a '.'
3012 character, but this is just a demo program. The application can be
3013 controlled by the following keys:
3015 ? - print current values og the CPM Timer registers
3016 b - enable interrupts and start timer
3017 e - stop timer and disable interrupts
3018 q - quit application
3021 ## Ready for S-Record download ...
3022 ~>examples/timer.srec
3023 1 2 3 4 5 6 7 8 9 10 11 ...
3024 [file transfer complete]
3026 ## Start Addr = 0x00040004
3029 ## Starting application at 0x00040004 ...
3032 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3035 [q, b, e, ?] Set interval 1000000 us
3038 [q, b, e, ?] ........
3039 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3042 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3045 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3048 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3050 [q, b, e, ?] ...Stopping timer
3052 [q, b, e, ?] ## Application terminated, rc = 0x0
3058 Over time, many people have reported problems when trying to use the
3059 "minicom" terminal emulation program for serial download. I (wd)
3060 consider minicom to be broken, and recommend not to use it. Under
3061 Unix, I recommend to use C-Kermit for general purpose use (and
3062 especially for kermit binary protocol download ("loadb" command), and
3063 use "cu" for S-Record download ("loads" command). See
3064 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3065 for help with kermit.
3068 Nevertheless, if you absolutely want to use it try adding this
3069 configuration to your "File transfer protocols" section:
3071 Name Program Name U/D FullScr IO-Red. Multi
3072 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3073 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3079 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3080 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3082 Building requires a cross environment; it is known to work on
3083 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3084 need gmake since the Makefiles are not compatible with BSD make).
3085 Note that the cross-powerpc package does not install include files;
3086 attempting to build U-Boot will fail because <machine/ansi.h> is
3087 missing. This file has to be installed and patched manually:
3089 # cd /usr/pkg/cross/powerpc-netbsd/include
3091 # ln -s powerpc machine
3092 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3093 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3095 Native builds *don't* work due to incompatibilities between native
3096 and U-Boot include files.
3098 Booting assumes that (the first part of) the image booted is a
3099 stage-2 loader which in turn loads and then invokes the kernel
3100 proper. Loader sources will eventually appear in the NetBSD source
3101 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3102 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3105 Implementation Internals:
3106 =========================
3108 The following is not intended to be a complete description of every
3109 implementation detail. However, it should help to understand the
3110 inner workings of U-Boot and make it easier to port it to custom
3114 Initial Stack, Global Data:
3115 ---------------------------
3117 The implementation of U-Boot is complicated by the fact that U-Boot
3118 starts running out of ROM (flash memory), usually without access to
3119 system RAM (because the memory controller is not initialized yet).
3120 This means that we don't have writable Data or BSS segments, and BSS
3121 is not initialized as zero. To be able to get a C environment working
3122 at all, we have to allocate at least a minimal stack. Implementation
3123 options for this are defined and restricted by the CPU used: Some CPU
3124 models provide on-chip memory (like the IMMR area on MPC8xx and
3125 MPC826x processors), on others (parts of) the data cache can be
3126 locked as (mis-) used as memory, etc.
3128 Chris Hallinan posted a good summary of these issues to the
3129 U-Boot mailing list:
3131 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3132 From: "Chris Hallinan" <clh@net1plus.com>
3133 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3136 Correct me if I'm wrong, folks, but the way I understand it
3137 is this: Using DCACHE as initial RAM for Stack, etc, does not
3138 require any physical RAM backing up the cache. The cleverness
3139 is that the cache is being used as a temporary supply of
3140 necessary storage before the SDRAM controller is setup. It's
3141 beyond the scope of this list to explain the details, but you
3142 can see how this works by studying the cache architecture and
3143 operation in the architecture and processor-specific manuals.
3145 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3146 is another option for the system designer to use as an
3147 initial stack/RAM area prior to SDRAM being available. Either
3148 option should work for you. Using CS 4 should be fine if your
3149 board designers haven't used it for something that would
3150 cause you grief during the initial boot! It is frequently not
3153 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3154 with your processor/board/system design. The default value
3155 you will find in any recent u-boot distribution in
3156 walnut.h should work for you. I'd set it to a value larger
3157 than your SDRAM module. If you have a 64MB SDRAM module, set
3158 it above 400_0000. Just make sure your board has no resources
3159 that are supposed to respond to that address! That code in
3160 start.S has been around a while and should work as is when
3161 you get the config right.
3166 It is essential to remember this, since it has some impact on the C
3167 code for the initialization procedures:
3169 * Initialized global data (data segment) is read-only. Do not attempt
3172 * Do not use any uninitialized global data (or implicitly initialized
3173 as zero data - BSS segment) at all - this is undefined, initiali-
3174 zation is performed later (when relocating to RAM).
