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_SPL_STACK_R_ADDR points into SDRAM
297 - preloader_console_init() can be called here - typically this is
298 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
299 spl_board_init() function containing this call
300 - loads U-Boot or (in falcon mode) Linux
303 Configuration Options:
304 ----------------------
306 Configuration depends on the combination of board and CPU type; all
307 such information is kept in a configuration file
308 "include/configs/<board_name>.h".
310 Example: For a TQM823L module, all configuration settings are in
311 "include/configs/TQM823L.h".
314 Many of the options are named exactly as the corresponding Linux
315 kernel configuration options. The intention is to make it easier to
316 build a config tool - later.
318 - ARM Platform Bus Type(CCI):
319 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
320 provides full cache coherency between two clusters of multi-core
321 CPUs and I/O coherency for devices and I/O masters
323 CONFIG_SYS_FSL_HAS_CCI400
325 Defined For SoC that has cache coherent interconnect
328 CONFIG_SYS_FSL_HAS_CCN504
330 Defined for SoC that has cache coherent interconnect CCN-504
332 The following options need to be configured:
334 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
336 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
341 Specifies that the core is a 64-bit PowerPC implementation (implements
342 the "64" category of the Power ISA). This is necessary for ePAPR
343 compliance, among other possible reasons.
345 CONFIG_SYS_FSL_TBCLK_DIV
347 Defines the core time base clock divider ratio compared to the
348 system clock. On most PQ3 devices this is 8, on newer QorIQ
349 devices it can be 16 or 32. The ratio varies from SoC to Soc.
351 CONFIG_SYS_FSL_PCIE_COMPAT
353 Defines the string to utilize when trying to match PCIe device
354 tree nodes for the given platform.
356 CONFIG_SYS_FSL_ERRATUM_A004510
358 Enables a workaround for erratum A004510. If set,
359 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
360 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
362 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
365 Defines one or two SoC revisions (low 8 bits of SVR)
366 for which the A004510 workaround should be applied.
368 The rest of SVR is either not relevant to the decision
369 of whether the erratum is present (e.g. p2040 versus
370 p2041) or is implied by the build target, which controls
371 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
373 See Freescale App Note 4493 for more information about
376 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
378 This is the value to write into CCSR offset 0x18600
379 according to the A004510 workaround.
381 CONFIG_SYS_FSL_DSP_DDR_ADDR
382 This value denotes start offset of DDR memory which is
383 connected exclusively to the DSP cores.
385 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
386 This value denotes start offset of M2 memory
387 which is directly connected to the DSP core.
389 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
390 This value denotes start offset of M3 memory which is directly
391 connected to the DSP core.
393 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
394 This value denotes start offset of DSP CCSR space.
396 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
397 Single Source Clock is clocking mode present in some of FSL SoC's.
398 In this mode, a single differential clock is used to supply
399 clocks to the sysclock, ddrclock and usbclock.
401 CONFIG_SYS_CPC_REINIT_F
402 This CONFIG is defined when the CPC is configured as SRAM at the
403 time of U-Boot entry and is required to be re-initialized.
405 - Generic CPU options:
406 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
408 Defines the endianess of the CPU. Implementation of those
409 values is arch specific.
412 Freescale DDR driver in use. This type of DDR controller is
413 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
415 CONFIG_SYS_FSL_DDR_ADDR
416 Freescale DDR memory-mapped register base.
418 CONFIG_SYS_FSL_DDR_EMU
419 Specify emulator support for DDR. Some DDR features such as
420 deskew training are not available.
422 CONFIG_SYS_FSL_DDRC_GEN1
423 Freescale DDR1 controller.
425 CONFIG_SYS_FSL_DDRC_GEN2
426 Freescale DDR2 controller.
428 CONFIG_SYS_FSL_DDRC_GEN3
429 Freescale DDR3 controller.
431 CONFIG_SYS_FSL_DDRC_GEN4
432 Freescale DDR4 controller.
434 CONFIG_SYS_FSL_DDRC_ARM_GEN3
435 Freescale DDR3 controller for ARM-based SoCs.
438 Board config to use DDR1. It can be enabled for SoCs with
439 Freescale DDR1 or DDR2 controllers, depending on the board
443 Board config to use DDR2. It can be enabled for SoCs with
444 Freescale DDR2 or DDR3 controllers, depending on the board
448 Board config to use DDR3. It can be enabled for SoCs with
449 Freescale DDR3 or DDR3L controllers.
452 Board config to use DDR3L. It can be enabled for SoCs with
455 CONFIG_SYS_FSL_IFC_BE
456 Defines the IFC controller register space as Big Endian
458 CONFIG_SYS_FSL_IFC_LE
459 Defines the IFC controller register space as Little Endian
461 CONFIG_SYS_FSL_IFC_CLK_DIV
462 Defines divider of platform clock(clock input to IFC controller).
464 CONFIG_SYS_FSL_LBC_CLK_DIV
465 Defines divider of platform clock(clock input to eLBC controller).
467 CONFIG_SYS_FSL_DDR_BE
468 Defines the DDR controller register space as Big Endian
470 CONFIG_SYS_FSL_DDR_LE
471 Defines the DDR controller register space as Little Endian
473 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
474 Physical address from the view of DDR controllers. It is the
475 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
476 it could be different for ARM SoCs.
478 CONFIG_SYS_FSL_DDR_INTLV_256B
479 DDR controller interleaving on 256-byte. This is a special
480 interleaving mode, handled by Dickens for Freescale layerscape
483 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
484 Number of controllers used as main memory.
486 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
487 Number of controllers used for other than main memory.
489 CONFIG_SYS_FSL_SEC_BE
490 Defines the SEC controller register space as Big Endian
492 CONFIG_SYS_FSL_SEC_LE
493 Defines the SEC controller register space as Little Endian
496 CONFIG_XWAY_SWAP_BYTES
498 Enable compilation of tools/xway-swap-bytes needed for Lantiq
499 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
500 be swapped if a flash programmer is used.
503 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
505 Select high exception vectors of the ARM core, e.g., do not
506 clear the V bit of the c1 register of CP15.
509 Generic timer clock source frequency.
511 COUNTER_FREQUENCY_REAL
512 Generic timer clock source frequency if the real clock is
513 different from COUNTER_FREQUENCY, and can only be determined
517 CONFIG_TEGRA_SUPPORT_NON_SECURE
519 Support executing U-Boot in non-secure (NS) mode. Certain
520 impossible actions will be skipped if the CPU is in NS mode,
521 such as ARM architectural timer initialization.
523 - Linux Kernel Interface:
524 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
526 When transferring memsize parameter to Linux, some versions
527 expect it to be in bytes, others in MB.
528 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
532 New kernel versions are expecting firmware settings to be
533 passed using flattened device trees (based on open firmware
537 * New libfdt-based support
538 * Adds the "fdt" command
539 * The bootm command automatically updates the fdt
541 OF_TBCLK - The timebase frequency.
543 boards with QUICC Engines require OF_QE to set UCC MAC
548 U-Boot can detect if an IDE device is present or not.
549 If not, and this new config option is activated, U-Boot
550 removes the ATA node from the DTS before booting Linux,
551 so the Linux IDE driver does not probe the device and
552 crash. This is needed for buggy hardware (uc101) where
553 no pull down resistor is connected to the signal IDE5V_DD7.
555 - vxWorks boot parameters:
557 bootvx constructs a valid bootline using the following
558 environments variables: bootdev, bootfile, ipaddr, netmask,
559 serverip, gatewayip, hostname, othbootargs.
560 It loads the vxWorks image pointed bootfile.
562 Note: If a "bootargs" environment is defined, it will override
563 the defaults discussed just above.
565 - Cache Configuration for ARM:
566 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
568 CONFIG_SYS_PL310_BASE - Physical base address of PL310
569 controller register space
574 If you have Amba PrimeCell PL011 UARTs, set this variable to
575 the clock speed of the UARTs.
579 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
580 define this to a list of base addresses for each (supported)
581 port. See e.g. include/configs/versatile.h
583 CONFIG_SERIAL_HW_FLOW_CONTROL
585 Define this variable to enable hw flow control in serial driver.
586 Current user of this option is drivers/serial/nsl16550.c driver
588 - Serial Download Echo Mode:
590 If defined to 1, all characters received during a
591 serial download (using the "loads" command) are
592 echoed back. This might be needed by some terminal
593 emulations (like "cu"), but may as well just take
594 time on others. This setting #define's the initial
595 value of the "loads_echo" environment variable.
597 - Removal of commands
598 If no commands are needed to boot, you can disable
599 CONFIG_CMDLINE to remove them. In this case, the command line
600 will not be available, and when U-Boot wants to execute the
601 boot command (on start-up) it will call board_run_command()
602 instead. This can reduce image size significantly for very
603 simple boot procedures.
605 - Regular expression support:
607 If this variable is defined, U-Boot is linked against
608 the SLRE (Super Light Regular Expression) library,
609 which adds regex support to some commands, as for
610 example "env grep" and "setexpr".
613 CONFIG_SYS_WATCHDOG_FREQ
614 Some platforms automatically call WATCHDOG_RESET()
615 from the timer interrupt handler every
616 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
617 board configuration file, a default of CONFIG_SYS_HZ/2
618 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
619 to 0 disables calling WATCHDOG_RESET() from the timer
624 When CONFIG_CMD_DATE is selected, the type of the RTC
625 has to be selected, too. Define exactly one of the
628 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
629 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
630 CONFIG_RTC_MC146818 - use MC146818 RTC
631 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
632 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
633 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
634 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
635 CONFIG_RTC_DS164x - use Dallas DS164x RTC
636 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
637 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
638 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
639 CONFIG_SYS_RV3029_TCR - enable trickle charger on
642 Note that if the RTC uses I2C, then the I2C interface
643 must also be configured. See I2C Support, below.
646 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
648 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
649 chip-ngpio pairs that tell the PCA953X driver the number of
650 pins supported by a particular chip.
652 Note that if the GPIO device uses I2C, then the I2C interface
653 must also be configured. See I2C Support, below.
656 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
657 accesses and can checksum them or write a list of them out
658 to memory. See the 'iotrace' command for details. This is
659 useful for testing device drivers since it can confirm that
660 the driver behaves the same way before and after a code
661 change. Currently this is supported on sandbox and arm. To
662 add support for your architecture, add '#include <iotrace.h>'
663 to the bottom of arch/<arch>/include/asm/io.h and test.
665 Example output from the 'iotrace stats' command is below.
666 Note that if the trace buffer is exhausted, the checksum will
667 still continue to operate.
670 Start: 10000000 (buffer start address)
671 Size: 00010000 (buffer size)
672 Offset: 00000120 (current buffer offset)
673 Output: 10000120 (start + offset)
674 Count: 00000018 (number of trace records)
675 CRC32: 9526fb66 (CRC32 of all trace records)
679 When CONFIG_TIMESTAMP is selected, the timestamp
680 (date and time) of an image is printed by image
681 commands like bootm or iminfo. This option is
682 automatically enabled when you select CONFIG_CMD_DATE .
684 - Partition Labels (disklabels) Supported:
685 Zero or more of the following:
686 CONFIG_MAC_PARTITION Apple's MacOS partition table.
687 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
688 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
689 bootloader. Note 2TB partition limit; see
691 CONFIG_SCSI) you must configure support for at
692 least one non-MTD partition type as well.
697 Set this to enable support for disks larger than 137GB
698 Also look at CONFIG_SYS_64BIT_LBA.
699 Whithout these , LBA48 support uses 32bit variables and will 'only'
700 support disks up to 2.1TB.
702 CONFIG_SYS_64BIT_LBA:
703 When enabled, makes the IDE subsystem use 64bit sector addresses.
706 - NETWORK Support (PCI):
708 Utility code for direct access to the SPI bus on Intel 8257x.
709 This does not do anything useful unless you set at least one
710 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
713 Support for National dp83815 chips.
716 Support for National dp8382[01] gigabit chips.
718 - NETWORK Support (other):
720 Support for the Calxeda XGMAC device
723 Support for SMSC's LAN91C96 chips.
725 CONFIG_LAN91C96_USE_32_BIT
726 Define this to enable 32 bit addressing
729 Support for SMSC's LAN91C111 chip
732 Define this to hold the physical address
733 of the device (I/O space)
735 CONFIG_SMC_USE_32_BIT
736 Define this if data bus is 32 bits
738 CONFIG_SMC_USE_IOFUNCS
739 Define this to use i/o functions instead of macros
740 (some hardware wont work with macros)
742 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
743 Define this if you have more then 3 PHYs.
746 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
748 CONFIG_FTGMAC100_EGIGA
749 Define this to use GE link update with gigabit PHY.
750 Define this if FTGMAC100 is connected to gigabit PHY.
751 If your system has 10/100 PHY only, it might not occur
752 wrong behavior. Because PHY usually return timeout or
753 useless data when polling gigabit status and gigabit
754 control registers. This behavior won't affect the
755 correctnessof 10/100 link speed update.
