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 /nds32 Files generic to NDS32 architecture
138 /nios2 Files generic to Altera NIOS2 architecture
139 /powerpc Files generic to PowerPC architecture
140 /riscv Files generic to RISC-V architecture
141 /sandbox Files generic to HW-independent "sandbox"
142 /sh Files generic to SH architecture
143 /x86 Files generic to x86 architecture
144 /xtensa Files generic to Xtensa architecture
145 /api Machine/arch-independent API for external apps
146 /board Board-dependent files
147 /boot Support for images and booting
148 /cmd U-Boot commands functions
149 /common Misc architecture-independent functions
150 /configs Board default configuration files
151 /disk Code for disk drive partition handling
152 /doc Documentation (a mix of ReST and READMEs)
153 /drivers Device drivers
154 /dts Makefile for building internal U-Boot fdt.
155 /env Environment support
156 /examples Example code for standalone applications, etc.
157 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
158 /include Header Files
159 /lib Library routines generic to all architectures
160 /Licenses Various license files
162 /post Power On Self Test
163 /scripts Various build scripts and Makefiles
164 /test Various unit test files
165 /tools Tools to build and sign FIT images, etc.
167 Software Configuration:
168 =======================
170 Configuration is usually done using C preprocessor defines; the
171 rationale behind that is to avoid dead code whenever possible.
173 There are two classes of configuration variables:
175 * Configuration _OPTIONS_:
176 These are selectable by the user and have names beginning with
179 * Configuration _SETTINGS_:
180 These depend on the hardware etc. and should not be meddled with if
181 you don't know what you're doing; they have names beginning with
184 Previously, all configuration was done by hand, which involved creating
185 symbolic links and editing configuration files manually. More recently,
186 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
187 allowing you to use the "make menuconfig" command to configure your
191 Selection of Processor Architecture and Board Type:
192 ---------------------------------------------------
194 For all supported boards there are ready-to-use default
195 configurations available; just type "make <board_name>_defconfig".
197 Example: For a TQM823L module type:
200 make TQM823L_defconfig
202 Note: If you're looking for the default configuration file for a board
203 you're sure used to be there but is now missing, check the file
204 doc/README.scrapyard for a list of no longer supported boards.
209 U-Boot can be built natively to run on a Linux host using the 'sandbox'
210 board. This allows feature development which is not board- or architecture-
211 specific to be undertaken on a native platform. The sandbox is also used to
212 run some of U-Boot's tests.
214 See doc/arch/sandbox.rst for more details.
217 Board Initialisation Flow:
218 --------------------------
220 This is the intended start-up flow for boards. This should apply for both
221 SPL and U-Boot proper (i.e. they both follow the same rules).
223 Note: "SPL" stands for "Secondary Program Loader," which is explained in
224 more detail later in this file.
226 At present, SPL mostly uses a separate code path, but the function names
227 and roles of each function are the same. Some boards or architectures
228 may not conform to this. At least most ARM boards which use
229 CONFIG_SPL_FRAMEWORK conform to this.
231 Execution typically starts with an architecture-specific (and possibly
232 CPU-specific) start.S file, such as:
234 - arch/arm/cpu/armv7/start.S
235 - arch/powerpc/cpu/mpc83xx/start.S
236 - arch/mips/cpu/start.S
238 and so on. From there, three functions are called; the purpose and
239 limitations of each of these functions are described below.
242 - purpose: essential init to permit execution to reach board_init_f()
243 - no global_data or BSS
244 - there is no stack (ARMv7 may have one but it will soon be removed)
245 - must not set up SDRAM or use console
246 - must only do the bare minimum to allow execution to continue to
248 - this is almost never needed
249 - return normally from this function
252 - purpose: set up the machine ready for running board_init_r():
253 i.e. SDRAM and serial UART
254 - global_data is available
256 - BSS is not available, so you cannot use global/static variables,
257 only stack variables and global_data
259 Non-SPL-specific notes:
260 - dram_init() is called to set up DRAM. If already done in SPL this
264 - you can override the entire board_init_f() function with your own
266 - preloader_console_init() can be called here in extremis
267 - should set up SDRAM, and anything needed to make the UART work
268 - there is no need to clear BSS, it will be done by crt0.S
269 - for specific scenarios on certain architectures an early BSS *can*
270 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
271 of BSS prior to entering board_init_f()) but doing so is discouraged.
272 Instead it is strongly recommended to architect any code changes
273 or additions such to not depend on the availability of BSS during
274 board_init_f() as indicated in other sections of this README to
275 maintain compatibility and consistency across the entire code base.
276 - must return normally from this function (don't call board_init_r()
279 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
280 this point the stack and global_data are relocated to below
281 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
285 - purpose: main execution, common code
286 - global_data is available
288 - BSS is available, all static/global variables can be used
289 - execution eventually continues to main_loop()
291 Non-SPL-specific notes:
292 - U-Boot is relocated to the top of memory and is now running from
296 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
297 CONFIG_SPL_STACK_R_ADDR points into SDRAM
298 - preloader_console_init() can be called here - typically this is
299 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
300 spl_board_init() function containing this call
301 - loads U-Boot or (in falcon mode) Linux
304 Configuration Options:
305 ----------------------
307 Configuration depends on the combination of board and CPU type; all
308 such information is kept in a configuration file
309 "include/configs/<board_name>.h".
311 Example: For a TQM823L module, all configuration settings are in
312 "include/configs/TQM823L.h".
315 Many of the options are named exactly as the corresponding Linux
316 kernel configuration options. The intention is to make it easier to
317 build a config tool - later.
319 - ARM Platform Bus Type(CCI):
320 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
321 provides full cache coherency between two clusters of multi-core
322 CPUs and I/O coherency for devices and I/O masters
324 CONFIG_SYS_FSL_HAS_CCI400
326 Defined For SoC that has cache coherent interconnect
329 CONFIG_SYS_FSL_HAS_CCN504
331 Defined for SoC that has cache coherent interconnect CCN-504
333 The following options need to be configured:
335 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
337 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
342 Specifies that the core is a 64-bit PowerPC implementation (implements
343 the "64" category of the Power ISA). This is necessary for ePAPR
344 compliance, among other possible reasons.
346 CONFIG_SYS_FSL_TBCLK_DIV
348 Defines the core time base clock divider ratio compared to the
349 system clock. On most PQ3 devices this is 8, on newer QorIQ
350 devices it can be 16 or 32. The ratio varies from SoC to Soc.
352 CONFIG_SYS_FSL_PCIE_COMPAT
354 Defines the string to utilize when trying to match PCIe device
355 tree nodes for the given platform.
357 CONFIG_SYS_FSL_ERRATUM_A004510
359 Enables a workaround for erratum A004510. If set,
360 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
361 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
364 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
366 Defines one or two SoC revisions (low 8 bits of SVR)
367 for which the A004510 workaround should be applied.
369 The rest of SVR is either not relevant to the decision
370 of whether the erratum is present (e.g. p2040 versus
371 p2041) or is implied by the build target, which controls
372 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
374 See Freescale App Note 4493 for more information about
377 CONFIG_A003399_NOR_WORKAROUND
378 Enables a workaround for IFC erratum A003399. It is only
379 required during NOR boot.
381 CONFIG_A008044_WORKAROUND
382 Enables a workaround for T1040/T1042 erratum A008044. It is only
383 required during NAND boot and valid for Rev 1.0 SoC revision
385 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
387 This is the value to write into CCSR offset 0x18600
388 according to the A004510 workaround.
390 CONFIG_SYS_FSL_DSP_DDR_ADDR
391 This value denotes start offset of DDR memory which is
392 connected exclusively to the DSP cores.
394 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
395 This value denotes start offset of M2 memory
396 which is directly connected to the DSP core.
398 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
399 This value denotes start offset of M3 memory which is directly
400 connected to the DSP core.
402 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
403 This value denotes start offset of DSP CCSR space.
405 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
406 Single Source Clock is clocking mode present in some of FSL SoC's.
407 In this mode, a single differential clock is used to supply
408 clocks to the sysclock, ddrclock and usbclock.
410 CONFIG_SYS_CPC_REINIT_F
411 This CONFIG is defined when the CPC is configured as SRAM at the
412 time of U-Boot entry and is required to be re-initialized.
415 Indicates this SoC supports deep sleep feature. If deep sleep is
416 supported, core will start to execute uboot when wakes up.
418 - Generic CPU options:
419 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
421 Defines the endianess of the CPU. Implementation of those
422 values is arch specific.
425 Freescale DDR driver in use. This type of DDR controller is
426 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
428 CONFIG_SYS_FSL_DDR_ADDR
429 Freescale DDR memory-mapped register base.
431 CONFIG_SYS_FSL_DDR_EMU
432 Specify emulator support for DDR. Some DDR features such as
433 deskew training are not available.
435 CONFIG_SYS_FSL_DDRC_GEN1
436 Freescale DDR1 controller.
438 CONFIG_SYS_FSL_DDRC_GEN2
439 Freescale DDR2 controller.
441 CONFIG_SYS_FSL_DDRC_GEN3
442 Freescale DDR3 controller.
444 CONFIG_SYS_FSL_DDRC_GEN4
445 Freescale DDR4 controller.
447 CONFIG_SYS_FSL_DDRC_ARM_GEN3
448 Freescale DDR3 controller for ARM-based SoCs.
451 Board config to use DDR1. It can be enabled for SoCs with
452 Freescale DDR1 or DDR2 controllers, depending on the board
456 Board config to use DDR2. It can be enabled for SoCs with
457 Freescale DDR2 or DDR3 controllers, depending on the board
461 Board config to use DDR3. It can be enabled for SoCs with
462 Freescale DDR3 or DDR3L controllers.
465 Board config to use DDR3L. It can be enabled for SoCs with
468 CONFIG_SYS_FSL_IFC_BE
469 Defines the IFC controller register space as Big Endian
471 CONFIG_SYS_FSL_IFC_LE
472 Defines the IFC controller register space as Little Endian
474 CONFIG_SYS_FSL_IFC_CLK_DIV
475 Defines divider of platform clock(clock input to IFC controller).
477 CONFIG_SYS_FSL_LBC_CLK_DIV
478 Defines divider of platform clock(clock input to eLBC controller).
480 CONFIG_SYS_FSL_DDR_BE
481 Defines the DDR controller register space as Big Endian
483 CONFIG_SYS_FSL_DDR_LE
484 Defines the DDR controller register space as Little Endian
486 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
487 Physical address from the view of DDR controllers. It is the
488 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
489 it could be different for ARM SoCs.
491 CONFIG_SYS_FSL_DDR_INTLV_256B
492 DDR controller interleaving on 256-byte. This is a special
493 interleaving mode, handled by Dickens for Freescale layerscape
496 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
497 Number of controllers used as main memory.
499 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
500 Number of controllers used for other than main memory.
502 CONFIG_SYS_FSL_HAS_DP_DDR
503 Defines the SoC has DP-DDR used for DPAA.
505 CONFIG_SYS_FSL_SEC_BE
506 Defines the SEC controller register space as Big Endian
508 CONFIG_SYS_FSL_SEC_LE
509 Defines the SEC controller register space as Little Endian
512 CONFIG_SYS_INIT_SP_OFFSET
514 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
515 pointer. This is needed for the temporary stack before
518 CONFIG_XWAY_SWAP_BYTES
520 Enable compilation of tools/xway-swap-bytes needed for Lantiq
521 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
522 be swapped if a flash programmer is used.
525 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
527 Select high exception vectors of the ARM core, e.g., do not
528 clear the V bit of the c1 register of CP15.
531 Generic timer clock source frequency.
533 COUNTER_FREQUENCY_REAL
534 Generic timer clock source frequency if the real clock is
535 different from COUNTER_FREQUENCY, and can only be determined
539 CONFIG_TEGRA_SUPPORT_NON_SECURE
541 Support executing U-Boot in non-secure (NS) mode. Certain
542 impossible actions will be skipped if the CPU is in NS mode,
543 such as ARM architectural timer initialization.
545 - Linux Kernel Interface:
546 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
548 When transferring memsize parameter to Linux, some versions
549 expect it to be in bytes, others in MB.
550 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
554 New kernel versions are expecting firmware settings to be
555 passed using flattened device trees (based on open firmware
559 * New libfdt-based support
560 * Adds the "fdt" command
561 * The bootm command automatically updates the fdt
563 OF_TBCLK - The timebase frequency.
565 boards with QUICC Engines require OF_QE to set UCC MAC
568 CONFIG_OF_SYSTEM_SETUP
570 Other code has addition modification that it wants to make
571 to the flat device tree before handing it off to the kernel.
572 This causes ft_system_setup() to be called before booting
577 U-Boot can detect if an IDE device is present or not.
578 If not, and this new config option is activated, U-Boot
579 removes the ATA node from the DTS before booting Linux,
580 so the Linux IDE driver does not probe the device and
581 crash. This is needed for buggy hardware (uc101) where
582 no pull down resistor is connected to the signal IDE5V_DD7.
584 - vxWorks boot parameters:
586 bootvx constructs a valid bootline using the following
587 environments variables: bootdev, bootfile, ipaddr, netmask,
588 serverip, gatewayip, hostname, othbootargs.
589 It loads the vxWorks image pointed bootfile.
591 Note: If a "bootargs" environment is defined, it will override
592 the defaults discussed just above.
594 - Cache Configuration for ARM:
595 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
597 CONFIG_SYS_PL310_BASE - Physical base address of PL310
598 controller register space
603 If you have Amba PrimeCell PL011 UARTs, set this variable to
604 the clock speed of the UARTs.
608 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
609 define this to a list of base addresses for each (supported)
610 port. See e.g. include/configs/versatile.h
612 CONFIG_SERIAL_HW_FLOW_CONTROL
614 Define this variable to enable hw flow control in serial driver.
615 Current user of this option is drivers/serial/nsl16550.c driver
617 - Serial Download Echo Mode:
619 If defined to 1, all characters received during a
620 serial download (using the "loads" command) are
621 echoed back. This might be needed by some terminal
622 emulations (like "cu"), but may as well just take
623 time on others. This setting #define's the initial
624 value of the "loads_echo" environment variable.
