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_SYS_INIT_SP_OFFSET
498 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
499 pointer. This is needed for the temporary stack before
502 CONFIG_XWAY_SWAP_BYTES
504 Enable compilation of tools/xway-swap-bytes needed for Lantiq
505 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
506 be swapped if a flash programmer is used.
509 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
511 Select high exception vectors of the ARM core, e.g., do not
512 clear the V bit of the c1 register of CP15.
515 Generic timer clock source frequency.
517 COUNTER_FREQUENCY_REAL
518 Generic timer clock source frequency if the real clock is
519 different from COUNTER_FREQUENCY, and can only be determined
523 CONFIG_TEGRA_SUPPORT_NON_SECURE
525 Support executing U-Boot in non-secure (NS) mode. Certain
526 impossible actions will be skipped if the CPU is in NS mode,
527 such as ARM architectural timer initialization.
529 - Linux Kernel Interface:
530 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
532 When transferring memsize parameter to Linux, some versions
533 expect it to be in bytes, others in MB.
534 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
538 New kernel versions are expecting firmware settings to be
539 passed using flattened device trees (based on open firmware
543 * New libfdt-based support
544 * Adds the "fdt" command
545 * The bootm command automatically updates the fdt
547 OF_TBCLK - The timebase frequency.
549 boards with QUICC Engines require OF_QE to set UCC MAC
554 U-Boot can detect if an IDE device is present or not.
555 If not, and this new config option is activated, U-Boot
556 removes the ATA node from the DTS before booting Linux,
557 so the Linux IDE driver does not probe the device and
558 crash. This is needed for buggy hardware (uc101) where
559 no pull down resistor is connected to the signal IDE5V_DD7.
561 - vxWorks boot parameters:
563 bootvx constructs a valid bootline using the following
564 environments variables: bootdev, bootfile, ipaddr, netmask,
565 serverip, gatewayip, hostname, othbootargs.
566 It loads the vxWorks image pointed bootfile.
568 Note: If a "bootargs" environment is defined, it will override
569 the defaults discussed just above.
571 - Cache Configuration for ARM:
572 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
574 CONFIG_SYS_PL310_BASE - Physical base address of PL310
575 controller register space
580 If you have Amba PrimeCell PL011 UARTs, set this variable to
581 the clock speed of the UARTs.
585 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
586 define this to a list of base addresses for each (supported)
587 port. See e.g. include/configs/versatile.h
589 CONFIG_SERIAL_HW_FLOW_CONTROL
591 Define this variable to enable hw flow control in serial driver.
592 Current user of this option is drivers/serial/nsl16550.c driver
594 - Serial Download Echo Mode:
596 If defined to 1, all characters received during a
597 serial download (using the "loads" command) are
598 echoed back. This might be needed by some terminal
599 emulations (like "cu"), but may as well just take
600 time on others. This setting #define's the initial
601 value of the "loads_echo" environment variable.
603 - Removal of commands
604 If no commands are needed to boot, you can disable
605 CONFIG_CMDLINE to remove them. In this case, the command line
606 will not be available, and when U-Boot wants to execute the
607 boot command (on start-up) it will call board_run_command()
608 instead. This can reduce image size significantly for very
609 simple boot procedures.
611 - Regular expression support:
613 If this variable is defined, U-Boot is linked against
614 the SLRE (Super Light Regular Expression) library,
615 which adds regex support to some commands, as for
616 example "env grep" and "setexpr".
619 CONFIG_SYS_WATCHDOG_FREQ
620 Some platforms automatically call WATCHDOG_RESET()
621 from the timer interrupt handler every
622 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
623 board configuration file, a default of CONFIG_SYS_HZ/2
624 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
625 to 0 disables calling WATCHDOG_RESET() from the timer
630 When CONFIG_CMD_DATE is selected, the type of the RTC
631 has to be selected, too. Define exactly one of the
634 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
635 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
636 CONFIG_RTC_MC146818 - use MC146818 RTC
637 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
638 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
639 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
640 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
641 CONFIG_RTC_DS164x - use Dallas DS164x RTC
642 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
643 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
644 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
645 CONFIG_SYS_RV3029_TCR - enable trickle charger on
648 Note that if the RTC uses I2C, then the I2C interface
649 must also be configured. See I2C Support, below.
652 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
654 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
655 chip-ngpio pairs that tell the PCA953X driver the number of
656 pins supported by a particular chip.
658 Note that if the GPIO device uses I2C, then the I2C interface
659 must also be configured. See I2C Support, below.
662 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
663 accesses and can checksum them or write a list of them out
664 to memory. See the 'iotrace' command for details. This is
665 useful for testing device drivers since it can confirm that
666 the driver behaves the same way before and after a code
667 change. Currently this is supported on sandbox and arm. To
668 add support for your architecture, add '#include <iotrace.h>'
669 to the bottom of arch/<arch>/include/asm/io.h and test.
671 Example output from the 'iotrace stats' command is below.
672 Note that if the trace buffer is exhausted, the checksum will
673 still continue to operate.
676 Start: 10000000 (buffer start address)
677 Size: 00010000 (buffer size)
678 Offset: 00000120 (current buffer offset)
679 Output: 10000120 (start + offset)
680 Count: 00000018 (number of trace records)
681 CRC32: 9526fb66 (CRC32 of all trace records)
685 When CONFIG_TIMESTAMP is selected, the timestamp
686 (date and time) of an image is printed by image
687 commands like bootm or iminfo. This option is
688 automatically enabled when you select CONFIG_CMD_DATE .
690 - Partition Labels (disklabels) Supported:
691 Zero or more of the following:
692 CONFIG_MAC_PARTITION Apple's MacOS partition table.
693 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
694 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
695 bootloader. Note 2TB partition limit; see
697 CONFIG_SCSI) you must configure support for at
698 least one non-MTD partition type as well.
703 Set this to enable support for disks larger than 137GB
704 Also look at CONFIG_SYS_64BIT_LBA.
705 Whithout these , LBA48 support uses 32bit variables and will 'only'
706 support disks up to 2.1TB.
708 CONFIG_SYS_64BIT_LBA:
709 When enabled, makes the IDE subsystem use 64bit sector addresses.
712 - NETWORK Support (PCI):
714 Utility code for direct access to the SPI bus on Intel 8257x.
715 This does not do anything useful unless you set at least one
716 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
719 Support for National dp83815 chips.
722 Support for National dp8382[01] gigabit chips.
724 - NETWORK Support (other):
726 Support for the Calxeda XGMAC device
729 Support for SMSC's LAN91C96 chips.
731 CONFIG_LAN91C96_USE_32_BIT
732 Define this to enable 32 bit addressing
735 Support for SMSC's LAN91C111 chip
738 Define this to hold the physical address
739 of the device (I/O space)
741 CONFIG_SMC_USE_32_BIT
742 Define this if data bus is 32 bits
744 CONFIG_SMC_USE_IOFUNCS
745 Define this to use i/o functions instead of macros
746 (some hardware wont work with macros)
748 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
749 Define this if you have more then 3 PHYs.
752 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
754 CONFIG_FTGMAC100_EGIGA
755 Define this to use GE link update with gigabit PHY.
756 Define this if FTGMAC100 is connected to gigabit PHY.
757 If your system has 10/100 PHY only, it might not occur
758 wrong behavior. Because PHY usually return timeout or
759 useless data when polling gigabit status and gigabit
760 control registers. This behavior won't affect the
761 correctnessof 10/100 link speed update.
764 Support for Renesas on-chip Ethernet controller
766 CONFIG_SH_ETHER_USE_PORT
767 Define the number of ports to be used
769 CONFIG_SH_ETHER_PHY_ADDR
770 Define the ETH PHY's address
772 CONFIG_SH_ETHER_CACHE_WRITEBACK
773 If this option is set, the driver enables cache flush.
779 CONFIG_TPM_TIS_INFINEON
780 Support for Infineon i2c bus TPM devices. Only one device
781 per system is supported at this time.
783 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
784 Define the burst count bytes upper limit
787 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
789 CONFIG_TPM_ST33ZP24_I2C
790 Support for STMicroelectronics ST33ZP24 I2C devices.
791 Requires TPM_ST33ZP24 and I2C.
793 CONFIG_TPM_ST33ZP24_SPI
794 Support for STMicroelectronics ST33ZP24 SPI devices.
795 Requires TPM_ST33ZP24 and SPI.
798 Support for Atmel TWI TPM device. Requires I2C support.
801 Support for generic parallel port TPM devices. Only one device
802 per system is supported at this time.
804 CONFIG_TPM_TIS_BASE_ADDRESS
805 Base address where the generic TPM device is mapped
806 to. Contemporary x86 systems usually map it at
810 Define this to enable the TPM support library which provides
811 functional interfaces to some TPM commands.
812 Requires support for a TPM device.
814 CONFIG_TPM_AUTH_SESSIONS
815 Define this to enable authorized functions in the TPM library.
816 Requires CONFIG_TPM and CONFIG_SHA1.
819 At the moment only the UHCI host controller is
820 supported (PIP405, MIP405); define
821 CONFIG_USB_UHCI to enable it.
822 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
823 and define CONFIG_USB_STORAGE to enable the USB
826 Supported are USB Keyboards and USB Floppy drives
829 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
830 txfilltuning field in the EHCI controller on reset.
832 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
836 Define the below if you wish to use the USB console.
837 Once firmware is rebuilt from a serial console issue the
838 command "setenv stdin usbtty; setenv stdout usbtty" and
839 attach your USB cable. The Unix command "dmesg" should print
840 it has found a new device. The environment variable usbtty
841 can be set to gserial or cdc_acm to enable your device to
842 appear to a USB host as a Linux gserial device or a
843 Common Device Class Abstract Control Model serial device.
844 If you select usbtty = gserial you should be able to enumerate
846 # modprobe usbserial vendor=0xVendorID product=0xProductID
847 else if using cdc_acm, simply setting the environment
848 variable usbtty to be cdc_acm should suffice. The following
849 might be defined in YourBoardName.h
852 Define this to build a UDC device
855 Define this to have a tty type of device available to
856 talk to the UDC device
859 Define this to enable the high speed support for usb
860 device and usbtty. If this feature is enabled, a routine
861 int is_usbd_high_speed(void)
862 also needs to be defined by the driver to dynamically poll
863 whether the enumeration has succeded at high speed or full
866 If you have a USB-IF assigned VendorID then you may wish to
867 define your own vendor specific values either in BoardName.h
868 or directly in usbd_vendor_info.h. If you don't define
869 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
870 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
871 should pretend to be a Linux device to it's target host.
873 CONFIG_USBD_MANUFACTURER
874 Define this string as the name of your company for
875 - CONFIG_USBD_MANUFACTURER "my company"
877 CONFIG_USBD_PRODUCT_NAME
878 Define this string as the name of your product
879 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
882 Define this as your assigned Vendor ID from the USB
883 Implementors Forum. This *must* be a genuine Vendor ID
884 to avoid polluting the USB namespace.
885 - CONFIG_USBD_VENDORID 0xFFFF
887 CONFIG_USBD_PRODUCTID
888 Define this as the unique Product ID
890 - CONFIG_USBD_PRODUCTID 0xFFFF
892 - ULPI Layer Support:
893 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
894 the generic ULPI layer. The generic layer accesses the ULPI PHY
895 via the platform viewport, so you need both the genric layer and
896 the viewport enabled. Currently only Chipidea/ARC based
897 viewport is supported.
898 To enable the ULPI layer support, define CONFIG_USB_ULPI and
899 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
900 If your ULPI phy needs a different reference clock than the
901 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
902 the appropriate value in Hz.
905 The MMC controller on the Intel PXA is supported. To
906 enable this define CONFIG_MMC. The MMC can be
907 accessed from the boot prompt by mapping the device
908 to physical memory similar to flash. Command line is
909 enabled with CONFIG_CMD_MMC. The MMC driver also works with
910 the FAT fs. This is enabled with CONFIG_CMD_FAT.