758 Support for Renesas on-chip Ethernet controller
760 CONFIG_SH_ETHER_USE_PORT
761 Define the number of ports to be used
763 CONFIG_SH_ETHER_PHY_ADDR
764 Define the ETH PHY's address
766 CONFIG_SH_ETHER_CACHE_WRITEBACK
767 If this option is set, the driver enables cache flush.
773 CONFIG_TPM_TIS_INFINEON
774 Support for Infineon i2c bus TPM devices. Only one device
775 per system is supported at this time.
777 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
778 Define the burst count bytes upper limit
781 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
783 CONFIG_TPM_ST33ZP24_I2C
784 Support for STMicroelectronics ST33ZP24 I2C devices.
785 Requires TPM_ST33ZP24 and I2C.
787 CONFIG_TPM_ST33ZP24_SPI
788 Support for STMicroelectronics ST33ZP24 SPI devices.
789 Requires TPM_ST33ZP24 and SPI.
792 Support for Atmel TWI TPM device. Requires I2C support.
795 Support for generic parallel port TPM devices. Only one device
796 per system is supported at this time.
798 CONFIG_TPM_TIS_BASE_ADDRESS
799 Base address where the generic TPM device is mapped
800 to. Contemporary x86 systems usually map it at
804 Define this to enable the TPM support library which provides
805 functional interfaces to some TPM commands.
806 Requires support for a TPM device.
808 CONFIG_TPM_AUTH_SESSIONS
809 Define this to enable authorized functions in the TPM library.
810 Requires CONFIG_TPM and CONFIG_SHA1.
813 At the moment only the UHCI host controller is
814 supported (PIP405, MIP405); define
815 CONFIG_USB_UHCI to enable it.
816 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
817 and define CONFIG_USB_STORAGE to enable the USB
820 Supported are USB Keyboards and USB Floppy drives
823 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
824 txfilltuning field in the EHCI controller on reset.
826 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
830 Define the below if you wish to use the USB console.
831 Once firmware is rebuilt from a serial console issue the
832 command "setenv stdin usbtty; setenv stdout usbtty" and
833 attach your USB cable. The Unix command "dmesg" should print
834 it has found a new device. The environment variable usbtty
835 can be set to gserial or cdc_acm to enable your device to
836 appear to a USB host as a Linux gserial device or a
837 Common Device Class Abstract Control Model serial device.
838 If you select usbtty = gserial you should be able to enumerate
840 # modprobe usbserial vendor=0xVendorID product=0xProductID
841 else if using cdc_acm, simply setting the environment
842 variable usbtty to be cdc_acm should suffice. The following
843 might be defined in YourBoardName.h
846 Define this to build a UDC device
849 Define this to have a tty type of device available to
850 talk to the UDC device
853 Define this to enable the high speed support for usb
854 device and usbtty. If this feature is enabled, a routine
855 int is_usbd_high_speed(void)
856 also needs to be defined by the driver to dynamically poll
857 whether the enumeration has succeded at high speed or full
860 If you have a USB-IF assigned VendorID then you may wish to
861 define your own vendor specific values either in BoardName.h
862 or directly in usbd_vendor_info.h. If you don't define
863 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
864 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
865 should pretend to be a Linux device to it's target host.
867 CONFIG_USBD_MANUFACTURER
868 Define this string as the name of your company for
869 - CONFIG_USBD_MANUFACTURER "my company"
871 CONFIG_USBD_PRODUCT_NAME
872 Define this string as the name of your product
873 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
876 Define this as your assigned Vendor ID from the USB
877 Implementors Forum. This *must* be a genuine Vendor ID
878 to avoid polluting the USB namespace.
879 - CONFIG_USBD_VENDORID 0xFFFF
881 CONFIG_USBD_PRODUCTID
882 Define this as the unique Product ID
884 - CONFIG_USBD_PRODUCTID 0xFFFF
886 - ULPI Layer Support:
887 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
888 the generic ULPI layer. The generic layer accesses the ULPI PHY
889 via the platform viewport, so you need both the genric layer and
890 the viewport enabled. Currently only Chipidea/ARC based
891 viewport is supported.
892 To enable the ULPI layer support, define CONFIG_USB_ULPI and
893 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
894 If your ULPI phy needs a different reference clock than the
895 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
896 the appropriate value in Hz.
899 The MMC controller on the Intel PXA is supported. To
900 enable this define CONFIG_MMC. The MMC can be
901 accessed from the boot prompt by mapping the device
902 to physical memory similar to flash. Command line is
903 enabled with CONFIG_CMD_MMC. The MMC driver also works with
904 the FAT fs. This is enabled with CONFIG_CMD_FAT.
907 Support for Renesas on-chip MMCIF controller
910 Define the base address of MMCIF registers
913 Define the clock frequency for MMCIF
915 - USB Device Firmware Update (DFU) class support:
917 This enables the USB portion of the DFU USB class
920 This enables support for exposing NAND devices via DFU.
923 This enables support for exposing RAM via DFU.
924 Note: DFU spec refer to non-volatile memory usage, but
925 allow usages beyond the scope of spec - here RAM usage,
926 one that would help mostly the developer.
928 CONFIG_SYS_DFU_DATA_BUF_SIZE
929 Dfu transfer uses a buffer before writing data to the
930 raw storage device. Make the size (in bytes) of this buffer
931 configurable. The size of this buffer is also configurable
932 through the "dfu_bufsiz" environment variable.
934 CONFIG_SYS_DFU_MAX_FILE_SIZE
935 When updating files rather than the raw storage device,
936 we use a static buffer to copy the file into and then write
937 the buffer once we've been given the whole file. Define
938 this to the maximum filesize (in bytes) for the buffer.
939 Default is 4 MiB if undefined.
941 DFU_DEFAULT_POLL_TIMEOUT
942 Poll timeout [ms], is the timeout a device can send to the
943 host. The host must wait for this timeout before sending
944 a subsequent DFU_GET_STATUS request to the device.
946 DFU_MANIFEST_POLL_TIMEOUT
947 Poll timeout [ms], which the device sends to the host when
948 entering dfuMANIFEST state. Host waits this timeout, before
949 sending again an USB request to the device.
951 - Journaling Flash filesystem support:
952 CONFIG_SYS_JFFS2_FIRST_SECTOR,
953 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
954 Define these for a default partition on a NOR device
957 See Kconfig help for available keyboard drivers.
959 - LCD Support: CONFIG_LCD
961 Define this to enable LCD support (for output to LCD
962 display); also select one of the supported displays
963 by defining one of these:
965 CONFIG_NEC_NL6448AC33:
967 NEC NL6448AC33-18. Active, color, single scan.
969 CONFIG_NEC_NL6448BC20
971 NEC NL6448BC20-08. 6.5", 640x480.
972 Active, color, single scan.
974 CONFIG_NEC_NL6448BC33_54
976 NEC NL6448BC33-54. 10.4", 640x480.
977 Active, color, single scan.
981 Sharp 320x240. Active, color, single scan.
982 It isn't 16x9, and I am not sure what it is.
984 CONFIG_SHARP_LQ64D341
986 Sharp LQ64D341 display, 640x480.
987 Active, color, single scan.
991 HLD1045 display, 640x480.
992 Active, color, single scan.
996 Optrex CBL50840-2 NF-FW 99 22 M5
998 Hitachi LMG6912RPFC-00T
1002 320x240. Black & white.
1004 CONFIG_LCD_ALIGNMENT
1006 Normally the LCD is page-aligned (typically 4KB). If this is
1007 defined then the LCD will be aligned to this value instead.
1008 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1009 here, since it is cheaper to change data cache settings on
1010 a per-section basis.
1015 Sometimes, for example if the display is mounted in portrait
1016 mode or even if it's mounted landscape but rotated by 180degree,
1017 we need to rotate our content of the display relative to the
1018 framebuffer, so that user can read the messages which are
1020 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1021 initialized with a given rotation from "vl_rot" out of
1022 "vidinfo_t" which is provided by the board specific code.
1023 The value for vl_rot is coded as following (matching to
1024 fbcon=rotate:<n> linux-kernel commandline):
1025 0 = no rotation respectively 0 degree
1026 1 = 90 degree rotation
1027 2 = 180 degree rotation
1028 3 = 270 degree rotation
1030 If CONFIG_LCD_ROTATION is not defined, the console will be
1031 initialized with 0degree rotation.
1034 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1036 The clock frequency of the MII bus
1038 CONFIG_PHY_CMD_DELAY (ppc4xx)
1040 Some PHY like Intel LXT971A need extra delay after
1041 command issued before MII status register can be read
1046 Define a default value for the IP address to use for
1047 the default Ethernet interface, in case this is not
1048 determined through e.g. bootp.
1049 (Environment variable "ipaddr")
1051 - Server IP address:
1054 Defines a default value for the IP address of a TFTP
1055 server to contact when using the "tftboot" command.
1056 (Environment variable "serverip")
1058 - Gateway IP address:
1061 Defines a default value for the IP address of the
1062 default router where packets to other networks are
1064 (Environment variable "gatewayip")
1069 Defines a default value for the subnet mask (or
1070 routing prefix) which is used to determine if an IP
1071 address belongs to the local subnet or needs to be
1072 forwarded through a router.
1073 (Environment variable "netmask")
1075 - BOOTP Recovery Mode:
1076 CONFIG_BOOTP_RANDOM_DELAY
1078 If you have many targets in a network that try to
1079 boot using BOOTP, you may want to avoid that all
1080 systems send out BOOTP requests at precisely the same
1081 moment (which would happen for instance at recovery
1082 from a power failure, when all systems will try to
1083 boot, thus flooding the BOOTP server. Defining
1084 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1085 inserted before sending out BOOTP requests. The
1086 following delays are inserted then:
1088 1st BOOTP request: delay 0 ... 1 sec
1089 2nd BOOTP request: delay 0 ... 2 sec
1090 3rd BOOTP request: delay 0 ... 4 sec
1092 BOOTP requests: delay 0 ... 8 sec
1094 CONFIG_BOOTP_ID_CACHE_SIZE
1096 BOOTP packets are uniquely identified using a 32-bit ID. The
1097 server will copy the ID from client requests to responses and
1098 U-Boot will use this to determine if it is the destination of
1099 an incoming response. Some servers will check that addresses
1100 aren't in use before handing them out (usually using an ARP
1101 ping) and therefore take up to a few hundred milliseconds to
1102 respond. Network congestion may also influence the time it
1103 takes for a response to make it back to the client. If that
1104 time is too long, U-Boot will retransmit requests. In order
1105 to allow earlier responses to still be accepted after these
1106 retransmissions, U-Boot's BOOTP client keeps a small cache of
1107 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1108 cache. The default is to keep IDs for up to four outstanding
1109 requests. Increasing this will allow U-Boot to accept offers
1110 from a BOOTP client in networks with unusually high latency.
1112 - DHCP Advanced Options:
1114 - Link-local IP address negotiation:
1115 Negotiate with other link-local clients on the local network
1116 for an address that doesn't require explicit configuration.
1117 This is especially useful if a DHCP server cannot be guaranteed
1118 to exist in all environments that the device must operate.
1120 See doc/README.link-local for more information.
1122 - MAC address from environment variables
1124 FDT_SEQ_MACADDR_FROM_ENV
1126 Fix-up device tree with MAC addresses fetched sequentially from
1127 environment variables. This config work on assumption that
1128 non-usable ethernet node of device-tree are either not present
1129 or their status has been marked as "disabled".
1132 CONFIG_CDP_DEVICE_ID
1134 The device id used in CDP trigger frames.
1136 CONFIG_CDP_DEVICE_ID_PREFIX
1138 A two character string which is prefixed to the MAC address
1143 A printf format string which contains the ascii name of
1144 the port. Normally is set to "eth%d" which sets
1145 eth0 for the first Ethernet, eth1 for the second etc.