626 - Removal of commands
627 If no commands are needed to boot, you can disable
628 CONFIG_CMDLINE to remove them. In this case, the command line
629 will not be available, and when U-Boot wants to execute the
630 boot command (on start-up) it will call board_run_command()
631 instead. This can reduce image size significantly for very
632 simple boot procedures.
634 - Regular expression support:
636 If this variable is defined, U-Boot is linked against
637 the SLRE (Super Light Regular Expression) library,
638 which adds regex support to some commands, as for
639 example "env grep" and "setexpr".
642 CONFIG_SYS_WATCHDOG_FREQ
643 Some platforms automatically call WATCHDOG_RESET()
644 from the timer interrupt handler every
645 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
646 board configuration file, a default of CONFIG_SYS_HZ/2
647 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
648 to 0 disables calling WATCHDOG_RESET() from the timer
653 When CONFIG_CMD_DATE is selected, the type of the RTC
654 has to be selected, too. Define exactly one of the
657 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
658 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
659 CONFIG_RTC_MC146818 - use MC146818 RTC
660 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
661 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
662 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
663 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
664 CONFIG_RTC_DS164x - use Dallas DS164x RTC
665 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
666 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
667 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
668 CONFIG_SYS_RV3029_TCR - enable trickle charger on
671 Note that if the RTC uses I2C, then the I2C interface
672 must also be configured. See I2C Support, below.
675 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
677 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
678 chip-ngpio pairs that tell the PCA953X driver the number of
679 pins supported by a particular chip.
681 Note that if the GPIO device uses I2C, then the I2C interface
682 must also be configured. See I2C Support, below.
685 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
686 accesses and can checksum them or write a list of them out
687 to memory. See the 'iotrace' command for details. This is
688 useful for testing device drivers since it can confirm that
689 the driver behaves the same way before and after a code
690 change. Currently this is supported on sandbox and arm. To
691 add support for your architecture, add '#include <iotrace.h>'
692 to the bottom of arch/<arch>/include/asm/io.h and test.
694 Example output from the 'iotrace stats' command is below.
695 Note that if the trace buffer is exhausted, the checksum will
696 still continue to operate.
699 Start: 10000000 (buffer start address)
700 Size: 00010000 (buffer size)
701 Offset: 00000120 (current buffer offset)
702 Output: 10000120 (start + offset)
703 Count: 00000018 (number of trace records)
704 CRC32: 9526fb66 (CRC32 of all trace records)
708 When CONFIG_TIMESTAMP is selected, the timestamp
709 (date and time) of an image is printed by image
710 commands like bootm or iminfo. This option is
711 automatically enabled when you select CONFIG_CMD_DATE .
713 - Partition Labels (disklabels) Supported:
714 Zero or more of the following:
715 CONFIG_MAC_PARTITION Apple's MacOS partition table.
716 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
717 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
718 bootloader. Note 2TB partition limit; see
720 CONFIG_SCSI) you must configure support for at
721 least one non-MTD partition type as well.
726 Set this to enable support for disks larger than 137GB
727 Also look at CONFIG_SYS_64BIT_LBA.
728 Whithout these , LBA48 support uses 32bit variables and will 'only'
729 support disks up to 2.1TB.
731 CONFIG_SYS_64BIT_LBA:
732 When enabled, makes the IDE subsystem use 64bit sector addresses.
735 - NETWORK Support (PCI):
737 Utility code for direct access to the SPI bus on Intel 8257x.
738 This does not do anything useful unless you set at least one
739 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
742 Support for National dp83815 chips.
745 Support for National dp8382[01] gigabit chips.
747 - NETWORK Support (other):
749 Support for the Calxeda XGMAC device
752 Support for SMSC's LAN91C96 chips.
754 CONFIG_LAN91C96_USE_32_BIT
755 Define this to enable 32 bit addressing
758 Support for SMSC's LAN91C111 chip
761 Define this to hold the physical address
762 of the device (I/O space)
764 CONFIG_SMC_USE_32_BIT
765 Define this if data bus is 32 bits
767 CONFIG_SMC_USE_IOFUNCS
768 Define this to use i/o functions instead of macros
769 (some hardware wont work with macros)
771 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
772 Define this if you have more then 3 PHYs.
775 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
777 CONFIG_FTGMAC100_EGIGA
778 Define this to use GE link update with gigabit PHY.
779 Define this if FTGMAC100 is connected to gigabit PHY.
780 If your system has 10/100 PHY only, it might not occur
781 wrong behavior. Because PHY usually return timeout or
782 useless data when polling gigabit status and gigabit
783 control registers. This behavior won't affect the
784 correctnessof 10/100 link speed update.
787 Support for Renesas on-chip Ethernet controller
789 CONFIG_SH_ETHER_USE_PORT
790 Define the number of ports to be used
792 CONFIG_SH_ETHER_PHY_ADDR
793 Define the ETH PHY's address
795 CONFIG_SH_ETHER_CACHE_WRITEBACK
796 If this option is set, the driver enables cache flush.
802 CONFIG_TPM_TIS_INFINEON
803 Support for Infineon i2c bus TPM devices. Only one device
804 per system is supported at this time.
806 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
807 Define the burst count bytes upper limit
810 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
812 CONFIG_TPM_ST33ZP24_I2C
813 Support for STMicroelectronics ST33ZP24 I2C devices.
814 Requires TPM_ST33ZP24 and I2C.
816 CONFIG_TPM_ST33ZP24_SPI
817 Support for STMicroelectronics ST33ZP24 SPI devices.
818 Requires TPM_ST33ZP24 and SPI.
821 Support for Atmel TWI TPM device. Requires I2C support.
824 Support for generic parallel port TPM devices. Only one device
825 per system is supported at this time.
827 CONFIG_TPM_TIS_BASE_ADDRESS
828 Base address where the generic TPM device is mapped
829 to. Contemporary x86 systems usually map it at
833 Define this to enable the TPM support library which provides
834 functional interfaces to some TPM commands.
835 Requires support for a TPM device.
837 CONFIG_TPM_AUTH_SESSIONS
838 Define this to enable authorized functions in the TPM library.
839 Requires CONFIG_TPM and CONFIG_SHA1.
842 At the moment only the UHCI host controller is
843 supported (PIP405, MIP405); define
844 CONFIG_USB_UHCI to enable it.
845 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
846 and define CONFIG_USB_STORAGE to enable the USB
849 Supported are USB Keyboards and USB Floppy drives
852 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
853 txfilltuning field in the EHCI controller on reset.
855 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
859 Define the below if you wish to use the USB console.
860 Once firmware is rebuilt from a serial console issue the
861 command "setenv stdin usbtty; setenv stdout usbtty" and
862 attach your USB cable. The Unix command "dmesg" should print
863 it has found a new device. The environment variable usbtty
864 can be set to gserial or cdc_acm to enable your device to
865 appear to a USB host as a Linux gserial device or a
866 Common Device Class Abstract Control Model serial device.
867 If you select usbtty = gserial you should be able to enumerate
869 # modprobe usbserial vendor=0xVendorID product=0xProductID
870 else if using cdc_acm, simply setting the environment
871 variable usbtty to be cdc_acm should suffice. The following
872 might be defined in YourBoardName.h
875 Define this to build a UDC device
878 Define this to have a tty type of device available to
879 talk to the UDC device
882 Define this to enable the high speed support for usb
883 device and usbtty. If this feature is enabled, a routine
884 int is_usbd_high_speed(void)
885 also needs to be defined by the driver to dynamically poll
886 whether the enumeration has succeded at high speed or full
889 If you have a USB-IF assigned VendorID then you may wish to
890 define your own vendor specific values either in BoardName.h
891 or directly in usbd_vendor_info.h. If you don't define
892 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
893 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
894 should pretend to be a Linux device to it's target host.
896 CONFIG_USBD_MANUFACTURER
897 Define this string as the name of your company for
898 - CONFIG_USBD_MANUFACTURER "my company"
900 CONFIG_USBD_PRODUCT_NAME
901 Define this string as the name of your product
902 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
905 Define this as your assigned Vendor ID from the USB
906 Implementors Forum. This *must* be a genuine Vendor ID
907 to avoid polluting the USB namespace.
908 - CONFIG_USBD_VENDORID 0xFFFF
910 CONFIG_USBD_PRODUCTID
911 Define this as the unique Product ID
913 - CONFIG_USBD_PRODUCTID 0xFFFF
915 - ULPI Layer Support:
916 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
917 the generic ULPI layer. The generic layer accesses the ULPI PHY
918 via the platform viewport, so you need both the genric layer and
919 the viewport enabled. Currently only Chipidea/ARC based
920 viewport is supported.
921 To enable the ULPI layer support, define CONFIG_USB_ULPI and
922 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
923 If your ULPI phy needs a different reference clock than the
924 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
925 the appropriate value in Hz.
928 The MMC controller on the Intel PXA is supported. To
929 enable this define CONFIG_MMC. The MMC can be
930 accessed from the boot prompt by mapping the device
931 to physical memory similar to flash. Command line is
932 enabled with CONFIG_CMD_MMC. The MMC driver also works with
933 the FAT fs. This is enabled with CONFIG_CMD_FAT.
936 Support for Renesas on-chip MMCIF controller
939 Define the base address of MMCIF registers
942 Define the clock frequency for MMCIF
944 - USB Device Firmware Update (DFU) class support:
946 This enables the USB portion of the DFU USB class
949 This enables support for exposing NAND devices via DFU.
952 This enables support for exposing RAM via DFU.
953 Note: DFU spec refer to non-volatile memory usage, but
954 allow usages beyond the scope of spec - here RAM usage,
955 one that would help mostly the developer.
957 CONFIG_SYS_DFU_DATA_BUF_SIZE
958 Dfu transfer uses a buffer before writing data to the
959 raw storage device. Make the size (in bytes) of this buffer
960 configurable. The size of this buffer is also configurable
961 through the "dfu_bufsiz" environment variable.
963 CONFIG_SYS_DFU_MAX_FILE_SIZE
964 When updating files rather than the raw storage device,
965 we use a static buffer to copy the file into and then write
966 the buffer once we've been given the whole file. Define
967 this to the maximum filesize (in bytes) for the buffer.
968 Default is 4 MiB if undefined.
970 DFU_DEFAULT_POLL_TIMEOUT
971 Poll timeout [ms], is the timeout a device can send to the
972 host. The host must wait for this timeout before sending
973 a subsequent DFU_GET_STATUS request to the device.
975 DFU_MANIFEST_POLL_TIMEOUT
976 Poll timeout [ms], which the device sends to the host when
977 entering dfuMANIFEST state. Host waits this timeout, before
978 sending again an USB request to the device.
980 - Journaling Flash filesystem support:
981 CONFIG_SYS_JFFS2_FIRST_SECTOR,
982 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
983 Define these for a default partition on a NOR device
986 See Kconfig help for available keyboard drivers.
990 Enable the Freescale DIU video driver. Reference boards for
991 SOCs that have a DIU should define this macro to enable DIU
992 support, and should also define these other macros:
997 CONFIG_VIDEO_SW_CURSOR
998 CONFIG_VGA_AS_SINGLE_DEVICE
999 CONFIG_VIDEO_BMP_LOGO
1001 The DIU driver will look for the 'video-mode' environment
1002 variable, and if defined, enable the DIU as a console during
1003 boot. See the documentation file doc/README.video for a
1004 description of this variable.
1006 - LCD Support: CONFIG_LCD
1008 Define this to enable LCD support (for output to LCD
1009 display); also select one of the supported displays
1010 by defining one of these:
1014 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1016 CONFIG_NEC_NL6448AC33:
1018 NEC NL6448AC33-18. Active, color, single scan.
1020 CONFIG_NEC_NL6448BC20
1022 NEC NL6448BC20-08. 6.5", 640x480.
1023 Active, color, single scan.
1025 CONFIG_NEC_NL6448BC33_54
1027 NEC NL6448BC33-54. 10.4", 640x480.
1028 Active, color, single scan.
1032 Sharp 320x240. Active, color, single scan.
1033 It isn't 16x9, and I am not sure what it is.
1035 CONFIG_SHARP_LQ64D341
1037 Sharp LQ64D341 display, 640x480.
1038 Active, color, single scan.
1042 HLD1045 display, 640x480.
1043 Active, color, single scan.
1047 Optrex CBL50840-2 NF-FW 99 22 M5
1049 Hitachi LMG6912RPFC-00T
1053 320x240. Black & white.
1055 CONFIG_LCD_ALIGNMENT
1057 Normally the LCD is page-aligned (typically 4KB). If this is
1058 defined then the LCD will be aligned to this value instead.
1059 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1060 here, since it is cheaper to change data cache settings on
1061 a per-section basis.
1066 Sometimes, for example if the display is mounted in portrait
1067 mode or even if it's mounted landscape but rotated by 180degree,
1068 we need to rotate our content of the display relative to the
1069 framebuffer, so that user can read the messages which are
1071 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1072 initialized with a given rotation from "vl_rot" out of
1073 "vidinfo_t" which is provided by the board specific code.
1074 The value for vl_rot is coded as following (matching to
1075 fbcon=rotate:<n> linux-kernel commandline):
1076 0 = no rotation respectively 0 degree
1077 1 = 90 degree rotation
1078 2 = 180 degree rotation
1079 3 = 270 degree rotation
1081 If CONFIG_LCD_ROTATION is not defined, the console will be
1082 initialized with 0degree rotation.
1086 Support drawing of RLE8-compressed bitmaps on the LCD.
1089 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1091 The clock frequency of the MII bus
1093 CONFIG_PHY_RESET_DELAY
1095 Some PHY like Intel LXT971A need extra delay after
1096 reset before any MII register access is possible.
1097 For such PHY, set this option to the usec delay
1098 required. (minimum 300usec for LXT971A)
1100 CONFIG_PHY_CMD_DELAY (ppc4xx)
1102 Some PHY like Intel LXT971A need extra delay after
1103 command issued before MII status register can be read
1108 Define a default value for the IP address to use for
1109 the default Ethernet interface, in case this is not
1110 determined through e.g. bootp.
