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_A008044_WORKAROUND
378 Enables a workaround for T1040/T1042 erratum A008044. It is only
379 required during NAND boot and valid for Rev 1.0 SoC revision
381 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
383 This is the value to write into CCSR offset 0x18600
384 according to the A004510 workaround.
386 CONFIG_SYS_FSL_DSP_DDR_ADDR
387 This value denotes start offset of DDR memory which is
388 connected exclusively to the DSP cores.
390 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
391 This value denotes start offset of M2 memory
392 which is directly connected to the DSP core.
394 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
395 This value denotes start offset of M3 memory which is directly
396 connected to the DSP core.
398 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
399 This value denotes start offset of DSP CCSR space.
401 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
402 Single Source Clock is clocking mode present in some of FSL SoC's.
403 In this mode, a single differential clock is used to supply
404 clocks to the sysclock, ddrclock and usbclock.
406 CONFIG_SYS_CPC_REINIT_F
407 This CONFIG is defined when the CPC is configured as SRAM at the
408 time of U-Boot entry and is required to be re-initialized.
411 Indicates this SoC supports deep sleep feature. If deep sleep is
412 supported, core will start to execute uboot when wakes up.
414 - Generic CPU options:
415 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
417 Defines the endianess of the CPU. Implementation of those
418 values is arch specific.
421 Freescale DDR driver in use. This type of DDR controller is
422 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
424 CONFIG_SYS_FSL_DDR_ADDR
425 Freescale DDR memory-mapped register base.
427 CONFIG_SYS_FSL_DDR_EMU
428 Specify emulator support for DDR. Some DDR features such as
429 deskew training are not available.
431 CONFIG_SYS_FSL_DDRC_GEN1
432 Freescale DDR1 controller.
434 CONFIG_SYS_FSL_DDRC_GEN2
435 Freescale DDR2 controller.
437 CONFIG_SYS_FSL_DDRC_GEN3
438 Freescale DDR3 controller.
440 CONFIG_SYS_FSL_DDRC_GEN4
441 Freescale DDR4 controller.
443 CONFIG_SYS_FSL_DDRC_ARM_GEN3
444 Freescale DDR3 controller for ARM-based SoCs.
447 Board config to use DDR1. It can be enabled for SoCs with
448 Freescale DDR1 or DDR2 controllers, depending on the board
452 Board config to use DDR2. It can be enabled for SoCs with
453 Freescale DDR2 or DDR3 controllers, depending on the board
457 Board config to use DDR3. It can be enabled for SoCs with
458 Freescale DDR3 or DDR3L controllers.
461 Board config to use DDR3L. It can be enabled for SoCs with
464 CONFIG_SYS_FSL_IFC_BE
465 Defines the IFC controller register space as Big Endian
467 CONFIG_SYS_FSL_IFC_LE
468 Defines the IFC controller register space as Little Endian
470 CONFIG_SYS_FSL_IFC_CLK_DIV
471 Defines divider of platform clock(clock input to IFC controller).
473 CONFIG_SYS_FSL_LBC_CLK_DIV
474 Defines divider of platform clock(clock input to eLBC controller).
476 CONFIG_SYS_FSL_DDR_BE
477 Defines the DDR controller register space as Big Endian
479 CONFIG_SYS_FSL_DDR_LE
480 Defines the DDR controller register space as Little Endian
482 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
483 Physical address from the view of DDR controllers. It is the
484 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
485 it could be different for ARM SoCs.
487 CONFIG_SYS_FSL_DDR_INTLV_256B
488 DDR controller interleaving on 256-byte. This is a special
489 interleaving mode, handled by Dickens for Freescale layerscape
492 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
493 Number of controllers used as main memory.
495 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
496 Number of controllers used for other than main memory.
498 CONFIG_SYS_FSL_HAS_DP_DDR
499 Defines the SoC has DP-DDR used for DPAA.
501 CONFIG_SYS_FSL_SEC_BE
502 Defines the SEC controller register space as Big Endian
504 CONFIG_SYS_FSL_SEC_LE
505 Defines the SEC controller register space as Little Endian
508 CONFIG_SYS_INIT_SP_OFFSET
510 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
511 pointer. This is needed for the temporary stack before
514 CONFIG_XWAY_SWAP_BYTES
516 Enable compilation of tools/xway-swap-bytes needed for Lantiq
517 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
518 be swapped if a flash programmer is used.
521 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
523 Select high exception vectors of the ARM core, e.g., do not
524 clear the V bit of the c1 register of CP15.
527 Generic timer clock source frequency.
529 COUNTER_FREQUENCY_REAL
530 Generic timer clock source frequency if the real clock is
531 different from COUNTER_FREQUENCY, and can only be determined
535 CONFIG_TEGRA_SUPPORT_NON_SECURE
537 Support executing U-Boot in non-secure (NS) mode. Certain
538 impossible actions will be skipped if the CPU is in NS mode,
539 such as ARM architectural timer initialization.
541 - Linux Kernel Interface:
542 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
544 When transferring memsize parameter to Linux, some versions
545 expect it to be in bytes, others in MB.
546 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
550 New kernel versions are expecting firmware settings to be
551 passed using flattened device trees (based on open firmware
555 * New libfdt-based support
556 * Adds the "fdt" command
557 * The bootm command automatically updates the fdt
559 OF_TBCLK - The timebase frequency.
561 boards with QUICC Engines require OF_QE to set UCC MAC
566 U-Boot can detect if an IDE device is present or not.
567 If not, and this new config option is activated, U-Boot
568 removes the ATA node from the DTS before booting Linux,
569 so the Linux IDE driver does not probe the device and
570 crash. This is needed for buggy hardware (uc101) where
571 no pull down resistor is connected to the signal IDE5V_DD7.
573 - vxWorks boot parameters:
575 bootvx constructs a valid bootline using the following
576 environments variables: bootdev, bootfile, ipaddr, netmask,
577 serverip, gatewayip, hostname, othbootargs.
578 It loads the vxWorks image pointed bootfile.
580 Note: If a "bootargs" environment is defined, it will override
581 the defaults discussed just above.
583 - Cache Configuration for ARM:
584 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
586 CONFIG_SYS_PL310_BASE - Physical base address of PL310
587 controller register space
592 If you have Amba PrimeCell PL011 UARTs, set this variable to
593 the clock speed of the UARTs.
597 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
598 define this to a list of base addresses for each (supported)
599 port. See e.g. include/configs/versatile.h
601 CONFIG_SERIAL_HW_FLOW_CONTROL
603 Define this variable to enable hw flow control in serial driver.
604 Current user of this option is drivers/serial/nsl16550.c driver
606 - Serial Download Echo Mode:
608 If defined to 1, all characters received during a
609 serial download (using the "loads" command) are
610 echoed back. This might be needed by some terminal
611 emulations (like "cu"), but may as well just take
612 time on others. This setting #define's the initial
613 value of the "loads_echo" environment variable.
615 - Removal of commands
616 If no commands are needed to boot, you can disable
617 CONFIG_CMDLINE to remove them. In this case, the command line
618 will not be available, and when U-Boot wants to execute the
619 boot command (on start-up) it will call board_run_command()
620 instead. This can reduce image size significantly for very
621 simple boot procedures.
623 - Regular expression support:
625 If this variable is defined, U-Boot is linked against
626 the SLRE (Super Light Regular Expression) library,
627 which adds regex support to some commands, as for
628 example "env grep" and "setexpr".
631 CONFIG_SYS_WATCHDOG_FREQ
632 Some platforms automatically call WATCHDOG_RESET()
633 from the timer interrupt handler every
634 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
635 board configuration file, a default of CONFIG_SYS_HZ/2
636 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
637 to 0 disables calling WATCHDOG_RESET() from the timer
642 When CONFIG_CMD_DATE is selected, the type of the RTC
643 has to be selected, too. Define exactly one of the
646 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
647 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
648 CONFIG_RTC_MC146818 - use MC146818 RTC
649 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
650 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
651 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
652 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
653 CONFIG_RTC_DS164x - use Dallas DS164x RTC
654 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
655 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
656 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
657 CONFIG_SYS_RV3029_TCR - enable trickle charger on
660 Note that if the RTC uses I2C, then the I2C interface
661 must also be configured. See I2C Support, below.
664 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
666 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
667 chip-ngpio pairs that tell the PCA953X driver the number of
668 pins supported by a particular chip.
670 Note that if the GPIO device uses I2C, then the I2C interface
671 must also be configured. See I2C Support, below.
674 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
675 accesses and can checksum them or write a list of them out
676 to memory. See the 'iotrace' command for details. This is
677 useful for testing device drivers since it can confirm that
678 the driver behaves the same way before and after a code
679 change. Currently this is supported on sandbox and arm. To
680 add support for your architecture, add '#include <iotrace.h>'
681 to the bottom of arch/<arch>/include/asm/io.h and test.