913 Support for Renesas on-chip MMCIF controller
916 Define the base address of MMCIF registers
919 Define the clock frequency for MMCIF
921 - USB Device Firmware Update (DFU) class support:
923 This enables the USB portion of the DFU USB class
926 This enables support for exposing NAND devices via DFU.
929 This enables support for exposing RAM via DFU.
930 Note: DFU spec refer to non-volatile memory usage, but
931 allow usages beyond the scope of spec - here RAM usage,
932 one that would help mostly the developer.
934 CONFIG_SYS_DFU_DATA_BUF_SIZE
935 Dfu transfer uses a buffer before writing data to the
936 raw storage device. Make the size (in bytes) of this buffer
937 configurable. The size of this buffer is also configurable
938 through the "dfu_bufsiz" environment variable.
940 CONFIG_SYS_DFU_MAX_FILE_SIZE
941 When updating files rather than the raw storage device,
942 we use a static buffer to copy the file into and then write
943 the buffer once we've been given the whole file. Define
944 this to the maximum filesize (in bytes) for the buffer.
945 Default is 4 MiB if undefined.
947 DFU_DEFAULT_POLL_TIMEOUT
948 Poll timeout [ms], is the timeout a device can send to the
949 host. The host must wait for this timeout before sending
950 a subsequent DFU_GET_STATUS request to the device.
952 DFU_MANIFEST_POLL_TIMEOUT
953 Poll timeout [ms], which the device sends to the host when
954 entering dfuMANIFEST state. Host waits this timeout, before
955 sending again an USB request to the device.
957 - Journaling Flash filesystem support:
958 CONFIG_SYS_JFFS2_FIRST_SECTOR,
959 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
960 Define these for a default partition on a NOR device
963 See Kconfig help for available keyboard drivers.
965 - LCD Support: CONFIG_LCD
967 Define this to enable LCD support (for output to LCD
968 display); also select one of the supported displays
969 by defining one of these:
971 CONFIG_NEC_NL6448AC33:
973 NEC NL6448AC33-18. Active, color, single scan.
975 CONFIG_NEC_NL6448BC20
977 NEC NL6448BC20-08. 6.5", 640x480.
978 Active, color, single scan.
980 CONFIG_NEC_NL6448BC33_54
982 NEC NL6448BC33-54. 10.4", 640x480.
983 Active, color, single scan.
987 Sharp 320x240. Active, color, single scan.
988 It isn't 16x9, and I am not sure what it is.
990 CONFIG_SHARP_LQ64D341
992 Sharp LQ64D341 display, 640x480.
993 Active, color, single scan.
997 HLD1045 display, 640x480.
998 Active, color, single scan.
1002 Optrex CBL50840-2 NF-FW 99 22 M5
1004 Hitachi LMG6912RPFC-00T
1008 320x240. Black & white.
1010 CONFIG_LCD_ALIGNMENT
1012 Normally the LCD is page-aligned (typically 4KB). If this is
1013 defined then the LCD will be aligned to this value instead.
1014 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1015 here, since it is cheaper to change data cache settings on
1016 a per-section basis.
1021 Sometimes, for example if the display is mounted in portrait
1022 mode or even if it's mounted landscape but rotated by 180degree,
1023 we need to rotate our content of the display relative to the
1024 framebuffer, so that user can read the messages which are
1026 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1027 initialized with a given rotation from "vl_rot" out of
1028 "vidinfo_t" which is provided by the board specific code.
1029 The value for vl_rot is coded as following (matching to
1030 fbcon=rotate:<n> linux-kernel commandline):
1031 0 = no rotation respectively 0 degree
1032 1 = 90 degree rotation
1033 2 = 180 degree rotation
1034 3 = 270 degree rotation
1036 If CONFIG_LCD_ROTATION is not defined, the console will be
1037 initialized with 0degree rotation.
1040 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1042 The clock frequency of the MII bus
1044 CONFIG_PHY_CMD_DELAY (ppc4xx)
1046 Some PHY like Intel LXT971A need extra delay after
1047 command issued before MII status register can be read
1052 Define a default value for the IP address to use for
1053 the default Ethernet interface, in case this is not
1054 determined through e.g. bootp.
1055 (Environment variable "ipaddr")
1057 - Server IP address:
1060 Defines a default value for the IP address of a TFTP
1061 server to contact when using the "tftboot" command.
1062 (Environment variable "serverip")
1064 - Gateway IP address:
1067 Defines a default value for the IP address of the
1068 default router where packets to other networks are
1070 (Environment variable "gatewayip")
1075 Defines a default value for the subnet mask (or
1076 routing prefix) which is used to determine if an IP
1077 address belongs to the local subnet or needs to be
1078 forwarded through a router.
1079 (Environment variable "netmask")
1081 - BOOTP Recovery Mode:
1082 CONFIG_BOOTP_RANDOM_DELAY
1084 If you have many targets in a network that try to
1085 boot using BOOTP, you may want to avoid that all
1086 systems send out BOOTP requests at precisely the same
1087 moment (which would happen for instance at recovery
1088 from a power failure, when all systems will try to
1089 boot, thus flooding the BOOTP server. Defining
1090 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1091 inserted before sending out BOOTP requests. The
1092 following delays are inserted then:
1094 1st BOOTP request: delay 0 ... 1 sec
1095 2nd BOOTP request: delay 0 ... 2 sec
1096 3rd BOOTP request: delay 0 ... 4 sec
1098 BOOTP requests: delay 0 ... 8 sec
1100 CONFIG_BOOTP_ID_CACHE_SIZE
1102 BOOTP packets are uniquely identified using a 32-bit ID. The
1103 server will copy the ID from client requests to responses and
1104 U-Boot will use this to determine if it is the destination of
1105 an incoming response. Some servers will check that addresses
1106 aren't in use before handing them out (usually using an ARP
1107 ping) and therefore take up to a few hundred milliseconds to
1108 respond. Network congestion may also influence the time it
1109 takes for a response to make it back to the client. If that
1110 time is too long, U-Boot will retransmit requests. In order
1111 to allow earlier responses to still be accepted after these
1112 retransmissions, U-Boot's BOOTP client keeps a small cache of
1113 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1114 cache. The default is to keep IDs for up to four outstanding
1115 requests. Increasing this will allow U-Boot to accept offers
1116 from a BOOTP client in networks with unusually high latency.
1118 - DHCP Advanced Options:
1120 - Link-local IP address negotiation:
1121 Negotiate with other link-local clients on the local network
1122 for an address that doesn't require explicit configuration.
1123 This is especially useful if a DHCP server cannot be guaranteed
1124 to exist in all environments that the device must operate.
1126 See doc/README.link-local for more information.
1128 - MAC address from environment variables
1130 FDT_SEQ_MACADDR_FROM_ENV
1132 Fix-up device tree with MAC addresses fetched sequentially from
1133 environment variables. This config work on assumption that
1134 non-usable ethernet node of device-tree are either not present
1135 or their status has been marked as "disabled".
1138 CONFIG_CDP_DEVICE_ID
1140 The device id used in CDP trigger frames.
1142 CONFIG_CDP_DEVICE_ID_PREFIX
1144 A two character string which is prefixed to the MAC address
1149 A printf format string which contains the ascii name of
1150 the port. Normally is set to "eth%d" which sets
1151 eth0 for the first Ethernet, eth1 for the second etc.
1153 CONFIG_CDP_CAPABILITIES
1155 A 32bit integer which indicates the device capabilities;
1156 0x00000010 for a normal host which does not forwards.
1160 An ascii string containing the version of the software.
1164 An ascii string containing the name of the platform.
1168 A 32bit integer sent on the trigger.
1170 CONFIG_CDP_POWER_CONSUMPTION
1172 A 16bit integer containing the power consumption of the
1173 device in .1 of milliwatts.
1175 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1177 A byte containing the id of the VLAN.
1179 - Status LED: CONFIG_LED_STATUS
1181 Several configurations allow to display the current
1182 status using a LED. For instance, the LED will blink
1183 fast while running U-Boot code, stop blinking as
1184 soon as a reply to a BOOTP request was received, and
1185 start blinking slow once the Linux kernel is running
1186 (supported by a status LED driver in the Linux
1187 kernel). Defining CONFIG_LED_STATUS enables this
1192 CONFIG_LED_STATUS_GPIO
1193 The status LED can be connected to a GPIO pin.
1194 In such cases, the gpio_led driver can be used as a
1195 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1196 to include the gpio_led driver in the U-Boot binary.
1198 CONFIG_GPIO_LED_INVERTED_TABLE
1199 Some GPIO connected LEDs may have inverted polarity in which
1200 case the GPIO high value corresponds to LED off state and
1201 GPIO low value corresponds to LED on state.
1202 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1203 with a list of GPIO LEDs that have inverted polarity.
1206 CONFIG_SYS_NUM_I2C_BUSES
1207 Hold the number of i2c buses you want to use.
1209 CONFIG_SYS_I2C_DIRECT_BUS
1210 define this, if you don't use i2c muxes on your hardware.
1211 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1214 CONFIG_SYS_I2C_MAX_HOPS
1215 define how many muxes are maximal consecutively connected
1216 on one i2c bus. If you not use i2c muxes, omit this
1219 CONFIG_SYS_I2C_BUSES
1220 hold a list of buses you want to use, only used if
1221 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1222 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1223 CONFIG_SYS_NUM_I2C_BUSES = 9:
1225 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1226 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1227 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1228 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1229 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1230 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1231 {1, {I2C_NULL_HOP}}, \
1232 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1233 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1237 bus 0 on adapter 0 without a mux
1238 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1239 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1240 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1241 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1242 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1243 bus 6 on adapter 1 without a mux
1244 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1245 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1247 If you do not have i2c muxes on your board, omit this define.
1249 - Legacy I2C Support:
1250 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1251 then the following macros need to be defined (examples are
1252 from include/configs/lwmon.h):
1256 (Optional). Any commands necessary to enable the I2C
1257 controller or configure ports.
1259 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1263 The code necessary to make the I2C data line active
1264 (driven). If the data line is open collector, this
1267 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1271 The code necessary to make the I2C data line tri-stated
1272 (inactive). If the data line is open collector, this
1275 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1279 Code that returns true if the I2C data line is high,
1282 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1286 If <bit> is true, sets the I2C data line high. If it
1287 is false, it clears it (low).
1289 eg: #define I2C_SDA(bit) \
1290 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1291 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1295 If <bit> is true, sets the I2C clock line high. If it
1296 is false, it clears it (low).
1298 eg: #define I2C_SCL(bit) \
1299 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1300 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1304 This delay is invoked four times per clock cycle so this
1305 controls the rate of data transfer. The data rate thus
1306 is 1 / (I2C_DELAY * 4). Often defined to be something
1309 #define I2C_DELAY udelay(2)
1311 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1313 If your arch supports the generic GPIO framework (asm/gpio.h),
1314 then you may alternatively define the two GPIOs that are to be
1315 used as SCL / SDA. Any of the previous I2C_xxx macros will
1316 have GPIO-based defaults assigned to them as appropriate.
1318 You should define these to the GPIO value as given directly to
1319 the generic GPIO functions.
1321 CONFIG_SYS_I2C_INIT_BOARD
1323 When a board is reset during an i2c bus transfer
1324 chips might think that the current transfer is still
1325 in progress. On some boards it is possible to access
1326 the i2c SCLK line directly, either by using the
1327 processor pin as a GPIO or by having a second pin
1328 connected to the bus. If this option is defined a
1329 custom i2c_init_board() routine in boards/xxx/board.c
1330 is run early in the boot sequence.
1332 CONFIG_I2C_MULTI_BUS
1334 This option allows the use of multiple I2C buses, each of which
1335 must have a controller. At any point in time, only one bus is
1336 active. To switch to a different bus, use the 'i2c dev' command.