1111 (Environment variable "ipaddr")
1113 - Server IP address:
1116 Defines a default value for the IP address of a TFTP
1117 server to contact when using the "tftboot" command.
1118 (Environment variable "serverip")
1120 - Gateway IP address:
1123 Defines a default value for the IP address of the
1124 default router where packets to other networks are
1126 (Environment variable "gatewayip")
1131 Defines a default value for the subnet mask (or
1132 routing prefix) which is used to determine if an IP
1133 address belongs to the local subnet or needs to be
1134 forwarded through a router.
1135 (Environment variable "netmask")
1137 - BOOTP Recovery Mode:
1138 CONFIG_BOOTP_RANDOM_DELAY
1140 If you have many targets in a network that try to
1141 boot using BOOTP, you may want to avoid that all
1142 systems send out BOOTP requests at precisely the same
1143 moment (which would happen for instance at recovery
1144 from a power failure, when all systems will try to
1145 boot, thus flooding the BOOTP server. Defining
1146 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1147 inserted before sending out BOOTP requests. The
1148 following delays are inserted then:
1150 1st BOOTP request: delay 0 ... 1 sec
1151 2nd BOOTP request: delay 0 ... 2 sec
1152 3rd BOOTP request: delay 0 ... 4 sec
1154 BOOTP requests: delay 0 ... 8 sec
1156 CONFIG_BOOTP_ID_CACHE_SIZE
1158 BOOTP packets are uniquely identified using a 32-bit ID. The
1159 server will copy the ID from client requests to responses and
1160 U-Boot will use this to determine if it is the destination of
1161 an incoming response. Some servers will check that addresses
1162 aren't in use before handing them out (usually using an ARP
1163 ping) and therefore take up to a few hundred milliseconds to
1164 respond. Network congestion may also influence the time it
1165 takes for a response to make it back to the client. If that
1166 time is too long, U-Boot will retransmit requests. In order
1167 to allow earlier responses to still be accepted after these
1168 retransmissions, U-Boot's BOOTP client keeps a small cache of
1169 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1170 cache. The default is to keep IDs for up to four outstanding
1171 requests. Increasing this will allow U-Boot to accept offers
1172 from a BOOTP client in networks with unusually high latency.
1174 - DHCP Advanced Options:
1176 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1178 A 32bit value in microseconds for a delay between
1179 receiving a "DHCP Offer" and sending the "DHCP Request".
1180 This fixes a problem with certain DHCP servers that don't
1181 respond 100% of the time to a "DHCP request". E.g. On an
1182 AT91RM9200 processor running at 180MHz, this delay needed
1183 to be *at least* 15,000 usec before a Windows Server 2003
1184 DHCP server would reply 100% of the time. I recommend at
1185 least 50,000 usec to be safe. The alternative is to hope
1186 that one of the retries will be successful but note that
1187 the DHCP timeout and retry process takes a longer than
1190 - Link-local IP address negotiation:
1191 Negotiate with other link-local clients on the local network
1192 for an address that doesn't require explicit configuration.
1193 This is especially useful if a DHCP server cannot be guaranteed
1194 to exist in all environments that the device must operate.
1196 See doc/README.link-local for more information.
1198 - MAC address from environment variables
1200 FDT_SEQ_MACADDR_FROM_ENV
1202 Fix-up device tree with MAC addresses fetched sequentially from
1203 environment variables. This config work on assumption that
1204 non-usable ethernet node of device-tree are either not present
1205 or their status has been marked as "disabled".
1208 CONFIG_CDP_DEVICE_ID
1210 The device id used in CDP trigger frames.
1212 CONFIG_CDP_DEVICE_ID_PREFIX
1214 A two character string which is prefixed to the MAC address
1219 A printf format string which contains the ascii name of
1220 the port. Normally is set to "eth%d" which sets
1221 eth0 for the first Ethernet, eth1 for the second etc.
1223 CONFIG_CDP_CAPABILITIES
1225 A 32bit integer which indicates the device capabilities;
1226 0x00000010 for a normal host which does not forwards.
1230 An ascii string containing the version of the software.
1234 An ascii string containing the name of the platform.
1238 A 32bit integer sent on the trigger.
1240 CONFIG_CDP_POWER_CONSUMPTION
1242 A 16bit integer containing the power consumption of the
1243 device in .1 of milliwatts.
1245 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1247 A byte containing the id of the VLAN.
1249 - Status LED: CONFIG_LED_STATUS
1251 Several configurations allow to display the current
1252 status using a LED. For instance, the LED will blink
1253 fast while running U-Boot code, stop blinking as
1254 soon as a reply to a BOOTP request was received, and
1255 start blinking slow once the Linux kernel is running
1256 (supported by a status LED driver in the Linux
1257 kernel). Defining CONFIG_LED_STATUS enables this
1262 CONFIG_LED_STATUS_GPIO
1263 The status LED can be connected to a GPIO pin.
1264 In such cases, the gpio_led driver can be used as a
1265 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1266 to include the gpio_led driver in the U-Boot binary.
1268 CONFIG_GPIO_LED_INVERTED_TABLE
1269 Some GPIO connected LEDs may have inverted polarity in which
1270 case the GPIO high value corresponds to LED off state and
1271 GPIO low value corresponds to LED on state.
1272 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1273 with a list of GPIO LEDs that have inverted polarity.
1276 CONFIG_SYS_NUM_I2C_BUSES
1277 Hold the number of i2c buses you want to use.
1279 CONFIG_SYS_I2C_DIRECT_BUS
1280 define this, if you don't use i2c muxes on your hardware.
1281 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1284 CONFIG_SYS_I2C_MAX_HOPS
1285 define how many muxes are maximal consecutively connected
1286 on one i2c bus. If you not use i2c muxes, omit this
1289 CONFIG_SYS_I2C_BUSES
1290 hold a list of buses you want to use, only used if
1291 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1292 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1293 CONFIG_SYS_NUM_I2C_BUSES = 9:
1295 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1296 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1297 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1298 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1299 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1300 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1301 {1, {I2C_NULL_HOP}}, \
1302 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1303 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1307 bus 0 on adapter 0 without a mux
1308 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1309 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1310 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1311 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1312 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1313 bus 6 on adapter 1 without a mux
1314 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1315 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1317 If you do not have i2c muxes on your board, omit this define.
1319 - Legacy I2C Support:
1320 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1321 then the following macros need to be defined (examples are
1322 from include/configs/lwmon.h):
1326 (Optional). Any commands necessary to enable the I2C
1327 controller or configure ports.
1329 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1333 The code necessary to make the I2C data line active
1334 (driven). If the data line is open collector, this
1337 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1341 The code necessary to make the I2C data line tri-stated
1342 (inactive). If the data line is open collector, this
1345 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1349 Code that returns true if the I2C data line is high,
1352 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1356 If <bit> is true, sets the I2C data line high. If it
1357 is false, it clears it (low).
1359 eg: #define I2C_SDA(bit) \
1360 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1361 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1365 If <bit> is true, sets the I2C clock line high. If it
1366 is false, it clears it (low).
1368 eg: #define I2C_SCL(bit) \
1369 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1370 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1374 This delay is invoked four times per clock cycle so this
1375 controls the rate of data transfer. The data rate thus
1376 is 1 / (I2C_DELAY * 4). Often defined to be something
1379 #define I2C_DELAY udelay(2)
1381 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1383 If your arch supports the generic GPIO framework (asm/gpio.h),
1384 then you may alternatively define the two GPIOs that are to be
1385 used as SCL / SDA. Any of the previous I2C_xxx macros will
1386 have GPIO-based defaults assigned to them as appropriate.
1388 You should define these to the GPIO value as given directly to
1389 the generic GPIO functions.
1391 CONFIG_SYS_I2C_INIT_BOARD
1393 When a board is reset during an i2c bus transfer
1394 chips might think that the current transfer is still
1395 in progress. On some boards it is possible to access
1396 the i2c SCLK line directly, either by using the
1397 processor pin as a GPIO or by having a second pin
1398 connected to the bus. If this option is defined a
1399 custom i2c_init_board() routine in boards/xxx/board.c
1400 is run early in the boot sequence.
1402 CONFIG_I2C_MULTI_BUS
1404 This option allows the use of multiple I2C buses, each of which
1405 must have a controller. At any point in time, only one bus is
1406 active. To switch to a different bus, use the 'i2c dev' command.
1407 Note that bus numbering is zero-based.
1409 CONFIG_SYS_I2C_NOPROBES
1411 This option specifies a list of I2C devices that will be skipped
1412 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1413 is set, specify a list of bus-device pairs. Otherwise, specify
1414 a 1D array of device addresses
1417 #undef CONFIG_I2C_MULTI_BUS
1418 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1420 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1422 #define CONFIG_I2C_MULTI_BUS
1423 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1425 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1427 CONFIG_SYS_SPD_BUS_NUM
1429 If defined, then this indicates the I2C bus number for DDR SPD.
1430 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1432 CONFIG_SYS_RTC_BUS_NUM
1434 If defined, then this indicates the I2C bus number for the RTC.
1435 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1437 CONFIG_SOFT_I2C_READ_REPEATED_START
1439 defining this will force the i2c_read() function in
1440 the soft_i2c driver to perform an I2C repeated start
1441 between writing the address pointer and reading the
1442 data. If this define is omitted the default behaviour
1443 of doing a stop-start sequence will be used. Most I2C
1444 devices can use either method, but some require one or
1447 - SPI Support: CONFIG_SPI
1449 Enables SPI driver (so far only tested with
1450 SPI EEPROM, also an instance works with Crystal A/D and
1451 D/As on the SACSng board)
1453 CONFIG_SYS_SPI_MXC_WAIT
1454 Timeout for waiting until spi transfer completed.
1455 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1457 - FPGA Support: CONFIG_FPGA
1459 Enables FPGA subsystem.
1461 CONFIG_FPGA_<vendor>
1463 Enables support for specific chip vendors.
1466 CONFIG_FPGA_<family>
1468 Enables support for FPGA family.
1469 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1473 Specify the number of FPGA devices to support.
1475 CONFIG_SYS_FPGA_PROG_FEEDBACK
1477 Enable printing of hash marks during FPGA configuration.
1479 CONFIG_SYS_FPGA_CHECK_BUSY
1481 Enable checks on FPGA configuration interface busy
1482 status by the configuration function. This option
1483 will require a board or device specific function to
1488 If defined, a function that provides delays in the FPGA
1489 configuration driver.
1491 CONFIG_SYS_FPGA_CHECK_CTRLC
1492 Allow Control-C to interrupt FPGA configuration
1494 CONFIG_SYS_FPGA_CHECK_ERROR
1496 Check for configuration errors during FPGA bitfile
1497 loading. For example, abort during Virtex II
1498 configuration if the INIT_B line goes low (which
1499 indicated a CRC error).
1501 CONFIG_SYS_FPGA_WAIT_INIT
1503 Maximum time to wait for the INIT_B line to de-assert
1504 after PROB_B has been de-asserted during a Virtex II
1505 FPGA configuration sequence. The default time is 500
1508 CONFIG_SYS_FPGA_WAIT_BUSY
1510 Maximum time to wait for BUSY to de-assert during
1511 Virtex II FPGA configuration. The default is 5 ms.
1513 CONFIG_SYS_FPGA_WAIT_CONFIG
1515 Time to wait after FPGA configuration. The default is
1518 - Vendor Parameter Protection:
1520 U-Boot considers the values of the environment
1521 variables "serial#" (Board Serial Number) and
1522 "ethaddr" (Ethernet Address) to be parameters that
1523 are set once by the board vendor / manufacturer, and
1524 protects these variables from casual modification by
1525 the user. Once set, these variables are read-only,
1526 and write or delete attempts are rejected. You can
1527 change this behaviour:
1529 If CONFIG_ENV_OVERWRITE is #defined in your config
1530 file, the write protection for vendor parameters is
1531 completely disabled. Anybody can change or delete
1534 Alternatively, if you define _both_ an ethaddr in the
1535 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1536 Ethernet address is installed in the environment,
1537 which can be changed exactly ONCE by the user. [The
1538 serial# is unaffected by this, i. e. it remains
1541 The same can be accomplished in a more flexible way
1542 for any variable by configuring the type of access
1543 to allow for those variables in the ".flags" variable
1544 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1549 Define this variable to enable the reservation of
1550 "protected RAM", i. e. RAM which is not overwritten
1551 by U-Boot. Define CONFIG_PRAM to hold the number of
1552 kB you want to reserve for pRAM. You can overwrite
1553 this default value by defining an environment
1554 variable "pram" to the number of kB you want to
1555 reserve. Note that the board info structure will
1556 still show the full amount of RAM. If pRAM is
1557 reserved, a new environment variable "mem" will
1558 automatically be defined to hold the amount of
1559 remaining RAM in a form that can be passed as boot
1560 argument to Linux, for instance like that:
1562 setenv bootargs ... mem=\${mem}
1565 This way you can tell Linux not to use this memory,
1566 either, which results in a memory region that will
1567 not be affected by reboots.
1569 *WARNING* If your board configuration uses automatic
1570 detection of the RAM size, you must make sure that
1571 this memory test is non-destructive. So far, the
1572 following board configurations are known to be
1575 IVMS8, IVML24, SPD8xx,
1576 HERMES, IP860, RPXlite, LWMON,
1580 CONFIG_NET_RETRY_COUNT
1582 This variable defines the number of retries for
1583 network operations like ARP, RARP, TFTP, or BOOTP
1584 before giving up the operation. If not defined, a
1585 default value of 5 is used.
1589 Timeout waiting for an ARP reply in milliseconds.
1593 Timeout in milliseconds used in NFS protocol.
1594 If you encounter "ERROR: Cannot umount" in nfs command,
1595 try longer timeout such as
1596 #define CONFIG_NFS_TIMEOUT 10000UL
1600 In the current implementation, the local variables
1601 space and global environment variables space are
1602 separated. Local variables are those you define by
1603 simply typing `name=value'. To access a local
1604 variable later on, you have write `$name' or
1605 `${name}'; to execute the contents of a variable
1606 directly type `$name' at the command prompt.