683 Example output from the 'iotrace stats' command is below.
684 Note that if the trace buffer is exhausted, the checksum will
685 still continue to operate.
688 Start: 10000000 (buffer start address)
689 Size: 00010000 (buffer size)
690 Offset: 00000120 (current buffer offset)
691 Output: 10000120 (start + offset)
692 Count: 00000018 (number of trace records)
693 CRC32: 9526fb66 (CRC32 of all trace records)
697 When CONFIG_TIMESTAMP is selected, the timestamp
698 (date and time) of an image is printed by image
699 commands like bootm or iminfo. This option is
700 automatically enabled when you select CONFIG_CMD_DATE .
702 - Partition Labels (disklabels) Supported:
703 Zero or more of the following:
704 CONFIG_MAC_PARTITION Apple's MacOS partition table.
705 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
706 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
707 bootloader. Note 2TB partition limit; see
709 CONFIG_SCSI) you must configure support for at
710 least one non-MTD partition type as well.
715 Set this to enable support for disks larger than 137GB
716 Also look at CONFIG_SYS_64BIT_LBA.
717 Whithout these , LBA48 support uses 32bit variables and will 'only'
718 support disks up to 2.1TB.
720 CONFIG_SYS_64BIT_LBA:
721 When enabled, makes the IDE subsystem use 64bit sector addresses.
724 - NETWORK Support (PCI):
726 Utility code for direct access to the SPI bus on Intel 8257x.
727 This does not do anything useful unless you set at least one
728 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
731 Support for National dp83815 chips.
734 Support for National dp8382[01] gigabit chips.
736 - NETWORK Support (other):
738 Support for the Calxeda XGMAC device
741 Support for SMSC's LAN91C96 chips.
743 CONFIG_LAN91C96_USE_32_BIT
744 Define this to enable 32 bit addressing
747 Support for SMSC's LAN91C111 chip
750 Define this to hold the physical address
751 of the device (I/O space)
753 CONFIG_SMC_USE_32_BIT
754 Define this if data bus is 32 bits
756 CONFIG_SMC_USE_IOFUNCS
757 Define this to use i/o functions instead of macros
758 (some hardware wont work with macros)
760 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
761 Define this if you have more then 3 PHYs.
764 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
766 CONFIG_FTGMAC100_EGIGA
767 Define this to use GE link update with gigabit PHY.
768 Define this if FTGMAC100 is connected to gigabit PHY.
769 If your system has 10/100 PHY only, it might not occur
770 wrong behavior. Because PHY usually return timeout or
771 useless data when polling gigabit status and gigabit
772 control registers. This behavior won't affect the
773 correctnessof 10/100 link speed update.
776 Support for Renesas on-chip Ethernet controller
778 CONFIG_SH_ETHER_USE_PORT
779 Define the number of ports to be used
781 CONFIG_SH_ETHER_PHY_ADDR
782 Define the ETH PHY's address
784 CONFIG_SH_ETHER_CACHE_WRITEBACK
785 If this option is set, the driver enables cache flush.
791 CONFIG_TPM_TIS_INFINEON
792 Support for Infineon i2c bus TPM devices. Only one device
793 per system is supported at this time.
795 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
796 Define the burst count bytes upper limit
799 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
801 CONFIG_TPM_ST33ZP24_I2C
802 Support for STMicroelectronics ST33ZP24 I2C devices.
803 Requires TPM_ST33ZP24 and I2C.
805 CONFIG_TPM_ST33ZP24_SPI
806 Support for STMicroelectronics ST33ZP24 SPI devices.
807 Requires TPM_ST33ZP24 and SPI.
810 Support for Atmel TWI TPM device. Requires I2C support.
813 Support for generic parallel port TPM devices. Only one device
814 per system is supported at this time.
816 CONFIG_TPM_TIS_BASE_ADDRESS
817 Base address where the generic TPM device is mapped
818 to. Contemporary x86 systems usually map it at
822 Define this to enable the TPM support library which provides
823 functional interfaces to some TPM commands.
824 Requires support for a TPM device.
826 CONFIG_TPM_AUTH_SESSIONS
827 Define this to enable authorized functions in the TPM library.
828 Requires CONFIG_TPM and CONFIG_SHA1.
831 At the moment only the UHCI host controller is
832 supported (PIP405, MIP405); define
833 CONFIG_USB_UHCI to enable it.
834 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
835 and define CONFIG_USB_STORAGE to enable the USB
838 Supported are USB Keyboards and USB Floppy drives
841 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
842 txfilltuning field in the EHCI controller on reset.
844 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
848 Define the below if you wish to use the USB console.
849 Once firmware is rebuilt from a serial console issue the
850 command "setenv stdin usbtty; setenv stdout usbtty" and
851 attach your USB cable. The Unix command "dmesg" should print
852 it has found a new device. The environment variable usbtty
853 can be set to gserial or cdc_acm to enable your device to
854 appear to a USB host as a Linux gserial device or a
855 Common Device Class Abstract Control Model serial device.
856 If you select usbtty = gserial you should be able to enumerate
858 # modprobe usbserial vendor=0xVendorID product=0xProductID
859 else if using cdc_acm, simply setting the environment
860 variable usbtty to be cdc_acm should suffice. The following
861 might be defined in YourBoardName.h
864 Define this to build a UDC device
867 Define this to have a tty type of device available to
868 talk to the UDC device
871 Define this to enable the high speed support for usb
872 device and usbtty. If this feature is enabled, a routine
873 int is_usbd_high_speed(void)
874 also needs to be defined by the driver to dynamically poll
875 whether the enumeration has succeded at high speed or full
878 If you have a USB-IF assigned VendorID then you may wish to
879 define your own vendor specific values either in BoardName.h
880 or directly in usbd_vendor_info.h. If you don't define
881 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
882 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
883 should pretend to be a Linux device to it's target host.
885 CONFIG_USBD_MANUFACTURER
886 Define this string as the name of your company for
887 - CONFIG_USBD_MANUFACTURER "my company"
889 CONFIG_USBD_PRODUCT_NAME
890 Define this string as the name of your product
891 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
894 Define this as your assigned Vendor ID from the USB
895 Implementors Forum. This *must* be a genuine Vendor ID
896 to avoid polluting the USB namespace.
897 - CONFIG_USBD_VENDORID 0xFFFF
899 CONFIG_USBD_PRODUCTID
900 Define this as the unique Product ID
902 - CONFIG_USBD_PRODUCTID 0xFFFF
904 - ULPI Layer Support:
905 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
906 the generic ULPI layer. The generic layer accesses the ULPI PHY
907 via the platform viewport, so you need both the genric layer and
908 the viewport enabled. Currently only Chipidea/ARC based
909 viewport is supported.
910 To enable the ULPI layer support, define CONFIG_USB_ULPI and
911 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
912 If your ULPI phy needs a different reference clock than the
913 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
914 the appropriate value in Hz.
917 The MMC controller on the Intel PXA is supported. To
918 enable this define CONFIG_MMC. The MMC can be
919 accessed from the boot prompt by mapping the device
920 to physical memory similar to flash. Command line is
921 enabled with CONFIG_CMD_MMC. The MMC driver also works with
922 the FAT fs. This is enabled with CONFIG_CMD_FAT.
925 Support for Renesas on-chip MMCIF controller
928 Define the base address of MMCIF registers
931 Define the clock frequency for MMCIF
933 - USB Device Firmware Update (DFU) class support:
935 This enables the USB portion of the DFU USB class
938 This enables support for exposing NAND devices via DFU.
941 This enables support for exposing RAM via DFU.
942 Note: DFU spec refer to non-volatile memory usage, but
943 allow usages beyond the scope of spec - here RAM usage,
944 one that would help mostly the developer.
946 CONFIG_SYS_DFU_DATA_BUF_SIZE
947 Dfu transfer uses a buffer before writing data to the
948 raw storage device. Make the size (in bytes) of this buffer
949 configurable. The size of this buffer is also configurable
950 through the "dfu_bufsiz" environment variable.
952 CONFIG_SYS_DFU_MAX_FILE_SIZE
953 When updating files rather than the raw storage device,
954 we use a static buffer to copy the file into and then write
955 the buffer once we've been given the whole file. Define
956 this to the maximum filesize (in bytes) for the buffer.
957 Default is 4 MiB if undefined.
959 DFU_DEFAULT_POLL_TIMEOUT
960 Poll timeout [ms], is the timeout a device can send to the
961 host. The host must wait for this timeout before sending
962 a subsequent DFU_GET_STATUS request to the device.
964 DFU_MANIFEST_POLL_TIMEOUT
965 Poll timeout [ms], which the device sends to the host when
966 entering dfuMANIFEST state. Host waits this timeout, before
967 sending again an USB request to the device.