1337 Note that bus numbering is zero-based.
1339 CONFIG_SYS_I2C_NOPROBES
1341 This option specifies a list of I2C devices that will be skipped
1342 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1343 is set, specify a list of bus-device pairs. Otherwise, specify
1344 a 1D array of device addresses
1347 #undef CONFIG_I2C_MULTI_BUS
1348 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1350 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1352 #define CONFIG_I2C_MULTI_BUS
1353 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1355 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1357 CONFIG_SYS_SPD_BUS_NUM
1359 If defined, then this indicates the I2C bus number for DDR SPD.
1360 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1362 CONFIG_SYS_RTC_BUS_NUM
1364 If defined, then this indicates the I2C bus number for the RTC.
1365 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1367 CONFIG_SOFT_I2C_READ_REPEATED_START
1369 defining this will force the i2c_read() function in
1370 the soft_i2c driver to perform an I2C repeated start
1371 between writing the address pointer and reading the
1372 data. If this define is omitted the default behaviour
1373 of doing a stop-start sequence will be used. Most I2C
1374 devices can use either method, but some require one or
1377 - SPI Support: CONFIG_SPI
1379 Enables SPI driver (so far only tested with
1380 SPI EEPROM, also an instance works with Crystal A/D and
1381 D/As on the SACSng board)
1383 CONFIG_SYS_SPI_MXC_WAIT
1384 Timeout for waiting until spi transfer completed.
1385 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1387 - FPGA Support: CONFIG_FPGA
1389 Enables FPGA subsystem.
1391 CONFIG_FPGA_<vendor>
1393 Enables support for specific chip vendors.
1396 CONFIG_FPGA_<family>
1398 Enables support for FPGA family.
1399 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1403 Specify the number of FPGA devices to support.
1405 CONFIG_SYS_FPGA_PROG_FEEDBACK
1407 Enable printing of hash marks during FPGA configuration.
1409 CONFIG_SYS_FPGA_CHECK_BUSY
1411 Enable checks on FPGA configuration interface busy
1412 status by the configuration function. This option
1413 will require a board or device specific function to
1418 If defined, a function that provides delays in the FPGA
1419 configuration driver.
1421 CONFIG_SYS_FPGA_CHECK_CTRLC
1422 Allow Control-C to interrupt FPGA configuration
1424 CONFIG_SYS_FPGA_CHECK_ERROR
1426 Check for configuration errors during FPGA bitfile
1427 loading. For example, abort during Virtex II
1428 configuration if the INIT_B line goes low (which
1429 indicated a CRC error).
1431 CONFIG_SYS_FPGA_WAIT_INIT
1433 Maximum time to wait for the INIT_B line to de-assert
1434 after PROB_B has been de-asserted during a Virtex II
1435 FPGA configuration sequence. The default time is 500
1438 CONFIG_SYS_FPGA_WAIT_BUSY
1440 Maximum time to wait for BUSY to de-assert during
1441 Virtex II FPGA configuration. The default is 5 ms.
1443 CONFIG_SYS_FPGA_WAIT_CONFIG
1445 Time to wait after FPGA configuration. The default is
1448 - Vendor Parameter Protection:
1450 U-Boot considers the values of the environment
1451 variables "serial#" (Board Serial Number) and
1452 "ethaddr" (Ethernet Address) to be parameters that
1453 are set once by the board vendor / manufacturer, and
1454 protects these variables from casual modification by
1455 the user. Once set, these variables are read-only,
1456 and write or delete attempts are rejected. You can
1457 change this behaviour:
1459 If CONFIG_ENV_OVERWRITE is #defined in your config
1460 file, the write protection for vendor parameters is
1461 completely disabled. Anybody can change or delete
1464 Alternatively, if you define _both_ an ethaddr in the
1465 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1466 Ethernet address is installed in the environment,
1467 which can be changed exactly ONCE by the user. [The
1468 serial# is unaffected by this, i. e. it remains
1471 The same can be accomplished in a more flexible way
1472 for any variable by configuring the type of access
1473 to allow for those variables in the ".flags" variable
1474 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1479 Define this variable to enable the reservation of
1480 "protected RAM", i. e. RAM which is not overwritten
1481 by U-Boot. Define CONFIG_PRAM to hold the number of
1482 kB you want to reserve for pRAM. You can overwrite
1483 this default value by defining an environment
1484 variable "pram" to the number of kB you want to
1485 reserve. Note that the board info structure will
1486 still show the full amount of RAM. If pRAM is
1487 reserved, a new environment variable "mem" will
1488 automatically be defined to hold the amount of
1489 remaining RAM in a form that can be passed as boot
1490 argument to Linux, for instance like that:
1492 setenv bootargs ... mem=\${mem}
1495 This way you can tell Linux not to use this memory,
1496 either, which results in a memory region that will
1497 not be affected by reboots.
1499 *WARNING* If your board configuration uses automatic
1500 detection of the RAM size, you must make sure that
1501 this memory test is non-destructive. So far, the
1502 following board configurations are known to be
1505 IVMS8, IVML24, SPD8xx,
1506 HERMES, IP860, RPXlite, LWMON,
1512 In the current implementation, the local variables
1513 space and global environment variables space are
1514 separated. Local variables are those you define by
1515 simply typing `name=value'. To access a local
1516 variable later on, you have write `$name' or
1517 `${name}'; to execute the contents of a variable
1518 directly type `$name' at the command prompt.
1520 Global environment variables are those you use
1521 setenv/printenv to work with. To run a command stored
1522 in such a variable, you need to use the run command,
1523 and you must not use the '$' sign to access them.
1525 To store commands and special characters in a
1526 variable, please use double quotation marks
1527 surrounding the whole text of the variable, instead
1528 of the backslashes before semicolons and special
1531 - Default Environment:
1532 CONFIG_EXTRA_ENV_SETTINGS
1534 Define this to contain any number of null terminated
1535 strings (variable = value pairs) that will be part of
1536 the default environment compiled into the boot image.
1538 For example, place something like this in your
1539 board's config file:
1541 #define CONFIG_EXTRA_ENV_SETTINGS \
1545 Warning: This method is based on knowledge about the
1546 internal format how the environment is stored by the
1547 U-Boot code. This is NOT an official, exported
1548 interface! Although it is unlikely that this format
1549 will change soon, there is no guarantee either.
1550 You better know what you are doing here.
1552 Note: overly (ab)use of the default environment is
1553 discouraged. Make sure to check other ways to preset
1554 the environment like the "source" command or the
1557 CONFIG_DELAY_ENVIRONMENT
1559 Normally the environment is loaded when the board is
1560 initialised so that it is available to U-Boot. This inhibits
1561 that so that the environment is not available until
1562 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1563 this is instead controlled by the value of
1564 /config/load-environment.
1566 CONFIG_STANDALONE_LOAD_ADDR
1568 This option defines a board specific value for the
1569 address where standalone program gets loaded, thus
1570 overwriting the architecture dependent default
1573 - Frame Buffer Address:
1576 Define CONFIG_FB_ADDR if you want to use specific
1577 address for frame buffer. This is typically the case
1578 when using a graphics controller has separate video
1579 memory. U-Boot will then place the frame buffer at
1580 the given address instead of dynamically reserving it
1581 in system RAM by calling lcd_setmem(), which grabs
1582 the memory for the frame buffer depending on the
1583 configured panel size.
1585 Please see board_init_f function.
1587 - Automatic software updates via TFTP server
1589 CONFIG_UPDATE_TFTP_CNT_MAX
1590 CONFIG_UPDATE_TFTP_MSEC_MAX
1592 These options enable and control the auto-update feature;
1593 for a more detailed description refer to doc/README.update.
1595 - MTD Support (mtdparts command, UBI support)
1596 CONFIG_MTD_UBI_WL_THRESHOLD
1597 This parameter defines the maximum difference between the highest
1598 erase counter value and the lowest erase counter value of eraseblocks
1599 of UBI devices. When this threshold is exceeded, UBI starts performing
1600 wear leveling by means of moving data from eraseblock with low erase
1601 counter to eraseblocks with high erase counter.
1603 The default value should be OK for SLC NAND flashes, NOR flashes and
1604 other flashes which have eraseblock life-cycle 100000 or more.
1605 However, in case of MLC NAND flashes which typically have eraseblock
1606 life-cycle less than 10000, the threshold should be lessened (e.g.,
1607 to 128 or 256, although it does not have to be power of 2).
1611 CONFIG_MTD_UBI_BEB_LIMIT
1612 This option specifies the maximum bad physical eraseblocks UBI
1613 expects on the MTD device (per 1024 eraseblocks). If the
1614 underlying flash does not admit of bad eraseblocks (e.g. NOR
1615 flash), this value is ignored.
1617 NAND datasheets often specify the minimum and maximum NVM
1618 (Number of Valid Blocks) for the flashes' endurance lifetime.
1619 The maximum expected bad eraseblocks per 1024 eraseblocks
1620 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1621 which gives 20 for most NANDs (MaxNVB is basically the total
1622 count of eraseblocks on the chip).
1624 To put it differently, if this value is 20, UBI will try to
1625 reserve about 1.9% of physical eraseblocks for bad blocks
1626 handling. And that will be 1.9% of eraseblocks on the entire
1627 NAND chip, not just the MTD partition UBI attaches. This means
1628 that if you have, say, a NAND flash chip admits maximum 40 bad
1629 eraseblocks, and it is split on two MTD partitions of the same
1630 size, UBI will reserve 40 eraseblocks when attaching a
1635 CONFIG_MTD_UBI_FASTMAP
1636 Fastmap is a mechanism which allows attaching an UBI device
1637 in nearly constant time. Instead of scanning the whole MTD device it
1638 only has to locate a checkpoint (called fastmap) on the device.
1639 The on-flash fastmap contains all information needed to attach
1640 the device. Using fastmap makes only sense on large devices where
1641 attaching by scanning takes long. UBI will not automatically install
1642 a fastmap on old images, but you can set the UBI parameter
1643 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1644 that fastmap-enabled images are still usable with UBI implementations
1645 without fastmap support. On typical flash devices the whole fastmap
1646 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1648 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1649 Set this parameter to enable fastmap automatically on images
1653 CONFIG_MTD_UBI_FM_DEBUG
1654 Enable UBI fastmap debug
1659 Enable building of SPL globally.
1661 CONFIG_SPL_MAX_FOOTPRINT
1662 Maximum size in memory allocated to the SPL, BSS included.
1663 When defined, the linker checks that the actual memory
1664 used by SPL from _start to __bss_end does not exceed it.
1665 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1666 must not be both defined at the same time.
1669 Maximum size of the SPL image (text, data, rodata, and
1670 linker lists sections), BSS excluded.
1671 When defined, the linker checks that the actual size does
1674 CONFIG_SPL_RELOC_TEXT_BASE
1675 Address to relocate to. If unspecified, this is equal to
1676 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1678 CONFIG_SPL_BSS_START_ADDR
1679 Link address for the BSS within the SPL binary.
1681 CONFIG_SPL_BSS_MAX_SIZE
1682 Maximum size in memory allocated to the SPL BSS.
1683 When defined, the linker checks that the actual memory used
1684 by SPL from __bss_start to __bss_end does not exceed it.
1685 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1686 must not be both defined at the same time.
1689 Adress of the start of the stack SPL will use
1691 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1692 When defined, SPL will panic() if the image it has
1693 loaded does not have a signature.
1694 Defining this is useful when code which loads images
1695 in SPL cannot guarantee that absolutely all read errors
1697 An example is the LPC32XX MLC NAND driver, which will
1698 consider that a completely unreadable NAND block is bad,
1699 and thus should be skipped silently.
1701 CONFIG_SPL_RELOC_STACK
1702 Adress of the start of the stack SPL will use after
1703 relocation. If unspecified, this is equal to
1706 CONFIG_SYS_SPL_MALLOC_START
1707 Starting address of the malloc pool used in SPL.
1708 When this option is set the full malloc is used in SPL and
1709 it is set up by spl_init() and before that, the simple malloc()
1710 can be used if CONFIG_SYS_MALLOC_F is defined.
1712 CONFIG_SYS_SPL_MALLOC_SIZE
1713 The size of the malloc pool used in SPL.
1715 CONFIG_SPL_DISPLAY_PRINT
1716 For ARM, enable an optional function to print more information
1717 about the running system.