1608 Global environment variables are those you use
1609 setenv/printenv to work with. To run a command stored
1610 in such a variable, you need to use the run command,
1611 and you must not use the '$' sign to access them.
1613 To store commands and special characters in a
1614 variable, please use double quotation marks
1615 surrounding the whole text of the variable, instead
1616 of the backslashes before semicolons and special
1619 - Command Line Editing and History:
1620 CONFIG_CMDLINE_PS_SUPPORT
1622 Enable support for changing the command prompt string
1623 at run-time. Only static string is supported so far.
1624 The string is obtained from environment variables PS1
1627 - Default Environment:
1628 CONFIG_EXTRA_ENV_SETTINGS
1630 Define this to contain any number of null terminated
1631 strings (variable = value pairs) that will be part of
1632 the default environment compiled into the boot image.
1634 For example, place something like this in your
1635 board's config file:
1637 #define CONFIG_EXTRA_ENV_SETTINGS \
1641 Warning: This method is based on knowledge about the
1642 internal format how the environment is stored by the
1643 U-Boot code. This is NOT an official, exported
1644 interface! Although it is unlikely that this format
1645 will change soon, there is no guarantee either.
1646 You better know what you are doing here.
1648 Note: overly (ab)use of the default environment is
1649 discouraged. Make sure to check other ways to preset
1650 the environment like the "source" command or the
1653 CONFIG_DELAY_ENVIRONMENT
1655 Normally the environment is loaded when the board is
1656 initialised so that it is available to U-Boot. This inhibits
1657 that so that the environment is not available until
1658 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1659 this is instead controlled by the value of
1660 /config/load-environment.
1662 - TFTP Fixed UDP Port:
1665 If this is defined, the environment variable tftpsrcp
1666 is used to supply the TFTP UDP source port value.
1667 If tftpsrcp isn't defined, the normal pseudo-random port
1668 number generator is used.
1670 Also, the environment variable tftpdstp is used to supply
1671 the TFTP UDP destination port value. If tftpdstp isn't
1672 defined, the normal port 69 is used.
1674 The purpose for tftpsrcp is to allow a TFTP server to
1675 blindly start the TFTP transfer using the pre-configured
1676 target IP address and UDP port. This has the effect of
1677 "punching through" the (Windows XP) firewall, allowing
1678 the remainder of the TFTP transfer to proceed normally.
1679 A better solution is to properly configure the firewall,
1680 but sometimes that is not allowed.
1682 CONFIG_STANDALONE_LOAD_ADDR
1684 This option defines a board specific value for the
1685 address where standalone program gets loaded, thus
1686 overwriting the architecture dependent default
1689 - Frame Buffer Address:
1692 Define CONFIG_FB_ADDR if you want to use specific
1693 address for frame buffer. This is typically the case
1694 when using a graphics controller has separate video
1695 memory. U-Boot will then place the frame buffer at
1696 the given address instead of dynamically reserving it
1697 in system RAM by calling lcd_setmem(), which grabs
1698 the memory for the frame buffer depending on the
1699 configured panel size.
1701 Please see board_init_f function.
1703 - Automatic software updates via TFTP server
1705 CONFIG_UPDATE_TFTP_CNT_MAX
1706 CONFIG_UPDATE_TFTP_MSEC_MAX
1708 These options enable and control the auto-update feature;
1709 for a more detailed description refer to doc/README.update.
1711 - MTD Support (mtdparts command, UBI support)
1712 CONFIG_MTD_UBI_WL_THRESHOLD
1713 This parameter defines the maximum difference between the highest
1714 erase counter value and the lowest erase counter value of eraseblocks
1715 of UBI devices. When this threshold is exceeded, UBI starts performing
1716 wear leveling by means of moving data from eraseblock with low erase
1717 counter to eraseblocks with high erase counter.
1719 The default value should be OK for SLC NAND flashes, NOR flashes and
1720 other flashes which have eraseblock life-cycle 100000 or more.
1721 However, in case of MLC NAND flashes which typically have eraseblock
1722 life-cycle less than 10000, the threshold should be lessened (e.g.,
1723 to 128 or 256, although it does not have to be power of 2).
1727 CONFIG_MTD_UBI_BEB_LIMIT
1728 This option specifies the maximum bad physical eraseblocks UBI
1729 expects on the MTD device (per 1024 eraseblocks). If the
1730 underlying flash does not admit of bad eraseblocks (e.g. NOR
1731 flash), this value is ignored.
1733 NAND datasheets often specify the minimum and maximum NVM
1734 (Number of Valid Blocks) for the flashes' endurance lifetime.
1735 The maximum expected bad eraseblocks per 1024 eraseblocks
1736 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1737 which gives 20 for most NANDs (MaxNVB is basically the total
1738 count of eraseblocks on the chip).
1740 To put it differently, if this value is 20, UBI will try to
1741 reserve about 1.9% of physical eraseblocks for bad blocks
1742 handling. And that will be 1.9% of eraseblocks on the entire
1743 NAND chip, not just the MTD partition UBI attaches. This means
1744 that if you have, say, a NAND flash chip admits maximum 40 bad
1745 eraseblocks, and it is split on two MTD partitions of the same
1746 size, UBI will reserve 40 eraseblocks when attaching a
1751 CONFIG_MTD_UBI_FASTMAP
1752 Fastmap is a mechanism which allows attaching an UBI device
1753 in nearly constant time. Instead of scanning the whole MTD device it
1754 only has to locate a checkpoint (called fastmap) on the device.
1755 The on-flash fastmap contains all information needed to attach
1756 the device. Using fastmap makes only sense on large devices where
1757 attaching by scanning takes long. UBI will not automatically install
1758 a fastmap on old images, but you can set the UBI parameter
1759 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1760 that fastmap-enabled images are still usable with UBI implementations
1761 without fastmap support. On typical flash devices the whole fastmap
1762 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1764 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1765 Set this parameter to enable fastmap automatically on images
1769 CONFIG_MTD_UBI_FM_DEBUG
1770 Enable UBI fastmap debug
1775 Enable building of SPL globally.
1777 CONFIG_SPL_MAX_FOOTPRINT
1778 Maximum size in memory allocated to the SPL, BSS included.
1779 When defined, the linker checks that the actual memory
1780 used by SPL from _start to __bss_end does not exceed it.
1781 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1782 must not be both defined at the same time.
1785 Maximum size of the SPL image (text, data, rodata, and
1786 linker lists sections), BSS excluded.
1787 When defined, the linker checks that the actual size does
1790 CONFIG_SPL_RELOC_TEXT_BASE
1791 Address to relocate to. If unspecified, this is equal to
1792 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1794 CONFIG_SPL_BSS_START_ADDR
1795 Link address for the BSS within the SPL binary.
1797 CONFIG_SPL_BSS_MAX_SIZE
1798 Maximum size in memory allocated to the SPL BSS.
1799 When defined, the linker checks that the actual memory used
1800 by SPL from __bss_start to __bss_end does not exceed it.
1801 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1802 must not be both defined at the same time.
1805 Adress of the start of the stack SPL will use
1807 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1808 When defined, SPL will panic() if the image it has
1809 loaded does not have a signature.
1810 Defining this is useful when code which loads images
1811 in SPL cannot guarantee that absolutely all read errors
1813 An example is the LPC32XX MLC NAND driver, which will
1814 consider that a completely unreadable NAND block is bad,
1815 and thus should be skipped silently.
1817 CONFIG_SPL_RELOC_STACK
1818 Adress of the start of the stack SPL will use after
1819 relocation. If unspecified, this is equal to
1822 CONFIG_SYS_SPL_MALLOC_START
1823 Starting address of the malloc pool used in SPL.
1824 When this option is set the full malloc is used in SPL and
1825 it is set up by spl_init() and before that, the simple malloc()
1826 can be used if CONFIG_SYS_MALLOC_F is defined.
1828 CONFIG_SYS_SPL_MALLOC_SIZE
1829 The size of the malloc pool used in SPL.
1831 CONFIG_SPL_DISPLAY_PRINT
1832 For ARM, enable an optional function to print more information
1833 about the running system.
1835 CONFIG_SPL_INIT_MINIMAL
1836 Arch init code should be built for a very small image
1838 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
1839 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
1840 Sector and number of sectors to load kernel argument
1841 parameters from when MMC is being used in raw mode
1844 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
1845 Filename to read to load U-Boot when reading from filesystem
1847 CONFIG_SPL_FS_LOAD_KERNEL_NAME
1848 Filename to read to load kernel uImage when reading
1849 from filesystem (for Falcon mode)
1851 CONFIG_SPL_FS_LOAD_ARGS_NAME
1852 Filename to read to load kernel argument parameters
1853 when reading from filesystem (for Falcon mode)
1855 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1856 Set this for NAND SPL on PPC mpc83xx targets, so that
1857 start.S waits for the rest of the SPL to load before
1858 continuing (the hardware starts execution after just
1859 loading the first page rather than the full 4K).
1861 CONFIG_SPL_SKIP_RELOCATE
1862 Avoid SPL relocation
1864 CONFIG_SPL_NAND_IDENT
1865 SPL uses the chip ID list to identify the NAND flash.
1866 Requires CONFIG_SPL_NAND_BASE.
1869 Support for a lightweight UBI (fastmap) scanner and
1872 CONFIG_SPL_NAND_RAW_ONLY
1873 Support to boot only raw u-boot.bin images. Use this only
1874 if you need to save space.
1876 CONFIG_SPL_COMMON_INIT_DDR
1877 Set for common ddr init with serial presence detect in
1880 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1881 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1882 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1883 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1884 CONFIG_SYS_NAND_ECCBYTES
1885 Defines the size and behavior of the NAND that SPL uses
1888 CONFIG_SYS_NAND_U_BOOT_DST
1889 Location in memory to load U-Boot to
1891 CONFIG_SYS_NAND_U_BOOT_SIZE
1892 Size of image to load
1894 CONFIG_SYS_NAND_U_BOOT_START
1895 Entry point in loaded image to jump to
1897 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1898 Define this if you need to first read the OOB and then the
1899 data. This is used, for example, on davinci platforms.
1901 CONFIG_SPL_RAM_DEVICE
1902 Support for running image already present in ram, in SPL binary
1905 Image offset to which the SPL should be padded before appending
1906 the SPL payload. By default, this is defined as
1907 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1908 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1909 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1912 Final target image containing SPL and payload. Some SPLs
1913 use an arch-specific makefile fragment instead, for
1914 example if more than one image needs to be produced.
1916 CONFIG_SPL_FIT_PRINT
1917 Printing information about a FIT image adds quite a bit of
1918 code to SPL. So this is normally disabled in SPL. Use this
1919 option to re-enable it. This will affect the output of the
1920 bootm command when booting a FIT image.
1924 Enable building of TPL globally.
1927 Image offset to which the TPL should be padded before appending
1928 the TPL payload. By default, this is defined as
1929 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1930 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1931 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1933 - Interrupt support (PPC):
1935 There are common interrupt_init() and timer_interrupt()
1936 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1937 for CPU specific initialization. interrupt_init_cpu()
1938 should set decrementer_count to appropriate value. If
1939 CPU resets decrementer automatically after interrupt
1940 (ppc4xx) it should set decrementer_count to zero.
1941 timer_interrupt() calls timer_interrupt_cpu() for CPU
1942 specific handling. If board has watchdog / status_led
1943 / other_activity_monitor it works automatically from
1944 general timer_interrupt().
1947 Board initialization settings:
1948 ------------------------------
1950 During Initialization u-boot calls a number of board specific functions
1951 to allow the preparation of board specific prerequisites, e.g. pin setup
1952 before drivers are initialized. To enable these callbacks the
1953 following configuration macros have to be defined. Currently this is
1954 architecture specific, so please check arch/your_architecture/lib/board.c
1955 typically in board_init_f() and board_init_r().
1957 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1958 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1959 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1961 Configuration Settings:
1962 -----------------------
1964 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1965 Optionally it can be defined to support 64-bit memory commands.
1967 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1968 undefine this when you're short of memory.
1970 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1971 width of the commands listed in the 'help' command output.
1973 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1974 prompt for user input.
1976 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
1978 - CONFIG_SYS_PBSIZE: Buffer size for Console output
1980 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
1982 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
1983 the application (usually a Linux kernel) when it is
1986 - CONFIG_SYS_BAUDRATE_TABLE:
1987 List of legal baudrate settings for this board.
1989 - CONFIG_SYS_MEM_RESERVE_SECURE
1990 Only implemented for ARMv8 for now.
1991 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1992 is substracted from total RAM and won't be reported to OS.
1993 This memory can be used as secure memory. A variable
1994 gd->arch.secure_ram is used to track the location. In systems
1995 the RAM base is not zero, or RAM is divided into banks,
1996 this variable needs to be recalcuated to get the address.
1998 - CONFIG_SYS_MEM_TOP_HIDE:
1999 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2000 this specified memory area will get subtracted from the top
2001 (end) of RAM and won't get "touched" at all by U-Boot. By
2002 fixing up gd->ram_size the Linux kernel should gets passed
2003 the now "corrected" memory size and won't touch it either.
2004 This should work for arch/ppc and arch/powerpc. Only Linux
2005 board ports in arch/powerpc with bootwrapper support that
2006 recalculate the memory size from the SDRAM controller setup
2007 will have to get fixed in Linux additionally.
2009 This option can be used as a workaround for the 440EPx/GRx
2010 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2013 WARNING: Please make sure that this value is a multiple of
2014 the Linux page size (normally 4k). If this is not the case,
2015 then the end address of the Linux memory will be located at a
2016 non page size aligned address and this could cause major
2019 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2020 Enable temporary baudrate change while serial download
2022 - CONFIG_SYS_SDRAM_BASE:
2023 Physical start address of SDRAM. _Must_ be 0 here.
2025 - CONFIG_SYS_FLASH_BASE:
2026 Physical start address of Flash memory.
2028 - CONFIG_SYS_MONITOR_BASE:
2029 Physical start address of boot monitor code (set by
2030 make config files to be same as the text base address
2031 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2032 CONFIG_SYS_FLASH_BASE when booting from flash.