1147 CONFIG_CDP_CAPABILITIES
1149 A 32bit integer which indicates the device capabilities;
1150 0x00000010 for a normal host which does not forwards.
1154 An ascii string containing the version of the software.
1158 An ascii string containing the name of the platform.
1162 A 32bit integer sent on the trigger.
1164 CONFIG_CDP_POWER_CONSUMPTION
1166 A 16bit integer containing the power consumption of the
1167 device in .1 of milliwatts.
1169 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1171 A byte containing the id of the VLAN.
1173 - Status LED: CONFIG_LED_STATUS
1175 Several configurations allow to display the current
1176 status using a LED. For instance, the LED will blink
1177 fast while running U-Boot code, stop blinking as
1178 soon as a reply to a BOOTP request was received, and
1179 start blinking slow once the Linux kernel is running
1180 (supported by a status LED driver in the Linux
1181 kernel). Defining CONFIG_LED_STATUS enables this
1186 CONFIG_LED_STATUS_GPIO
1187 The status LED can be connected to a GPIO pin.
1188 In such cases, the gpio_led driver can be used as a
1189 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1190 to include the gpio_led driver in the U-Boot binary.
1192 CONFIG_GPIO_LED_INVERTED_TABLE
1193 Some GPIO connected LEDs may have inverted polarity in which
1194 case the GPIO high value corresponds to LED off state and
1195 GPIO low value corresponds to LED on state.
1196 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1197 with a list of GPIO LEDs that have inverted polarity.
1200 CONFIG_SYS_NUM_I2C_BUSES
1201 Hold the number of i2c buses you want to use.
1203 CONFIG_SYS_I2C_DIRECT_BUS
1204 define this, if you don't use i2c muxes on your hardware.
1205 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1208 CONFIG_SYS_I2C_MAX_HOPS
1209 define how many muxes are maximal consecutively connected
1210 on one i2c bus. If you not use i2c muxes, omit this
1213 CONFIG_SYS_I2C_BUSES
1214 hold a list of buses you want to use, only used if
1215 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1216 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1217 CONFIG_SYS_NUM_I2C_BUSES = 9:
1219 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1220 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1221 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1222 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1223 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1224 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1225 {1, {I2C_NULL_HOP}}, \
1226 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1227 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1231 bus 0 on adapter 0 without a mux
1232 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1233 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1234 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1235 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1236 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1237 bus 6 on adapter 1 without a mux
1238 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1239 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1241 If you do not have i2c muxes on your board, omit this define.
1243 - Legacy I2C Support:
1244 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1245 then the following macros need to be defined (examples are
1246 from include/configs/lwmon.h):
1250 (Optional). Any commands necessary to enable the I2C
1251 controller or configure ports.
1253 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1257 The code necessary to make the I2C data line active
1258 (driven). If the data line is open collector, this
1261 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1265 The code necessary to make the I2C data line tri-stated
1266 (inactive). If the data line is open collector, this
1269 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1273 Code that returns true if the I2C data line is high,
1276 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1280 If <bit> is true, sets the I2C data line high. If it
1281 is false, it clears it (low).
1283 eg: #define I2C_SDA(bit) \
1284 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1285 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1289 If <bit> is true, sets the I2C clock line high. If it
1290 is false, it clears it (low).
1292 eg: #define I2C_SCL(bit) \
1293 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1294 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1298 This delay is invoked four times per clock cycle so this
1299 controls the rate of data transfer. The data rate thus
1300 is 1 / (I2C_DELAY * 4). Often defined to be something
1303 #define I2C_DELAY udelay(2)
1305 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1307 If your arch supports the generic GPIO framework (asm/gpio.h),
1308 then you may alternatively define the two GPIOs that are to be
1309 used as SCL / SDA. Any of the previous I2C_xxx macros will
1310 have GPIO-based defaults assigned to them as appropriate.
1312 You should define these to the GPIO value as given directly to
1313 the generic GPIO functions.
1315 CONFIG_SYS_I2C_INIT_BOARD
1317 When a board is reset during an i2c bus transfer
1318 chips might think that the current transfer is still
1319 in progress. On some boards it is possible to access
1320 the i2c SCLK line directly, either by using the
1321 processor pin as a GPIO or by having a second pin
1322 connected to the bus. If this option is defined a
1323 custom i2c_init_board() routine in boards/xxx/board.c
1324 is run early in the boot sequence.
1326 CONFIG_I2C_MULTI_BUS
1328 This option allows the use of multiple I2C buses, each of which
1329 must have a controller. At any point in time, only one bus is
1330 active. To switch to a different bus, use the 'i2c dev' command.
1331 Note that bus numbering is zero-based.
1333 CONFIG_SYS_I2C_NOPROBES
1335 This option specifies a list of I2C devices that will be skipped
1336 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1337 is set, specify a list of bus-device pairs. Otherwise, specify
1338 a 1D array of device addresses
1341 #undef CONFIG_I2C_MULTI_BUS
1342 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1344 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1346 #define CONFIG_I2C_MULTI_BUS
1347 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1349 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1351 CONFIG_SYS_SPD_BUS_NUM
1353 If defined, then this indicates the I2C bus number for DDR SPD.
1354 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1356 CONFIG_SYS_RTC_BUS_NUM
1358 If defined, then this indicates the I2C bus number for the RTC.
1359 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1361 CONFIG_SOFT_I2C_READ_REPEATED_START
1363 defining this will force the i2c_read() function in
1364 the soft_i2c driver to perform an I2C repeated start
1365 between writing the address pointer and reading the
1366 data. If this define is omitted the default behaviour
1367 of doing a stop-start sequence will be used. Most I2C
1368 devices can use either method, but some require one or
1371 - SPI Support: CONFIG_SPI
1373 Enables SPI driver (so far only tested with
1374 SPI EEPROM, also an instance works with Crystal A/D and
1375 D/As on the SACSng board)
1377 CONFIG_SYS_SPI_MXC_WAIT
1378 Timeout for waiting until spi transfer completed.
1379 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1381 - FPGA Support: CONFIG_FPGA
1383 Enables FPGA subsystem.
1385 CONFIG_FPGA_<vendor>
1387 Enables support for specific chip vendors.
1390 CONFIG_FPGA_<family>
1392 Enables support for FPGA family.
1393 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1397 Specify the number of FPGA devices to support.
1399 CONFIG_SYS_FPGA_PROG_FEEDBACK
1401 Enable printing of hash marks during FPGA configuration.
1403 CONFIG_SYS_FPGA_CHECK_BUSY
1405 Enable checks on FPGA configuration interface busy
1406 status by the configuration function. This option
1407 will require a board or device specific function to
1412 If defined, a function that provides delays in the FPGA
1413 configuration driver.
1415 CONFIG_SYS_FPGA_CHECK_CTRLC
1416 Allow Control-C to interrupt FPGA configuration
1418 CONFIG_SYS_FPGA_CHECK_ERROR
1420 Check for configuration errors during FPGA bitfile
1421 loading. For example, abort during Virtex II
1422 configuration if the INIT_B line goes low (which
1423 indicated a CRC error).
1425 CONFIG_SYS_FPGA_WAIT_INIT
1427 Maximum time to wait for the INIT_B line to de-assert
1428 after PROB_B has been de-asserted during a Virtex II
1429 FPGA configuration sequence. The default time is 500
1432 CONFIG_SYS_FPGA_WAIT_BUSY
1434 Maximum time to wait for BUSY to de-assert during
1435 Virtex II FPGA configuration. The default is 5 ms.
1437 CONFIG_SYS_FPGA_WAIT_CONFIG
1439 Time to wait after FPGA configuration. The default is
1442 - Vendor Parameter Protection:
1444 U-Boot considers the values of the environment
1445 variables "serial#" (Board Serial Number) and
1446 "ethaddr" (Ethernet Address) to be parameters that
1447 are set once by the board vendor / manufacturer, and
1448 protects these variables from casual modification by
1449 the user. Once set, these variables are read-only,
1450 and write or delete attempts are rejected. You can
1451 change this behaviour:
1453 If CONFIG_ENV_OVERWRITE is #defined in your config
1454 file, the write protection for vendor parameters is
1455 completely disabled. Anybody can change or delete
1458 Alternatively, if you define _both_ an ethaddr in the
1459 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1460 Ethernet address is installed in the environment,
1461 which can be changed exactly ONCE by the user. [The
1462 serial# is unaffected by this, i. e. it remains
1465 The same can be accomplished in a more flexible way
1466 for any variable by configuring the type of access
1467 to allow for those variables in the ".flags" variable
1468 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1473 Define this variable to enable the reservation of
1474 "protected RAM", i. e. RAM which is not overwritten
1475 by U-Boot. Define CONFIG_PRAM to hold the number of
1476 kB you want to reserve for pRAM. You can overwrite
1477 this default value by defining an environment
1478 variable "pram" to the number of kB you want to
1479 reserve. Note that the board info structure will
1480 still show the full amount of RAM. If pRAM is
1481 reserved, a new environment variable "mem" will
1482 automatically be defined to hold the amount of
1483 remaining RAM in a form that can be passed as boot
1484 argument to Linux, for instance like that:
1486 setenv bootargs ... mem=\${mem}
1489 This way you can tell Linux not to use this memory,
1490 either, which results in a memory region that will
1491 not be affected by reboots.
1493 *WARNING* If your board configuration uses automatic
1494 detection of the RAM size, you must make sure that
1495 this memory test is non-destructive. So far, the
1496 following board configurations are known to be
1499 IVMS8, IVML24, SPD8xx,
1500 HERMES, IP860, RPXlite, LWMON,
1506 In the current implementation, the local variables
1507 space and global environment variables space are
1508 separated. Local variables are those you define by
1509 simply typing `name=value'. To access a local
1510 variable later on, you have write `$name' or
1511 `${name}'; to execute the contents of a variable
1512 directly type `$name' at the command prompt.
1514 Global environment variables are those you use
1515 setenv/printenv to work with. To run a command stored
1516 in such a variable, you need to use the run command,
1517 and you must not use the '$' sign to access them.
1519 To store commands and special characters in a
1520 variable, please use double quotation marks
1521 surrounding the whole text of the variable, instead
1522 of the backslashes before semicolons and special
1525 - Default Environment:
1526 CONFIG_EXTRA_ENV_SETTINGS
1528 Define this to contain any number of null terminated
1529 strings (variable = value pairs) that will be part of
1530 the default environment compiled into the boot image.
1532 For example, place something like this in your
1533 board's config file:
1535 #define CONFIG_EXTRA_ENV_SETTINGS \
1539 Warning: This method is based on knowledge about the
1540 internal format how the environment is stored by the
1541 U-Boot code. This is NOT an official, exported
1542 interface! Although it is unlikely that this format
1543 will change soon, there is no guarantee either.
1544 You better know what you are doing here.
1546 Note: overly (ab)use of the default environment is
1547 discouraged. Make sure to check other ways to preset
1548 the environment like the "source" command or the
1551 CONFIG_DELAY_ENVIRONMENT
1553 Normally the environment is loaded when the board is
1554 initialised so that it is available to U-Boot. This inhibits
1555 that so that the environment is not available until
1556 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1557 this is instead controlled by the value of
1558 /config/load-environment.
1560 CONFIG_STANDALONE_LOAD_ADDR
1562 This option defines a board specific value for the
1563 address where standalone program gets loaded, thus
1564 overwriting the architecture dependent default
1567 - Frame Buffer Address:
1570 Define CONFIG_FB_ADDR if you want to use specific
1571 address for frame buffer. This is typically the case
1572 when using a graphics controller has separate video
1573 memory. U-Boot will then place the frame buffer at
1574 the given address instead of dynamically reserving it
1575 in system RAM by calling lcd_setmem(), which grabs
1576 the memory for the frame buffer depending on the
1577 configured panel size.
1579 Please see board_init_f function.
1581 - Automatic software updates via TFTP server
1583 CONFIG_UPDATE_TFTP_CNT_MAX
1584 CONFIG_UPDATE_TFTP_MSEC_MAX
1586 These options enable and control the auto-update feature;
1587 for a more detailed description refer to doc/README.update.
1589 - MTD Support (mtdparts command, UBI support)
1590 CONFIG_MTD_UBI_WL_THRESHOLD
1591 This parameter defines the maximum difference between the highest
1592 erase counter value and the lowest erase counter value of eraseblocks
1593 of UBI devices. When this threshold is exceeded, UBI starts performing
1594 wear leveling by means of moving data from eraseblock with low erase
1595 counter to eraseblocks with high erase counter.