969 - Journaling Flash filesystem support:
970 CONFIG_SYS_JFFS2_FIRST_SECTOR,
971 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
972 Define these for a default partition on a NOR device
975 See Kconfig help for available keyboard drivers.
979 Enable the Freescale DIU video driver. Reference boards for
980 SOCs that have a DIU should define this macro to enable DIU
981 support, and should also define these other macros:
986 CONFIG_VIDEO_SW_CURSOR
987 CONFIG_VGA_AS_SINGLE_DEVICE
988 CONFIG_VIDEO_BMP_LOGO
990 The DIU driver will look for the 'video-mode' environment
991 variable, and if defined, enable the DIU as a console during
992 boot. See the documentation file doc/README.video for a
993 description of this variable.
995 - LCD Support: CONFIG_LCD
997 Define this to enable LCD support (for output to LCD
998 display); also select one of the supported displays
999 by defining one of these:
1003 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1005 CONFIG_NEC_NL6448AC33:
1007 NEC NL6448AC33-18. Active, color, single scan.
1009 CONFIG_NEC_NL6448BC20
1011 NEC NL6448BC20-08. 6.5", 640x480.
1012 Active, color, single scan.
1014 CONFIG_NEC_NL6448BC33_54
1016 NEC NL6448BC33-54. 10.4", 640x480.
1017 Active, color, single scan.
1021 Sharp 320x240. Active, color, single scan.
1022 It isn't 16x9, and I am not sure what it is.
1024 CONFIG_SHARP_LQ64D341
1026 Sharp LQ64D341 display, 640x480.
1027 Active, color, single scan.
1031 HLD1045 display, 640x480.
1032 Active, color, single scan.
1036 Optrex CBL50840-2 NF-FW 99 22 M5
1038 Hitachi LMG6912RPFC-00T
1042 320x240. Black & white.
1044 CONFIG_LCD_ALIGNMENT
1046 Normally the LCD is page-aligned (typically 4KB). If this is
1047 defined then the LCD will be aligned to this value instead.
1048 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1049 here, since it is cheaper to change data cache settings on
1050 a per-section basis.
1055 Sometimes, for example if the display is mounted in portrait
1056 mode or even if it's mounted landscape but rotated by 180degree,
1057 we need to rotate our content of the display relative to the
1058 framebuffer, so that user can read the messages which are
1060 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1061 initialized with a given rotation from "vl_rot" out of
1062 "vidinfo_t" which is provided by the board specific code.
1063 The value for vl_rot is coded as following (matching to
1064 fbcon=rotate:<n> linux-kernel commandline):
1065 0 = no rotation respectively 0 degree
1066 1 = 90 degree rotation
1067 2 = 180 degree rotation
1068 3 = 270 degree rotation
1070 If CONFIG_LCD_ROTATION is not defined, the console will be
1071 initialized with 0degree rotation.
1075 Support drawing of RLE8-compressed bitmaps on the LCD.
1078 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1080 The clock frequency of the MII bus
1082 CONFIG_PHY_RESET_DELAY
1084 Some PHY like Intel LXT971A need extra delay after
1085 reset before any MII register access is possible.
1086 For such PHY, set this option to the usec delay
1087 required. (minimum 300usec for LXT971A)
1089 CONFIG_PHY_CMD_DELAY (ppc4xx)
1091 Some PHY like Intel LXT971A need extra delay after
1092 command issued before MII status register can be read
1097 Define a default value for the IP address to use for
1098 the default Ethernet interface, in case this is not
1099 determined through e.g. bootp.
1100 (Environment variable "ipaddr")
1102 - Server IP address:
1105 Defines a default value for the IP address of a TFTP
1106 server to contact when using the "tftboot" command.
1107 (Environment variable "serverip")
1109 - Gateway IP address:
1112 Defines a default value for the IP address of the
1113 default router where packets to other networks are
1115 (Environment variable "gatewayip")
1120 Defines a default value for the subnet mask (or
1121 routing prefix) which is used to determine if an IP
1122 address belongs to the local subnet or needs to be
1123 forwarded through a router.
1124 (Environment variable "netmask")
1126 - BOOTP Recovery Mode:
1127 CONFIG_BOOTP_RANDOM_DELAY
1129 If you have many targets in a network that try to
1130 boot using BOOTP, you may want to avoid that all
1131 systems send out BOOTP requests at precisely the same
1132 moment (which would happen for instance at recovery
1133 from a power failure, when all systems will try to
1134 boot, thus flooding the BOOTP server. Defining
1135 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1136 inserted before sending out BOOTP requests. The
1137 following delays are inserted then:
1139 1st BOOTP request: delay 0 ... 1 sec
1140 2nd BOOTP request: delay 0 ... 2 sec
1141 3rd BOOTP request: delay 0 ... 4 sec
1143 BOOTP requests: delay 0 ... 8 sec
1145 CONFIG_BOOTP_ID_CACHE_SIZE
1147 BOOTP packets are uniquely identified using a 32-bit ID. The
1148 server will copy the ID from client requests to responses and
1149 U-Boot will use this to determine if it is the destination of
1150 an incoming response. Some servers will check that addresses
1151 aren't in use before handing them out (usually using an ARP
1152 ping) and therefore take up to a few hundred milliseconds to
1153 respond. Network congestion may also influence the time it
1154 takes for a response to make it back to the client. If that
1155 time is too long, U-Boot will retransmit requests. In order
1156 to allow earlier responses to still be accepted after these
1157 retransmissions, U-Boot's BOOTP client keeps a small cache of
1158 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1159 cache. The default is to keep IDs for up to four outstanding
1160 requests. Increasing this will allow U-Boot to accept offers
1161 from a BOOTP client in networks with unusually high latency.
1163 - DHCP Advanced Options:
1165 - Link-local IP address negotiation:
1166 Negotiate with other link-local clients on the local network
1167 for an address that doesn't require explicit configuration.
1168 This is especially useful if a DHCP server cannot be guaranteed
1169 to exist in all environments that the device must operate.
1171 See doc/README.link-local for more information.
1173 - MAC address from environment variables
1175 FDT_SEQ_MACADDR_FROM_ENV
1177 Fix-up device tree with MAC addresses fetched sequentially from
1178 environment variables. This config work on assumption that
1179 non-usable ethernet node of device-tree are either not present
1180 or their status has been marked as "disabled".
1183 CONFIG_CDP_DEVICE_ID
1185 The device id used in CDP trigger frames.
1187 CONFIG_CDP_DEVICE_ID_PREFIX
1189 A two character string which is prefixed to the MAC address
1194 A printf format string which contains the ascii name of
1195 the port. Normally is set to "eth%d" which sets
1196 eth0 for the first Ethernet, eth1 for the second etc.
1198 CONFIG_CDP_CAPABILITIES
1200 A 32bit integer which indicates the device capabilities;
1201 0x00000010 for a normal host which does not forwards.
1205 An ascii string containing the version of the software.
1209 An ascii string containing the name of the platform.
1213 A 32bit integer sent on the trigger.
1215 CONFIG_CDP_POWER_CONSUMPTION
1217 A 16bit integer containing the power consumption of the
1218 device in .1 of milliwatts.
1220 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1222 A byte containing the id of the VLAN.
1224 - Status LED: CONFIG_LED_STATUS
1226 Several configurations allow to display the current
1227 status using a LED. For instance, the LED will blink
1228 fast while running U-Boot code, stop blinking as
1229 soon as a reply to a BOOTP request was received, and
1230 start blinking slow once the Linux kernel is running
1231 (supported by a status LED driver in the Linux
1232 kernel). Defining CONFIG_LED_STATUS enables this
1237 CONFIG_LED_STATUS_GPIO
1238 The status LED can be connected to a GPIO pin.
1239 In such cases, the gpio_led driver can be used as a
1240 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1241 to include the gpio_led driver in the U-Boot binary.
1243 CONFIG_GPIO_LED_INVERTED_TABLE
1244 Some GPIO connected LEDs may have inverted polarity in which
1245 case the GPIO high value corresponds to LED off state and
1246 GPIO low value corresponds to LED on state.
1247 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1248 with a list of GPIO LEDs that have inverted polarity.
1251 CONFIG_SYS_NUM_I2C_BUSES
1252 Hold the number of i2c buses you want to use.
1254 CONFIG_SYS_I2C_DIRECT_BUS
1255 define this, if you don't use i2c muxes on your hardware.