2034 - CONFIG_SYS_MONITOR_LEN:
2035 Size of memory reserved for monitor code, used to
2036 determine _at_compile_time_ (!) if the environment is
2037 embedded within the U-Boot image, or in a separate
2040 - CONFIG_SYS_MALLOC_LEN:
2041 Size of DRAM reserved for malloc() use.
2043 - CONFIG_SYS_MALLOC_F_LEN
2044 Size of the malloc() pool for use before relocation. If
2045 this is defined, then a very simple malloc() implementation
2046 will become available before relocation. The address is just
2047 below the global data, and the stack is moved down to make
2050 This feature allocates regions with increasing addresses
2051 within the region. calloc() is supported, but realloc()
2052 is not available. free() is supported but does nothing.
2053 The memory will be freed (or in fact just forgotten) when
2054 U-Boot relocates itself.
2056 - CONFIG_SYS_MALLOC_SIMPLE
2057 Provides a simple and small malloc() and calloc() for those
2058 boards which do not use the full malloc in SPL (which is
2059 enabled with CONFIG_SYS_SPL_MALLOC_START).
2061 - CONFIG_SYS_NONCACHED_MEMORY:
2062 Size of non-cached memory area. This area of memory will be
2063 typically located right below the malloc() area and mapped
2064 uncached in the MMU. This is useful for drivers that would
2065 otherwise require a lot of explicit cache maintenance. For
2066 some drivers it's also impossible to properly maintain the
2067 cache. For example if the regions that need to be flushed
2068 are not a multiple of the cache-line size, *and* padding
2069 cannot be allocated between the regions to align them (i.e.
2070 if the HW requires a contiguous array of regions, and the
2071 size of each region is not cache-aligned), then a flush of
2072 one region may result in overwriting data that hardware has
2073 written to another region in the same cache-line. This can
2074 happen for example in network drivers where descriptors for
2075 buffers are typically smaller than the CPU cache-line (e.g.
2076 16 bytes vs. 32 or 64 bytes).
2078 Non-cached memory is only supported on 32-bit ARM at present.
2080 - CONFIG_SYS_BOOTM_LEN:
2081 Normally compressed uImages are limited to an
2082 uncompressed size of 8 MBytes. If this is not enough,
2083 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2084 to adjust this setting to your needs.
2086 - CONFIG_SYS_BOOTMAPSZ:
2087 Maximum size of memory mapped by the startup code of
2088 the Linux kernel; all data that must be processed by
2089 the Linux kernel (bd_info, boot arguments, FDT blob if
2090 used) must be put below this limit, unless "bootm_low"
2091 environment variable is defined and non-zero. In such case
2092 all data for the Linux kernel must be between "bootm_low"
2093 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2094 variable "bootm_mapsize" will override the value of
2095 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2096 then the value in "bootm_size" will be used instead.
2098 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2099 Enable initrd_high functionality. If defined then the
2100 initrd_high feature is enabled and the bootm ramdisk subcommand
2103 - CONFIG_SYS_BOOT_GET_CMDLINE:
2104 Enables allocating and saving kernel cmdline in space between
2105 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2107 - CONFIG_SYS_BOOT_GET_KBD:
2108 Enables allocating and saving a kernel copy of the bd_info in
2109 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2111 - CONFIG_SYS_MAX_FLASH_SECT:
2112 Max number of sectors on a Flash chip
2114 - CONFIG_SYS_FLASH_ERASE_TOUT:
2115 Timeout for Flash erase operations (in ms)
2117 - CONFIG_SYS_FLASH_WRITE_TOUT:
2118 Timeout for Flash write operations (in ms)
2120 - CONFIG_SYS_FLASH_LOCK_TOUT
2121 Timeout for Flash set sector lock bit operation (in ms)
2123 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2124 Timeout for Flash clear lock bits operation (in ms)
2126 - CONFIG_SYS_FLASH_PROTECTION
2127 If defined, hardware flash sectors protection is used
2128 instead of U-Boot software protection.
2130 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2132 Enable TFTP transfers directly to flash memory;
2133 without this option such a download has to be
2134 performed in two steps: (1) download to RAM, and (2)
2135 copy from RAM to flash.
2137 The two-step approach is usually more reliable, since
2138 you can check if the download worked before you erase
2139 the flash, but in some situations (when system RAM is
2140 too limited to allow for a temporary copy of the
2141 downloaded image) this option may be very useful.
2143 - CONFIG_SYS_FLASH_CFI:
2144 Define if the flash driver uses extra elements in the
2145 common flash structure for storing flash geometry.
2147 - CONFIG_FLASH_CFI_DRIVER
2148 This option also enables the building of the cfi_flash driver
2149 in the drivers directory
2151 - CONFIG_FLASH_CFI_MTD
2152 This option enables the building of the cfi_mtd driver
2153 in the drivers directory. The driver exports CFI flash
2156 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2157 Use buffered writes to flash.
2159 - CONFIG_FLASH_SPANSION_S29WS_N
2160 s29ws-n MirrorBit flash has non-standard addresses for buffered
2163 - CONFIG_SYS_FLASH_QUIET_TEST
2164 If this option is defined, the common CFI flash doesn't
2165 print it's warning upon not recognized FLASH banks. This
2166 is useful, if some of the configured banks are only
2167 optionally available.
2169 - CONFIG_FLASH_SHOW_PROGRESS
2170 If defined (must be an integer), print out countdown
2171 digits and dots. Recommended value: 45 (9..1) for 80
2172 column displays, 15 (3..1) for 40 column displays.
2174 - CONFIG_FLASH_VERIFY
2175 If defined, the content of the flash (destination) is compared
2176 against the source after the write operation. An error message
2177 will be printed when the contents are not identical.
2178 Please note that this option is useless in nearly all cases,
2179 since such flash programming errors usually are detected earlier
2180 while unprotecting/erasing/programming. Please only enable
2181 this option if you really know what you are doing.
2183 - CONFIG_SYS_RX_ETH_BUFFER:
2184 Defines the number of Ethernet receive buffers. On some
2185 Ethernet controllers it is recommended to set this value
2186 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2187 buffers can be full shortly after enabling the interface
2188 on high Ethernet traffic.
2189 Defaults to 4 if not defined.
2191 - CONFIG_ENV_MAX_ENTRIES
2193 Maximum number of entries in the hash table that is used
2194 internally to store the environment settings. The default
2195 setting is supposed to be generous and should work in most
2196 cases. This setting can be used to tune behaviour; see
2197 lib/hashtable.c for details.
2199 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2200 - CONFIG_ENV_FLAGS_LIST_STATIC
2201 Enable validation of the values given to environment variables when
2202 calling env set. Variables can be restricted to only decimal,
2203 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2204 the variables can also be restricted to IP address or MAC address.
2206 The format of the list is:
2207 type_attribute = [s|d|x|b|i|m]
2208 access_attribute = [a|r|o|c]
2209 attributes = type_attribute[access_attribute]
2210 entry = variable_name[:attributes]
2213 The type attributes are:
2214 s - String (default)
2217 b - Boolean ([1yYtT|0nNfF])
2221 The access attributes are:
2227 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2228 Define this to a list (string) to define the ".flags"
2229 environment variable in the default or embedded environment.
2231 - CONFIG_ENV_FLAGS_LIST_STATIC
2232 Define this to a list (string) to define validation that
2233 should be done if an entry is not found in the ".flags"
2234 environment variable. To override a setting in the static
2235 list, simply add an entry for the same variable name to the
2238 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2239 regular expression. This allows multiple variables to define the same
2240 flags without explicitly listing them for each variable.
2242 The following definitions that deal with the placement and management
2243 of environment data (variable area); in general, we support the
2244 following configurations:
2246 - CONFIG_BUILD_ENVCRC:
2248 Builds up envcrc with the target environment so that external utils
2249 may easily extract it and embed it in final U-Boot images.
2251 BE CAREFUL! The first access to the environment happens quite early
2252 in U-Boot initialization (when we try to get the setting of for the
2253 console baudrate). You *MUST* have mapped your NVRAM area then, or
2256 Please note that even with NVRAM we still use a copy of the
2257 environment in RAM: we could work on NVRAM directly, but we want to
2258 keep settings there always unmodified except somebody uses "saveenv"
2259 to save the current settings.
2261 BE CAREFUL! For some special cases, the local device can not use
2262 "saveenv" command. For example, the local device will get the
2263 environment stored in a remote NOR flash by SRIO or PCIE link,
2264 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2266 - CONFIG_NAND_ENV_DST
2268 Defines address in RAM to which the nand_spl code should copy the
2269 environment. If redundant environment is used, it will be copied to
2270 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2272 Please note that the environment is read-only until the monitor
2273 has been relocated to RAM and a RAM copy of the environment has been
2274 created; also, when using EEPROM you will have to use env_get_f()
2275 until then to read environment variables.
2277 The environment is protected by a CRC32 checksum. Before the monitor
2278 is relocated into RAM, as a result of a bad CRC you will be working
2279 with the compiled-in default environment - *silently*!!! [This is
2280 necessary, because the first environment variable we need is the
2281 "baudrate" setting for the console - if we have a bad CRC, we don't
2282 have any device yet where we could complain.]
2284 Note: once the monitor has been relocated, then it will complain if
2285 the default environment is used; a new CRC is computed as soon as you
2286 use the "saveenv" command to store a valid environment.
2288 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2289 Echo the inverted Ethernet link state to the fault LED.
2291 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2292 also needs to be defined.
2294 - CONFIG_SYS_FAULT_MII_ADDR:
2295 MII address of the PHY to check for the Ethernet link state.
2297 - CONFIG_NS16550_MIN_FUNCTIONS:
2298 Define this if you desire to only have use of the NS16550_init
2299 and NS16550_putc functions for the serial driver located at
2300 drivers/serial/ns16550.c. This option is useful for saving
2301 space for already greatly restricted images, including but not
2302 limited to NAND_SPL configurations.
2304 - CONFIG_DISPLAY_BOARDINFO
2305 Display information about the board that U-Boot is running on
2306 when U-Boot starts up. The board function checkboard() is called
2309 - CONFIG_DISPLAY_BOARDINFO_LATE
2310 Similar to the previous option, but display this information
2311 later, once stdio is running and output goes to the LCD, if
2314 - CONFIG_BOARD_SIZE_LIMIT:
2315 Maximum size of the U-Boot image. When defined, the
2316 build system checks that the actual size does not
2319 Low Level (hardware related) configuration options:
2320 ---------------------------------------------------
2322 - CONFIG_SYS_CACHELINE_SIZE:
2323 Cache Line Size of the CPU.
2325 - CONFIG_SYS_CCSRBAR_DEFAULT:
2326 Default (power-on reset) physical address of CCSR on Freescale
2329 - CONFIG_SYS_CCSRBAR:
2330 Virtual address of CCSR. On a 32-bit build, this is typically
2331 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2333 - CONFIG_SYS_CCSRBAR_PHYS:
2334 Physical address of CCSR. CCSR can be relocated to a new
2335 physical address, if desired. In this case, this macro should
2336 be set to that address. Otherwise, it should be set to the
2337 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2338 is typically relocated on 36-bit builds. It is recommended
2339 that this macro be defined via the _HIGH and _LOW macros:
2341 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2342 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2344 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2345 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2346 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2347 used in assembly code, so it must not contain typecasts or
2348 integer size suffixes (e.g. "ULL").
2350 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2351 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2352 used in assembly code, so it must not contain typecasts or
2353 integer size suffixes (e.g. "ULL").
2355 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2356 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2357 forced to a value that ensures that CCSR is not relocated.
2359 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2360 DO NOT CHANGE unless you know exactly what you're
2361 doing! (11-4) [MPC8xx systems only]
2363 - CONFIG_SYS_INIT_RAM_ADDR:
2365 Start address of memory area that can be used for
2366 initial data and stack; please note that this must be
2367 writable memory that is working WITHOUT special
2368 initialization, i. e. you CANNOT use normal RAM which
2369 will become available only after programming the
2370 memory controller and running certain initialization
2373 U-Boot uses the following memory types:
2374 - MPC8xx: IMMR (internal memory of the CPU)
2376 - CONFIG_SYS_GBL_DATA_OFFSET:
2378 Offset of the initial data structure in the memory
2379 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2380 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2381 data is located at the end of the available space
2382 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2383 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2384 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2385 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2388 On the MPC824X (or other systems that use the data
2389 cache for initial memory) the address chosen for
2390 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2391 point to an otherwise UNUSED address space between
2392 the top of RAM and the start of the PCI space.
2394 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2396 - CONFIG_SYS_OR_TIMING_SDRAM:
2399 - CONFIG_SYS_MAMR_PTA:
2400 periodic timer for refresh
2403 Chip has SRIO or not
2406 Board has SRIO 1 port available
2409 Board has SRIO 2 port available
2411 - CONFIG_SRIO_PCIE_BOOT_MASTER
2412 Board can support master function for Boot from SRIO and PCIE
2414 - CONFIG_SYS_SRIOn_MEM_VIRT:
2415 Virtual Address of SRIO port 'n' memory region
2417 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2418 Physical Address of SRIO port 'n' memory region
2420 - CONFIG_SYS_SRIOn_MEM_SIZE:
2421 Size of SRIO port 'n' memory region
2423 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2424 Defined to tell the NAND controller that the NAND chip is using
2426 Not all NAND drivers use this symbol.
2427 Example of drivers that use it:
2428 - drivers/mtd/nand/raw/ndfc.c
2429 - drivers/mtd/nand/raw/mxc_nand.c
2431 - CONFIG_SYS_NDFC_EBC0_CFG
2432 Sets the EBC0_CFG register for the NDFC. If not defined
2433 a default value will be used.
2436 Get DDR timing information from an I2C EEPROM. Common
2437 with pluggable memory modules such as SODIMMs
2440 I2C address of the SPD EEPROM
2442 - CONFIG_SYS_SPD_BUS_NUM
2443 If SPD EEPROM is on an I2C bus other than the first
2444 one, specify here. Note that the value must resolve
2445 to something your driver can deal with.