1597 The default value should be OK for SLC NAND flashes, NOR flashes and
1598 other flashes which have eraseblock life-cycle 100000 or more.
1599 However, in case of MLC NAND flashes which typically have eraseblock
1600 life-cycle less than 10000, the threshold should be lessened (e.g.,
1601 to 128 or 256, although it does not have to be power of 2).
1605 CONFIG_MTD_UBI_BEB_LIMIT
1606 This option specifies the maximum bad physical eraseblocks UBI
1607 expects on the MTD device (per 1024 eraseblocks). If the
1608 underlying flash does not admit of bad eraseblocks (e.g. NOR
1609 flash), this value is ignored.
1611 NAND datasheets often specify the minimum and maximum NVM
1612 (Number of Valid Blocks) for the flashes' endurance lifetime.
1613 The maximum expected bad eraseblocks per 1024 eraseblocks
1614 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1615 which gives 20 for most NANDs (MaxNVB is basically the total
1616 count of eraseblocks on the chip).
1618 To put it differently, if this value is 20, UBI will try to
1619 reserve about 1.9% of physical eraseblocks for bad blocks
1620 handling. And that will be 1.9% of eraseblocks on the entire
1621 NAND chip, not just the MTD partition UBI attaches. This means
1622 that if you have, say, a NAND flash chip admits maximum 40 bad
1623 eraseblocks, and it is split on two MTD partitions of the same
1624 size, UBI will reserve 40 eraseblocks when attaching a
1629 CONFIG_MTD_UBI_FASTMAP
1630 Fastmap is a mechanism which allows attaching an UBI device
1631 in nearly constant time. Instead of scanning the whole MTD device it
1632 only has to locate a checkpoint (called fastmap) on the device.
1633 The on-flash fastmap contains all information needed to attach
1634 the device. Using fastmap makes only sense on large devices where
1635 attaching by scanning takes long. UBI will not automatically install
1636 a fastmap on old images, but you can set the UBI parameter
1637 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1638 that fastmap-enabled images are still usable with UBI implementations
1639 without fastmap support. On typical flash devices the whole fastmap
1640 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1642 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1643 Set this parameter to enable fastmap automatically on images
1647 CONFIG_MTD_UBI_FM_DEBUG
1648 Enable UBI fastmap debug
1653 Enable building of SPL globally.
1655 CONFIG_SPL_RELOC_TEXT_BASE
1656 Address to relocate to. If unspecified, this is equal to
1657 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1659 CONFIG_SPL_BSS_START_ADDR
1660 Link address for the BSS within the SPL binary.
1663 Adress of the start of the stack SPL will use
1665 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1666 When defined, SPL will panic() if the image it has
1667 loaded does not have a signature.
1668 Defining this is useful when code which loads images
1669 in SPL cannot guarantee that absolutely all read errors
1671 An example is the LPC32XX MLC NAND driver, which will
1672 consider that a completely unreadable NAND block is bad,
1673 and thus should be skipped silently.
1675 CONFIG_SPL_RELOC_STACK
1676 Adress of the start of the stack SPL will use after
1677 relocation. If unspecified, this is equal to
1680 CONFIG_SYS_SPL_MALLOC_START
1681 Starting address of the malloc pool used in SPL.
1682 When this option is set the full malloc is used in SPL and
1683 it is set up by spl_init() and before that, the simple malloc()
1684 can be used if CONFIG_SYS_MALLOC_F is defined.
1686 CONFIG_SYS_SPL_MALLOC_SIZE
1687 The size of the malloc pool used in SPL.
1689 CONFIG_SPL_DISPLAY_PRINT
1690 For ARM, enable an optional function to print more information
1691 about the running system.
1693 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
1694 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
1695 Sector and number of sectors to load kernel argument
1696 parameters from when MMC is being used in raw mode
1699 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1700 Set this for NAND SPL on PPC mpc83xx targets, so that
1701 start.S waits for the rest of the SPL to load before
1702 continuing (the hardware starts execution after just
1703 loading the first page rather than the full 4K).
1706 Support for a lightweight UBI (fastmap) scanner and
1709 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1710 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1711 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1712 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1713 CONFIG_SYS_NAND_ECCBYTES
1714 Defines the size and behavior of the NAND that SPL uses
1717 CONFIG_SYS_NAND_U_BOOT_DST
1718 Location in memory to load U-Boot to
1720 CONFIG_SYS_NAND_U_BOOT_SIZE
1721 Size of image to load
1723 CONFIG_SYS_NAND_U_BOOT_START
1724 Entry point in loaded image to jump to
1726 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1727 Define this if you need to first read the OOB and then the
1728 data. This is used, for example, on davinci platforms.
1730 CONFIG_SPL_RAM_DEVICE
1731 Support for running image already present in ram, in SPL binary
1734 Final target image containing SPL and payload. Some SPLs
1735 use an arch-specific makefile fragment instead, for
1736 example if more than one image needs to be produced.
1738 CONFIG_SPL_FIT_PRINT
1739 Printing information about a FIT image adds quite a bit of
1740 code to SPL. So this is normally disabled in SPL. Use this
1741 option to re-enable it. This will affect the output of the
1742 bootm command when booting a FIT image.
1744 - Interrupt support (PPC):
1746 There are common interrupt_init() and timer_interrupt()
1747 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1748 for CPU specific initialization. interrupt_init_cpu()
1749 should set decrementer_count to appropriate value. If
1750 CPU resets decrementer automatically after interrupt
1751 (ppc4xx) it should set decrementer_count to zero.
1752 timer_interrupt() calls timer_interrupt_cpu() for CPU
1753 specific handling. If board has watchdog / status_led
1754 / other_activity_monitor it works automatically from
1755 general timer_interrupt().
1758 Board initialization settings:
1759 ------------------------------
1761 During Initialization u-boot calls a number of board specific functions
1762 to allow the preparation of board specific prerequisites, e.g. pin setup
1763 before drivers are initialized. To enable these callbacks the
1764 following configuration macros have to be defined. Currently this is
1765 architecture specific, so please check arch/your_architecture/lib/board.c
1766 typically in board_init_f() and board_init_r().
1768 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1769 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1770 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1772 Configuration Settings:
1773 -----------------------
1775 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1776 Optionally it can be defined to support 64-bit memory commands.
1778 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1779 undefine this when you're short of memory.
1781 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1782 width of the commands listed in the 'help' command output.
1784 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1785 prompt for user input.
1787 - CONFIG_SYS_BAUDRATE_TABLE:
1788 List of legal baudrate settings for this board.
1790 - CONFIG_SYS_MEM_RESERVE_SECURE
1791 Only implemented for ARMv8 for now.
1792 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1793 is substracted from total RAM and won't be reported to OS.
1794 This memory can be used as secure memory. A variable
1795 gd->arch.secure_ram is used to track the location. In systems
1796 the RAM base is not zero, or RAM is divided into banks,
1797 this variable needs to be recalcuated to get the address.
1799 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1800 Enable temporary baudrate change while serial download
1802 - CONFIG_SYS_SDRAM_BASE:
1803 Physical start address of SDRAM. _Must_ be 0 here.
1805 - CONFIG_SYS_FLASH_BASE:
1806 Physical start address of Flash memory.
1808 - CONFIG_SYS_MONITOR_LEN:
1809 Size of memory reserved for monitor code, used to
1810 determine _at_compile_time_ (!) if the environment is
1811 embedded within the U-Boot image, or in a separate
1814 - CONFIG_SYS_MALLOC_LEN:
1815 Size of DRAM reserved for malloc() use.
1817 - CONFIG_SYS_MALLOC_F_LEN
1818 Size of the malloc() pool for use before relocation. If
1819 this is defined, then a very simple malloc() implementation
1820 will become available before relocation. The address is just
1821 below the global data, and the stack is moved down to make
1824 This feature allocates regions with increasing addresses
1825 within the region. calloc() is supported, but realloc()
1826 is not available. free() is supported but does nothing.
1827 The memory will be freed (or in fact just forgotten) when
1828 U-Boot relocates itself.
1830 - CONFIG_SYS_MALLOC_SIMPLE
1831 Provides a simple and small malloc() and calloc() for those
1832 boards which do not use the full malloc in SPL (which is
1833 enabled with CONFIG_SYS_SPL_MALLOC_START).
1835 - CONFIG_SYS_NONCACHED_MEMORY:
1836 Size of non-cached memory area. This area of memory will be
1837 typically located right below the malloc() area and mapped
1838 uncached in the MMU. This is useful for drivers that would
1839 otherwise require a lot of explicit cache maintenance. For
1840 some drivers it's also impossible to properly maintain the
1841 cache. For example if the regions that need to be flushed
1842 are not a multiple of the cache-line size, *and* padding
1843 cannot be allocated between the regions to align them (i.e.
1844 if the HW requires a contiguous array of regions, and the
1845 size of each region is not cache-aligned), then a flush of
1846 one region may result in overwriting data that hardware has
1847 written to another region in the same cache-line. This can
1848 happen for example in network drivers where descriptors for
1849 buffers are typically smaller than the CPU cache-line (e.g.
1850 16 bytes vs. 32 or 64 bytes).
1852 Non-cached memory is only supported on 32-bit ARM at present.
1854 - CONFIG_SYS_BOOTM_LEN:
1855 Normally compressed uImages are limited to an
1856 uncompressed size of 8 MBytes. If this is not enough,
1857 you can define CONFIG_SYS_BOOTM_LEN in your board config file
1858 to adjust this setting to your needs.
1860 - CONFIG_SYS_BOOTMAPSZ:
1861 Maximum size of memory mapped by the startup code of
1862 the Linux kernel; all data that must be processed by
1863 the Linux kernel (bd_info, boot arguments, FDT blob if
1864 used) must be put below this limit, unless "bootm_low"
1865 environment variable is defined and non-zero. In such case
1866 all data for the Linux kernel must be between "bootm_low"
1867 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
1868 variable "bootm_mapsize" will override the value of
1869 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
1870 then the value in "bootm_size" will be used instead.
1872 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
1873 Enable initrd_high functionality. If defined then the
1874 initrd_high feature is enabled and the bootm ramdisk subcommand
1877 - CONFIG_SYS_BOOT_GET_CMDLINE:
1878 Enables allocating and saving kernel cmdline in space between
1879 "bootm_low" and "bootm_low" + BOOTMAPSZ.
1881 - CONFIG_SYS_BOOT_GET_KBD:
1882 Enables allocating and saving a kernel copy of the bd_info in
1883 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
1885 - CONFIG_SYS_MAX_FLASH_SECT:
1886 Max number of sectors on a Flash chip
1888 - CONFIG_SYS_FLASH_ERASE_TOUT:
1889 Timeout for Flash erase operations (in ms)
1891 - CONFIG_SYS_FLASH_WRITE_TOUT:
1892 Timeout for Flash write operations (in ms)
1894 - CONFIG_SYS_FLASH_LOCK_TOUT
1895 Timeout for Flash set sector lock bit operation (in ms)
1897 - CONFIG_SYS_FLASH_UNLOCK_TOUT
1898 Timeout for Flash clear lock bits operation (in ms)
1900 - CONFIG_SYS_FLASH_PROTECTION
1901 If defined, hardware flash sectors protection is used
1902 instead of U-Boot software protection.
1904 - CONFIG_SYS_DIRECT_FLASH_TFTP:
1906 Enable TFTP transfers directly to flash memory;
1907 without this option such a download has to be
1908 performed in two steps: (1) download to RAM, and (2)
1909 copy from RAM to flash.
1911 The two-step approach is usually more reliable, since
1912 you can check if the download worked before you erase
1913 the flash, but in some situations (when system RAM is
1914 too limited to allow for a temporary copy of the
1915 downloaded image) this option may be very useful.
1917 - CONFIG_SYS_FLASH_CFI:
1918 Define if the flash driver uses extra elements in the
1919 common flash structure for storing flash geometry.
1921 - CONFIG_FLASH_CFI_DRIVER
1922 This option also enables the building of the cfi_flash driver
1923 in the drivers directory
1925 - CONFIG_FLASH_CFI_MTD
1926 This option enables the building of the cfi_mtd driver
1927 in the drivers directory. The driver exports CFI flash
1930 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
1931 Use buffered writes to flash.
1933 - CONFIG_FLASH_SPANSION_S29WS_N
1934 s29ws-n MirrorBit flash has non-standard addresses for buffered
1937 - CONFIG_SYS_FLASH_QUIET_TEST
1938 If this option is defined, the common CFI flash doesn't
1939 print it's warning upon not recognized FLASH banks. This
1940 is useful, if some of the configured banks are only
1941 optionally available.