1256 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1259 CONFIG_SYS_I2C_MAX_HOPS
1260 define how many muxes are maximal consecutively connected
1261 on one i2c bus. If you not use i2c muxes, omit this
1264 CONFIG_SYS_I2C_BUSES
1265 hold a list of buses you want to use, only used if
1266 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1267 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1268 CONFIG_SYS_NUM_I2C_BUSES = 9:
1270 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1271 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1272 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1273 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1274 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1275 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1276 {1, {I2C_NULL_HOP}}, \
1277 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1278 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1282 bus 0 on adapter 0 without a mux
1283 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1284 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1285 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1286 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1287 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1288 bus 6 on adapter 1 without a mux
1289 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1290 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1292 If you do not have i2c muxes on your board, omit this define.
1294 - Legacy I2C Support:
1295 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1296 then the following macros need to be defined (examples are
1297 from include/configs/lwmon.h):
1301 (Optional). Any commands necessary to enable the I2C
1302 controller or configure ports.
1304 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1308 The code necessary to make the I2C data line active
1309 (driven). If the data line is open collector, this
1312 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1316 The code necessary to make the I2C data line tri-stated
1317 (inactive). If the data line is open collector, this
1320 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1324 Code that returns true if the I2C data line is high,
1327 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1331 If <bit> is true, sets the I2C data line high. If it
1332 is false, it clears it (low).
1334 eg: #define I2C_SDA(bit) \
1335 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1336 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1340 If <bit> is true, sets the I2C clock line high. If it
1341 is false, it clears it (low).
1343 eg: #define I2C_SCL(bit) \
1344 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1345 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1349 This delay is invoked four times per clock cycle so this
1350 controls the rate of data transfer. The data rate thus
1351 is 1 / (I2C_DELAY * 4). Often defined to be something
1354 #define I2C_DELAY udelay(2)
1356 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1358 If your arch supports the generic GPIO framework (asm/gpio.h),
1359 then you may alternatively define the two GPIOs that are to be
1360 used as SCL / SDA. Any of the previous I2C_xxx macros will
1361 have GPIO-based defaults assigned to them as appropriate.
1363 You should define these to the GPIO value as given directly to
1364 the generic GPIO functions.
1366 CONFIG_SYS_I2C_INIT_BOARD
1368 When a board is reset during an i2c bus transfer
1369 chips might think that the current transfer is still
1370 in progress. On some boards it is possible to access
1371 the i2c SCLK line directly, either by using the
1372 processor pin as a GPIO or by having a second pin
1373 connected to the bus. If this option is defined a
1374 custom i2c_init_board() routine in boards/xxx/board.c
1375 is run early in the boot sequence.
1377 CONFIG_I2C_MULTI_BUS
1379 This option allows the use of multiple I2C buses, each of which
1380 must have a controller. At any point in time, only one bus is
1381 active. To switch to a different bus, use the 'i2c dev' command.
1382 Note that bus numbering is zero-based.
1384 CONFIG_SYS_I2C_NOPROBES
1386 This option specifies a list of I2C devices that will be skipped
1387 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1388 is set, specify a list of bus-device pairs. Otherwise, specify
1389 a 1D array of device addresses
1392 #undef CONFIG_I2C_MULTI_BUS
1393 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1395 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1397 #define CONFIG_I2C_MULTI_BUS
1398 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1400 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1402 CONFIG_SYS_SPD_BUS_NUM
1404 If defined, then this indicates the I2C bus number for DDR SPD.
1405 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1407 CONFIG_SYS_RTC_BUS_NUM
1409 If defined, then this indicates the I2C bus number for the RTC.
1410 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1412 CONFIG_SOFT_I2C_READ_REPEATED_START
1414 defining this will force the i2c_read() function in
1415 the soft_i2c driver to perform an I2C repeated start
1416 between writing the address pointer and reading the
1417 data. If this define is omitted the default behaviour
1418 of doing a stop-start sequence will be used. Most I2C
1419 devices can use either method, but some require one or
1422 - SPI Support: CONFIG_SPI
1424 Enables SPI driver (so far only tested with
1425 SPI EEPROM, also an instance works with Crystal A/D and
1426 D/As on the SACSng board)
1428 CONFIG_SYS_SPI_MXC_WAIT
1429 Timeout for waiting until spi transfer completed.
1430 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1432 - FPGA Support: CONFIG_FPGA
1434 Enables FPGA subsystem.
1436 CONFIG_FPGA_<vendor>
1438 Enables support for specific chip vendors.
1441 CONFIG_FPGA_<family>
1443 Enables support for FPGA family.
1444 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1448 Specify the number of FPGA devices to support.
1450 CONFIG_SYS_FPGA_PROG_FEEDBACK
1452 Enable printing of hash marks during FPGA configuration.
1454 CONFIG_SYS_FPGA_CHECK_BUSY
1456 Enable checks on FPGA configuration interface busy
1457 status by the configuration function. This option
1458 will require a board or device specific function to
1463 If defined, a function that provides delays in the FPGA
1464 configuration driver.
1466 CONFIG_SYS_FPGA_CHECK_CTRLC
1467 Allow Control-C to interrupt FPGA configuration
1469 CONFIG_SYS_FPGA_CHECK_ERROR
1471 Check for configuration errors during FPGA bitfile
1472 loading. For example, abort during Virtex II
1473 configuration if the INIT_B line goes low (which
1474 indicated a CRC error).
1476 CONFIG_SYS_FPGA_WAIT_INIT
1478 Maximum time to wait for the INIT_B line to de-assert
1479 after PROB_B has been de-asserted during a Virtex II
1480 FPGA configuration sequence. The default time is 500
1483 CONFIG_SYS_FPGA_WAIT_BUSY
1485 Maximum time to wait for BUSY to de-assert during
1486 Virtex II FPGA configuration. The default is 5 ms.
1488 CONFIG_SYS_FPGA_WAIT_CONFIG
1490 Time to wait after FPGA configuration. The default is
1493 - Vendor Parameter Protection:
1495 U-Boot considers the values of the environment
1496 variables "serial#" (Board Serial Number) and
1497 "ethaddr" (Ethernet Address) to be parameters that
1498 are set once by the board vendor / manufacturer, and
1499 protects these variables from casual modification by
1500 the user. Once set, these variables are read-only,
1501 and write or delete attempts are rejected. You can
1502 change this behaviour:
1504 If CONFIG_ENV_OVERWRITE is #defined in your config
1505 file, the write protection for vendor parameters is
1506 completely disabled. Anybody can change or delete
1509 Alternatively, if you define _both_ an ethaddr in the
1510 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1511 Ethernet address is installed in the environment,
1512 which can be changed exactly ONCE by the user. [The
1513 serial# is unaffected by this, i. e. it remains
1516 The same can be accomplished in a more flexible way
1517 for any variable by configuring the type of access
1518 to allow for those variables in the ".flags" variable
1519 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1524 Define this variable to enable the reservation of
1525 "protected RAM", i. e. RAM which is not overwritten
1526 by U-Boot. Define CONFIG_PRAM to hold the number of
1527 kB you want to reserve for pRAM. You can overwrite
1528 this default value by defining an environment
1529 variable "pram" to the number of kB you want to
1530 reserve. Note that the board info structure will
1531 still show the full amount of RAM. If pRAM is
1532 reserved, a new environment variable "mem" will
1533 automatically be defined to hold the amount of
1534 remaining RAM in a form that can be passed as boot
1535 argument to Linux, for instance like that:
1537 setenv bootargs ... mem=\${mem}
1540 This way you can tell Linux not to use this memory,
1541 either, which results in a memory region that will
1542 not be affected by reboots.
1544 *WARNING* If your board configuration uses automatic
1545 detection of the RAM size, you must make sure that
1546 this memory test is non-destructive. So far, the
1547 following board configurations are known to be
1550 IVMS8, IVML24, SPD8xx,
1551 HERMES, IP860, RPXlite, LWMON,
1555 CONFIG_NET_RETRY_COUNT
1557 This variable defines the number of retries for
1558 network operations like ARP, RARP, TFTP, or BOOTP
1559 before giving up the operation. If not defined, a
1560 default value of 5 is used.
1564 Timeout waiting for an ARP reply in milliseconds.
1568 Timeout in milliseconds used in NFS protocol.
1569 If you encounter "ERROR: Cannot umount" in nfs command,
1570 try longer timeout such as
1571 #define CONFIG_NFS_TIMEOUT 10000UL
1575 In the current implementation, the local variables
1576 space and global environment variables space are
1577 separated. Local variables are those you define by
1578 simply typing `name=value'. To access a local
1579 variable later on, you have write `$name' or
1580 `${name}'; to execute the contents of a variable
1581 directly type `$name' at the command prompt.
1583 Global environment variables are those you use
1584 setenv/printenv to work with. To run a command stored
1585 in such a variable, you need to use the run command,
1586 and you must not use the '$' sign to access them.
1588 To store commands and special characters in a
1589 variable, please use double quotation marks
1590 surrounding the whole text of the variable, instead
1591 of the backslashes before semicolons and special
1594 - Command Line Editing and History:
1595 CONFIG_CMDLINE_PS_SUPPORT
1597 Enable support for changing the command prompt string
1598 at run-time. Only static string is supported so far.