1719 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
1720 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
1721 Sector and number of sectors to load kernel argument
1722 parameters from when MMC is being used in raw mode
1725 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
1726 Filename to read to load U-Boot when reading from filesystem
1728 CONFIG_SPL_FS_LOAD_KERNEL_NAME
1729 Filename to read to load kernel uImage when reading
1730 from filesystem (for Falcon mode)
1732 CONFIG_SPL_FS_LOAD_ARGS_NAME
1733 Filename to read to load kernel argument parameters
1734 when reading from filesystem (for Falcon mode)
1736 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1737 Set this for NAND SPL on PPC mpc83xx targets, so that
1738 start.S waits for the rest of the SPL to load before
1739 continuing (the hardware starts execution after just
1740 loading the first page rather than the full 4K).
1743 Support for a lightweight UBI (fastmap) scanner and
1746 CONFIG_SPL_NAND_RAW_ONLY
1747 Support to boot only raw u-boot.bin images. Use this only
1748 if you need to save space.
1750 CONFIG_SPL_COMMON_INIT_DDR
1751 Set for common ddr init with serial presence detect in
1754 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1755 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1756 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1757 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1758 CONFIG_SYS_NAND_ECCBYTES
1759 Defines the size and behavior of the NAND that SPL uses
1762 CONFIG_SYS_NAND_U_BOOT_DST
1763 Location in memory to load U-Boot to
1765 CONFIG_SYS_NAND_U_BOOT_SIZE
1766 Size of image to load
1768 CONFIG_SYS_NAND_U_BOOT_START
1769 Entry point in loaded image to jump to
1771 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1772 Define this if you need to first read the OOB and then the
1773 data. This is used, for example, on davinci platforms.
1775 CONFIG_SPL_RAM_DEVICE
1776 Support for running image already present in ram, in SPL binary
1779 Image offset to which the SPL should be padded before appending
1780 the SPL payload. By default, this is defined as
1781 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1782 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1783 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1786 Final target image containing SPL and payload. Some SPLs
1787 use an arch-specific makefile fragment instead, for
1788 example if more than one image needs to be produced.
1790 CONFIG_SPL_FIT_PRINT
1791 Printing information about a FIT image adds quite a bit of
1792 code to SPL. So this is normally disabled in SPL. Use this
1793 option to re-enable it. This will affect the output of the
1794 bootm command when booting a FIT image.
1798 Enable building of TPL globally.
1801 Image offset to which the TPL should be padded before appending
1802 the TPL payload. By default, this is defined as
1803 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1804 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1805 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1807 - Interrupt support (PPC):
1809 There are common interrupt_init() and timer_interrupt()
1810 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1811 for CPU specific initialization. interrupt_init_cpu()
1812 should set decrementer_count to appropriate value. If
1813 CPU resets decrementer automatically after interrupt
1814 (ppc4xx) it should set decrementer_count to zero.
1815 timer_interrupt() calls timer_interrupt_cpu() for CPU
1816 specific handling. If board has watchdog / status_led
1817 / other_activity_monitor it works automatically from
1818 general timer_interrupt().
1821 Board initialization settings:
1822 ------------------------------
1824 During Initialization u-boot calls a number of board specific functions
1825 to allow the preparation of board specific prerequisites, e.g. pin setup
1826 before drivers are initialized. To enable these callbacks the
1827 following configuration macros have to be defined. Currently this is
1828 architecture specific, so please check arch/your_architecture/lib/board.c
1829 typically in board_init_f() and board_init_r().
1831 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1832 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1833 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1835 Configuration Settings:
1836 -----------------------
1838 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1839 Optionally it can be defined to support 64-bit memory commands.
1841 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1842 undefine this when you're short of memory.
1844 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1845 width of the commands listed in the 'help' command output.
1847 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1848 prompt for user input.
1850 - CONFIG_SYS_BAUDRATE_TABLE:
1851 List of legal baudrate settings for this board.
1853 - CONFIG_SYS_MEM_RESERVE_SECURE
1854 Only implemented for ARMv8 for now.
1855 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1856 is substracted from total RAM and won't be reported to OS.
1857 This memory can be used as secure memory. A variable
1858 gd->arch.secure_ram is used to track the location. In systems
1859 the RAM base is not zero, or RAM is divided into banks,
1860 this variable needs to be recalcuated to get the address.
1862 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1863 Enable temporary baudrate change while serial download
1865 - CONFIG_SYS_SDRAM_BASE:
1866 Physical start address of SDRAM. _Must_ be 0 here.
1868 - CONFIG_SYS_FLASH_BASE:
1869 Physical start address of Flash memory.
1871 - CONFIG_SYS_MONITOR_LEN:
1872 Size of memory reserved for monitor code, used to
1873 determine _at_compile_time_ (!) if the environment is
1874 embedded within the U-Boot image, or in a separate
1877 - CONFIG_SYS_MALLOC_LEN:
1878 Size of DRAM reserved for malloc() use.
1880 - CONFIG_SYS_MALLOC_F_LEN
1881 Size of the malloc() pool for use before relocation. If
1882 this is defined, then a very simple malloc() implementation
1883 will become available before relocation. The address is just
1884 below the global data, and the stack is moved down to make
1887 This feature allocates regions with increasing addresses
1888 within the region. calloc() is supported, but realloc()
1889 is not available. free() is supported but does nothing.
1890 The memory will be freed (or in fact just forgotten) when
1891 U-Boot relocates itself.
1893 - CONFIG_SYS_MALLOC_SIMPLE
1894 Provides a simple and small malloc() and calloc() for those
1895 boards which do not use the full malloc in SPL (which is
1896 enabled with CONFIG_SYS_SPL_MALLOC_START).
1898 - CONFIG_SYS_NONCACHED_MEMORY:
1899 Size of non-cached memory area. This area of memory will be
1900 typically located right below the malloc() area and mapped
1901 uncached in the MMU. This is useful for drivers that would
1902 otherwise require a lot of explicit cache maintenance. For
1903 some drivers it's also impossible to properly maintain the
1904 cache. For example if the regions that need to be flushed
1905 are not a multiple of the cache-line size, *and* padding
1906 cannot be allocated between the regions to align them (i.e.
1907 if the HW requires a contiguous array of regions, and the
1908 size of each region is not cache-aligned), then a flush of
1909 one region may result in overwriting data that hardware has
1910 written to another region in the same cache-line. This can
1911 happen for example in network drivers where descriptors for
1912 buffers are typically smaller than the CPU cache-line (e.g.
1913 16 bytes vs. 32 or 64 bytes).
1915 Non-cached memory is only supported on 32-bit ARM at present.
1917 - CONFIG_SYS_BOOTM_LEN:
1918 Normally compressed uImages are limited to an
1919 uncompressed size of 8 MBytes. If this is not enough,
1920 you can define CONFIG_SYS_BOOTM_LEN in your board config file
1921 to adjust this setting to your needs.
1923 - CONFIG_SYS_BOOTMAPSZ:
1924 Maximum size of memory mapped by the startup code of
1925 the Linux kernel; all data that must be processed by
1926 the Linux kernel (bd_info, boot arguments, FDT blob if
1927 used) must be put below this limit, unless "bootm_low"
1928 environment variable is defined and non-zero. In such case
1929 all data for the Linux kernel must be between "bootm_low"
1930 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
1931 variable "bootm_mapsize" will override the value of
1932 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
1933 then the value in "bootm_size" will be used instead.
1935 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
1936 Enable initrd_high functionality. If defined then the
1937 initrd_high feature is enabled and the bootm ramdisk subcommand
1940 - CONFIG_SYS_BOOT_GET_CMDLINE:
1941 Enables allocating and saving kernel cmdline in space between
1942 "bootm_low" and "bootm_low" + BOOTMAPSZ.
1944 - CONFIG_SYS_BOOT_GET_KBD:
1945 Enables allocating and saving a kernel copy of the bd_info in
1946 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
1948 - CONFIG_SYS_MAX_FLASH_SECT:
1949 Max number of sectors on a Flash chip
1951 - CONFIG_SYS_FLASH_ERASE_TOUT:
1952 Timeout for Flash erase operations (in ms)
1954 - CONFIG_SYS_FLASH_WRITE_TOUT:
1955 Timeout for Flash write operations (in ms)
1957 - CONFIG_SYS_FLASH_LOCK_TOUT
1958 Timeout for Flash set sector lock bit operation (in ms)
1960 - CONFIG_SYS_FLASH_UNLOCK_TOUT
1961 Timeout for Flash clear lock bits operation (in ms)
1963 - CONFIG_SYS_FLASH_PROTECTION
1964 If defined, hardware flash sectors protection is used
1965 instead of U-Boot software protection.
1967 - CONFIG_SYS_DIRECT_FLASH_TFTP:
1969 Enable TFTP transfers directly to flash memory;
1970 without this option such a download has to be
1971 performed in two steps: (1) download to RAM, and (2)
1972 copy from RAM to flash.
1974 The two-step approach is usually more reliable, since
1975 you can check if the download worked before you erase
1976 the flash, but in some situations (when system RAM is
1977 too limited to allow for a temporary copy of the
1978 downloaded image) this option may be very useful.
1980 - CONFIG_SYS_FLASH_CFI:
1981 Define if the flash driver uses extra elements in the
1982 common flash structure for storing flash geometry.
1984 - CONFIG_FLASH_CFI_DRIVER
1985 This option also enables the building of the cfi_flash driver
1986 in the drivers directory
1988 - CONFIG_FLASH_CFI_MTD
1989 This option enables the building of the cfi_mtd driver
1990 in the drivers directory. The driver exports CFI flash
1993 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
1994 Use buffered writes to flash.
1996 - CONFIG_FLASH_SPANSION_S29WS_N
1997 s29ws-n MirrorBit flash has non-standard addresses for buffered
2000 - CONFIG_SYS_FLASH_QUIET_TEST
2001 If this option is defined, the common CFI flash doesn't
2002 print it's warning upon not recognized FLASH banks. This
2003 is useful, if some of the configured banks are only
2004 optionally available.
2006 - CONFIG_FLASH_SHOW_PROGRESS
2007 If defined (must be an integer), print out countdown
2008 digits and dots. Recommended value: 45 (9..1) for 80
2009 column displays, 15 (3..1) for 40 column displays.
2011 - CONFIG_FLASH_VERIFY
2012 If defined, the content of the flash (destination) is compared
2013 against the source after the write operation. An error message
2014 will be printed when the contents are not identical.
2015 Please note that this option is useless in nearly all cases,
2016 since such flash programming errors usually are detected earlier
2017 while unprotecting/erasing/programming. Please only enable
2018 this option if you really know what you are doing.
2020 - CONFIG_ENV_MAX_ENTRIES
2022 Maximum number of entries in the hash table that is used
2023 internally to store the environment settings. The default
2024 setting is supposed to be generous and should work in most
2025 cases. This setting can be used to tune behaviour; see
2026 lib/hashtable.c for details.
2028 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2029 - CONFIG_ENV_FLAGS_LIST_STATIC
2030 Enable validation of the values given to environment variables when
2031 calling env set. Variables can be restricted to only decimal,
2032 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2033 the variables can also be restricted to IP address or MAC address.
2035 The format of the list is:
2036 type_attribute = [s|d|x|b|i|m]
2037 access_attribute = [a|r|o|c]
2038 attributes = type_attribute[access_attribute]
2039 entry = variable_name[:attributes]
2042 The type attributes are:
2043 s - String (default)
2046 b - Boolean ([1yYtT|0nNfF])
2050 The access attributes are:
2056 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2057 Define this to a list (string) to define the ".flags"
2058 environment variable in the default or embedded environment.
2060 - CONFIG_ENV_FLAGS_LIST_STATIC
2061 Define this to a list (string) to define validation that
2062 should be done if an entry is not found in the ".flags"
2063 environment variable. To override a setting in the static
2064 list, simply add an entry for the same variable name to the
2067 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2068 regular expression. This allows multiple variables to define the same
2069 flags without explicitly listing them for each variable.