1943 - CONFIG_FLASH_SHOW_PROGRESS
1944 If defined (must be an integer), print out countdown
1945 digits and dots. Recommended value: 45 (9..1) for 80
1946 column displays, 15 (3..1) for 40 column displays.
1948 - CONFIG_FLASH_VERIFY
1949 If defined, the content of the flash (destination) is compared
1950 against the source after the write operation. An error message
1951 will be printed when the contents are not identical.
1952 Please note that this option is useless in nearly all cases,
1953 since such flash programming errors usually are detected earlier
1954 while unprotecting/erasing/programming. Please only enable
1955 this option if you really know what you are doing.
1957 - CONFIG_ENV_MAX_ENTRIES
1959 Maximum number of entries in the hash table that is used
1960 internally to store the environment settings. The default
1961 setting is supposed to be generous and should work in most
1962 cases. This setting can be used to tune behaviour; see
1963 lib/hashtable.c for details.
1965 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1966 - CONFIG_ENV_FLAGS_LIST_STATIC
1967 Enable validation of the values given to environment variables when
1968 calling env set. Variables can be restricted to only decimal,
1969 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
1970 the variables can also be restricted to IP address or MAC address.
1972 The format of the list is:
1973 type_attribute = [s|d|x|b|i|m]
1974 access_attribute = [a|r|o|c]
1975 attributes = type_attribute[access_attribute]
1976 entry = variable_name[:attributes]
1979 The type attributes are:
1980 s - String (default)
1983 b - Boolean ([1yYtT|0nNfF])
1987 The access attributes are:
1993 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1994 Define this to a list (string) to define the ".flags"
1995 environment variable in the default or embedded environment.
1997 - CONFIG_ENV_FLAGS_LIST_STATIC
1998 Define this to a list (string) to define validation that
1999 should be done if an entry is not found in the ".flags"
2000 environment variable. To override a setting in the static
2001 list, simply add an entry for the same variable name to the
2004 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2005 regular expression. This allows multiple variables to define the same
2006 flags without explicitly listing them for each variable.
2008 The following definitions that deal with the placement and management
2009 of environment data (variable area); in general, we support the
2010 following configurations:
2012 - CONFIG_BUILD_ENVCRC:
2014 Builds up envcrc with the target environment so that external utils
2015 may easily extract it and embed it in final U-Boot images.
2017 BE CAREFUL! The first access to the environment happens quite early
2018 in U-Boot initialization (when we try to get the setting of for the
2019 console baudrate). You *MUST* have mapped your NVRAM area then, or
2022 Please note that even with NVRAM we still use a copy of the
2023 environment in RAM: we could work on NVRAM directly, but we want to
2024 keep settings there always unmodified except somebody uses "saveenv"
2025 to save the current settings.
2027 BE CAREFUL! For some special cases, the local device can not use
2028 "saveenv" command. For example, the local device will get the
2029 environment stored in a remote NOR flash by SRIO or PCIE link,
2030 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2032 - CONFIG_NAND_ENV_DST
2034 Defines address in RAM to which the nand_spl code should copy the
2035 environment. If redundant environment is used, it will be copied to
2036 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2038 Please note that the environment is read-only until the monitor
2039 has been relocated to RAM and a RAM copy of the environment has been
2040 created; also, when using EEPROM you will have to use env_get_f()
2041 until then to read environment variables.
2043 The environment is protected by a CRC32 checksum. Before the monitor
2044 is relocated into RAM, as a result of a bad CRC you will be working
2045 with the compiled-in default environment - *silently*!!! [This is
2046 necessary, because the first environment variable we need is the
2047 "baudrate" setting for the console - if we have a bad CRC, we don't
2048 have any device yet where we could complain.]
2050 Note: once the monitor has been relocated, then it will complain if
2051 the default environment is used; a new CRC is computed as soon as you
2052 use the "saveenv" command to store a valid environment.
2054 - CONFIG_SYS_FAULT_MII_ADDR:
2055 MII address of the PHY to check for the Ethernet link state.
2057 - CONFIG_NS16550_MIN_FUNCTIONS:
2058 Define this if you desire to only have use of the NS16550_init
2059 and NS16550_putc functions for the serial driver located at
2060 drivers/serial/ns16550.c. This option is useful for saving
2061 space for already greatly restricted images, including but not
2062 limited to NAND_SPL configurations.
2064 - CONFIG_DISPLAY_BOARDINFO
2065 Display information about the board that U-Boot is running on
2066 when U-Boot starts up. The board function checkboard() is called
2069 - CONFIG_DISPLAY_BOARDINFO_LATE
2070 Similar to the previous option, but display this information
2071 later, once stdio is running and output goes to the LCD, if
2074 Low Level (hardware related) configuration options:
2075 ---------------------------------------------------
2077 - CONFIG_SYS_CACHELINE_SIZE:
2078 Cache Line Size of the CPU.
2080 - CONFIG_SYS_CCSRBAR_DEFAULT:
2081 Default (power-on reset) physical address of CCSR on Freescale
2084 - CONFIG_SYS_CCSRBAR:
2085 Virtual address of CCSR. On a 32-bit build, this is typically
2086 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2088 - CONFIG_SYS_CCSRBAR_PHYS:
2089 Physical address of CCSR. CCSR can be relocated to a new
2090 physical address, if desired. In this case, this macro should
2091 be set to that address. Otherwise, it should be set to the
2092 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2093 is typically relocated on 36-bit builds. It is recommended
2094 that this macro be defined via the _HIGH and _LOW macros:
2096 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2097 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2099 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2100 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2101 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2102 used in assembly code, so it must not contain typecasts or
2103 integer size suffixes (e.g. "ULL").
2105 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2106 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2107 used in assembly code, so it must not contain typecasts or
2108 integer size suffixes (e.g. "ULL").
2110 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2111 DO NOT CHANGE unless you know exactly what you're
2112 doing! (11-4) [MPC8xx systems only]
2114 - CONFIG_SYS_INIT_RAM_ADDR:
2116 Start address of memory area that can be used for
2117 initial data and stack; please note that this must be
2118 writable memory that is working WITHOUT special
2119 initialization, i. e. you CANNOT use normal RAM which
2120 will become available only after programming the
2121 memory controller and running certain initialization
2124 U-Boot uses the following memory types:
2125 - MPC8xx: IMMR (internal memory of the CPU)
2127 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2129 - CONFIG_SYS_OR_TIMING_SDRAM:
2132 - CONFIG_SYS_MAMR_PTA:
2133 periodic timer for refresh
2136 Chip has SRIO or not
2139 Board has SRIO 1 port available
2142 Board has SRIO 2 port available
2144 - CONFIG_SRIO_PCIE_BOOT_MASTER
2145 Board can support master function for Boot from SRIO and PCIE
2147 - CONFIG_SYS_SRIOn_MEM_VIRT:
2148 Virtual Address of SRIO port 'n' memory region
2150 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2151 Physical Address of SRIO port 'n' memory region
2153 - CONFIG_SYS_SRIOn_MEM_SIZE:
2154 Size of SRIO port 'n' memory region
2156 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2157 Defined to tell the NAND controller that the NAND chip is using
2159 Not all NAND drivers use this symbol.
2160 Example of drivers that use it:
2161 - drivers/mtd/nand/raw/ndfc.c
2162 - drivers/mtd/nand/raw/mxc_nand.c
2164 - CONFIG_SYS_NDFC_EBC0_CFG
2165 Sets the EBC0_CFG register for the NDFC. If not defined
2166 a default value will be used.
2169 Get DDR timing information from an I2C EEPROM. Common
2170 with pluggable memory modules such as SODIMMs
2173 I2C address of the SPD EEPROM
2175 - CONFIG_SYS_SPD_BUS_NUM
2176 If SPD EEPROM is on an I2C bus other than the first
2177 one, specify here. Note that the value must resolve
2178 to something your driver can deal with.
2180 - CONFIG_SYS_DDR_RAW_TIMING
2181 Get DDR timing information from other than SPD. Common with
2182 soldered DDR chips onboard without SPD. DDR raw timing
2183 parameters are extracted from datasheet and hard-coded into
2184 header files or board specific files.
2186 - CONFIG_FSL_DDR_INTERACTIVE
2187 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2189 - CONFIG_FSL_DDR_SYNC_REFRESH
2190 Enable sync of refresh for multiple controllers.
2192 - CONFIG_FSL_DDR_BIST
2193 Enable built-in memory test for Freescale DDR controllers.
2195 - CONFIG_SYS_83XX_DDR_USES_CS0
2196 Only for 83xx systems. If specified, then DDR should
2197 be configured using CS0 and CS1 instead of CS2 and CS3.
2200 Enable RMII mode for all FECs.
2201 Note that this is a global option, we can't
2202 have one FEC in standard MII mode and another in RMII mode.
2204 - CONFIG_CRC32_VERIFY
2205 Add a verify option to the crc32 command.
2208 => crc32 -v <address> <count> <crc32>
2210 Where address/count indicate a memory area
2211 and crc32 is the correct crc32 which the
2215 Add the "loopw" memory command. This only takes effect if
2216 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2218 - CONFIG_CMD_MX_CYCLIC
2219 Add the "mdc" and "mwc" memory commands. These are cyclic
2224 This command will print 4 bytes (10,11,12,13) each 500 ms.
2226 => mwc.l 100 12345678 10
2227 This command will write 12345678 to address 100 all 10 ms.
2229 This only takes effect if the memory commands are activated
2230 globally (CONFIG_CMD_MEMORY).
2233 Set when the currently-running compilation is for an artifact
2234 that will end up in the SPL (as opposed to the TPL or U-Boot
2235 proper). Code that needs stage-specific behavior should check
2239 Set when the currently-running compilation is for an artifact
2240 that will end up in the TPL (as opposed to the SPL or U-Boot
2241 proper). Code that needs stage-specific behavior should check
2244 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2245 Only for 85xx systems. If this variable is specified, the section
2246 .resetvec is not kept and the section .bootpg is placed in the
2247 previous 4k of the .text section.
2249 - CONFIG_ARCH_MAP_SYSMEM
2250 Generally U-Boot (and in particular the md command) uses
2251 effective address. It is therefore not necessary to regard
2252 U-Boot address as virtual addresses that need to be translated
2253 to physical addresses. However, sandbox requires this, since
2254 it maintains its own little RAM buffer which contains all
2255 addressable memory. This option causes some memory accesses
2256 to be mapped through map_sysmem() / unmap_sysmem().
2258 - CONFIG_X86_RESET_VECTOR
2259 If defined, the x86 reset vector code is included. This is not
2260 needed when U-Boot is running from Coreboot.
2262 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2263 Option to disable subpage write in NAND driver
2264 driver that uses this:
2265 drivers/mtd/nand/raw/davinci_nand.c
2267 Freescale QE/FMAN Firmware Support:
2268 -----------------------------------
2270 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2271 loading of "firmware", which is encoded in the QE firmware binary format.
2272 This firmware often needs to be loaded during U-Boot booting, so macros
2273 are used to identify the storage device (NOR flash, SPI, etc) and the address
2276 - CONFIG_SYS_FMAN_FW_ADDR
2277 The address in the storage device where the FMAN microcode is located. The
2278 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2281 - CONFIG_SYS_QE_FW_ADDR
2282 The address in the storage device where the QE microcode is located. The
2283 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2286 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2287 The maximum possible size of the firmware. The firmware binary format
2288 has a field that specifies the actual size of the firmware, but it
2289 might not be possible to read any part of the firmware unless some
2290 local storage is allocated to hold the entire firmware first.
2292 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2293 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2294 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2295 virtual address in NOR flash.
2297 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2298 Specifies that QE/FMAN firmware is located in NAND flash.
2299 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2301 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2302 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2303 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2305 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2306 Specifies that QE/FMAN firmware is located in the remote (master)
2307 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2308 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2309 window->master inbound window->master LAW->the ucode address in
2310 master's memory space.
2312 Freescale Layerscape Management Complex Firmware Support:
2313 ---------------------------------------------------------
2314 The Freescale Layerscape Management Complex (MC) supports the loading of
2316 This firmware often needs to be loaded during U-Boot booting, so macros
2317 are used to identify the storage device (NOR flash, SPI, etc) and the address
2320 - CONFIG_FSL_MC_ENET
2321 Enable the MC driver for Layerscape SoCs.
2323 Freescale Layerscape Debug Server Support:
2324 -------------------------------------------
2325 The Freescale Layerscape Debug Server Support supports the loading of
2326 "Debug Server firmware" and triggering SP boot-rom.