1599 The string is obtained from environment variables PS1
1602 - Default Environment:
1603 CONFIG_EXTRA_ENV_SETTINGS
1605 Define this to contain any number of null terminated
1606 strings (variable = value pairs) that will be part of
1607 the default environment compiled into the boot image.
1609 For example, place something like this in your
1610 board's config file:
1612 #define CONFIG_EXTRA_ENV_SETTINGS \
1616 Warning: This method is based on knowledge about the
1617 internal format how the environment is stored by the
1618 U-Boot code. This is NOT an official, exported
1619 interface! Although it is unlikely that this format
1620 will change soon, there is no guarantee either.
1621 You better know what you are doing here.
1623 Note: overly (ab)use of the default environment is
1624 discouraged. Make sure to check other ways to preset
1625 the environment like the "source" command or the
1628 CONFIG_DELAY_ENVIRONMENT
1630 Normally the environment is loaded when the board is
1631 initialised so that it is available to U-Boot. This inhibits
1632 that so that the environment is not available until
1633 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1634 this is instead controlled by the value of
1635 /config/load-environment.
1637 - TFTP Fixed UDP Port:
1640 If this is defined, the environment variable tftpsrcp
1641 is used to supply the TFTP UDP source port value.
1642 If tftpsrcp isn't defined, the normal pseudo-random port
1643 number generator is used.
1645 Also, the environment variable tftpdstp is used to supply
1646 the TFTP UDP destination port value. If tftpdstp isn't
1647 defined, the normal port 69 is used.
1649 The purpose for tftpsrcp is to allow a TFTP server to
1650 blindly start the TFTP transfer using the pre-configured
1651 target IP address and UDP port. This has the effect of
1652 "punching through" the (Windows XP) firewall, allowing
1653 the remainder of the TFTP transfer to proceed normally.
1654 A better solution is to properly configure the firewall,
1655 but sometimes that is not allowed.
1657 CONFIG_STANDALONE_LOAD_ADDR
1659 This option defines a board specific value for the
1660 address where standalone program gets loaded, thus
1661 overwriting the architecture dependent default
1664 - Frame Buffer Address:
1667 Define CONFIG_FB_ADDR if you want to use specific
1668 address for frame buffer. This is typically the case
1669 when using a graphics controller has separate video
1670 memory. U-Boot will then place the frame buffer at
1671 the given address instead of dynamically reserving it
1672 in system RAM by calling lcd_setmem(), which grabs
1673 the memory for the frame buffer depending on the
1674 configured panel size.
1676 Please see board_init_f function.
1678 - Automatic software updates via TFTP server
1680 CONFIG_UPDATE_TFTP_CNT_MAX
1681 CONFIG_UPDATE_TFTP_MSEC_MAX
1683 These options enable and control the auto-update feature;
1684 for a more detailed description refer to doc/README.update.
1686 - MTD Support (mtdparts command, UBI support)
1687 CONFIG_MTD_UBI_WL_THRESHOLD
1688 This parameter defines the maximum difference between the highest
1689 erase counter value and the lowest erase counter value of eraseblocks
1690 of UBI devices. When this threshold is exceeded, UBI starts performing
1691 wear leveling by means of moving data from eraseblock with low erase
1692 counter to eraseblocks with high erase counter.
1694 The default value should be OK for SLC NAND flashes, NOR flashes and
1695 other flashes which have eraseblock life-cycle 100000 or more.
1696 However, in case of MLC NAND flashes which typically have eraseblock
1697 life-cycle less than 10000, the threshold should be lessened (e.g.,
1698 to 128 or 256, although it does not have to be power of 2).
1702 CONFIG_MTD_UBI_BEB_LIMIT
1703 This option specifies the maximum bad physical eraseblocks UBI
1704 expects on the MTD device (per 1024 eraseblocks). If the
1705 underlying flash does not admit of bad eraseblocks (e.g. NOR
1706 flash), this value is ignored.
1708 NAND datasheets often specify the minimum and maximum NVM
1709 (Number of Valid Blocks) for the flashes' endurance lifetime.
1710 The maximum expected bad eraseblocks per 1024 eraseblocks
1711 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1712 which gives 20 for most NANDs (MaxNVB is basically the total
1713 count of eraseblocks on the chip).
1715 To put it differently, if this value is 20, UBI will try to
1716 reserve about 1.9% of physical eraseblocks for bad blocks
1717 handling. And that will be 1.9% of eraseblocks on the entire
1718 NAND chip, not just the MTD partition UBI attaches. This means
1719 that if you have, say, a NAND flash chip admits maximum 40 bad
1720 eraseblocks, and it is split on two MTD partitions of the same
1721 size, UBI will reserve 40 eraseblocks when attaching a
1726 CONFIG_MTD_UBI_FASTMAP
1727 Fastmap is a mechanism which allows attaching an UBI device
1728 in nearly constant time. Instead of scanning the whole MTD device it
1729 only has to locate a checkpoint (called fastmap) on the device.
1730 The on-flash fastmap contains all information needed to attach
1731 the device. Using fastmap makes only sense on large devices where
1732 attaching by scanning takes long. UBI will not automatically install
1733 a fastmap on old images, but you can set the UBI parameter
1734 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1735 that fastmap-enabled images are still usable with UBI implementations
1736 without fastmap support. On typical flash devices the whole fastmap
1737 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1739 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1740 Set this parameter to enable fastmap automatically on images
1744 CONFIG_MTD_UBI_FM_DEBUG
1745 Enable UBI fastmap debug
1750 Enable building of SPL globally.
1752 CONFIG_SPL_MAX_FOOTPRINT
1753 Maximum size in memory allocated to the SPL, BSS included.
1754 When defined, the linker checks that the actual memory
1755 used by SPL from _start to __bss_end does not exceed it.
1756 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1757 must not be both defined at the same time.
1760 Maximum size of the SPL image (text, data, rodata, and
1761 linker lists sections), BSS excluded.
1762 When defined, the linker checks that the actual size does
1765 CONFIG_SPL_RELOC_TEXT_BASE
1766 Address to relocate to. If unspecified, this is equal to
1767 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1769 CONFIG_SPL_BSS_START_ADDR
1770 Link address for the BSS within the SPL binary.
1772 CONFIG_SPL_BSS_MAX_SIZE
1773 Maximum size in memory allocated to the SPL BSS.
1774 When defined, the linker checks that the actual memory used
1775 by SPL from __bss_start to __bss_end does not exceed it.
1776 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1777 must not be both defined at the same time.
1780 Adress of the start of the stack SPL will use
1782 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1783 When defined, SPL will panic() if the image it has
1784 loaded does not have a signature.
1785 Defining this is useful when code which loads images
1786 in SPL cannot guarantee that absolutely all read errors
1788 An example is the LPC32XX MLC NAND driver, which will
1789 consider that a completely unreadable NAND block is bad,
1790 and thus should be skipped silently.
1792 CONFIG_SPL_RELOC_STACK
1793 Adress of the start of the stack SPL will use after
1794 relocation. If unspecified, this is equal to
1797 CONFIG_SYS_SPL_MALLOC_START
1798 Starting address of the malloc pool used in SPL.
1799 When this option is set the full malloc is used in SPL and
1800 it is set up by spl_init() and before that, the simple malloc()
1801 can be used if CONFIG_SYS_MALLOC_F is defined.
1803 CONFIG_SYS_SPL_MALLOC_SIZE
1804 The size of the malloc pool used in SPL.
1806 CONFIG_SPL_DISPLAY_PRINT
1807 For ARM, enable an optional function to print more information
1808 about the running system.
1810 CONFIG_SPL_INIT_MINIMAL
1811 Arch init code should be built for a very small image
1813 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
1814 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
1815 Sector and number of sectors to load kernel argument
1816 parameters from when MMC is being used in raw mode
1819 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
1820 Filename to read to load U-Boot when reading from filesystem
1822 CONFIG_SPL_FS_LOAD_KERNEL_NAME
1823 Filename to read to load kernel uImage when reading
1824 from filesystem (for Falcon mode)
1826 CONFIG_SPL_FS_LOAD_ARGS_NAME
1827 Filename to read to load kernel argument parameters
1828 when reading from filesystem (for Falcon mode)
1830 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1831 Set this for NAND SPL on PPC mpc83xx targets, so that
1832 start.S waits for the rest of the SPL to load before
1833 continuing (the hardware starts execution after just
1834 loading the first page rather than the full 4K).
1836 CONFIG_SPL_SKIP_RELOCATE
1837 Avoid SPL relocation
1840 Support for a lightweight UBI (fastmap) scanner and
1843 CONFIG_SPL_NAND_RAW_ONLY
1844 Support to boot only raw u-boot.bin images. Use this only
1845 if you need to save space.