2071 The following definitions that deal with the placement and management
2072 of environment data (variable area); in general, we support the
2073 following configurations:
2075 - CONFIG_BUILD_ENVCRC:
2077 Builds up envcrc with the target environment so that external utils
2078 may easily extract it and embed it in final U-Boot images.
2080 BE CAREFUL! The first access to the environment happens quite early
2081 in U-Boot initialization (when we try to get the setting of for the
2082 console baudrate). You *MUST* have mapped your NVRAM area then, or
2085 Please note that even with NVRAM we still use a copy of the
2086 environment in RAM: we could work on NVRAM directly, but we want to
2087 keep settings there always unmodified except somebody uses "saveenv"
2088 to save the current settings.
2090 BE CAREFUL! For some special cases, the local device can not use
2091 "saveenv" command. For example, the local device will get the
2092 environment stored in a remote NOR flash by SRIO or PCIE link,
2093 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2095 - CONFIG_NAND_ENV_DST
2097 Defines address in RAM to which the nand_spl code should copy the
2098 environment. If redundant environment is used, it will be copied to
2099 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2101 Please note that the environment is read-only until the monitor
2102 has been relocated to RAM and a RAM copy of the environment has been
2103 created; also, when using EEPROM you will have to use env_get_f()
2104 until then to read environment variables.
2106 The environment is protected by a CRC32 checksum. Before the monitor
2107 is relocated into RAM, as a result of a bad CRC you will be working
2108 with the compiled-in default environment - *silently*!!! [This is
2109 necessary, because the first environment variable we need is the
2110 "baudrate" setting for the console - if we have a bad CRC, we don't
2111 have any device yet where we could complain.]
2113 Note: once the monitor has been relocated, then it will complain if
2114 the default environment is used; a new CRC is computed as soon as you
2115 use the "saveenv" command to store a valid environment.
2117 - CONFIG_SYS_FAULT_MII_ADDR:
2118 MII address of the PHY to check for the Ethernet link state.
2120 - CONFIG_NS16550_MIN_FUNCTIONS:
2121 Define this if you desire to only have use of the NS16550_init
2122 and NS16550_putc functions for the serial driver located at
2123 drivers/serial/ns16550.c. This option is useful for saving
2124 space for already greatly restricted images, including but not
2125 limited to NAND_SPL configurations.
2127 - CONFIG_DISPLAY_BOARDINFO
2128 Display information about the board that U-Boot is running on
2129 when U-Boot starts up. The board function checkboard() is called
2132 - CONFIG_DISPLAY_BOARDINFO_LATE
2133 Similar to the previous option, but display this information
2134 later, once stdio is running and output goes to the LCD, if
2137 Low Level (hardware related) configuration options:
2138 ---------------------------------------------------
2140 - CONFIG_SYS_CACHELINE_SIZE:
2141 Cache Line Size of the CPU.
2143 - CONFIG_SYS_CCSRBAR_DEFAULT:
2144 Default (power-on reset) physical address of CCSR on Freescale
2147 - CONFIG_SYS_CCSRBAR:
2148 Virtual address of CCSR. On a 32-bit build, this is typically
2149 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2151 - CONFIG_SYS_CCSRBAR_PHYS:
2152 Physical address of CCSR. CCSR can be relocated to a new
2153 physical address, if desired. In this case, this macro should
2154 be set to that address. Otherwise, it should be set to the
2155 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2156 is typically relocated on 36-bit builds. It is recommended
2157 that this macro be defined via the _HIGH and _LOW macros:
2159 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2160 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2162 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2163 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2164 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2165 used in assembly code, so it must not contain typecasts or
2166 integer size suffixes (e.g. "ULL").
2168 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2169 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2170 used in assembly code, so it must not contain typecasts or
2171 integer size suffixes (e.g. "ULL").
2173 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2174 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2175 forced to a value that ensures that CCSR is not relocated.
2177 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2178 DO NOT CHANGE unless you know exactly what you're
2179 doing! (11-4) [MPC8xx systems only]
2181 - CONFIG_SYS_INIT_RAM_ADDR:
2183 Start address of memory area that can be used for
2184 initial data and stack; please note that this must be
2185 writable memory that is working WITHOUT special
2186 initialization, i. e. you CANNOT use normal RAM which
2187 will become available only after programming the
2188 memory controller and running certain initialization
2191 U-Boot uses the following memory types:
2192 - MPC8xx: IMMR (internal memory of the CPU)
2194 - CONFIG_SYS_GBL_DATA_OFFSET:
2196 Offset of the initial data structure in the memory
2197 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2198 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2199 data is located at the end of the available space
2200 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2201 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2202 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2203 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2206 On the MPC824X (or other systems that use the data
2207 cache for initial memory) the address chosen for
2208 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2209 point to an otherwise UNUSED address space between
2210 the top of RAM and the start of the PCI space.
2212 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2214 - CONFIG_SYS_OR_TIMING_SDRAM:
2217 - CONFIG_SYS_MAMR_PTA:
2218 periodic timer for refresh
2221 Chip has SRIO or not
2224 Board has SRIO 1 port available
2227 Board has SRIO 2 port available
2229 - CONFIG_SRIO_PCIE_BOOT_MASTER
2230 Board can support master function for Boot from SRIO and PCIE
2232 - CONFIG_SYS_SRIOn_MEM_VIRT:
2233 Virtual Address of SRIO port 'n' memory region
2235 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2236 Physical Address of SRIO port 'n' memory region
2238 - CONFIG_SYS_SRIOn_MEM_SIZE:
2239 Size of SRIO port 'n' memory region
2241 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2242 Defined to tell the NAND controller that the NAND chip is using
2244 Not all NAND drivers use this symbol.
2245 Example of drivers that use it:
2246 - drivers/mtd/nand/raw/ndfc.c
2247 - drivers/mtd/nand/raw/mxc_nand.c
2249 - CONFIG_SYS_NDFC_EBC0_CFG
2250 Sets the EBC0_CFG register for the NDFC. If not defined
2251 a default value will be used.
2254 Get DDR timing information from an I2C EEPROM. Common
2255 with pluggable memory modules such as SODIMMs
2258 I2C address of the SPD EEPROM
2260 - CONFIG_SYS_SPD_BUS_NUM
2261 If SPD EEPROM is on an I2C bus other than the first
2262 one, specify here. Note that the value must resolve
2263 to something your driver can deal with.
2265 - CONFIG_SYS_DDR_RAW_TIMING
2266 Get DDR timing information from other than SPD. Common with
2267 soldered DDR chips onboard without SPD. DDR raw timing
2268 parameters are extracted from datasheet and hard-coded into
2269 header files or board specific files.
2271 - CONFIG_FSL_DDR_INTERACTIVE
2272 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2274 - CONFIG_FSL_DDR_SYNC_REFRESH
2275 Enable sync of refresh for multiple controllers.
2277 - CONFIG_FSL_DDR_BIST
2278 Enable built-in memory test for Freescale DDR controllers.
2280 - CONFIG_SYS_83XX_DDR_USES_CS0
2281 Only for 83xx systems. If specified, then DDR should
2282 be configured using CS0 and CS1 instead of CS2 and CS3.
2285 Enable RMII mode for all FECs.
2286 Note that this is a global option, we can't
2287 have one FEC in standard MII mode and another in RMII mode.
2289 - CONFIG_CRC32_VERIFY
2290 Add a verify option to the crc32 command.
2293 => crc32 -v <address> <count> <crc32>
2295 Where address/count indicate a memory area
2296 and crc32 is the correct crc32 which the
2300 Add the "loopw" memory command. This only takes effect if
2301 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2303 - CONFIG_CMD_MX_CYCLIC
2304 Add the "mdc" and "mwc" memory commands. These are cyclic
2309 This command will print 4 bytes (10,11,12,13) each 500 ms.
2311 => mwc.l 100 12345678 10
2312 This command will write 12345678 to address 100 all 10 ms.
2314 This only takes effect if the memory commands are activated
2315 globally (CONFIG_CMD_MEMORY).
2318 Set when the currently-running compilation is for an artifact
2319 that will end up in the SPL (as opposed to the TPL or U-Boot
2320 proper). Code that needs stage-specific behavior should check
2324 Set when the currently-running compilation is for an artifact
2325 that will end up in the TPL (as opposed to the SPL or U-Boot
2326 proper). Code that needs stage-specific behavior should check
2329 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2330 Only for 85xx systems. If this variable is specified, the section
2331 .resetvec is not kept and the section .bootpg is placed in the
2332 previous 4k of the .text section.
2334 - CONFIG_ARCH_MAP_SYSMEM
2335 Generally U-Boot (and in particular the md command) uses
2336 effective address. It is therefore not necessary to regard
2337 U-Boot address as virtual addresses that need to be translated
2338 to physical addresses. However, sandbox requires this, since
2339 it maintains its own little RAM buffer which contains all
2340 addressable memory. This option causes some memory accesses
2341 to be mapped through map_sysmem() / unmap_sysmem().
2343 - CONFIG_X86_RESET_VECTOR
2344 If defined, the x86 reset vector code is included. This is not
2345 needed when U-Boot is running from Coreboot.
2347 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2348 Option to disable subpage write in NAND driver
2349 driver that uses this:
2350 drivers/mtd/nand/raw/davinci_nand.c
2352 Freescale QE/FMAN Firmware Support:
2353 -----------------------------------
2355 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2356 loading of "firmware", which is encoded in the QE firmware binary format.
2357 This firmware often needs to be loaded during U-Boot booting, so macros
2358 are used to identify the storage device (NOR flash, SPI, etc) and the address
2361 - CONFIG_SYS_FMAN_FW_ADDR
2362 The address in the storage device where the FMAN microcode is located. The
2363 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2366 - CONFIG_SYS_QE_FW_ADDR
2367 The address in the storage device where the QE microcode is located. The
2368 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2371 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2372 The maximum possible size of the firmware. The firmware binary format
2373 has a field that specifies the actual size of the firmware, but it
2374 might not be possible to read any part of the firmware unless some
2375 local storage is allocated to hold the entire firmware first.
2377 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2378 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2379 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2380 virtual address in NOR flash.
2382 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2383 Specifies that QE/FMAN firmware is located in NAND flash.
2384 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2386 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2387 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2388 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2390 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2391 Specifies that QE/FMAN firmware is located in the remote (master)
2392 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2393 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2394 window->master inbound window->master LAW->the ucode address in
2395 master's memory space.
2397 Freescale Layerscape Management Complex Firmware Support:
2398 ---------------------------------------------------------
2399 The Freescale Layerscape Management Complex (MC) supports the loading of
2401 This firmware often needs to be loaded during U-Boot booting, so macros
2402 are used to identify the storage device (NOR flash, SPI, etc) and the address
2405 - CONFIG_FSL_MC_ENET
2406 Enable the MC driver for Layerscape SoCs.
2408 Freescale Layerscape Debug Server Support:
2409 -------------------------------------------
2410 The Freescale Layerscape Debug Server Support supports the loading of
2411 "Debug Server firmware" and triggering SP boot-rom.
2412 This firmware often needs to be loaded during U-Boot booting.
2414 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2415 Define alignment of reserved memory MC requires
2420 In order to achieve reproducible builds, timestamps used in the U-Boot build
2421 process have to be set to a fixed value.
2423 This is done using the SOURCE_DATE_EPOCH environment variable.
2424 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2425 option for U-Boot or an environment variable in U-Boot.
2427 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2429 Building the Software:
2430 ======================
2432 Building U-Boot has been tested in several native build environments
2433 and in many different cross environments. Of course we cannot support
2434 all possibly existing versions of cross development tools in all
2435 (potentially obsolete) versions. In case of tool chain problems we
2436 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2437 which is extensively used to build and test U-Boot.
2439 If you are not using a native environment, it is assumed that you
2440 have GNU cross compiling tools available in your path. In this case,
2441 you must set the environment variable CROSS_COMPILE in your shell.