2327 This firmware often needs to be loaded during U-Boot booting.
2329 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2330 Define alignment of reserved memory MC requires
2335 In order to achieve reproducible builds, timestamps used in the U-Boot build
2336 process have to be set to a fixed value.
2338 This is done using the SOURCE_DATE_EPOCH environment variable.
2339 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2340 option for U-Boot or an environment variable in U-Boot.
2342 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2344 Building the Software:
2345 ======================
2347 Building U-Boot has been tested in several native build environments
2348 and in many different cross environments. Of course we cannot support
2349 all possibly existing versions of cross development tools in all
2350 (potentially obsolete) versions. In case of tool chain problems we
2351 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2352 which is extensively used to build and test U-Boot.
2354 If you are not using a native environment, it is assumed that you
2355 have GNU cross compiling tools available in your path. In this case,
2356 you must set the environment variable CROSS_COMPILE in your shell.
2357 Note that no changes to the Makefile or any other source files are
2358 necessary. For example using the ELDK on a 4xx CPU, please enter:
2360 $ CROSS_COMPILE=ppc_4xx-
2361 $ export CROSS_COMPILE
2363 U-Boot is intended to be simple to build. After installing the
2364 sources you must configure U-Boot for one specific board type. This
2369 where "NAME_defconfig" is the name of one of the existing configu-
2370 rations; see configs/*_defconfig for supported names.
2372 Note: for some boards special configuration names may exist; check if
2373 additional information is available from the board vendor; for
2374 instance, the TQM823L systems are available without (standard)
2375 or with LCD support. You can select such additional "features"
2376 when choosing the configuration, i. e.
2378 make TQM823L_defconfig
2379 - will configure for a plain TQM823L, i. e. no LCD support
2381 make TQM823L_LCD_defconfig
2382 - will configure for a TQM823L with U-Boot console on LCD
2387 Finally, type "make all", and you should get some working U-Boot
2388 images ready for download to / installation on your system:
2390 - "u-boot.bin" is a raw binary image
2391 - "u-boot" is an image in ELF binary format
2392 - "u-boot.srec" is in Motorola S-Record format
2394 By default the build is performed locally and the objects are saved
2395 in the source directory. One of the two methods can be used to change
2396 this behavior and build U-Boot to some external directory:
2398 1. Add O= to the make command line invocations:
2400 make O=/tmp/build distclean
2401 make O=/tmp/build NAME_defconfig
2402 make O=/tmp/build all
2404 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2406 export KBUILD_OUTPUT=/tmp/build
2411 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2414 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2415 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2416 For example to treat all compiler warnings as errors:
2418 make KCFLAGS=-Werror
2420 Please be aware that the Makefiles assume you are using GNU make, so
2421 for instance on NetBSD you might need to use "gmake" instead of
2425 If the system board that you have is not listed, then you will need
2426 to port U-Boot to your hardware platform. To do this, follow these
2429 1. Create a new directory to hold your board specific code. Add any
2430 files you need. In your board directory, you will need at least
2431 the "Makefile" and a "<board>.c".
2432 2. Create a new configuration file "include/configs/<board>.h" for
2434 3. If you're porting U-Boot to a new CPU, then also create a new
2435 directory to hold your CPU specific code. Add any files you need.
2436 4. Run "make <board>_defconfig" with your new name.
2437 5. Type "make", and you should get a working "u-boot.srec" file
2438 to be installed on your target system.
2439 6. Debug and solve any problems that might arise.
2440 [Of course, this last step is much harder than it sounds.]
2443 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2444 ==============================================================
2446 If you have modified U-Boot sources (for instance added a new board
2447 or support for new devices, a new CPU, etc.) you are expected to
2448 provide feedback to the other developers. The feedback normally takes
2449 the form of a "patch", i.e. a context diff against a certain (latest
2450 official or latest in the git repository) version of U-Boot sources.
2452 But before you submit such a patch, please verify that your modifi-
2453 cation did not break existing code. At least make sure that *ALL* of
2454 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2455 just run the buildman script (tools/buildman/buildman), which will
2456 configure and build U-Boot for ALL supported system. Be warned, this
2457 will take a while. Please see the buildman README, or run 'buildman -H'
2461 See also "U-Boot Porting Guide" below.
2464 Monitor Commands - Overview:
2465 ============================
2467 go - start application at address 'addr'
2468 run - run commands in an environment variable
2469 bootm - boot application image from memory
2470 bootp - boot image via network using BootP/TFTP protocol
2471 bootz - boot zImage from memory
2472 tftpboot- boot image via network using TFTP protocol
2473 and env variables "ipaddr" and "serverip"
2474 (and eventually "gatewayip")
2475 tftpput - upload a file via network using TFTP protocol
2476 rarpboot- boot image via network using RARP/TFTP protocol
2477 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2478 loads - load S-Record file over serial line
2479 loadb - load binary file over serial line (kermit mode)
2481 mm - memory modify (auto-incrementing)
2482 nm - memory modify (constant address)
2483 mw - memory write (fill)
2486 cmp - memory compare
2487 crc32 - checksum calculation
2488 i2c - I2C sub-system
2489 sspi - SPI utility commands
2490 base - print or set address offset
2491 printenv- print environment variables
2492 pwm - control pwm channels
2493 setenv - set environment variables
2494 saveenv - save environment variables to persistent storage
2495 protect - enable or disable FLASH write protection
2496 erase - erase FLASH memory
2497 flinfo - print FLASH memory information
2498 nand - NAND memory operations (see doc/README.nand)
2499 bdinfo - print Board Info structure
2500 iminfo - print header information for application image
2501 coninfo - print console devices and informations
2502 ide - IDE sub-system
2503 loop - infinite loop on address range
2504 loopw - infinite write loop on address range
2505 mtest - simple RAM test
2506 icache - enable or disable instruction cache
2507 dcache - enable or disable data cache
2508 reset - Perform RESET of the CPU
2509 echo - echo args to console
2510 version - print monitor version
2511 help - print online help
2512 ? - alias for 'help'
2515 Monitor Commands - Detailed Description:
2516 ========================================
2520 For now: just type "help <command>".
2523 Note for Redundant Ethernet Interfaces:
2524 =======================================
2526 Some boards come with redundant Ethernet interfaces; U-Boot supports
2527 such configurations and is capable of automatic selection of a
2528 "working" interface when needed. MAC assignment works as follows:
2530 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2531 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2532 "eth1addr" (=>eth1), "eth2addr", ...
2534 If the network interface stores some valid MAC address (for instance
2535 in SROM), this is used as default address if there is NO correspon-
2536 ding setting in the environment; if the corresponding environment
2537 variable is set, this overrides the settings in the card; that means:
2539 o If the SROM has a valid MAC address, and there is no address in the
2540 environment, the SROM's address is used.
2542 o If there is no valid address in the SROM, and a definition in the
2543 environment exists, then the value from the environment variable is
2546 o If both the SROM and the environment contain a MAC address, and
2547 both addresses are the same, this MAC address is used.
2549 o If both the SROM and the environment contain a MAC address, and the
2550 addresses differ, the value from the environment is used and a
2553 o If neither SROM nor the environment contain a MAC address, an error
2554 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2555 a random, locally-assigned MAC is used.
2557 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2558 will be programmed into hardware as part of the initialization process. This
2559 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2560 The naming convention is as follows:
2561 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2566 U-Boot is capable of booting (and performing other auxiliary operations on)
2567 images in two formats:
2569 New uImage format (FIT)
2570 -----------------------
2572 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2573 to Flattened Device Tree). It allows the use of images with multiple
2574 components (several kernels, ramdisks, etc.), with contents protected by
2575 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2581 Old image format is based on binary files which can be basically anything,
2582 preceded by a special header; see the definitions in include/image.h for
2583 details; basically, the header defines the following image properties:
2585 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2586 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2587 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2588 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2589 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2590 IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2591 Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
2592 * Compression Type (uncompressed, gzip, bzip2)
2598 The header is marked by a special Magic Number, and both the header
2599 and the data portions of the image are secured against corruption by
2606 Although U-Boot should support any OS or standalone application
2607 easily, the main focus has always been on Linux during the design of
2610 U-Boot includes many features that so far have been part of some
2611 special "boot loader" code within the Linux kernel. Also, any
2612 "initrd" images to be used are no longer part of one big Linux image;
2613 instead, kernel and "initrd" are separate images. This implementation
2614 serves several purposes:
2616 - the same features can be used for other OS or standalone
2617 applications (for instance: using compressed images to reduce the
2618 Flash memory footprint)
2620 - it becomes much easier to port new Linux kernel versions because
2621 lots of low-level, hardware dependent stuff are done by U-Boot
2623 - the same Linux kernel image can now be used with different "initrd"
2624 images; of course this also means that different kernel images can
2625 be run with the same "initrd". This makes testing easier (you don't
2626 have to build a new "zImage.initrd" Linux image when you just
2627 change a file in your "initrd"). Also, a field-upgrade of the
2628 software is easier now.
2634 Porting Linux to U-Boot based systems:
2635 ---------------------------------------
2637 U-Boot cannot save you from doing all the necessary modifications to
2638 configure the Linux device drivers for use with your target hardware
2639 (no, we don't intend to provide a full virtual machine interface to
2642 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2644 Just make sure your machine specific header file (for instance
2645 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2646 Information structure as we define in include/asm-<arch>/u-boot.h,
2647 and make sure that your definition of IMAP_ADDR uses the same value
2648 as your U-Boot configuration in CONFIG_SYS_IMMR.
2650 Note that U-Boot now has a driver model, a unified model for drivers.
2651 If you are adding a new driver, plumb it into driver model. If there
2652 is no uclass available, you are encouraged to create one. See
2656 Configuring the Linux kernel:
2657 -----------------------------
2659 No specific requirements for U-Boot. Make sure you have some root
2660 device (initial ramdisk, NFS) for your target system.
2663 Building a Linux Image:
2664 -----------------------
2666 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2667 not used. If you use recent kernel source, a new build target
2668 "uImage" will exist which automatically builds an image usable by
2669 U-Boot. Most older kernels also have support for a "pImage" target,
2670 which was introduced for our predecessor project PPCBoot and uses a
2671 100% compatible format.
2675 make TQM850L_defconfig
2680 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2681 encapsulate a compressed Linux kernel image with header information,
2682 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2684 * build a standard "vmlinux" kernel image (in ELF binary format):
2686 * convert the kernel into a raw binary image:
2688 ${CROSS_COMPILE}-objcopy -O binary \
2689 -R .note -R .comment \
2690 -S vmlinux linux.bin
2692 * compress the binary image:
2696 * package compressed binary image for U-Boot:
2698 mkimage -A ppc -O linux -T kernel -C gzip \
2699 -a 0 -e 0 -n "Linux Kernel Image" \
2700 -d linux.bin.gz uImage
2703 The "mkimage" tool can also be used to create ramdisk images for use
2704 with U-Boot, either separated from the Linux kernel image, or
2705 combined into one file. "mkimage" encapsulates the images with a 64
2706 byte header containing information about target architecture,
2707 operating system, image type, compression method, entry points, time
2708 stamp, CRC32 checksums, etc.
2710 "mkimage" can be called in two ways: to verify existing images and
2711 print the header information, or to build new images.
2713 In the first form (with "-l" option) mkimage lists the information
2714 contained in the header of an existing U-Boot image; this includes
2715 checksum verification:
2717 tools/mkimage -l image
2718 -l ==> list image header information
2720 The second form (with "-d" option) is used to build a U-Boot image
2721 from a "data file" which is used as image payload:
2723 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2724 -n name -d data_file image
2725 -A ==> set architecture to 'arch'
2726 -O ==> set operating system to 'os'
2727 -T ==> set image type to 'type'
2728 -C ==> set compression type 'comp'
2729 -a ==> set load address to 'addr' (hex)
2730 -e ==> set entry point to 'ep' (hex)
2731 -n ==> set image name to 'name'
2732 -d ==> use image data from 'datafile'
2734 Right now, all Linux kernels for PowerPC systems use the same load
2735 address (0x00000000), but the entry point address depends on the
2738 - 2.2.x kernels have the entry point at 0x0000000C,
2739 - 2.3.x and later kernels have the entry point at 0x00000000.