2447 - CONFIG_SYS_DDR_RAW_TIMING
2448 Get DDR timing information from other than SPD. Common with
2449 soldered DDR chips onboard without SPD. DDR raw timing
2450 parameters are extracted from datasheet and hard-coded into
2451 header files or board specific files.
2453 - CONFIG_FSL_DDR_INTERACTIVE
2454 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2456 - CONFIG_FSL_DDR_SYNC_REFRESH
2457 Enable sync of refresh for multiple controllers.
2459 - CONFIG_FSL_DDR_BIST
2460 Enable built-in memory test for Freescale DDR controllers.
2462 - CONFIG_SYS_83XX_DDR_USES_CS0
2463 Only for 83xx systems. If specified, then DDR should
2464 be configured using CS0 and CS1 instead of CS2 and CS3.
2467 Enable RMII mode for all FECs.
2468 Note that this is a global option, we can't
2469 have one FEC in standard MII mode and another in RMII mode.
2471 - CONFIG_CRC32_VERIFY
2472 Add a verify option to the crc32 command.
2475 => crc32 -v <address> <count> <crc32>
2477 Where address/count indicate a memory area
2478 and crc32 is the correct crc32 which the
2482 Add the "loopw" memory command. This only takes effect if
2483 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2485 - CONFIG_CMD_MX_CYCLIC
2486 Add the "mdc" and "mwc" memory commands. These are cyclic
2491 This command will print 4 bytes (10,11,12,13) each 500 ms.
2493 => mwc.l 100 12345678 10
2494 This command will write 12345678 to address 100 all 10 ms.
2496 This only takes effect if the memory commands are activated
2497 globally (CONFIG_CMD_MEMORY).
2500 Set when the currently-running compilation is for an artifact
2501 that will end up in the SPL (as opposed to the TPL or U-Boot
2502 proper). Code that needs stage-specific behavior should check
2506 Set when the currently-running compilation is for an artifact
2507 that will end up in the TPL (as opposed to the SPL or U-Boot
2508 proper). Code that needs stage-specific behavior should check
2511 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2512 Only for 85xx systems. If this variable is specified, the section
2513 .resetvec is not kept and the section .bootpg is placed in the
2514 previous 4k of the .text section.
2516 - CONFIG_ARCH_MAP_SYSMEM
2517 Generally U-Boot (and in particular the md command) uses
2518 effective address. It is therefore not necessary to regard
2519 U-Boot address as virtual addresses that need to be translated
2520 to physical addresses. However, sandbox requires this, since
2521 it maintains its own little RAM buffer which contains all
2522 addressable memory. This option causes some memory accesses
2523 to be mapped through map_sysmem() / unmap_sysmem().
2525 - CONFIG_X86_RESET_VECTOR
2526 If defined, the x86 reset vector code is included. This is not
2527 needed when U-Boot is running from Coreboot.
2529 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2530 Option to disable subpage write in NAND driver
2531 driver that uses this:
2532 drivers/mtd/nand/raw/davinci_nand.c
2534 Freescale QE/FMAN Firmware Support:
2535 -----------------------------------
2537 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2538 loading of "firmware", which is encoded in the QE firmware binary format.
2539 This firmware often needs to be loaded during U-Boot booting, so macros
2540 are used to identify the storage device (NOR flash, SPI, etc) and the address
2543 - CONFIG_SYS_FMAN_FW_ADDR
2544 The address in the storage device where the FMAN microcode is located. The
2545 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2548 - CONFIG_SYS_QE_FW_ADDR
2549 The address in the storage device where the QE microcode is located. The
2550 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2553 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2554 The maximum possible size of the firmware. The firmware binary format
2555 has a field that specifies the actual size of the firmware, but it
2556 might not be possible to read any part of the firmware unless some
2557 local storage is allocated to hold the entire firmware first.
2559 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2560 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2561 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2562 virtual address in NOR flash.
2564 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2565 Specifies that QE/FMAN firmware is located in NAND flash.
2566 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2568 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2569 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2570 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2572 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2573 Specifies that QE/FMAN firmware is located in the remote (master)
2574 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2575 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2576 window->master inbound window->master LAW->the ucode address in
2577 master's memory space.
2579 Freescale Layerscape Management Complex Firmware Support:
2580 ---------------------------------------------------------
2581 The Freescale Layerscape Management Complex (MC) supports the loading of
2583 This firmware often needs to be loaded during U-Boot booting, so macros
2584 are used to identify the storage device (NOR flash, SPI, etc) and the address
2587 - CONFIG_FSL_MC_ENET
2588 Enable the MC driver for Layerscape SoCs.
2590 Freescale Layerscape Debug Server Support:
2591 -------------------------------------------
2592 The Freescale Layerscape Debug Server Support supports the loading of
2593 "Debug Server firmware" and triggering SP boot-rom.
2594 This firmware often needs to be loaded during U-Boot booting.
2596 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2597 Define alignment of reserved memory MC requires
2602 In order to achieve reproducible builds, timestamps used in the U-Boot build
2603 process have to be set to a fixed value.
2605 This is done using the SOURCE_DATE_EPOCH environment variable.
2606 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2607 option for U-Boot or an environment variable in U-Boot.
2609 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2611 Building the Software:
2612 ======================
2614 Building U-Boot has been tested in several native build environments
2615 and in many different cross environments. Of course we cannot support
2616 all possibly existing versions of cross development tools in all
2617 (potentially obsolete) versions. In case of tool chain problems we
2618 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2619 which is extensively used to build and test U-Boot.
2621 If you are not using a native environment, it is assumed that you
2622 have GNU cross compiling tools available in your path. In this case,
2623 you must set the environment variable CROSS_COMPILE in your shell.
2624 Note that no changes to the Makefile or any other source files are
2625 necessary. For example using the ELDK on a 4xx CPU, please enter:
2627 $ CROSS_COMPILE=ppc_4xx-
2628 $ export CROSS_COMPILE
2630 U-Boot is intended to be simple to build. After installing the
2631 sources you must configure U-Boot for one specific board type. This
2636 where "NAME_defconfig" is the name of one of the existing configu-
2637 rations; see configs/*_defconfig for supported names.
2639 Note: for some boards special configuration names may exist; check if
2640 additional information is available from the board vendor; for
2641 instance, the TQM823L systems are available without (standard)
2642 or with LCD support. You can select such additional "features"
2643 when choosing the configuration, i. e.
2645 make TQM823L_defconfig
2646 - will configure for a plain TQM823L, i. e. no LCD support
2648 make TQM823L_LCD_defconfig
2649 - will configure for a TQM823L with U-Boot console on LCD
2654 Finally, type "make all", and you should get some working U-Boot
2655 images ready for download to / installation on your system:
2657 - "u-boot.bin" is a raw binary image
2658 - "u-boot" is an image in ELF binary format
2659 - "u-boot.srec" is in Motorola S-Record format
2661 By default the build is performed locally and the objects are saved
2662 in the source directory. One of the two methods can be used to change
2663 this behavior and build U-Boot to some external directory:
2665 1. Add O= to the make command line invocations:
2667 make O=/tmp/build distclean
2668 make O=/tmp/build NAME_defconfig
2669 make O=/tmp/build all
2671 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2673 export KBUILD_OUTPUT=/tmp/build
2678 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2681 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2682 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2683 For example to treat all compiler warnings as errors:
2685 make KCFLAGS=-Werror
2687 Please be aware that the Makefiles assume you are using GNU make, so
2688 for instance on NetBSD you might need to use "gmake" instead of
2692 If the system board that you have is not listed, then you will need
2693 to port U-Boot to your hardware platform. To do this, follow these
2696 1. Create a new directory to hold your board specific code. Add any
2697 files you need. In your board directory, you will need at least
2698 the "Makefile" and a "<board>.c".
2699 2. Create a new configuration file "include/configs/<board>.h" for
2701 3. If you're porting U-Boot to a new CPU, then also create a new
2702 directory to hold your CPU specific code. Add any files you need.
2703 4. Run "make <board>_defconfig" with your new name.
2704 5. Type "make", and you should get a working "u-boot.srec" file
2705 to be installed on your target system.
2706 6. Debug and solve any problems that might arise.
2707 [Of course, this last step is much harder than it sounds.]
2710 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2711 ==============================================================
2713 If you have modified U-Boot sources (for instance added a new board
2714 or support for new devices, a new CPU, etc.) you are expected to
2715 provide feedback to the other developers. The feedback normally takes
2716 the form of a "patch", i.e. a context diff against a certain (latest
2717 official or latest in the git repository) version of U-Boot sources.
2719 But before you submit such a patch, please verify that your modifi-
2720 cation did not break existing code. At least make sure that *ALL* of
2721 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2722 just run the buildman script (tools/buildman/buildman), which will
2723 configure and build U-Boot for ALL supported system. Be warned, this
2724 will take a while. Please see the buildman README, or run 'buildman -H'
2728 See also "U-Boot Porting Guide" below.
2731 Monitor Commands - Overview:
2732 ============================
2734 go - start application at address 'addr'
2735 run - run commands in an environment variable
2736 bootm - boot application image from memory
2737 bootp - boot image via network using BootP/TFTP protocol
2738 bootz - boot zImage from memory
2739 tftpboot- boot image via network using TFTP protocol
2740 and env variables "ipaddr" and "serverip"
2741 (and eventually "gatewayip")
2742 tftpput - upload a file via network using TFTP protocol
2743 rarpboot- boot image via network using RARP/TFTP protocol
2744 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2745 loads - load S-Record file over serial line
2746 loadb - load binary file over serial line (kermit mode)
2748 mm - memory modify (auto-incrementing)
2749 nm - memory modify (constant address)
2750 mw - memory write (fill)
2753 cmp - memory compare
2754 crc32 - checksum calculation
2755 i2c - I2C sub-system
2756 sspi - SPI utility commands
2757 base - print or set address offset
2758 printenv- print environment variables
2759 pwm - control pwm channels
2760 setenv - set environment variables
2761 saveenv - save environment variables to persistent storage
2762 protect - enable or disable FLASH write protection
2763 erase - erase FLASH memory
2764 flinfo - print FLASH memory information
2765 nand - NAND memory operations (see doc/README.nand)
2766 bdinfo - print Board Info structure
2767 iminfo - print header information for application image
2768 coninfo - print console devices and informations
2769 ide - IDE sub-system
2770 loop - infinite loop on address range
2771 loopw - infinite write loop on address range
2772 mtest - simple RAM test
2773 icache - enable or disable instruction cache
2774 dcache - enable or disable data cache
2775 reset - Perform RESET of the CPU
2776 echo - echo args to console
2777 version - print monitor version
2778 help - print online help
2779 ? - alias for 'help'
2782 Monitor Commands - Detailed Description:
2783 ========================================
2787 For now: just type "help <command>".
2790 Note for Redundant Ethernet Interfaces:
2791 =======================================
2793 Some boards come with redundant Ethernet interfaces; U-Boot supports
2794 such configurations and is capable of automatic selection of a
2795 "working" interface when needed. MAC assignment works as follows:
2797 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2798 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2799 "eth1addr" (=>eth1), "eth2addr", ...
2801 If the network interface stores some valid MAC address (for instance
2802 in SROM), this is used as default address if there is NO correspon-
2803 ding setting in the environment; if the corresponding environment
2804 variable is set, this overrides the settings in the card; that means:
2806 o If the SROM has a valid MAC address, and there is no address in the
2807 environment, the SROM's address is used.
2809 o If there is no valid address in the SROM, and a definition in the
2810 environment exists, then the value from the environment variable is
2813 o If both the SROM and the environment contain a MAC address, and
2814 both addresses are the same, this MAC address is used.
2816 o If both the SROM and the environment contain a MAC address, and the
2817 addresses differ, the value from the environment is used and a
2820 o If neither SROM nor the environment contain a MAC address, an error
2821 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2822 a random, locally-assigned MAC is used.
2824 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2825 will be programmed into hardware as part of the initialization process. This
2826 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2827 The naming convention is as follows:
2828 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2833 U-Boot is capable of booting (and performing other auxiliary operations on)
2834 images in two formats:
2836 New uImage format (FIT)
2837 -----------------------
2839 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2840 to Flattened Device Tree). It allows the use of images with multiple
2841 components (several kernels, ramdisks, etc.), with contents protected by
2842 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2848 Old image format is based on binary files which can be basically anything,
2849 preceded by a special header; see the definitions in include/image.h for
2850 details; basically, the header defines the following image properties:
2852 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2853 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2854 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2855 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2856 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2857 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2858 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
2859 * Compression Type (uncompressed, gzip, bzip2)
2865 The header is marked by a special Magic Number, and both the header
2866 and the data portions of the image are secured against corruption by
2873 Although U-Boot should support any OS or standalone application
2874 easily, the main focus has always been on Linux during the design of
2877 U-Boot includes many features that so far have been part of some
2878 special "boot loader" code within the Linux kernel. Also, any
2879 "initrd" images to be used are no longer part of one big Linux image;
2880 instead, kernel and "initrd" are separate images. This implementation
2881 serves several purposes:
2883 - the same features can be used for other OS or standalone
2884 applications (for instance: using compressed images to reduce the
2885 Flash memory footprint)
2887 - it becomes much easier to port new Linux kernel versions because
2888 lots of low-level, hardware dependent stuff are done by U-Boot
2890 - the same Linux kernel image can now be used with different "initrd"
2891 images; of course this also means that different kernel images can
2892 be run with the same "initrd". This makes testing easier (you don't
2893 have to build a new "zImage.initrd" Linux image when you just
2894 change a file in your "initrd"). Also, a field-upgrade of the
2895 software is easier now.
2901 Porting Linux to U-Boot based systems:
2902 ---------------------------------------
2904 U-Boot cannot save you from doing all the necessary modifications to
2905 configure the Linux device drivers for use with your target hardware
2906 (no, we don't intend to provide a full virtual machine interface to
2909 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2911 Just make sure your machine specific header file (for instance
2912 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2913 Information structure as we define in include/asm-<arch>/u-boot.h,
2914 and make sure that your definition of IMAP_ADDR uses the same value
2915 as your U-Boot configuration in CONFIG_SYS_IMMR.