2442 Note that no changes to the Makefile or any other source files are
2443 necessary. For example using the ELDK on a 4xx CPU, please enter:
2445 $ CROSS_COMPILE=ppc_4xx-
2446 $ export CROSS_COMPILE
2448 U-Boot is intended to be simple to build. After installing the
2449 sources you must configure U-Boot for one specific board type. This
2454 where "NAME_defconfig" is the name of one of the existing configu-
2455 rations; see configs/*_defconfig for supported names.
2457 Note: for some boards special configuration names may exist; check if
2458 additional information is available from the board vendor; for
2459 instance, the TQM823L systems are available without (standard)
2460 or with LCD support. You can select such additional "features"
2461 when choosing the configuration, i. e.
2463 make TQM823L_defconfig
2464 - will configure for a plain TQM823L, i. e. no LCD support
2466 make TQM823L_LCD_defconfig
2467 - will configure for a TQM823L with U-Boot console on LCD
2472 Finally, type "make all", and you should get some working U-Boot
2473 images ready for download to / installation on your system:
2475 - "u-boot.bin" is a raw binary image
2476 - "u-boot" is an image in ELF binary format
2477 - "u-boot.srec" is in Motorola S-Record format
2479 By default the build is performed locally and the objects are saved
2480 in the source directory. One of the two methods can be used to change
2481 this behavior and build U-Boot to some external directory:
2483 1. Add O= to the make command line invocations:
2485 make O=/tmp/build distclean
2486 make O=/tmp/build NAME_defconfig
2487 make O=/tmp/build all
2489 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2491 export KBUILD_OUTPUT=/tmp/build
2496 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2499 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2500 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2501 For example to treat all compiler warnings as errors:
2503 make KCFLAGS=-Werror
2505 Please be aware that the Makefiles assume you are using GNU make, so
2506 for instance on NetBSD you might need to use "gmake" instead of
2510 If the system board that you have is not listed, then you will need
2511 to port U-Boot to your hardware platform. To do this, follow these
2514 1. Create a new directory to hold your board specific code. Add any
2515 files you need. In your board directory, you will need at least
2516 the "Makefile" and a "<board>.c".
2517 2. Create a new configuration file "include/configs/<board>.h" for
2519 3. If you're porting U-Boot to a new CPU, then also create a new
2520 directory to hold your CPU specific code. Add any files you need.
2521 4. Run "make <board>_defconfig" with your new name.
2522 5. Type "make", and you should get a working "u-boot.srec" file
2523 to be installed on your target system.
2524 6. Debug and solve any problems that might arise.
2525 [Of course, this last step is much harder than it sounds.]
2528 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2529 ==============================================================
2531 If you have modified U-Boot sources (for instance added a new board
2532 or support for new devices, a new CPU, etc.) you are expected to
2533 provide feedback to the other developers. The feedback normally takes
2534 the form of a "patch", i.e. a context diff against a certain (latest
2535 official or latest in the git repository) version of U-Boot sources.
2537 But before you submit such a patch, please verify that your modifi-
2538 cation did not break existing code. At least make sure that *ALL* of
2539 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2540 just run the buildman script (tools/buildman/buildman), which will
2541 configure and build U-Boot for ALL supported system. Be warned, this
2542 will take a while. Please see the buildman README, or run 'buildman -H'
2546 See also "U-Boot Porting Guide" below.
2549 Monitor Commands - Overview:
2550 ============================
2552 go - start application at address 'addr'
2553 run - run commands in an environment variable
2554 bootm - boot application image from memory
2555 bootp - boot image via network using BootP/TFTP protocol
2556 bootz - boot zImage from memory
2557 tftpboot- boot image via network using TFTP protocol
2558 and env variables "ipaddr" and "serverip"
2559 (and eventually "gatewayip")
2560 tftpput - upload a file via network using TFTP protocol
2561 rarpboot- boot image via network using RARP/TFTP protocol
2562 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2563 loads - load S-Record file over serial line
2564 loadb - load binary file over serial line (kermit mode)
2566 mm - memory modify (auto-incrementing)
2567 nm - memory modify (constant address)
2568 mw - memory write (fill)
2571 cmp - memory compare
2572 crc32 - checksum calculation
2573 i2c - I2C sub-system
2574 sspi - SPI utility commands
2575 base - print or set address offset
2576 printenv- print environment variables
2577 pwm - control pwm channels
2578 setenv - set environment variables
2579 saveenv - save environment variables to persistent storage
2580 protect - enable or disable FLASH write protection
2581 erase - erase FLASH memory
2582 flinfo - print FLASH memory information
2583 nand - NAND memory operations (see doc/README.nand)
2584 bdinfo - print Board Info structure
2585 iminfo - print header information for application image
2586 coninfo - print console devices and informations
2587 ide - IDE sub-system
2588 loop - infinite loop on address range
2589 loopw - infinite write loop on address range
2590 mtest - simple RAM test
2591 icache - enable or disable instruction cache
2592 dcache - enable or disable data cache
2593 reset - Perform RESET of the CPU
2594 echo - echo args to console
2595 version - print monitor version
2596 help - print online help
2597 ? - alias for 'help'
2600 Monitor Commands - Detailed Description:
2601 ========================================
2605 For now: just type "help <command>".
2608 Note for Redundant Ethernet Interfaces:
2609 =======================================
2611 Some boards come with redundant Ethernet interfaces; U-Boot supports
2612 such configurations and is capable of automatic selection of a
2613 "working" interface when needed. MAC assignment works as follows:
2615 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2616 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2617 "eth1addr" (=>eth1), "eth2addr", ...
2619 If the network interface stores some valid MAC address (for instance
2620 in SROM), this is used as default address if there is NO correspon-
2621 ding setting in the environment; if the corresponding environment
2622 variable is set, this overrides the settings in the card; that means:
2624 o If the SROM has a valid MAC address, and there is no address in the
2625 environment, the SROM's address is used.
2627 o If there is no valid address in the SROM, and a definition in the
2628 environment exists, then the value from the environment variable is
2631 o If both the SROM and the environment contain a MAC address, and
2632 both addresses are the same, this MAC address is used.
2634 o If both the SROM and the environment contain a MAC address, and the
2635 addresses differ, the value from the environment is used and a
2638 o If neither SROM nor the environment contain a MAC address, an error
2639 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2640 a random, locally-assigned MAC is used.
2642 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2643 will be programmed into hardware as part of the initialization process. This
2644 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2645 The naming convention is as follows:
2646 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2651 U-Boot is capable of booting (and performing other auxiliary operations on)
2652 images in two formats:
2654 New uImage format (FIT)
2655 -----------------------
2657 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2658 to Flattened Device Tree). It allows the use of images with multiple
2659 components (several kernels, ramdisks, etc.), with contents protected by
2660 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2666 Old image format is based on binary files which can be basically anything,
2667 preceded by a special header; see the definitions in include/image.h for
2668 details; basically, the header defines the following image properties:
2670 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2671 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2672 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2673 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2674 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2675 IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2676 Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
2677 * Compression Type (uncompressed, gzip, bzip2)
2683 The header is marked by a special Magic Number, and both the header
2684 and the data portions of the image are secured against corruption by
2691 Although U-Boot should support any OS or standalone application
2692 easily, the main focus has always been on Linux during the design of
2695 U-Boot includes many features that so far have been part of some
2696 special "boot loader" code within the Linux kernel. Also, any
2697 "initrd" images to be used are no longer part of one big Linux image;
2698 instead, kernel and "initrd" are separate images. This implementation
2699 serves several purposes:
2701 - the same features can be used for other OS or standalone
2702 applications (for instance: using compressed images to reduce the
2703 Flash memory footprint)
2705 - it becomes much easier to port new Linux kernel versions because
2706 lots of low-level, hardware dependent stuff are done by U-Boot
2708 - the same Linux kernel image can now be used with different "initrd"
2709 images; of course this also means that different kernel images can
2710 be run with the same "initrd". This makes testing easier (you don't
2711 have to build a new "zImage.initrd" Linux image when you just
2712 change a file in your "initrd"). Also, a field-upgrade of the
2713 software is easier now.
2719 Porting Linux to U-Boot based systems:
2720 ---------------------------------------
2722 U-Boot cannot save you from doing all the necessary modifications to
2723 configure the Linux device drivers for use with your target hardware
2724 (no, we don't intend to provide a full virtual machine interface to
2727 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2729 Just make sure your machine specific header file (for instance
2730 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2731 Information structure as we define in include/asm-<arch>/u-boot.h,
2732 and make sure that your definition of IMAP_ADDR uses the same value
2733 as your U-Boot configuration in CONFIG_SYS_IMMR.
2735 Note that U-Boot now has a driver model, a unified model for drivers.
2736 If you are adding a new driver, plumb it into driver model. If there
2737 is no uclass available, you are encouraged to create one. See
2741 Configuring the Linux kernel:
2742 -----------------------------
2744 No specific requirements for U-Boot. Make sure you have some root
2745 device (initial ramdisk, NFS) for your target system.
2748 Building a Linux Image:
2749 -----------------------
2751 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2752 not used. If you use recent kernel source, a new build target
2753 "uImage" will exist which automatically builds an image usable by
2754 U-Boot. Most older kernels also have support for a "pImage" target,
2755 which was introduced for our predecessor project PPCBoot and uses a
2756 100% compatible format.
2760 make TQM850L_defconfig
2765 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2766 encapsulate a compressed Linux kernel image with header information,
2767 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2769 * build a standard "vmlinux" kernel image (in ELF binary format):
2771 * convert the kernel into a raw binary image:
2773 ${CROSS_COMPILE}-objcopy -O binary \
2774 -R .note -R .comment \
2775 -S vmlinux linux.bin
2777 * compress the binary image:
2781 * package compressed binary image for U-Boot:
2783 mkimage -A ppc -O linux -T kernel -C gzip \
2784 -a 0 -e 0 -n "Linux Kernel Image" \
2785 -d linux.bin.gz uImage
2788 The "mkimage" tool can also be used to create ramdisk images for use
2789 with U-Boot, either separated from the Linux kernel image, or
2790 combined into one file. "mkimage" encapsulates the images with a 64
2791 byte header containing information about target architecture,
2792 operating system, image type, compression method, entry points, time
2793 stamp, CRC32 checksums, etc.
2795 "mkimage" can be called in two ways: to verify existing images and
2796 print the header information, or to build new images.
2798 In the first form (with "-l" option) mkimage lists the information
2799 contained in the header of an existing U-Boot image; this includes
2800 checksum verification:
2802 tools/mkimage -l image
2803 -l ==> list image header information
2805 The second form (with "-d" option) is used to build a U-Boot image
2806 from a "data file" which is used as image payload:
2808 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2809 -n name -d data_file image
2810 -A ==> set architecture to 'arch'
2811 -O ==> set operating system to 'os'
2812 -T ==> set image type to 'type'
2813 -C ==> set compression type 'comp'
2814 -a ==> set load address to 'addr' (hex)
2815 -e ==> set entry point to 'ep' (hex)
2816 -n ==> set image name to 'name'
2817 -d ==> use image data from 'datafile'
2819 Right now, all Linux kernels for PowerPC systems use the same load
2820 address (0x00000000), but the entry point address depends on the
2823 - 2.2.x kernels have the entry point at 0x0000000C,
2824 - 2.3.x and later kernels have the entry point at 0x00000000.