3176 * Stack space is very limited. Avoid big data buffers or things like
3179 Having only the stack as writable memory limits means we cannot use
3180 normal global data to share information between the code. But it
3181 turned out that the implementation of U-Boot can be greatly
3182 simplified by making a global data structure (gd_t) available to all
3183 functions. We could pass a pointer to this data as argument to _all_
3184 functions, but this would bloat the code. Instead we use a feature of
3185 the GCC compiler (Global Register Variables) to share the data: we
3186 place a pointer (gd) to the global data into a register which we
3187 reserve for this purpose.
3189 When choosing a register for such a purpose we are restricted by the
3190 relevant (E)ABI specifications for the current architecture, and by
3191 GCC's implementation.
3193 For PowerPC, the following registers have specific use:
3195 R2: reserved for system use
3196 R3-R4: parameter passing and return values
3197 R5-R10: parameter passing
3198 R13: small data area pointer
3202 (U-Boot also uses R12 as internal GOT pointer. r12
3203 is a volatile register so r12 needs to be reset when
3204 going back and forth between asm and C)
3206 ==> U-Boot will use R2 to hold a pointer to the global data
3208 Note: on PPC, we could use a static initializer (since the
3209 address of the global data structure is known at compile time),
3210 but it turned out that reserving a register results in somewhat
3211 smaller code - although the code savings are not that big (on
3212 average for all boards 752 bytes for the whole U-Boot image,
3213 624 text + 127 data).
3215 On ARM, the following registers are used:
3217 R0: function argument word/integer result
3218 R1-R3: function argument word
3219 R9: platform specific
3220 R10: stack limit (used only if stack checking is enabled)
3221 R11: argument (frame) pointer
3222 R12: temporary workspace
3225 R15: program counter
3227 ==> U-Boot will use R9 to hold a pointer to the global data
3229 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3231 On Nios II, the ABI is documented here:
3232 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3234 ==> U-Boot will use gp to hold a pointer to the global data
3236 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3237 to access small data sections, so gp is free.
3239 On RISC-V, the following registers are used:
3241 x0: hard-wired zero (zero)
3242 x1: return address (ra)
3243 x2: stack pointer (sp)
3244 x3: global pointer (gp)
3245 x4: thread pointer (tp)
3246 x5: link register (t0)
3247 x8: frame pointer (fp)
3248 x10-x11: arguments/return values (a0-1)
3249 x12-x17: arguments (a2-7)
3250 x28-31: temporaries (t3-6)
3251 pc: program counter (pc)
3253 ==> U-Boot will use gp to hold a pointer to the global data
3258 U-Boot runs in system state and uses physical addresses, i.e. the
3259 MMU is not used either for address mapping nor for memory protection.
3261 The available memory is mapped to fixed addresses using the memory
3262 controller. In this process, a contiguous block is formed for each
3263 memory type (Flash, SDRAM, SRAM), even when it consists of several
3264 physical memory banks.
3266 U-Boot is installed in the first 128 kB of the first Flash bank (on
3267 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3268 booting and sizing and initializing DRAM, the code relocates itself
3269 to the upper end of DRAM. Immediately below the U-Boot code some
3270 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3271 configuration setting]. Below that, a structure with global Board
3272 Info data is placed, followed by the stack (growing downward).
3274 Additionally, some exception handler code is copied to the low 8 kB
3275 of DRAM (0x00000000 ... 0x00001FFF).
3277 So a typical memory configuration with 16 MB of DRAM could look like
3280 0x0000 0000 Exception Vector code
3283 0x0000 2000 Free for Application Use
3289 0x00FB FF20 Monitor Stack (Growing downward)
3290 0x00FB FFAC Board Info Data and permanent copy of global data
3291 0x00FC 0000 Malloc Arena
3294 0x00FE 0000 RAM Copy of Monitor Code
3295 ... eventually: LCD or video framebuffer
3296 ... eventually: pRAM (Protected RAM - unchanged by reset)
3297 0x00FF FFFF [End of RAM]
3300 System Initialization:
3301 ----------------------
3303 In the reset configuration, U-Boot starts at the reset entry point
3304 (on most PowerPC systems at address 0x00000100). Because of the reset
3305 configuration for CS0# this is a mirror of the on board Flash memory.
3306 To be able to re-map memory U-Boot then jumps to its link address.
3307 To be able to implement the initialization code in C, a (small!)
3308 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3309 which provide such a feature like), or in a locked part of the data
3310 cache. After that, U-Boot initializes the CPU core, the caches and
3313 Next, all (potentially) available memory banks are mapped using a
3314 preliminary mapping. For example, we put them on 512 MB boundaries
3315 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3316 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3317 programmed for SDRAM access. Using the temporary configuration, a
3318 simple memory test is run that determines the size of the SDRAM
3321 When there is more than one SDRAM bank, and the banks are of
3322 different size, the largest is mapped first. For equal size, the first
3323 bank (CS2#) is mapped first. The first mapping is always for address
3324 0x00000000, with any additional banks following immediately to create
3325 contiguous memory starting from 0.
3327 Then, the monitor installs itself at the upper end of the SDRAM area
3328 and allocates memory for use by malloc() and for the global Board
3329 Info data; also, the exception vector code is copied to the low RAM
3330 pages, and the final stack is set up.