2917 Note that U-Boot now has a driver model, a unified model for drivers.
2918 If you are adding a new driver, plumb it into driver model. If there
2919 is no uclass available, you are encouraged to create one. See
2923 Configuring the Linux kernel:
2924 -----------------------------
2926 No specific requirements for U-Boot. Make sure you have some root
2927 device (initial ramdisk, NFS) for your target system.
2930 Building a Linux Image:
2931 -----------------------
2933 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2934 not used. If you use recent kernel source, a new build target
2935 "uImage" will exist which automatically builds an image usable by
2936 U-Boot. Most older kernels also have support for a "pImage" target,
2937 which was introduced for our predecessor project PPCBoot and uses a
2938 100% compatible format.
2942 make TQM850L_defconfig
2947 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2948 encapsulate a compressed Linux kernel image with header information,
2949 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2951 * build a standard "vmlinux" kernel image (in ELF binary format):
2953 * convert the kernel into a raw binary image:
2955 ${CROSS_COMPILE}-objcopy -O binary \
2956 -R .note -R .comment \
2957 -S vmlinux linux.bin
2959 * compress the binary image:
2963 * package compressed binary image for U-Boot:
2965 mkimage -A ppc -O linux -T kernel -C gzip \
2966 -a 0 -e 0 -n "Linux Kernel Image" \
2967 -d linux.bin.gz uImage
2970 The "mkimage" tool can also be used to create ramdisk images for use
2971 with U-Boot, either separated from the Linux kernel image, or
2972 combined into one file. "mkimage" encapsulates the images with a 64
2973 byte header containing information about target architecture,
2974 operating system, image type, compression method, entry points, time
2975 stamp, CRC32 checksums, etc.
2977 "mkimage" can be called in two ways: to verify existing images and
2978 print the header information, or to build new images.
2980 In the first form (with "-l" option) mkimage lists the information
2981 contained in the header of an existing U-Boot image; this includes
2982 checksum verification:
2984 tools/mkimage -l image
2985 -l ==> list image header information
2987 The second form (with "-d" option) is used to build a U-Boot image
2988 from a "data file" which is used as image payload:
2990 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2991 -n name -d data_file image
2992 -A ==> set architecture to 'arch'
2993 -O ==> set operating system to 'os'
2994 -T ==> set image type to 'type'
2995 -C ==> set compression type 'comp'
2996 -a ==> set load address to 'addr' (hex)
2997 -e ==> set entry point to 'ep' (hex)
2998 -n ==> set image name to 'name'
2999 -d ==> use image data from 'datafile'
3001 Right now, all Linux kernels for PowerPC systems use the same load
3002 address (0x00000000), but the entry point address depends on the
3005 - 2.2.x kernels have the entry point at 0x0000000C,
3006 - 2.3.x and later kernels have the entry point at 0x00000000.
3008 So a typical call to build a U-Boot image would read:
3010 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3011 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3012 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3013 > examples/uImage.TQM850L
3014 Image Name: 2.4.4 kernel for TQM850L
3015 Created: Wed Jul 19 02:34:59 2000
3016 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3017 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3018 Load Address: 0x00000000
3019 Entry Point: 0x00000000
3021 To verify the contents of the image (or check for corruption):
3023 -> tools/mkimage -l examples/uImage.TQM850L
3024 Image Name: 2.4.4 kernel for TQM850L
3025 Created: Wed Jul 19 02:34:59 2000
3026 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3027 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3028 Load Address: 0x00000000
3029 Entry Point: 0x00000000
3031 NOTE: for embedded systems where boot time is critical you can trade
3032 speed for memory and install an UNCOMPRESSED image instead: this
3033 needs more space in Flash, but boots much faster since it does not
3034 need to be uncompressed:
3036 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3037 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3038 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3039 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3040 > examples/uImage.TQM850L-uncompressed
3041 Image Name: 2.4.4 kernel for TQM850L
3042 Created: Wed Jul 19 02:34:59 2000
3043 Image Type: PowerPC Linux Kernel Image (uncompressed)
3044 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3045 Load Address: 0x00000000
3046 Entry Point: 0x00000000
3049 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3050 when your kernel is intended to use an initial ramdisk:
3052 -> tools/mkimage -n 'Simple Ramdisk Image' \
3053 > -A ppc -O linux -T ramdisk -C gzip \
3054 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3055 Image Name: Simple Ramdisk Image
3056 Created: Wed Jan 12 14:01:50 2000
3057 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3058 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3059 Load Address: 0x00000000
3060 Entry Point: 0x00000000
3062 The "dumpimage" tool can be used to disassemble or list the contents of images
3063 built by mkimage. See dumpimage's help output (-h) for details.
3065 Installing a Linux Image:
3066 -------------------------
3068 To downloading a U-Boot image over the serial (console) interface,
3069 you must convert the image to S-Record format:
3071 objcopy -I binary -O srec examples/image examples/image.srec
3073 The 'objcopy' does not understand the information in the U-Boot
3074 image header, so the resulting S-Record file will be relative to
3075 address 0x00000000. To load it to a given address, you need to
3076 specify the target address as 'offset' parameter with the 'loads'
3079 Example: install the image to address 0x40100000 (which on the
3080 TQM8xxL is in the first Flash bank):
3082 => erase 40100000 401FFFFF
3088 ## Ready for S-Record download ...
3089 ~>examples/image.srec
3090 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3092 15989 15990 15991 15992
3093 [file transfer complete]
3095 ## Start Addr = 0x00000000
3098 You can check the success of the download using the 'iminfo' command;
3099 this includes a checksum verification so you can be sure no data
3100 corruption happened:
3104 ## Checking Image at 40100000 ...
3105 Image Name: 2.2.13 for initrd on TQM850L
3106 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3107 Data Size: 335725 Bytes = 327 kB = 0 MB
3108 Load Address: 00000000
3109 Entry Point: 0000000c
3110 Verifying Checksum ... OK
3116 The "bootm" command is used to boot an application that is stored in
3117 memory (RAM or Flash). In case of a Linux kernel image, the contents
3118 of the "bootargs" environment variable is passed to the kernel as
3119 parameters. You can check and modify this variable using the
3120 "printenv" and "setenv" commands:
3123 => printenv bootargs
3124 bootargs=root=/dev/ram
3126 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3128 => printenv bootargs
3129 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3132 ## Booting Linux kernel at 40020000 ...
3133 Image Name: 2.2.13 for NFS on TQM850L
3134 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3135 Data Size: 381681 Bytes = 372 kB = 0 MB
3136 Load Address: 00000000
3137 Entry Point: 0000000c
3138 Verifying Checksum ... OK
3139 Uncompressing Kernel Image ... OK
3140 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
3141 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3142 time_init: decrementer frequency = 187500000/60
3143 Calibrating delay loop... 49.77 BogoMIPS
3144 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3147 If you want to boot a Linux kernel with initial RAM disk, you pass
3148 the memory addresses of both the kernel and the initrd image (PPBCOOT
3149 format!) to the "bootm" command:
3151 => imi 40100000 40200000
3153 ## Checking Image at 40100000 ...
3154 Image Name: 2.2.13 for initrd on TQM850L
3155 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3156 Data Size: 335725 Bytes = 327 kB = 0 MB
3157 Load Address: 00000000
3158 Entry Point: 0000000c
3159 Verifying Checksum ... OK
3161 ## Checking Image at 40200000 ...
3162 Image Name: Simple Ramdisk Image
3163 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3164 Data Size: 566530 Bytes = 553 kB = 0 MB
3165 Load Address: 00000000
3166 Entry Point: 00000000
3167 Verifying Checksum ... OK
3169 => bootm 40100000 40200000
3170 ## Booting Linux kernel at 40100000 ...
3171 Image Name: 2.2.13 for initrd on TQM850L
3172 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3173 Data Size: 335725 Bytes = 327 kB = 0 MB
3174 Load Address: 00000000
3175 Entry Point: 0000000c
3176 Verifying Checksum ... OK
3177 Uncompressing Kernel Image ... OK
3178 ## Loading RAMDisk Image at 40200000 ...
3179 Image Name: Simple Ramdisk Image
3180 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3181 Data Size: 566530 Bytes = 553 kB = 0 MB
3182 Load Address: 00000000
3183 Entry Point: 00000000
3184 Verifying Checksum ... OK
3185 Loading Ramdisk ... OK
3186 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
3187 Boot arguments: root=/dev/ram
3188 time_init: decrementer frequency = 187500000/60
3189 Calibrating delay loop... 49.77 BogoMIPS
3191 RAMDISK: Compressed image found at block 0
3192 VFS: Mounted root (ext2 filesystem).
3196 Boot Linux and pass a flat device tree:
3199 First, U-Boot must be compiled with the appropriate defines. See the section
3200 titled "Linux Kernel Interface" above for a more in depth explanation. The
3201 following is an example of how to start a kernel and pass an updated
3207 oft=oftrees/mpc8540ads.dtb
3208 => tftp $oftaddr $oft
3209 Speed: 1000, full duplex
3211 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3212 Filename 'oftrees/mpc8540ads.dtb'.
3213 Load address: 0x300000
3216 Bytes transferred = 4106 (100a hex)
3217 => tftp $loadaddr $bootfile
3218 Speed: 1000, full duplex
3220 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3222 Load address: 0x200000
3223 Loading:############
3225 Bytes transferred = 1029407 (fb51f hex)
3230 => bootm $loadaddr - $oftaddr
3231 ## Booting image at 00200000 ...
3232 Image Name: Linux-2.6.17-dirty
3233 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3234 Data Size: 1029343 Bytes = 1005.2 kB
3235 Load Address: 00000000
3236 Entry Point: 00000000
3237 Verifying Checksum ... OK
3238 Uncompressing Kernel Image ... OK
3239 Booting using flat device tree at 0x300000
3240 Using MPC85xx ADS machine description
3241 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3245 More About U-Boot Image Types:
3246 ------------------------------
3248 U-Boot supports the following image types:
3250 "Standalone Programs" are directly runnable in the environment
3251 provided by U-Boot; it is expected that (if they behave
3252 well) you can continue to work in U-Boot after return from
3253 the Standalone Program.
3254 "OS Kernel Images" are usually images of some Embedded OS which
3255 will take over control completely. Usually these programs
3256 will install their own set of exception handlers, device
3257 drivers, set up the MMU, etc. - this means, that you cannot
3258 expect to re-enter U-Boot except by resetting the CPU.
3259 "RAMDisk Images" are more or less just data blocks, and their
3260 parameters (address, size) are passed to an OS kernel that is
3262 "Multi-File Images" contain several images, typically an OS
3263 (Linux) kernel image and one or more data images like
3264 RAMDisks. This construct is useful for instance when you want
3265 to boot over the network using BOOTP etc., where the boot
3266 server provides just a single image file, but you want to get
3267 for instance an OS kernel and a RAMDisk image.
3269 "Multi-File Images" start with a list of image sizes, each
3270 image size (in bytes) specified by an "uint32_t" in network
3271 byte order. This list is terminated by an "(uint32_t)0".
3272 Immediately after the terminating 0 follow the images, one by
3273 one, all aligned on "uint32_t" boundaries (size rounded up to
3274 a multiple of 4 bytes).
3276 "Firmware Images" are binary images containing firmware (like
3277 U-Boot or FPGA images) which usually will be programmed to
3280 "Script files" are command sequences that will be executed by
3281 U-Boot's command interpreter; this feature is especially
3282 useful when you configure U-Boot to use a real shell (hush)
3283 as command interpreter.
3285 Booting the Linux zImage:
3286 -------------------------
3288 On some platforms, it's possible to boot Linux zImage. This is done
3289 using the "bootz" command. The syntax of "bootz" command is the same
3290 as the syntax of "bootm" command.
3292 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3293 kernel with raw initrd images. The syntax is slightly different, the
3294 address of the initrd must be augmented by it's size, in the following
3295 format: "<initrd addres>:<initrd size>".
3301 One of the features of U-Boot is that you can dynamically load and
3302 run "standalone" applications, which can use some resources of
3303 U-Boot like console I/O functions or interrupt services.
3305 Two simple examples are included with the sources:
3310 'examples/hello_world.c' contains a small "Hello World" Demo
3311 application; it is automatically compiled when you build U-Boot.
3312 It's configured to run at address 0x00040004, so you can play with it
3316 ## Ready for S-Record download ...
3317 ~>examples/hello_world.srec
3318 1 2 3 4 5 6 7 8 9 10 11 ...
3319 [file transfer complete]
3321 ## Start Addr = 0x00040004
3323 => go 40004 Hello World! This is a test.
3324 ## Starting application at 0x00040004 ...
3335 Hit any key to exit ...
3337 ## Application terminated, rc = 0x0
3339 Another example, which demonstrates how to register a CPM interrupt
3340 handler with the U-Boot code, can be found in 'examples/timer.c'.
3341 Here, a CPM timer is set up to generate an interrupt every second.
3342 The interrupt service routine is trivial, just printing a '.'
3343 character, but this is just a demo program. The application can be
3344 controlled by the following keys:
3346 ? - print current values og the CPM Timer registers
3347 b - enable interrupts and start timer
3348 e - stop timer and disable interrupts
3349 q - quit application
3352 ## Ready for S-Record download ...
3353 ~>examples/timer.srec
3354 1 2 3 4 5 6 7 8 9 10 11 ...
3355 [file transfer complete]
3357 ## Start Addr = 0x00040004
3360 ## Starting application at 0x00040004 ...
3363 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3366 [q, b, e, ?] Set interval 1000000 us
3369 [q, b, e, ?] ........
3370 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3373 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3376 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3379 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3381 [q, b, e, ?] ...Stopping timer
3383 [q, b, e, ?] ## Application terminated, rc = 0x0
3389 Over time, many people have reported problems when trying to use the
3390 "minicom" terminal emulation program for serial download. I (wd)
3391 consider minicom to be broken, and recommend not to use it. Under
3392 Unix, I recommend to use C-Kermit for general purpose use (and
3393 especially for kermit binary protocol download ("loadb" command), and
3394 use "cu" for S-Record download ("loads" command). See
3395 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3396 for help with kermit.