1847 CONFIG_SPL_COMMON_INIT_DDR
1848 Set for common ddr init with serial presence detect in
1851 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1852 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1853 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1854 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1855 CONFIG_SYS_NAND_ECCBYTES
1856 Defines the size and behavior of the NAND that SPL uses
1859 CONFIG_SYS_NAND_U_BOOT_DST
1860 Location in memory to load U-Boot to
1862 CONFIG_SYS_NAND_U_BOOT_SIZE
1863 Size of image to load
1865 CONFIG_SYS_NAND_U_BOOT_START
1866 Entry point in loaded image to jump to
1868 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1869 Define this if you need to first read the OOB and then the
1870 data. This is used, for example, on davinci platforms.
1872 CONFIG_SPL_RAM_DEVICE
1873 Support for running image already present in ram, in SPL binary
1876 Image offset to which the SPL should be padded before appending
1877 the SPL payload. By default, this is defined as
1878 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1879 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1880 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1883 Final target image containing SPL and payload. Some SPLs
1884 use an arch-specific makefile fragment instead, for
1885 example if more than one image needs to be produced.
1887 CONFIG_SPL_FIT_PRINT
1888 Printing information about a FIT image adds quite a bit of
1889 code to SPL. So this is normally disabled in SPL. Use this
1890 option to re-enable it. This will affect the output of the
1891 bootm command when booting a FIT image.
1895 Enable building of TPL globally.
1898 Image offset to which the TPL should be padded before appending
1899 the TPL payload. By default, this is defined as
1900 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1901 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1902 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1904 - Interrupt support (PPC):
1906 There are common interrupt_init() and timer_interrupt()
1907 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1908 for CPU specific initialization. interrupt_init_cpu()
1909 should set decrementer_count to appropriate value. If
1910 CPU resets decrementer automatically after interrupt
1911 (ppc4xx) it should set decrementer_count to zero.
1912 timer_interrupt() calls timer_interrupt_cpu() for CPU
1913 specific handling. If board has watchdog / status_led
1914 / other_activity_monitor it works automatically from
1915 general timer_interrupt().
1918 Board initialization settings:
1919 ------------------------------
1921 During Initialization u-boot calls a number of board specific functions
1922 to allow the preparation of board specific prerequisites, e.g. pin setup
1923 before drivers are initialized. To enable these callbacks the
1924 following configuration macros have to be defined. Currently this is
1925 architecture specific, so please check arch/your_architecture/lib/board.c
1926 typically in board_init_f() and board_init_r().
1928 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1929 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1930 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1932 Configuration Settings:
1933 -----------------------
1935 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1936 Optionally it can be defined to support 64-bit memory commands.
1938 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1939 undefine this when you're short of memory.
1941 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1942 width of the commands listed in the 'help' command output.
1944 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1945 prompt for user input.
1947 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
1949 - CONFIG_SYS_PBSIZE: Buffer size for Console output
1951 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
1953 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
1954 the application (usually a Linux kernel) when it is
1957 - CONFIG_SYS_BAUDRATE_TABLE:
1958 List of legal baudrate settings for this board.
1960 - CONFIG_SYS_MEM_RESERVE_SECURE
1961 Only implemented for ARMv8 for now.
1962 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1963 is substracted from total RAM and won't be reported to OS.
1964 This memory can be used as secure memory. A variable
1965 gd->arch.secure_ram is used to track the location. In systems
1966 the RAM base is not zero, or RAM is divided into banks,
1967 this variable needs to be recalcuated to get the address.
1969 - CONFIG_SYS_MEM_TOP_HIDE:
1970 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
1971 this specified memory area will get subtracted from the top
1972 (end) of RAM and won't get "touched" at all by U-Boot. By
1973 fixing up gd->ram_size the Linux kernel should gets passed
1974 the now "corrected" memory size and won't touch it either.
1975 This should work for arch/ppc and arch/powerpc. Only Linux
1976 board ports in arch/powerpc with bootwrapper support that
1977 recalculate the memory size from the SDRAM controller setup
1978 will have to get fixed in Linux additionally.
1980 This option can be used as a workaround for the 440EPx/GRx
1981 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
1984 WARNING: Please make sure that this value is a multiple of
1985 the Linux page size (normally 4k). If this is not the case,
1986 then the end address of the Linux memory will be located at a
1987 non page size aligned address and this could cause major
1990 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1991 Enable temporary baudrate change while serial download
1993 - CONFIG_SYS_SDRAM_BASE:
1994 Physical start address of SDRAM. _Must_ be 0 here.
1996 - CONFIG_SYS_FLASH_BASE:
1997 Physical start address of Flash memory.
1999 - CONFIG_SYS_MONITOR_BASE:
2000 Physical start address of boot monitor code (set by
2001 make config files to be same as the text base address
2002 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2003 CONFIG_SYS_FLASH_BASE when booting from flash.
2005 - CONFIG_SYS_MONITOR_LEN:
2006 Size of memory reserved for monitor code, used to
2007 determine _at_compile_time_ (!) if the environment is
2008 embedded within the U-Boot image, or in a separate
2011 - CONFIG_SYS_MALLOC_LEN:
2012 Size of DRAM reserved for malloc() use.
2014 - CONFIG_SYS_MALLOC_F_LEN
2015 Size of the malloc() pool for use before relocation. If
2016 this is defined, then a very simple malloc() implementation
2017 will become available before relocation. The address is just
2018 below the global data, and the stack is moved down to make
2021 This feature allocates regions with increasing addresses
2022 within the region. calloc() is supported, but realloc()
2023 is not available. free() is supported but does nothing.
2024 The memory will be freed (or in fact just forgotten) when
2025 U-Boot relocates itself.
2027 - CONFIG_SYS_MALLOC_SIMPLE
2028 Provides a simple and small malloc() and calloc() for those
2029 boards which do not use the full malloc in SPL (which is
2030 enabled with CONFIG_SYS_SPL_MALLOC_START).
2032 - CONFIG_SYS_NONCACHED_MEMORY:
2033 Size of non-cached memory area. This area of memory will be
2034 typically located right below the malloc() area and mapped
2035 uncached in the MMU. This is useful for drivers that would
2036 otherwise require a lot of explicit cache maintenance. For
2037 some drivers it's also impossible to properly maintain the
2038 cache. For example if the regions that need to be flushed
2039 are not a multiple of the cache-line size, *and* padding
2040 cannot be allocated between the regions to align them (i.e.
2041 if the HW requires a contiguous array of regions, and the
2042 size of each region is not cache-aligned), then a flush of
2043 one region may result in overwriting data that hardware has
2044 written to another region in the same cache-line. This can
2045 happen for example in network drivers where descriptors for
2046 buffers are typically smaller than the CPU cache-line (e.g.
2047 16 bytes vs. 32 or 64 bytes).
2049 Non-cached memory is only supported on 32-bit ARM at present.
2051 - CONFIG_SYS_BOOTM_LEN:
2052 Normally compressed uImages are limited to an
2053 uncompressed size of 8 MBytes. If this is not enough,
2054 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2055 to adjust this setting to your needs.
2057 - CONFIG_SYS_BOOTMAPSZ:
2058 Maximum size of memory mapped by the startup code of
2059 the Linux kernel; all data that must be processed by
2060 the Linux kernel (bd_info, boot arguments, FDT blob if
2061 used) must be put below this limit, unless "bootm_low"
2062 environment variable is defined and non-zero. In such case
2063 all data for the Linux kernel must be between "bootm_low"
2064 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2065 variable "bootm_mapsize" will override the value of
2066 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2067 then the value in "bootm_size" will be used instead.
2069 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2070 Enable initrd_high functionality. If defined then the
2071 initrd_high feature is enabled and the bootm ramdisk subcommand
2074 - CONFIG_SYS_BOOT_GET_CMDLINE:
2075 Enables allocating and saving kernel cmdline in space between
2076 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2078 - CONFIG_SYS_BOOT_GET_KBD:
2079 Enables allocating and saving a kernel copy of the bd_info in
2080 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2082 - CONFIG_SYS_MAX_FLASH_SECT:
2083 Max number of sectors on a Flash chip
2085 - CONFIG_SYS_FLASH_ERASE_TOUT:
2086 Timeout for Flash erase operations (in ms)
2088 - CONFIG_SYS_FLASH_WRITE_TOUT:
2089 Timeout for Flash write operations (in ms)
2091 - CONFIG_SYS_FLASH_LOCK_TOUT
2092 Timeout for Flash set sector lock bit operation (in ms)
2094 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2095 Timeout for Flash clear lock bits operation (in ms)
2097 - CONFIG_SYS_FLASH_PROTECTION
2098 If defined, hardware flash sectors protection is used
2099 instead of U-Boot software protection.