2826 So a typical call to build a U-Boot image would read:
2828 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2829 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2830 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2831 > examples/uImage.TQM850L
2832 Image Name: 2.4.4 kernel for TQM850L
2833 Created: Wed Jul 19 02:34:59 2000
2834 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2835 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2836 Load Address: 0x00000000
2837 Entry Point: 0x00000000
2839 To verify the contents of the image (or check for corruption):
2841 -> tools/mkimage -l examples/uImage.TQM850L
2842 Image Name: 2.4.4 kernel for TQM850L
2843 Created: Wed Jul 19 02:34:59 2000
2844 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2845 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2846 Load Address: 0x00000000
2847 Entry Point: 0x00000000
2849 NOTE: for embedded systems where boot time is critical you can trade
2850 speed for memory and install an UNCOMPRESSED image instead: this
2851 needs more space in Flash, but boots much faster since it does not
2852 need to be uncompressed:
2854 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2855 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2856 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2857 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2858 > examples/uImage.TQM850L-uncompressed
2859 Image Name: 2.4.4 kernel for TQM850L
2860 Created: Wed Jul 19 02:34:59 2000
2861 Image Type: PowerPC Linux Kernel Image (uncompressed)
2862 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2863 Load Address: 0x00000000
2864 Entry Point: 0x00000000
2867 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2868 when your kernel is intended to use an initial ramdisk:
2870 -> tools/mkimage -n 'Simple Ramdisk Image' \
2871 > -A ppc -O linux -T ramdisk -C gzip \
2872 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2873 Image Name: Simple Ramdisk Image
2874 Created: Wed Jan 12 14:01:50 2000
2875 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2876 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2877 Load Address: 0x00000000
2878 Entry Point: 0x00000000
2880 The "dumpimage" tool can be used to disassemble or list the contents of images
2881 built by mkimage. See dumpimage's help output (-h) for details.
2883 Installing a Linux Image:
2884 -------------------------
2886 To downloading a U-Boot image over the serial (console) interface,
2887 you must convert the image to S-Record format:
2889 objcopy -I binary -O srec examples/image examples/image.srec
2891 The 'objcopy' does not understand the information in the U-Boot
2892 image header, so the resulting S-Record file will be relative to
2893 address 0x00000000. To load it to a given address, you need to
2894 specify the target address as 'offset' parameter with the 'loads'
2897 Example: install the image to address 0x40100000 (which on the
2898 TQM8xxL is in the first Flash bank):
2900 => erase 40100000 401FFFFF
2906 ## Ready for S-Record download ...
2907 ~>examples/image.srec
2908 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2910 15989 15990 15991 15992
2911 [file transfer complete]
2913 ## Start Addr = 0x00000000
2916 You can check the success of the download using the 'iminfo' command;
2917 this includes a checksum verification so you can be sure no data
2918 corruption happened:
2922 ## Checking Image at 40100000 ...
2923 Image Name: 2.2.13 for initrd on TQM850L
2924 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2925 Data Size: 335725 Bytes = 327 kB = 0 MB
2926 Load Address: 00000000
2927 Entry Point: 0000000c
2928 Verifying Checksum ... OK
2934 The "bootm" command is used to boot an application that is stored in
2935 memory (RAM or Flash). In case of a Linux kernel image, the contents
2936 of the "bootargs" environment variable is passed to the kernel as
2937 parameters. You can check and modify this variable using the
2938 "printenv" and "setenv" commands:
2941 => printenv bootargs
2942 bootargs=root=/dev/ram
2944 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2946 => printenv bootargs
2947 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2950 ## Booting Linux kernel at 40020000 ...
2951 Image Name: 2.2.13 for NFS on TQM850L
2952 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2953 Data Size: 381681 Bytes = 372 kB = 0 MB
2954 Load Address: 00000000
2955 Entry Point: 0000000c
2956 Verifying Checksum ... OK
2957 Uncompressing Kernel Image ... OK
2958 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
2959 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2960 time_init: decrementer frequency = 187500000/60
2961 Calibrating delay loop... 49.77 BogoMIPS
2962 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2965 If you want to boot a Linux kernel with initial RAM disk, you pass
2966 the memory addresses of both the kernel and the initrd image (PPBCOOT
2967 format!) to the "bootm" command:
2969 => imi 40100000 40200000
2971 ## Checking Image at 40100000 ...
2972 Image Name: 2.2.13 for initrd on TQM850L
2973 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2974 Data Size: 335725 Bytes = 327 kB = 0 MB
2975 Load Address: 00000000
2976 Entry Point: 0000000c
2977 Verifying Checksum ... OK
2979 ## Checking Image at 40200000 ...
2980 Image Name: Simple Ramdisk Image
2981 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2982 Data Size: 566530 Bytes = 553 kB = 0 MB
2983 Load Address: 00000000
2984 Entry Point: 00000000
2985 Verifying Checksum ... OK
2987 => bootm 40100000 40200000
2988 ## Booting Linux kernel at 40100000 ...
2989 Image Name: 2.2.13 for initrd on TQM850L
2990 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2991 Data Size: 335725 Bytes = 327 kB = 0 MB
2992 Load Address: 00000000
2993 Entry Point: 0000000c
2994 Verifying Checksum ... OK
2995 Uncompressing Kernel Image ... OK
2996 ## Loading RAMDisk Image at 40200000 ...
2997 Image Name: Simple Ramdisk Image
2998 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2999 Data Size: 566530 Bytes = 553 kB = 0 MB
3000 Load Address: 00000000
3001 Entry Point: 00000000
3002 Verifying Checksum ... OK
3003 Loading Ramdisk ... OK
3004 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
3005 Boot arguments: root=/dev/ram
3006 time_init: decrementer frequency = 187500000/60
3007 Calibrating delay loop... 49.77 BogoMIPS
3009 RAMDISK: Compressed image found at block 0
3010 VFS: Mounted root (ext2 filesystem).
3014 Boot Linux and pass a flat device tree:
3017 First, U-Boot must be compiled with the appropriate defines. See the section
3018 titled "Linux Kernel Interface" above for a more in depth explanation. The
3019 following is an example of how to start a kernel and pass an updated
3025 oft=oftrees/mpc8540ads.dtb
3026 => tftp $oftaddr $oft
3027 Speed: 1000, full duplex
3029 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3030 Filename 'oftrees/mpc8540ads.dtb'.
3031 Load address: 0x300000
3034 Bytes transferred = 4106 (100a hex)
3035 => tftp $loadaddr $bootfile
3036 Speed: 1000, full duplex
3038 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3040 Load address: 0x200000
3041 Loading:############
3043 Bytes transferred = 1029407 (fb51f hex)
3048 => bootm $loadaddr - $oftaddr
3049 ## Booting image at 00200000 ...
3050 Image Name: Linux-2.6.17-dirty
3051 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3052 Data Size: 1029343 Bytes = 1005.2 kB
3053 Load Address: 00000000
3054 Entry Point: 00000000
3055 Verifying Checksum ... OK
3056 Uncompressing Kernel Image ... OK
3057 Booting using flat device tree at 0x300000
3058 Using MPC85xx ADS machine description
3059 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3063 More About U-Boot Image Types:
3064 ------------------------------
3066 U-Boot supports the following image types:
3068 "Standalone Programs" are directly runnable in the environment
3069 provided by U-Boot; it is expected that (if they behave
3070 well) you can continue to work in U-Boot after return from
3071 the Standalone Program.
3072 "OS Kernel Images" are usually images of some Embedded OS which
3073 will take over control completely. Usually these programs
3074 will install their own set of exception handlers, device
3075 drivers, set up the MMU, etc. - this means, that you cannot
3076 expect to re-enter U-Boot except by resetting the CPU.
3077 "RAMDisk Images" are more or less just data blocks, and their
3078 parameters (address, size) are passed to an OS kernel that is
3080 "Multi-File Images" contain several images, typically an OS
3081 (Linux) kernel image and one or more data images like
3082 RAMDisks. This construct is useful for instance when you want
3083 to boot over the network using BOOTP etc., where the boot
3084 server provides just a single image file, but you want to get
3085 for instance an OS kernel and a RAMDisk image.
3087 "Multi-File Images" start with a list of image sizes, each
3088 image size (in bytes) specified by an "uint32_t" in network
3089 byte order. This list is terminated by an "(uint32_t)0".
3090 Immediately after the terminating 0 follow the images, one by
3091 one, all aligned on "uint32_t" boundaries (size rounded up to
3092 a multiple of 4 bytes).
3094 "Firmware Images" are binary images containing firmware (like
3095 U-Boot or FPGA images) which usually will be programmed to
3098 "Script files" are command sequences that will be executed by
3099 U-Boot's command interpreter; this feature is especially
3100 useful when you configure U-Boot to use a real shell (hush)
3101 as command interpreter.
3103 Booting the Linux zImage:
3104 -------------------------
3106 On some platforms, it's possible to boot Linux zImage. This is done
3107 using the "bootz" command. The syntax of "bootz" command is the same
3108 as the syntax of "bootm" command.
3110 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3111 kernel with raw initrd images. The syntax is slightly different, the
3112 address of the initrd must be augmented by it's size, in the following
3113 format: "<initrd addres>:<initrd size>".
3119 One of the features of U-Boot is that you can dynamically load and
3120 run "standalone" applications, which can use some resources of
3121 U-Boot like console I/O functions or interrupt services.
3123 Two simple examples are included with the sources:
3128 'examples/hello_world.c' contains a small "Hello World" Demo
3129 application; it is automatically compiled when you build U-Boot.
3130 It's configured to run at address 0x00040004, so you can play with it
3134 ## Ready for S-Record download ...
3135 ~>examples/hello_world.srec
3136 1 2 3 4 5 6 7 8 9 10 11 ...
3137 [file transfer complete]
3139 ## Start Addr = 0x00040004
3141 => go 40004 Hello World! This is a test.
3142 ## Starting application at 0x00040004 ...
3153 Hit any key to exit ...
3155 ## Application terminated, rc = 0x0
3157 Another example, which demonstrates how to register a CPM interrupt
3158 handler with the U-Boot code, can be found in 'examples/timer.c'.
3159 Here, a CPM timer is set up to generate an interrupt every second.
3160 The interrupt service routine is trivial, just printing a '.'
3161 character, but this is just a demo program. The application can be
3162 controlled by the following keys:
3164 ? - print current values og the CPM Timer registers
3165 b - enable interrupts and start timer
3166 e - stop timer and disable interrupts
3167 q - quit application
3170 ## Ready for S-Record download ...
3171 ~>examples/timer.srec
3172 1 2 3 4 5 6 7 8 9 10 11 ...
3173 [file transfer complete]
3175 ## Start Addr = 0x00040004
3178 ## Starting application at 0x00040004 ...
3181 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3184 [q, b, e, ?] Set interval 1000000 us
3187 [q, b, e, ?] ........
3188 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3191 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3194 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3197 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3199 [q, b, e, ?] ...Stopping timer
3201 [q, b, e, ?] ## Application terminated, rc = 0x0
3207 Over time, many people have reported problems when trying to use the
3208 "minicom" terminal emulation program for serial download. I (wd)
3209 consider minicom to be broken, and recommend not to use it. Under
3210 Unix, I recommend to use C-Kermit for general purpose use (and
3211 especially for kermit binary protocol download ("loadb" command), and
3212 use "cu" for S-Record download ("loads" command). See
3213 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3214 for help with kermit.
3217 Nevertheless, if you absolutely want to use it try adding this
3218 configuration to your "File transfer protocols" section:
3220 Name Program Name U/D FullScr IO-Red. Multi
3221 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3222 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3228 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3229 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3231 Building requires a cross environment; it is known to work on
3232 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3233 need gmake since the Makefiles are not compatible with BSD make).
3234 Note that the cross-powerpc package does not install include files;
3235 attempting to build U-Boot will fail because <machine/ansi.h> is
3236 missing. This file has to be installed and patched manually:
3238 # cd /usr/pkg/cross/powerpc-netbsd/include
3240 # ln -s powerpc machine
3241 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3242 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3244 Native builds *don't* work due to incompatibilities between native
3245 and U-Boot include files.
3247 Booting assumes that (the first part of) the image booted is a
3248 stage-2 loader which in turn loads and then invokes the kernel
3249 proper. Loader sources will eventually appear in the NetBSD source
3250 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3251 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3254 Implementation Internals:
3255 =========================
3257 The following is not intended to be a complete description of every
3258 implementation detail. However, it should help to understand the
3259 inner workings of U-Boot and make it easier to port it to custom
3263 Initial Stack, Global Data:
3264 ---------------------------
3266 The implementation of U-Boot is complicated by the fact that U-Boot
3267 starts running out of ROM (flash memory), usually without access to
3268 system RAM (because the memory controller is not initialized yet).