3332 Only after this relocation will you have a "normal" C environment;
3333 until that you are restricted in several ways, mostly because you are
3334 running from ROM, and because the code will have to be relocated to a
3338 U-Boot Porting Guide:
3339 ----------------------
3341 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3345 int main(int argc, char *argv[])
3347 sighandler_t no_more_time;
3349 signal(SIGALRM, no_more_time);
3350 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3352 if (available_money > available_manpower) {
3353 Pay consultant to port U-Boot;
3357 Download latest U-Boot source;
3359 Subscribe to u-boot mailing list;
3362 email("Hi, I am new to U-Boot, how do I get started?");
3365 Read the README file in the top level directory;
3366 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3367 Read applicable doc/README.*;
3368 Read the source, Luke;
3369 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3372 if (available_money > toLocalCurrency ($2500))
3375 Add a lot of aggravation and time;
3377 if (a similar board exists) { /* hopefully... */
3378 cp -a board/<similar> board/<myboard>
3379 cp include/configs/<similar>.h include/configs/<myboard>.h
3381 Create your own board support subdirectory;
3382 Create your own board include/configs/<myboard>.h file;
3384 Edit new board/<myboard> files
3385 Edit new include/configs/<myboard>.h
3390 Add / modify source code;
3394 email("Hi, I am having problems...");
3396 Send patch file to the U-Boot email list;
3397 if (reasonable critiques)
3398 Incorporate improvements from email list code review;
3400 Defend code as written;
3406 void no_more_time (int sig)
3415 All contributions to U-Boot should conform to the Linux kernel
3416 coding style; see the kernel coding style guide at
3417 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3418 script "scripts/Lindent" in your Linux kernel source directory.
3420 Source files originating from a different project (for example the
3421 MTD subsystem) are generally exempt from these guidelines and are not
3422 reformatted to ease subsequent migration to newer versions of those
3425 Please note that U-Boot is implemented in C (and to some small parts in
3426 Assembler); no C++ is used, so please do not use C++ style comments (//)
3429 Please also stick to the following formatting rules:
3430 - remove any trailing white space
3431 - use TAB characters for indentation and vertical alignment, not spaces
3432 - make sure NOT to use DOS '\r\n' line feeds
3433 - do not add more than 2 consecutive empty lines to source files
3434 - do not add trailing empty lines to source files
3436 Submissions which do not conform to the standards may be returned
3437 with a request to reformat the changes.
3443 Since the number of patches for U-Boot is growing, we need to
3444 establish some rules. Submissions which do not conform to these rules
3445 may be rejected, even when they contain important and valuable stuff.
3447 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3449 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3450 see https://lists.denx.de/listinfo/u-boot
3452 When you send a patch, please include the following information with
3455 * For bug fixes: a description of the bug and how your patch fixes
3456 this bug. Please try to include a way of demonstrating that the
3457 patch actually fixes something.
3459 * For new features: a description of the feature and your
3462 * For major contributions, add a MAINTAINERS file with your
3463 information and associated file and directory references.
3465 * When you add support for a new board, don't forget to add a
3466 maintainer e-mail address to the boards.cfg file, too.
3468 * If your patch adds new configuration options, don't forget to
3469 document these in the README file.
3471 * The patch itself. If you are using git (which is *strongly*
3472 recommended) you can easily generate the patch using the
3473 "git format-patch". If you then use "git send-email" to send it to
3474 the U-Boot mailing list, you will avoid most of the common problems
3475 with some other mail clients.
3477 If you cannot use git, use "diff -purN OLD NEW". If your version of
3478 diff does not support these options, then get the latest version of
3481 The current directory when running this command shall be the parent
3482 directory of the U-Boot source tree (i. e. please make sure that
3483 your patch includes sufficient directory information for the
3486 We prefer patches as plain text. MIME attachments are discouraged,
3487 and compressed attachments must not be used.
3489 * If one logical set of modifications affects or creates several
3490 files, all these changes shall be submitted in a SINGLE patch file.
3492 * Changesets that contain different, unrelated modifications shall be
3493 submitted as SEPARATE patches, one patch per changeset.
3498 * Before sending the patch, run the buildman script on your patched
3499 source tree and make sure that no errors or warnings are reported
3500 for any of the boards.
3502 * Keep your modifications to the necessary minimum: A patch
3503 containing several unrelated changes or arbitrary reformats will be
3504 returned with a request to re-formatting / split it.
3506 * If you modify existing code, make sure that your new code does not
3507 add to the memory footprint of the code ;-) Small is beautiful!
3508 When adding new features, these should compile conditionally only
3509 (using #ifdef), and the resulting code with the new feature
3510 disabled must not need more memory than the old code without your
3513 * Remember that there is a size limit of 100 kB per message on the
3514 u-boot mailing list. Bigger patches will be moderated. If they are
3515 reasonable and not too big, they will be acknowledged. But patches
3516 bigger than the size limit should be avoided.