2741 So a typical call to build a U-Boot image would read:
2743 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2744 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2745 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2746 > examples/uImage.TQM850L
2747 Image Name: 2.4.4 kernel for TQM850L
2748 Created: Wed Jul 19 02:34:59 2000
2749 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2750 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2751 Load Address: 0x00000000
2752 Entry Point: 0x00000000
2754 To verify the contents of the image (or check for corruption):
2756 -> tools/mkimage -l examples/uImage.TQM850L
2757 Image Name: 2.4.4 kernel for TQM850L
2758 Created: Wed Jul 19 02:34:59 2000
2759 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2760 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2761 Load Address: 0x00000000
2762 Entry Point: 0x00000000
2764 NOTE: for embedded systems where boot time is critical you can trade
2765 speed for memory and install an UNCOMPRESSED image instead: this
2766 needs more space in Flash, but boots much faster since it does not
2767 need to be uncompressed:
2769 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2770 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2771 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2772 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2773 > examples/uImage.TQM850L-uncompressed
2774 Image Name: 2.4.4 kernel for TQM850L
2775 Created: Wed Jul 19 02:34:59 2000
2776 Image Type: PowerPC Linux Kernel Image (uncompressed)
2777 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2778 Load Address: 0x00000000
2779 Entry Point: 0x00000000
2782 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2783 when your kernel is intended to use an initial ramdisk:
2785 -> tools/mkimage -n 'Simple Ramdisk Image' \
2786 > -A ppc -O linux -T ramdisk -C gzip \
2787 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2788 Image Name: Simple Ramdisk Image
2789 Created: Wed Jan 12 14:01:50 2000
2790 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2791 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2792 Load Address: 0x00000000
2793 Entry Point: 0x00000000
2795 The "dumpimage" tool can be used to disassemble or list the contents of images
2796 built by mkimage. See dumpimage's help output (-h) for details.
2798 Installing a Linux Image:
2799 -------------------------
2801 To downloading a U-Boot image over the serial (console) interface,
2802 you must convert the image to S-Record format:
2804 objcopy -I binary -O srec examples/image examples/image.srec
2806 The 'objcopy' does not understand the information in the U-Boot
2807 image header, so the resulting S-Record file will be relative to
2808 address 0x00000000. To load it to a given address, you need to
2809 specify the target address as 'offset' parameter with the 'loads'
2812 Example: install the image to address 0x40100000 (which on the
2813 TQM8xxL is in the first Flash bank):
2815 => erase 40100000 401FFFFF
2821 ## Ready for S-Record download ...
2822 ~>examples/image.srec
2823 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2825 15989 15990 15991 15992
2826 [file transfer complete]
2828 ## Start Addr = 0x00000000
2831 You can check the success of the download using the 'iminfo' command;
2832 this includes a checksum verification so you can be sure no data
2833 corruption happened:
2837 ## Checking Image at 40100000 ...
2838 Image Name: 2.2.13 for initrd on TQM850L
2839 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2840 Data Size: 335725 Bytes = 327 kB = 0 MB
2841 Load Address: 00000000
2842 Entry Point: 0000000c
2843 Verifying Checksum ... OK
2849 The "bootm" command is used to boot an application that is stored in
2850 memory (RAM or Flash). In case of a Linux kernel image, the contents
2851 of the "bootargs" environment variable is passed to the kernel as
2852 parameters. You can check and modify this variable using the
2853 "printenv" and "setenv" commands:
2856 => printenv bootargs
2857 bootargs=root=/dev/ram
2859 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2861 => printenv bootargs
2862 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2865 ## Booting Linux kernel at 40020000 ...
2866 Image Name: 2.2.13 for NFS on TQM850L
2867 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2868 Data Size: 381681 Bytes = 372 kB = 0 MB
2869 Load Address: 00000000
2870 Entry Point: 0000000c
2871 Verifying Checksum ... OK
2872 Uncompressing Kernel Image ... OK
2873 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
2874 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2875 time_init: decrementer frequency = 187500000/60
2876 Calibrating delay loop... 49.77 BogoMIPS
2877 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2880 If you want to boot a Linux kernel with initial RAM disk, you pass
2881 the memory addresses of both the kernel and the initrd image (PPBCOOT
2882 format!) to the "bootm" command:
2884 => imi 40100000 40200000
2886 ## Checking Image at 40100000 ...
2887 Image Name: 2.2.13 for initrd on TQM850L
2888 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2889 Data Size: 335725 Bytes = 327 kB = 0 MB
2890 Load Address: 00000000
2891 Entry Point: 0000000c
2892 Verifying Checksum ... OK
2894 ## Checking Image at 40200000 ...
2895 Image Name: Simple Ramdisk Image
2896 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2897 Data Size: 566530 Bytes = 553 kB = 0 MB
2898 Load Address: 00000000
2899 Entry Point: 00000000
2900 Verifying Checksum ... OK
2902 => bootm 40100000 40200000
2903 ## Booting Linux kernel at 40100000 ...
2904 Image Name: 2.2.13 for initrd on TQM850L
2905 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2906 Data Size: 335725 Bytes = 327 kB = 0 MB
2907 Load Address: 00000000
2908 Entry Point: 0000000c
2909 Verifying Checksum ... OK
2910 Uncompressing Kernel Image ... OK
2911 ## Loading RAMDisk Image at 40200000 ...
2912 Image Name: Simple Ramdisk Image
2913 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2914 Data Size: 566530 Bytes = 553 kB = 0 MB
2915 Load Address: 00000000
2916 Entry Point: 00000000
2917 Verifying Checksum ... OK
2918 Loading Ramdisk ... OK
2919 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
2920 Boot arguments: root=/dev/ram
2921 time_init: decrementer frequency = 187500000/60
2922 Calibrating delay loop... 49.77 BogoMIPS
2924 RAMDISK: Compressed image found at block 0
2925 VFS: Mounted root (ext2 filesystem).
2929 Boot Linux and pass a flat device tree:
2932 First, U-Boot must be compiled with the appropriate defines. See the section
2933 titled "Linux Kernel Interface" above for a more in depth explanation. The
2934 following is an example of how to start a kernel and pass an updated
2940 oft=oftrees/mpc8540ads.dtb
2941 => tftp $oftaddr $oft
2942 Speed: 1000, full duplex
2944 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
2945 Filename 'oftrees/mpc8540ads.dtb'.
2946 Load address: 0x300000
2949 Bytes transferred = 4106 (100a hex)
2950 => tftp $loadaddr $bootfile
2951 Speed: 1000, full duplex
2953 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
2955 Load address: 0x200000
2956 Loading:############
2958 Bytes transferred = 1029407 (fb51f hex)
2963 => bootm $loadaddr - $oftaddr
2964 ## Booting image at 00200000 ...
2965 Image Name: Linux-2.6.17-dirty
2966 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2967 Data Size: 1029343 Bytes = 1005.2 kB
2968 Load Address: 00000000
2969 Entry Point: 00000000
2970 Verifying Checksum ... OK
2971 Uncompressing Kernel Image ... OK
2972 Booting using flat device tree at 0x300000
2973 Using MPC85xx ADS machine description
2974 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
2978 More About U-Boot Image Types:
2979 ------------------------------
2981 U-Boot supports the following image types:
2983 "Standalone Programs" are directly runnable in the environment
2984 provided by U-Boot; it is expected that (if they behave
2985 well) you can continue to work in U-Boot after return from
2986 the Standalone Program.
2987 "OS Kernel Images" are usually images of some Embedded OS which
2988 will take over control completely. Usually these programs
2989 will install their own set of exception handlers, device
2990 drivers, set up the MMU, etc. - this means, that you cannot
2991 expect to re-enter U-Boot except by resetting the CPU.
2992 "RAMDisk Images" are more or less just data blocks, and their
2993 parameters (address, size) are passed to an OS kernel that is
2995 "Multi-File Images" contain several images, typically an OS
2996 (Linux) kernel image and one or more data images like
2997 RAMDisks. This construct is useful for instance when you want
2998 to boot over the network using BOOTP etc., where the boot
2999 server provides just a single image file, but you want to get
3000 for instance an OS kernel and a RAMDisk image.
3002 "Multi-File Images" start with a list of image sizes, each
3003 image size (in bytes) specified by an "uint32_t" in network
3004 byte order. This list is terminated by an "(uint32_t)0".
3005 Immediately after the terminating 0 follow the images, one by
3006 one, all aligned on "uint32_t" boundaries (size rounded up to
3007 a multiple of 4 bytes).
3009 "Firmware Images" are binary images containing firmware (like
3010 U-Boot or FPGA images) which usually will be programmed to
3013 "Script files" are command sequences that will be executed by
3014 U-Boot's command interpreter; this feature is especially
3015 useful when you configure U-Boot to use a real shell (hush)
3016 as command interpreter.
3018 Booting the Linux zImage:
3019 -------------------------
3021 On some platforms, it's possible to boot Linux zImage. This is done
3022 using the "bootz" command. The syntax of "bootz" command is the same
3023 as the syntax of "bootm" command.
3025 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3026 kernel with raw initrd images. The syntax is slightly different, the
3027 address of the initrd must be augmented by it's size, in the following
3028 format: "<initrd addres>:<initrd size>".
3034 One of the features of U-Boot is that you can dynamically load and
3035 run "standalone" applications, which can use some resources of
3036 U-Boot like console I/O functions or interrupt services.
3038 Two simple examples are included with the sources:
3043 'examples/hello_world.c' contains a small "Hello World" Demo
3044 application; it is automatically compiled when you build U-Boot.
3045 It's configured to run at address 0x00040004, so you can play with it
3049 ## Ready for S-Record download ...
3050 ~>examples/hello_world.srec
3051 1 2 3 4 5 6 7 8 9 10 11 ...
3052 [file transfer complete]
3054 ## Start Addr = 0x00040004
3056 => go 40004 Hello World! This is a test.
3057 ## Starting application at 0x00040004 ...
3068 Hit any key to exit ...
3070 ## Application terminated, rc = 0x0
3072 Another example, which demonstrates how to register a CPM interrupt
3073 handler with the U-Boot code, can be found in 'examples/timer.c'.
3074 Here, a CPM timer is set up to generate an interrupt every second.
3075 The interrupt service routine is trivial, just printing a '.'
3076 character, but this is just a demo program. The application can be
3077 controlled by the following keys:
3079 ? - print current values og the CPM Timer registers
3080 b - enable interrupts and start timer
3081 e - stop timer and disable interrupts
3082 q - quit application
3085 ## Ready for S-Record download ...
3086 ~>examples/timer.srec
3087 1 2 3 4 5 6 7 8 9 10 11 ...
3088 [file transfer complete]
3090 ## Start Addr = 0x00040004
3093 ## Starting application at 0x00040004 ...
3096 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3099 [q, b, e, ?] Set interval 1000000 us
3102 [q, b, e, ?] ........
3103 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3106 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3109 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3112 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3114 [q, b, e, ?] ...Stopping timer
3116 [q, b, e, ?] ## Application terminated, rc = 0x0
3122 Over time, many people have reported problems when trying to use the
3123 "minicom" terminal emulation program for serial download. I (wd)
3124 consider minicom to be broken, and recommend not to use it. Under
3125 Unix, I recommend to use C-Kermit for general purpose use (and
3126 especially for kermit binary protocol download ("loadb" command), and
3127 use "cu" for S-Record download ("loads" command). See
3128 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3129 for help with kermit.
3132 Nevertheless, if you absolutely want to use it try adding this
3133 configuration to your "File transfer protocols" section:
3135 Name Program Name U/D FullScr IO-Red. Multi
3136 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3137 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3143 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3144 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3146 Building requires a cross environment; it is known to work on
3147 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3148 need gmake since the Makefiles are not compatible with BSD make).
3149 Note that the cross-powerpc package does not install include files;
3150 attempting to build U-Boot will fail because <machine/ansi.h> is
3151 missing. This file has to be installed and patched manually:
3153 # cd /usr/pkg/cross/powerpc-netbsd/include
3155 # ln -s powerpc machine
3156 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3157 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3159 Native builds *don't* work due to incompatibilities between native
3160 and U-Boot include files.