2101 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2103 Enable TFTP transfers directly to flash memory;
2104 without this option such a download has to be
2105 performed in two steps: (1) download to RAM, and (2)
2106 copy from RAM to flash.
2108 The two-step approach is usually more reliable, since
2109 you can check if the download worked before you erase
2110 the flash, but in some situations (when system RAM is
2111 too limited to allow for a temporary copy of the
2112 downloaded image) this option may be very useful.
2114 - CONFIG_SYS_FLASH_CFI:
2115 Define if the flash driver uses extra elements in the
2116 common flash structure for storing flash geometry.
2118 - CONFIG_FLASH_CFI_DRIVER
2119 This option also enables the building of the cfi_flash driver
2120 in the drivers directory
2122 - CONFIG_FLASH_CFI_MTD
2123 This option enables the building of the cfi_mtd driver
2124 in the drivers directory. The driver exports CFI flash
2127 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2128 Use buffered writes to flash.
2130 - CONFIG_FLASH_SPANSION_S29WS_N
2131 s29ws-n MirrorBit flash has non-standard addresses for buffered
2134 - CONFIG_SYS_FLASH_QUIET_TEST
2135 If this option is defined, the common CFI flash doesn't
2136 print it's warning upon not recognized FLASH banks. This
2137 is useful, if some of the configured banks are only
2138 optionally available.
2140 - CONFIG_FLASH_SHOW_PROGRESS
2141 If defined (must be an integer), print out countdown
2142 digits and dots. Recommended value: 45 (9..1) for 80
2143 column displays, 15 (3..1) for 40 column displays.
2145 - CONFIG_FLASH_VERIFY
2146 If defined, the content of the flash (destination) is compared
2147 against the source after the write operation. An error message
2148 will be printed when the contents are not identical.
2149 Please note that this option is useless in nearly all cases,
2150 since such flash programming errors usually are detected earlier
2151 while unprotecting/erasing/programming. Please only enable
2152 this option if you really know what you are doing.
2154 - CONFIG_SYS_RX_ETH_BUFFER:
2155 Defines the number of Ethernet receive buffers. On some
2156 Ethernet controllers it is recommended to set this value
2157 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2158 buffers can be full shortly after enabling the interface
2159 on high Ethernet traffic.
2160 Defaults to 4 if not defined.
2162 - CONFIG_ENV_MAX_ENTRIES
2164 Maximum number of entries in the hash table that is used
2165 internally to store the environment settings. The default
2166 setting is supposed to be generous and should work in most
2167 cases. This setting can be used to tune behaviour; see
2168 lib/hashtable.c for details.
2170 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2171 - CONFIG_ENV_FLAGS_LIST_STATIC
2172 Enable validation of the values given to environment variables when
2173 calling env set. Variables can be restricted to only decimal,
2174 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2175 the variables can also be restricted to IP address or MAC address.
2177 The format of the list is:
2178 type_attribute = [s|d|x|b|i|m]
2179 access_attribute = [a|r|o|c]
2180 attributes = type_attribute[access_attribute]
2181 entry = variable_name[:attributes]
2184 The type attributes are:
2185 s - String (default)
2188 b - Boolean ([1yYtT|0nNfF])
2192 The access attributes are:
2198 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2199 Define this to a list (string) to define the ".flags"
2200 environment variable in the default or embedded environment.
2202 - CONFIG_ENV_FLAGS_LIST_STATIC
2203 Define this to a list (string) to define validation that
2204 should be done if an entry is not found in the ".flags"
2205 environment variable. To override a setting in the static
2206 list, simply add an entry for the same variable name to the
2209 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2210 regular expression. This allows multiple variables to define the same
2211 flags without explicitly listing them for each variable.
2213 The following definitions that deal with the placement and management
2214 of environment data (variable area); in general, we support the
2215 following configurations:
2217 - CONFIG_BUILD_ENVCRC:
2219 Builds up envcrc with the target environment so that external utils
2220 may easily extract it and embed it in final U-Boot images.
2222 BE CAREFUL! The first access to the environment happens quite early
2223 in U-Boot initialization (when we try to get the setting of for the
2224 console baudrate). You *MUST* have mapped your NVRAM area then, or
2227 Please note that even with NVRAM we still use a copy of the
2228 environment in RAM: we could work on NVRAM directly, but we want to
2229 keep settings there always unmodified except somebody uses "saveenv"
2230 to save the current settings.
2232 BE CAREFUL! For some special cases, the local device can not use
2233 "saveenv" command. For example, the local device will get the
2234 environment stored in a remote NOR flash by SRIO or PCIE link,
2235 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2237 - CONFIG_NAND_ENV_DST
2239 Defines address in RAM to which the nand_spl code should copy the
2240 environment. If redundant environment is used, it will be copied to
2241 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2243 Please note that the environment is read-only until the monitor
2244 has been relocated to RAM and a RAM copy of the environment has been
2245 created; also, when using EEPROM you will have to use env_get_f()
2246 until then to read environment variables.
2248 The environment is protected by a CRC32 checksum. Before the monitor
2249 is relocated into RAM, as a result of a bad CRC you will be working
2250 with the compiled-in default environment - *silently*!!! [This is
2251 necessary, because the first environment variable we need is the
2252 "baudrate" setting for the console - if we have a bad CRC, we don't
2253 have any device yet where we could complain.]
2255 Note: once the monitor has been relocated, then it will complain if
2256 the default environment is used; a new CRC is computed as soon as you
2257 use the "saveenv" command to store a valid environment.
2259 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2260 Echo the inverted Ethernet link state to the fault LED.
2262 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2263 also needs to be defined.
2265 - CONFIG_SYS_FAULT_MII_ADDR:
2266 MII address of the PHY to check for the Ethernet link state.
2268 - CONFIG_NS16550_MIN_FUNCTIONS:
2269 Define this if you desire to only have use of the NS16550_init
2270 and NS16550_putc functions for the serial driver located at
2271 drivers/serial/ns16550.c. This option is useful for saving
2272 space for already greatly restricted images, including but not
2273 limited to NAND_SPL configurations.
2275 - CONFIG_DISPLAY_BOARDINFO
2276 Display information about the board that U-Boot is running on
2277 when U-Boot starts up. The board function checkboard() is called
2280 - CONFIG_DISPLAY_BOARDINFO_LATE
2281 Similar to the previous option, but display this information
2282 later, once stdio is running and output goes to the LCD, if
2285 - CONFIG_BOARD_SIZE_LIMIT:
2286 Maximum size of the U-Boot image. When defined, the
2287 build system checks that the actual size does not
2290 Low Level (hardware related) configuration options:
2291 ---------------------------------------------------
2293 - CONFIG_SYS_CACHELINE_SIZE:
2294 Cache Line Size of the CPU.
2296 - CONFIG_SYS_CCSRBAR_DEFAULT:
2297 Default (power-on reset) physical address of CCSR on Freescale
2300 - CONFIG_SYS_CCSRBAR:
2301 Virtual address of CCSR. On a 32-bit build, this is typically
2302 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2304 - CONFIG_SYS_CCSRBAR_PHYS:
2305 Physical address of CCSR. CCSR can be relocated to a new
2306 physical address, if desired. In this case, this macro should
2307 be set to that address. Otherwise, it should be set to the
2308 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2309 is typically relocated on 36-bit builds. It is recommended
2310 that this macro be defined via the _HIGH and _LOW macros:
2312 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2313 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2315 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2316 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2317 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2318 used in assembly code, so it must not contain typecasts or
2319 integer size suffixes (e.g. "ULL").
2321 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2322 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2323 used in assembly code, so it must not contain typecasts or
2324 integer size suffixes (e.g. "ULL").
2326 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2327 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2328 forced to a value that ensures that CCSR is not relocated.
2330 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2331 DO NOT CHANGE unless you know exactly what you're
2332 doing! (11-4) [MPC8xx systems only]
2334 - CONFIG_SYS_INIT_RAM_ADDR:
2336 Start address of memory area that can be used for
2337 initial data and stack; please note that this must be
2338 writable memory that is working WITHOUT special
2339 initialization, i. e. you CANNOT use normal RAM which
2340 will become available only after programming the
2341 memory controller and running certain initialization
2344 U-Boot uses the following memory types:
2345 - MPC8xx: IMMR (internal memory of the CPU)
2347 - CONFIG_SYS_GBL_DATA_OFFSET:
2349 Offset of the initial data structure in the memory
2350 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2351 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2352 data is located at the end of the available space
2353 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2354 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2355 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2356 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2359 On the MPC824X (or other systems that use the data
2360 cache for initial memory) the address chosen for
2361 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2362 point to an otherwise UNUSED address space between
2363 the top of RAM and the start of the PCI space.