3399 Nevertheless, if you absolutely want to use it try adding this
3400 configuration to your "File transfer protocols" section:
3402 Name Program Name U/D FullScr IO-Red. Multi
3403 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3404 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3410 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3411 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3413 Building requires a cross environment; it is known to work on
3414 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3415 need gmake since the Makefiles are not compatible with BSD make).
3416 Note that the cross-powerpc package does not install include files;
3417 attempting to build U-Boot will fail because <machine/ansi.h> is
3418 missing. This file has to be installed and patched manually:
3420 # cd /usr/pkg/cross/powerpc-netbsd/include
3422 # ln -s powerpc machine
3423 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3424 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3426 Native builds *don't* work due to incompatibilities between native
3427 and U-Boot include files.
3429 Booting assumes that (the first part of) the image booted is a
3430 stage-2 loader which in turn loads and then invokes the kernel
3431 proper. Loader sources will eventually appear in the NetBSD source
3432 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3433 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3436 Implementation Internals:
3437 =========================
3439 The following is not intended to be a complete description of every
3440 implementation detail. However, it should help to understand the
3441 inner workings of U-Boot and make it easier to port it to custom
3445 Initial Stack, Global Data:
3446 ---------------------------
3448 The implementation of U-Boot is complicated by the fact that U-Boot
3449 starts running out of ROM (flash memory), usually without access to
3450 system RAM (because the memory controller is not initialized yet).
3451 This means that we don't have writable Data or BSS segments, and BSS
3452 is not initialized as zero. To be able to get a C environment working
3453 at all, we have to allocate at least a minimal stack. Implementation
3454 options for this are defined and restricted by the CPU used: Some CPU
3455 models provide on-chip memory (like the IMMR area on MPC8xx and
3456 MPC826x processors), on others (parts of) the data cache can be
3457 locked as (mis-) used as memory, etc.
3459 Chris Hallinan posted a good summary of these issues to the
3460 U-Boot mailing list:
3462 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3463 From: "Chris Hallinan" <clh@net1plus.com>
3464 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3467 Correct me if I'm wrong, folks, but the way I understand it
3468 is this: Using DCACHE as initial RAM for Stack, etc, does not
3469 require any physical RAM backing up the cache. The cleverness
3470 is that the cache is being used as a temporary supply of
3471 necessary storage before the SDRAM controller is setup. It's
3472 beyond the scope of this list to explain the details, but you
3473 can see how this works by studying the cache architecture and
3474 operation in the architecture and processor-specific manuals.
3476 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3477 is another option for the system designer to use as an
3478 initial stack/RAM area prior to SDRAM being available. Either
3479 option should work for you. Using CS 4 should be fine if your
3480 board designers haven't used it for something that would
3481 cause you grief during the initial boot! It is frequently not
3484 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3485 with your processor/board/system design. The default value
3486 you will find in any recent u-boot distribution in
3487 walnut.h should work for you. I'd set it to a value larger
3488 than your SDRAM module. If you have a 64MB SDRAM module, set
3489 it above 400_0000. Just make sure your board has no resources
3490 that are supposed to respond to that address! That code in
3491 start.S has been around a while and should work as is when
3492 you get the config right.
3497 It is essential to remember this, since it has some impact on the C
3498 code for the initialization procedures:
3500 * Initialized global data (data segment) is read-only. Do not attempt
3503 * Do not use any uninitialized global data (or implicitly initialized
3504 as zero data - BSS segment) at all - this is undefined, initiali-
3505 zation is performed later (when relocating to RAM).
3507 * Stack space is very limited. Avoid big data buffers or things like
3510 Having only the stack as writable memory limits means we cannot use
3511 normal global data to share information between the code. But it
3512 turned out that the implementation of U-Boot can be greatly
3513 simplified by making a global data structure (gd_t) available to all
3514 functions. We could pass a pointer to this data as argument to _all_
3515 functions, but this would bloat the code. Instead we use a feature of
3516 the GCC compiler (Global Register Variables) to share the data: we
3517 place a pointer (gd) to the global data into a register which we
3518 reserve for this purpose.
3520 When choosing a register for such a purpose we are restricted by the
3521 relevant (E)ABI specifications for the current architecture, and by
3522 GCC's implementation.
3524 For PowerPC, the following registers have specific use:
3526 R2: reserved for system use
3527 R3-R4: parameter passing and return values
3528 R5-R10: parameter passing
3529 R13: small data area pointer
3533 (U-Boot also uses R12 as internal GOT pointer. r12
3534 is a volatile register so r12 needs to be reset when
3535 going back and forth between asm and C)
3537 ==> U-Boot will use R2 to hold a pointer to the global data
3539 Note: on PPC, we could use a static initializer (since the
3540 address of the global data structure is known at compile time),
3541 but it turned out that reserving a register results in somewhat
3542 smaller code - although the code savings are not that big (on
3543 average for all boards 752 bytes for the whole U-Boot image,
3544 624 text + 127 data).
3546 On ARM, the following registers are used:
3548 R0: function argument word/integer result
3549 R1-R3: function argument word
3550 R9: platform specific
3551 R10: stack limit (used only if stack checking is enabled)
3552 R11: argument (frame) pointer
3553 R12: temporary workspace
3556 R15: program counter
3558 ==> U-Boot will use R9 to hold a pointer to the global data
3560 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3562 On Nios II, the ABI is documented here:
3563 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3565 ==> U-Boot will use gp to hold a pointer to the global data
3567 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3568 to access small data sections, so gp is free.
3570 On NDS32, the following registers are used:
3572 R0-R1: argument/return
3574 R15: temporary register for assembler
3575 R16: trampoline register
3576 R28: frame pointer (FP)
3577 R29: global pointer (GP)
3578 R30: link register (LP)
3579 R31: stack pointer (SP)
3580 PC: program counter (PC)
3582 ==> U-Boot will use R10 to hold a pointer to the global data
3584 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3585 or current versions of GCC may "optimize" the code too much.
3587 On RISC-V, the following registers are used:
3589 x0: hard-wired zero (zero)
3590 x1: return address (ra)
3591 x2: stack pointer (sp)
3592 x3: global pointer (gp)
3593 x4: thread pointer (tp)
3594 x5: link register (t0)
3595 x8: frame pointer (fp)
3596 x10-x11: arguments/return values (a0-1)
3597 x12-x17: arguments (a2-7)
3598 x28-31: temporaries (t3-6)
3599 pc: program counter (pc)
3601 ==> U-Boot will use gp to hold a pointer to the global data
3606 U-Boot runs in system state and uses physical addresses, i.e. the
3607 MMU is not used either for address mapping nor for memory protection.
3609 The available memory is mapped to fixed addresses using the memory
3610 controller. In this process, a contiguous block is formed for each
3611 memory type (Flash, SDRAM, SRAM), even when it consists of several
3612 physical memory banks.
3614 U-Boot is installed in the first 128 kB of the first Flash bank (on
3615 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3616 booting and sizing and initializing DRAM, the code relocates itself
3617 to the upper end of DRAM. Immediately below the U-Boot code some
3618 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3619 configuration setting]. Below that, a structure with global Board
3620 Info data is placed, followed by the stack (growing downward).
3622 Additionally, some exception handler code is copied to the low 8 kB
3623 of DRAM (0x00000000 ... 0x00001FFF).
3625 So a typical memory configuration with 16 MB of DRAM could look like
3628 0x0000 0000 Exception Vector code
3631 0x0000 2000 Free for Application Use
3637 0x00FB FF20 Monitor Stack (Growing downward)
3638 0x00FB FFAC Board Info Data and permanent copy of global data
3639 0x00FC 0000 Malloc Arena
3642 0x00FE 0000 RAM Copy of Monitor Code
3643 ... eventually: LCD or video framebuffer
3644 ... eventually: pRAM (Protected RAM - unchanged by reset)
3645 0x00FF FFFF [End of RAM]
3648 System Initialization:
3649 ----------------------
3651 In the reset configuration, U-Boot starts at the reset entry point
3652 (on most PowerPC systems at address 0x00000100). Because of the reset
3653 configuration for CS0# this is a mirror of the on board Flash memory.
3654 To be able to re-map memory U-Boot then jumps to its link address.
3655 To be able to implement the initialization code in C, a (small!)
3656 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3657 which provide such a feature like), or in a locked part of the data
3658 cache. After that, U-Boot initializes the CPU core, the caches and
3661 Next, all (potentially) available memory banks are mapped using a
3662 preliminary mapping. For example, we put them on 512 MB boundaries
3663 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3664 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3665 programmed for SDRAM access. Using the temporary configuration, a
3666 simple memory test is run that determines the size of the SDRAM
3669 When there is more than one SDRAM bank, and the banks are of
3670 different size, the largest is mapped first. For equal size, the first
3671 bank (CS2#) is mapped first. The first mapping is always for address
3672 0x00000000, with any additional banks following immediately to create
3673 contiguous memory starting from 0.
3675 Then, the monitor installs itself at the upper end of the SDRAM area
3676 and allocates memory for use by malloc() and for the global Board
3677 Info data; also, the exception vector code is copied to the low RAM
3678 pages, and the final stack is set up.
3680 Only after this relocation will you have a "normal" C environment;
3681 until that you are restricted in several ways, mostly because you are
3682 running from ROM, and because the code will have to be relocated to a
3686 U-Boot Porting Guide:
3687 ----------------------
3689 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3693 int main(int argc, char *argv[])
3695 sighandler_t no_more_time;
3697 signal(SIGALRM, no_more_time);
3698 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3700 if (available_money > available_manpower) {
3701 Pay consultant to port U-Boot;
3705 Download latest U-Boot source;
3707 Subscribe to u-boot mailing list;
3710 email("Hi, I am new to U-Boot, how do I get started?");
3713 Read the README file in the top level directory;
3714 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3715 Read applicable doc/README.*;
3716 Read the source, Luke;
3717 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3720 if (available_money > toLocalCurrency ($2500))
3723 Add a lot of aggravation and time;
3725 if (a similar board exists) { /* hopefully... */
3726 cp -a board/<similar> board/<myboard>
3727 cp include/configs/<similar>.h include/configs/<myboard>.h
3729 Create your own board support subdirectory;
3730 Create your own board include/configs/<myboard>.h file;
3732 Edit new board/<myboard> files
3733 Edit new include/configs/<myboard>.h
3738 Add / modify source code;
3742 email("Hi, I am having problems...");
3744 Send patch file to the U-Boot email list;
3745 if (reasonable critiques)
3746 Incorporate improvements from email list code review;
3748 Defend code as written;
3754 void no_more_time (int sig)
3763 All contributions to U-Boot should conform to the Linux kernel
3764 coding style; see the kernel coding style guide at
3765 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3766 script "scripts/Lindent" in your Linux kernel source directory.
3768 Source files originating from a different project (for example the
3769 MTD subsystem) are generally exempt from these guidelines and are not
3770 reformatted to ease subsequent migration to newer versions of those
3773 Please note that U-Boot is implemented in C (and to some small parts in
3774 Assembler); no C++ is used, so please do not use C++ style comments (//)
3777 Please also stick to the following formatting rules:
3778 - remove any trailing white space
3779 - use TAB characters for indentation and vertical alignment, not spaces
3780 - make sure NOT to use DOS '\r\n' line feeds
3781 - do not add more than 2 consecutive empty lines to source files
3782 - do not add trailing empty lines to source files
3784 Submissions which do not conform to the standards may be returned
3785 with a request to reformat the changes.
3791 Since the number of patches for U-Boot is growing, we need to
3792 establish some rules. Submissions which do not conform to these rules
3793 may be rejected, even when they contain important and valuable stuff.
3795 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3797 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3798 see https://lists.denx.de/listinfo/u-boot
3800 When you send a patch, please include the following information with
3803 * For bug fixes: a description of the bug and how your patch fixes
3804 this bug. Please try to include a way of demonstrating that the
3805 patch actually fixes something.
3807 * For new features: a description of the feature and your
3810 * For major contributions, add a MAINTAINERS file with your
3811 information and associated file and directory references.
3813 * When you add support for a new board, don't forget to add a
3814 maintainer e-mail address to the boards.cfg file, too.
3816 * If your patch adds new configuration options, don't forget to
3817 document these in the README file.
3819 * The patch itself. If you are using git (which is *strongly*
3820 recommended) you can easily generate the patch using the
3821 "git format-patch". If you then use "git send-email" to send it to
3822 the U-Boot mailing list, you will avoid most of the common problems
3823 with some other mail clients.
3825 If you cannot use git, use "diff -purN OLD NEW". If your version of
3826 diff does not support these options, then get the latest version of
3829 The current directory when running this command shall be the parent
3830 directory of the U-Boot source tree (i. e. please make sure that
3831 your patch includes sufficient directory information for the
3834 We prefer patches as plain text. MIME attachments are discouraged,
3835 and compressed attachments must not be used.
3837 * If one logical set of modifications affects or creates several
3838 files, all these changes shall be submitted in a SINGLE patch file.
3840 * Changesets that contain different, unrelated modifications shall be
3841 submitted as SEPARATE patches, one patch per changeset.
3846 * Before sending the patch, run the buildman script on your patched
3847 source tree and make sure that no errors or warnings are reported
3848 for any of the boards.
3850 * Keep your modifications to the necessary minimum: A patch
3851 containing several unrelated changes or arbitrary reformats will be
3852 returned with a request to re-formatting / split it.
3854 * If you modify existing code, make sure that your new code does not
3855 add to the memory footprint of the code ;-) Small is beautiful!
3856 When adding new features, these should compile conditionally only
3857 (using #ifdef), and the resulting code with the new feature
3858 disabled must not need more memory than the old code without your
3861 * Remember that there is a size limit of 100 kB per message on the
3862 u-boot mailing list. Bigger patches will be moderated. If they are
3863 reasonable and not too big, they will be acknowledged. But patches
3864 bigger than the size limit should be avoided.