3162 Booting assumes that (the first part of) the image booted is a
3163 stage-2 loader which in turn loads and then invokes the kernel
3164 proper. Loader sources will eventually appear in the NetBSD source
3165 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3166 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3169 Implementation Internals:
3170 =========================
3172 The following is not intended to be a complete description of every
3173 implementation detail. However, it should help to understand the
3174 inner workings of U-Boot and make it easier to port it to custom
3178 Initial Stack, Global Data:
3179 ---------------------------
3181 The implementation of U-Boot is complicated by the fact that U-Boot
3182 starts running out of ROM (flash memory), usually without access to
3183 system RAM (because the memory controller is not initialized yet).
3184 This means that we don't have writable Data or BSS segments, and BSS
3185 is not initialized as zero. To be able to get a C environment working
3186 at all, we have to allocate at least a minimal stack. Implementation
3187 options for this are defined and restricted by the CPU used: Some CPU
3188 models provide on-chip memory (like the IMMR area on MPC8xx and
3189 MPC826x processors), on others (parts of) the data cache can be
3190 locked as (mis-) used as memory, etc.
3192 Chris Hallinan posted a good summary of these issues to the
3193 U-Boot mailing list:
3195 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3196 From: "Chris Hallinan" <clh@net1plus.com>
3197 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3200 Correct me if I'm wrong, folks, but the way I understand it
3201 is this: Using DCACHE as initial RAM for Stack, etc, does not
3202 require any physical RAM backing up the cache. The cleverness
3203 is that the cache is being used as a temporary supply of
3204 necessary storage before the SDRAM controller is setup. It's
3205 beyond the scope of this list to explain the details, but you
3206 can see how this works by studying the cache architecture and
3207 operation in the architecture and processor-specific manuals.
3209 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3210 is another option for the system designer to use as an
3211 initial stack/RAM area prior to SDRAM being available. Either
3212 option should work for you. Using CS 4 should be fine if your
3213 board designers haven't used it for something that would
3214 cause you grief during the initial boot! It is frequently not
3217 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3218 with your processor/board/system design. The default value
3219 you will find in any recent u-boot distribution in
3220 walnut.h should work for you. I'd set it to a value larger
3221 than your SDRAM module. If you have a 64MB SDRAM module, set
3222 it above 400_0000. Just make sure your board has no resources
3223 that are supposed to respond to that address! That code in
3224 start.S has been around a while and should work as is when
3225 you get the config right.
3230 It is essential to remember this, since it has some impact on the C
3231 code for the initialization procedures:
3233 * Initialized global data (data segment) is read-only. Do not attempt
3236 * Do not use any uninitialized global data (or implicitly initialized
3237 as zero data - BSS segment) at all - this is undefined, initiali-
3238 zation is performed later (when relocating to RAM).
3240 * Stack space is very limited. Avoid big data buffers or things like
3243 Having only the stack as writable memory limits means we cannot use
3244 normal global data to share information between the code. But it
3245 turned out that the implementation of U-Boot can be greatly
3246 simplified by making a global data structure (gd_t) available to all
3247 functions. We could pass a pointer to this data as argument to _all_
3248 functions, but this would bloat the code. Instead we use a feature of
3249 the GCC compiler (Global Register Variables) to share the data: we
3250 place a pointer (gd) to the global data into a register which we
3251 reserve for this purpose.
3253 When choosing a register for such a purpose we are restricted by the
3254 relevant (E)ABI specifications for the current architecture, and by
3255 GCC's implementation.
3257 For PowerPC, the following registers have specific use:
3259 R2: reserved for system use
3260 R3-R4: parameter passing and return values
3261 R5-R10: parameter passing
3262 R13: small data area pointer
3266 (U-Boot also uses R12 as internal GOT pointer. r12
3267 is a volatile register so r12 needs to be reset when
3268 going back and forth between asm and C)
3270 ==> U-Boot will use R2 to hold a pointer to the global data
3272 Note: on PPC, we could use a static initializer (since the
3273 address of the global data structure is known at compile time),
3274 but it turned out that reserving a register results in somewhat
3275 smaller code - although the code savings are not that big (on
3276 average for all boards 752 bytes for the whole U-Boot image,
3277 624 text + 127 data).
3279 On ARM, the following registers are used:
3281 R0: function argument word/integer result
3282 R1-R3: function argument word
3283 R9: platform specific
3284 R10: stack limit (used only if stack checking is enabled)
3285 R11: argument (frame) pointer
3286 R12: temporary workspace
3289 R15: program counter
3291 ==> U-Boot will use R9 to hold a pointer to the global data
3293 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3295 On Nios II, the ABI is documented here:
3296 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3298 ==> U-Boot will use gp to hold a pointer to the global data
3300 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3301 to access small data sections, so gp is free.
3303 On RISC-V, the following registers are used:
3305 x0: hard-wired zero (zero)
3306 x1: return address (ra)
3307 x2: stack pointer (sp)
3308 x3: global pointer (gp)
3309 x4: thread pointer (tp)
3310 x5: link register (t0)
3311 x8: frame pointer (fp)
3312 x10-x11: arguments/return values (a0-1)
3313 x12-x17: arguments (a2-7)
3314 x28-31: temporaries (t3-6)
3315 pc: program counter (pc)
3317 ==> U-Boot will use gp to hold a pointer to the global data
3322 U-Boot runs in system state and uses physical addresses, i.e. the
3323 MMU is not used either for address mapping nor for memory protection.
3325 The available memory is mapped to fixed addresses using the memory
3326 controller. In this process, a contiguous block is formed for each
3327 memory type (Flash, SDRAM, SRAM), even when it consists of several
3328 physical memory banks.
3330 U-Boot is installed in the first 128 kB of the first Flash bank (on
3331 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3332 booting and sizing and initializing DRAM, the code relocates itself
3333 to the upper end of DRAM. Immediately below the U-Boot code some
3334 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3335 configuration setting]. Below that, a structure with global Board
3336 Info data is placed, followed by the stack (growing downward).
3338 Additionally, some exception handler code is copied to the low 8 kB
3339 of DRAM (0x00000000 ... 0x00001FFF).
3341 So a typical memory configuration with 16 MB of DRAM could look like
3344 0x0000 0000 Exception Vector code
3347 0x0000 2000 Free for Application Use
3353 0x00FB FF20 Monitor Stack (Growing downward)
3354 0x00FB FFAC Board Info Data and permanent copy of global data
3355 0x00FC 0000 Malloc Arena
3358 0x00FE 0000 RAM Copy of Monitor Code
3359 ... eventually: LCD or video framebuffer
3360 ... eventually: pRAM (Protected RAM - unchanged by reset)
3361 0x00FF FFFF [End of RAM]
3364 System Initialization:
3365 ----------------------
3367 In the reset configuration, U-Boot starts at the reset entry point
3368 (on most PowerPC systems at address 0x00000100). Because of the reset
3369 configuration for CS0# this is a mirror of the on board Flash memory.
3370 To be able to re-map memory U-Boot then jumps to its link address.
3371 To be able to implement the initialization code in C, a (small!)
3372 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3373 which provide such a feature like), or in a locked part of the data
3374 cache. After that, U-Boot initializes the CPU core, the caches and
3377 Next, all (potentially) available memory banks are mapped using a
3378 preliminary mapping. For example, we put them on 512 MB boundaries
3379 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3380 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3381 programmed for SDRAM access. Using the temporary configuration, a
3382 simple memory test is run that determines the size of the SDRAM
3385 When there is more than one SDRAM bank, and the banks are of
3386 different size, the largest is mapped first. For equal size, the first
3387 bank (CS2#) is mapped first. The first mapping is always for address
3388 0x00000000, with any additional banks following immediately to create
3389 contiguous memory starting from 0.
3391 Then, the monitor installs itself at the upper end of the SDRAM area
3392 and allocates memory for use by malloc() and for the global Board
3393 Info data; also, the exception vector code is copied to the low RAM
3394 pages, and the final stack is set up.
3396 Only after this relocation will you have a "normal" C environment;
3397 until that you are restricted in several ways, mostly because you are
3398 running from ROM, and because the code will have to be relocated to a
3402 U-Boot Porting Guide:
3403 ----------------------
3405 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3409 int main(int argc, char *argv[])
3411 sighandler_t no_more_time;
3413 signal(SIGALRM, no_more_time);
3414 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3416 if (available_money > available_manpower) {
3417 Pay consultant to port U-Boot;
3421 Download latest U-Boot source;
3423 Subscribe to u-boot mailing list;
3426 email("Hi, I am new to U-Boot, how do I get started?");
3429 Read the README file in the top level directory;
3430 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3431 Read applicable doc/README.*;
3432 Read the source, Luke;
3433 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3436 if (available_money > toLocalCurrency ($2500))
3439 Add a lot of aggravation and time;
3441 if (a similar board exists) { /* hopefully... */
3442 cp -a board/<similar> board/<myboard>
3443 cp include/configs/<similar>.h include/configs/<myboard>.h
3445 Create your own board support subdirectory;
3446 Create your own board include/configs/<myboard>.h file;
3448 Edit new board/<myboard> files
3449 Edit new include/configs/<myboard>.h
3454 Add / modify source code;
3458 email("Hi, I am having problems...");
3460 Send patch file to the U-Boot email list;
3461 if (reasonable critiques)
3462 Incorporate improvements from email list code review;
3464 Defend code as written;
3470 void no_more_time (int sig)
3479 All contributions to U-Boot should conform to the Linux kernel
3480 coding style; see the kernel coding style guide at
3481 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3482 script "scripts/Lindent" in your Linux kernel source directory.
3484 Source files originating from a different project (for example the
3485 MTD subsystem) are generally exempt from these guidelines and are not
3486 reformatted to ease subsequent migration to newer versions of those
3489 Please note that U-Boot is implemented in C (and to some small parts in
3490 Assembler); no C++ is used, so please do not use C++ style comments (//)
3493 Please also stick to the following formatting rules:
3494 - remove any trailing white space
3495 - use TAB characters for indentation and vertical alignment, not spaces
3496 - make sure NOT to use DOS '\r\n' line feeds
3497 - do not add more than 2 consecutive empty lines to source files
3498 - do not add trailing empty lines to source files
3500 Submissions which do not conform to the standards may be returned
3501 with a request to reformat the changes.
3507 Since the number of patches for U-Boot is growing, we need to
3508 establish some rules. Submissions which do not conform to these rules
3509 may be rejected, even when they contain important and valuable stuff.
3511 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3513 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3514 see https://lists.denx.de/listinfo/u-boot
3516 When you send a patch, please include the following information with
3519 * For bug fixes: a description of the bug and how your patch fixes
3520 this bug. Please try to include a way of demonstrating that the
3521 patch actually fixes something.
3523 * For new features: a description of the feature and your
3526 * For major contributions, add a MAINTAINERS file with your
3527 information and associated file and directory references.
3529 * When you add support for a new board, don't forget to add a
3530 maintainer e-mail address to the boards.cfg file, too.
3532 * If your patch adds new configuration options, don't forget to
3533 document these in the README file.
3535 * The patch itself. If you are using git (which is *strongly*
3536 recommended) you can easily generate the patch using the
3537 "git format-patch". If you then use "git send-email" to send it to
3538 the U-Boot mailing list, you will avoid most of the common problems
3539 with some other mail clients.
3541 If you cannot use git, use "diff -purN OLD NEW". If your version of
3542 diff does not support these options, then get the latest version of
3545 The current directory when running this command shall be the parent
3546 directory of the U-Boot source tree (i. e. please make sure that
3547 your patch includes sufficient directory information for the
3550 We prefer patches as plain text. MIME attachments are discouraged,
3551 and compressed attachments must not be used.
3553 * If one logical set of modifications affects or creates several
3554 files, all these changes shall be submitted in a SINGLE patch file.
3556 * Changesets that contain different, unrelated modifications shall be
3557 submitted as SEPARATE patches, one patch per changeset.
3562 * Before sending the patch, run the buildman script on your patched
3563 source tree and make sure that no errors or warnings are reported
3564 for any of the boards.
3566 * Keep your modifications to the necessary minimum: A patch
3567 containing several unrelated changes or arbitrary reformats will be
3568 returned with a request to re-formatting / split it.
3570 * If you modify existing code, make sure that your new code does not
3571 add to the memory footprint of the code ;-) Small is beautiful!
3572 When adding new features, these should compile conditionally only
3573 (using #ifdef), and the resulting code with the new feature
3574 disabled must not need more memory than the old code without your
3577 * Remember that there is a size limit of 100 kB per message on the
3578 u-boot mailing list. Bigger patches will be moderated. If they are
3579 reasonable and not too big, they will be acknowledged. But patches
3580 bigger than the size limit should be avoided.