3269 This means that we don't have writable Data or BSS segments, and BSS
3270 is not initialized as zero. To be able to get a C environment working
3271 at all, we have to allocate at least a minimal stack. Implementation
3272 options for this are defined and restricted by the CPU used: Some CPU
3273 models provide on-chip memory (like the IMMR area on MPC8xx and
3274 MPC826x processors), on others (parts of) the data cache can be
3275 locked as (mis-) used as memory, etc.
3277 Chris Hallinan posted a good summary of these issues to the
3278 U-Boot mailing list:
3280 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3281 From: "Chris Hallinan" <clh@net1plus.com>
3282 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3285 Correct me if I'm wrong, folks, but the way I understand it
3286 is this: Using DCACHE as initial RAM for Stack, etc, does not
3287 require any physical RAM backing up the cache. The cleverness
3288 is that the cache is being used as a temporary supply of
3289 necessary storage before the SDRAM controller is setup. It's
3290 beyond the scope of this list to explain the details, but you
3291 can see how this works by studying the cache architecture and
3292 operation in the architecture and processor-specific manuals.
3294 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3295 is another option for the system designer to use as an
3296 initial stack/RAM area prior to SDRAM being available. Either
3297 option should work for you. Using CS 4 should be fine if your
3298 board designers haven't used it for something that would
3299 cause you grief during the initial boot! It is frequently not
3302 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3303 with your processor/board/system design. The default value
3304 you will find in any recent u-boot distribution in
3305 walnut.h should work for you. I'd set it to a value larger
3306 than your SDRAM module. If you have a 64MB SDRAM module, set
3307 it above 400_0000. Just make sure your board has no resources
3308 that are supposed to respond to that address! That code in
3309 start.S has been around a while and should work as is when
3310 you get the config right.
3315 It is essential to remember this, since it has some impact on the C
3316 code for the initialization procedures:
3318 * Initialized global data (data segment) is read-only. Do not attempt
3321 * Do not use any uninitialized global data (or implicitly initialized
3322 as zero data - BSS segment) at all - this is undefined, initiali-
3323 zation is performed later (when relocating to RAM).
3325 * Stack space is very limited. Avoid big data buffers or things like
3328 Having only the stack as writable memory limits means we cannot use
3329 normal global data to share information between the code. But it
3330 turned out that the implementation of U-Boot can be greatly
3331 simplified by making a global data structure (gd_t) available to all
3332 functions. We could pass a pointer to this data as argument to _all_
3333 functions, but this would bloat the code. Instead we use a feature of
3334 the GCC compiler (Global Register Variables) to share the data: we
3335 place a pointer (gd) to the global data into a register which we
3336 reserve for this purpose.
3338 When choosing a register for such a purpose we are restricted by the
3339 relevant (E)ABI specifications for the current architecture, and by
3340 GCC's implementation.
3342 For PowerPC, the following registers have specific use:
3344 R2: reserved for system use
3345 R3-R4: parameter passing and return values
3346 R5-R10: parameter passing
3347 R13: small data area pointer
3351 (U-Boot also uses R12 as internal GOT pointer. r12
3352 is a volatile register so r12 needs to be reset when
3353 going back and forth between asm and C)
3355 ==> U-Boot will use R2 to hold a pointer to the global data
3357 Note: on PPC, we could use a static initializer (since the
3358 address of the global data structure is known at compile time),
3359 but it turned out that reserving a register results in somewhat
3360 smaller code - although the code savings are not that big (on
3361 average for all boards 752 bytes for the whole U-Boot image,
3362 624 text + 127 data).
3364 On ARM, the following registers are used:
3366 R0: function argument word/integer result
3367 R1-R3: function argument word
3368 R9: platform specific
3369 R10: stack limit (used only if stack checking is enabled)
3370 R11: argument (frame) pointer
3371 R12: temporary workspace
3374 R15: program counter
3376 ==> U-Boot will use R9 to hold a pointer to the global data
3378 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3380 On Nios II, the ABI is documented here:
3381 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3383 ==> U-Boot will use gp to hold a pointer to the global data
3385 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3386 to access small data sections, so gp is free.
3388 On RISC-V, the following registers are used:
3390 x0: hard-wired zero (zero)
3391 x1: return address (ra)
3392 x2: stack pointer (sp)
3393 x3: global pointer (gp)
3394 x4: thread pointer (tp)
3395 x5: link register (t0)
3396 x8: frame pointer (fp)
3397 x10-x11: arguments/return values (a0-1)
3398 x12-x17: arguments (a2-7)
3399 x28-31: temporaries (t3-6)
3400 pc: program counter (pc)
3402 ==> U-Boot will use gp to hold a pointer to the global data
3407 U-Boot runs in system state and uses physical addresses, i.e. the
3408 MMU is not used either for address mapping nor for memory protection.
3410 The available memory is mapped to fixed addresses using the memory
3411 controller. In this process, a contiguous block is formed for each
3412 memory type (Flash, SDRAM, SRAM), even when it consists of several
3413 physical memory banks.
3415 U-Boot is installed in the first 128 kB of the first Flash bank (on
3416 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3417 booting and sizing and initializing DRAM, the code relocates itself
3418 to the upper end of DRAM. Immediately below the U-Boot code some
3419 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3420 configuration setting]. Below that, a structure with global Board
3421 Info data is placed, followed by the stack (growing downward).
3423 Additionally, some exception handler code is copied to the low 8 kB
3424 of DRAM (0x00000000 ... 0x00001FFF).
3426 So a typical memory configuration with 16 MB of DRAM could look like
3429 0x0000 0000 Exception Vector code
3432 0x0000 2000 Free for Application Use
3438 0x00FB FF20 Monitor Stack (Growing downward)
3439 0x00FB FFAC Board Info Data and permanent copy of global data
3440 0x00FC 0000 Malloc Arena
3443 0x00FE 0000 RAM Copy of Monitor Code
3444 ... eventually: LCD or video framebuffer
3445 ... eventually: pRAM (Protected RAM - unchanged by reset)
3446 0x00FF FFFF [End of RAM]
3449 System Initialization:
3450 ----------------------
3452 In the reset configuration, U-Boot starts at the reset entry point
3453 (on most PowerPC systems at address 0x00000100). Because of the reset
3454 configuration for CS0# this is a mirror of the on board Flash memory.
3455 To be able to re-map memory U-Boot then jumps to its link address.
3456 To be able to implement the initialization code in C, a (small!)
3457 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3458 which provide such a feature like), or in a locked part of the data
3459 cache. After that, U-Boot initializes the CPU core, the caches and
3462 Next, all (potentially) available memory banks are mapped using a
3463 preliminary mapping. For example, we put them on 512 MB boundaries
3464 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3465 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3466 programmed for SDRAM access. Using the temporary configuration, a
3467 simple memory test is run that determines the size of the SDRAM
3470 When there is more than one SDRAM bank, and the banks are of
3471 different size, the largest is mapped first. For equal size, the first
3472 bank (CS2#) is mapped first. The first mapping is always for address
3473 0x00000000, with any additional banks following immediately to create
3474 contiguous memory starting from 0.
3476 Then, the monitor installs itself at the upper end of the SDRAM area
3477 and allocates memory for use by malloc() and for the global Board
3478 Info data; also, the exception vector code is copied to the low RAM
3479 pages, and the final stack is set up.
3481 Only after this relocation will you have a "normal" C environment;
3482 until that you are restricted in several ways, mostly because you are
3483 running from ROM, and because the code will have to be relocated to a
3487 U-Boot Porting Guide:
3488 ----------------------
3490 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3494 int main(int argc, char *argv[])
3496 sighandler_t no_more_time;
3498 signal(SIGALRM, no_more_time);
3499 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3501 if (available_money > available_manpower) {
3502 Pay consultant to port U-Boot;
3506 Download latest U-Boot source;
3508 Subscribe to u-boot mailing list;
3511 email("Hi, I am new to U-Boot, how do I get started?");
3514 Read the README file in the top level directory;
3515 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3516 Read applicable doc/README.*;
3517 Read the source, Luke;
3518 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3521 if (available_money > toLocalCurrency ($2500))
3524 Add a lot of aggravation and time;
3526 if (a similar board exists) { /* hopefully... */
3527 cp -a board/<similar> board/<myboard>
3528 cp include/configs/<similar>.h include/configs/<myboard>.h
3530 Create your own board support subdirectory;
3531 Create your own board include/configs/<myboard>.h file;
3533 Edit new board/<myboard> files
3534 Edit new include/configs/<myboard>.h
3539 Add / modify source code;
3543 email("Hi, I am having problems...");
3545 Send patch file to the U-Boot email list;
3546 if (reasonable critiques)
3547 Incorporate improvements from email list code review;
3549 Defend code as written;
3555 void no_more_time (int sig)
3564 All contributions to U-Boot should conform to the Linux kernel
3565 coding style; see the kernel coding style guide at
3566 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3567 script "scripts/Lindent" in your Linux kernel source directory.
3569 Source files originating from a different project (for example the
3570 MTD subsystem) are generally exempt from these guidelines and are not
3571 reformatted to ease subsequent migration to newer versions of those
3574 Please note that U-Boot is implemented in C (and to some small parts in
3575 Assembler); no C++ is used, so please do not use C++ style comments (//)
3578 Please also stick to the following formatting rules:
3579 - remove any trailing white space
3580 - use TAB characters for indentation and vertical alignment, not spaces
3581 - make sure NOT to use DOS '\r\n' line feeds
3582 - do not add more than 2 consecutive empty lines to source files
3583 - do not add trailing empty lines to source files
3585 Submissions which do not conform to the standards may be returned
3586 with a request to reformat the changes.
3592 Since the number of patches for U-Boot is growing, we need to
3593 establish some rules. Submissions which do not conform to these rules
3594 may be rejected, even when they contain important and valuable stuff.
3596 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3598 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3599 see https://lists.denx.de/listinfo/u-boot
3601 When you send a patch, please include the following information with
3604 * For bug fixes: a description of the bug and how your patch fixes
3605 this bug. Please try to include a way of demonstrating that the
3606 patch actually fixes something.
3608 * For new features: a description of the feature and your
3611 * For major contributions, add a MAINTAINERS file with your
3612 information and associated file and directory references.
3614 * When you add support for a new board, don't forget to add a
3615 maintainer e-mail address to the boards.cfg file, too.
3617 * If your patch adds new configuration options, don't forget to
3618 document these in the README file.
3620 * The patch itself. If you are using git (which is *strongly*
3621 recommended) you can easily generate the patch using the
3622 "git format-patch". If you then use "git send-email" to send it to
3623 the U-Boot mailing list, you will avoid most of the common problems
3624 with some other mail clients.
3626 If you cannot use git, use "diff -purN OLD NEW". If your version of
3627 diff does not support these options, then get the latest version of
3630 The current directory when running this command shall be the parent
3631 directory of the U-Boot source tree (i. e. please make sure that
3632 your patch includes sufficient directory information for the
3635 We prefer patches as plain text. MIME attachments are discouraged,
3636 and compressed attachments must not be used.
3638 * If one logical set of modifications affects or creates several
3639 files, all these changes shall be submitted in a SINGLE patch file.
3641 * Changesets that contain different, unrelated modifications shall be
3642 submitted as SEPARATE patches, one patch per changeset.
3647 * Before sending the patch, run the buildman script on your patched
3648 source tree and make sure that no errors or warnings are reported
3649 for any of the boards.
3651 * Keep your modifications to the necessary minimum: A patch
3652 containing several unrelated changes or arbitrary reformats will be
3653 returned with a request to re-formatting / split it.
3655 * If you modify existing code, make sure that your new code does not
3656 add to the memory footprint of the code ;-) Small is beautiful!
3657 When adding new features, these should compile conditionally only
3658 (using #ifdef), and the resulting code with the new feature
3659 disabled must not need more memory than the old code without your
3662 * Remember that there is a size limit of 100 kB per message on the
3663 u-boot mailing list. Bigger patches will be moderated. If they are
3664 reasonable and not too big, they will be acknowledged. But patches
3665 bigger than the size limit should be avoided.
projects / platform / kernel / u-boot.git / blob