2365 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2367 - CONFIG_SYS_OR_TIMING_SDRAM:
2370 - CONFIG_SYS_MAMR_PTA:
2371 periodic timer for refresh
2374 Chip has SRIO or not
2377 Board has SRIO 1 port available
2380 Board has SRIO 2 port available
2382 - CONFIG_SRIO_PCIE_BOOT_MASTER
2383 Board can support master function for Boot from SRIO and PCIE
2385 - CONFIG_SYS_SRIOn_MEM_VIRT:
2386 Virtual Address of SRIO port 'n' memory region
2388 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2389 Physical Address of SRIO port 'n' memory region
2391 - CONFIG_SYS_SRIOn_MEM_SIZE:
2392 Size of SRIO port 'n' memory region
2394 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2395 Defined to tell the NAND controller that the NAND chip is using
2397 Not all NAND drivers use this symbol.
2398 Example of drivers that use it:
2399 - drivers/mtd/nand/raw/ndfc.c
2400 - drivers/mtd/nand/raw/mxc_nand.c
2402 - CONFIG_SYS_NDFC_EBC0_CFG
2403 Sets the EBC0_CFG register for the NDFC. If not defined
2404 a default value will be used.
2407 Get DDR timing information from an I2C EEPROM. Common
2408 with pluggable memory modules such as SODIMMs
2411 I2C address of the SPD EEPROM
2413 - CONFIG_SYS_SPD_BUS_NUM
2414 If SPD EEPROM is on an I2C bus other than the first
2415 one, specify here. Note that the value must resolve
2416 to something your driver can deal with.
2418 - CONFIG_SYS_DDR_RAW_TIMING
2419 Get DDR timing information from other than SPD. Common with
2420 soldered DDR chips onboard without SPD. DDR raw timing
2421 parameters are extracted from datasheet and hard-coded into
2422 header files or board specific files.
2424 - CONFIG_FSL_DDR_INTERACTIVE
2425 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2427 - CONFIG_FSL_DDR_SYNC_REFRESH
2428 Enable sync of refresh for multiple controllers.
2430 - CONFIG_FSL_DDR_BIST
2431 Enable built-in memory test for Freescale DDR controllers.
2433 - CONFIG_SYS_83XX_DDR_USES_CS0
2434 Only for 83xx systems. If specified, then DDR should
2435 be configured using CS0 and CS1 instead of CS2 and CS3.
2438 Enable RMII mode for all FECs.
2439 Note that this is a global option, we can't
2440 have one FEC in standard MII mode and another in RMII mode.
2442 - CONFIG_CRC32_VERIFY
2443 Add a verify option to the crc32 command.
2446 => crc32 -v <address> <count> <crc32>
2448 Where address/count indicate a memory area
2449 and crc32 is the correct crc32 which the
2453 Add the "loopw" memory command. This only takes effect if
2454 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2456 - CONFIG_CMD_MX_CYCLIC
2457 Add the "mdc" and "mwc" memory commands. These are cyclic
2462 This command will print 4 bytes (10,11,12,13) each 500 ms.
2464 => mwc.l 100 12345678 10
2465 This command will write 12345678 to address 100 all 10 ms.
2467 This only takes effect if the memory commands are activated
2468 globally (CONFIG_CMD_MEMORY).
2471 Set when the currently-running compilation is for an artifact
2472 that will end up in the SPL (as opposed to the TPL or U-Boot
2473 proper). Code that needs stage-specific behavior should check
2477 Set when the currently-running compilation is for an artifact
2478 that will end up in the TPL (as opposed to the SPL or U-Boot
2479 proper). Code that needs stage-specific behavior should check
2482 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2483 Only for 85xx systems. If this variable is specified, the section
2484 .resetvec is not kept and the section .bootpg is placed in the
2485 previous 4k of the .text section.
2487 - CONFIG_ARCH_MAP_SYSMEM
2488 Generally U-Boot (and in particular the md command) uses
2489 effective address. It is therefore not necessary to regard
2490 U-Boot address as virtual addresses that need to be translated
2491 to physical addresses. However, sandbox requires this, since
2492 it maintains its own little RAM buffer which contains all
2493 addressable memory. This option causes some memory accesses
2494 to be mapped through map_sysmem() / unmap_sysmem().
2496 - CONFIG_X86_RESET_VECTOR
2497 If defined, the x86 reset vector code is included. This is not
2498 needed when U-Boot is running from Coreboot.
2500 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2501 Option to disable subpage write in NAND driver
2502 driver that uses this:
2503 drivers/mtd/nand/raw/davinci_nand.c
2505 Freescale QE/FMAN Firmware Support:
2506 -----------------------------------
2508 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2509 loading of "firmware", which is encoded in the QE firmware binary format.
2510 This firmware often needs to be loaded during U-Boot booting, so macros
2511 are used to identify the storage device (NOR flash, SPI, etc) and the address
2514 - CONFIG_SYS_FMAN_FW_ADDR
2515 The address in the storage device where the FMAN microcode is located. The
2516 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2519 - CONFIG_SYS_QE_FW_ADDR
2520 The address in the storage device where the QE microcode is located. The
2521 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2524 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2525 The maximum possible size of the firmware. The firmware binary format
2526 has a field that specifies the actual size of the firmware, but it
2527 might not be possible to read any part of the firmware unless some
2528 local storage is allocated to hold the entire firmware first.
2530 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2531 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2532 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2533 virtual address in NOR flash.
2535 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2536 Specifies that QE/FMAN firmware is located in NAND flash.
2537 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2539 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2540 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2541 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2543 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2544 Specifies that QE/FMAN firmware is located in the remote (master)
2545 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2546 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2547 window->master inbound window->master LAW->the ucode address in
2548 master's memory space.
2550 Freescale Layerscape Management Complex Firmware Support:
2551 ---------------------------------------------------------
2552 The Freescale Layerscape Management Complex (MC) supports the loading of
2554 This firmware often needs to be loaded during U-Boot booting, so macros
2555 are used to identify the storage device (NOR flash, SPI, etc) and the address
2558 - CONFIG_FSL_MC_ENET
2559 Enable the MC driver for Layerscape SoCs.
2561 Freescale Layerscape Debug Server Support:
2562 -------------------------------------------
2563 The Freescale Layerscape Debug Server Support supports the loading of
2564 "Debug Server firmware" and triggering SP boot-rom.
2565 This firmware often needs to be loaded during U-Boot booting.
2567 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2568 Define alignment of reserved memory MC requires
2573 In order to achieve reproducible builds, timestamps used in the U-Boot build
2574 process have to be set to a fixed value.
2576 This is done using the SOURCE_DATE_EPOCH environment variable.
2577 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2578 option for U-Boot or an environment variable in U-Boot.
2580 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2582 Building the Software:
2583 ======================
2585 Building U-Boot has been tested in several native build environments
2586 and in many different cross environments. Of course we cannot support
2587 all possibly existing versions of cross development tools in all
2588 (potentially obsolete) versions. In case of tool chain problems we
2589 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2590 which is extensively used to build and test U-Boot.
2592 If you are not using a native environment, it is assumed that you
2593 have GNU cross compiling tools available in your path. In this case,
2594 you must set the environment variable CROSS_COMPILE in your shell.
2595 Note that no changes to the Makefile or any other source files are
2596 necessary. For example using the ELDK on a 4xx CPU, please enter:
2598 $ CROSS_COMPILE=ppc_4xx-
2599 $ export CROSS_COMPILE
2601 U-Boot is intended to be simple to build. After installing the
2602 sources you must configure U-Boot for one specific board type. This
2607 where "NAME_defconfig" is the name of one of the existing configu-
2608 rations; see configs/*_defconfig for supported names.
2610 Note: for some boards special configuration names may exist; check if
2611 additional information is available from the board vendor; for
2612 instance, the TQM823L systems are available without (standard)
2613 or with LCD support. You can select such additional "features"
2614 when choosing the configuration, i. e.
2616 make TQM823L_defconfig
2617 - will configure for a plain TQM823L, i. e. no LCD support
2619 make TQM823L_LCD_defconfig
2620 - will configure for a TQM823L with U-Boot console on LCD
2625 Finally, type "make all", and you should get some working U-Boot
2626 images ready for download to / installation on your system:
2628 - "u-boot.bin" is a raw binary image
2629 - "u-boot" is an image in ELF binary format
2630 - "u-boot.srec" is in Motorola S-Record format
2632 By default the build is performed locally and the objects are saved
2633 in the source directory. One of the two methods can be used to change
2634 this behavior and build U-Boot to some external directory:
2636 1. Add O= to the make command line invocations:
2638 make O=/tmp/build distclean
2639 make O=/tmp/build NAME_defconfig
2640 make O=/tmp/build all
2642 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2644 export KBUILD_OUTPUT=/tmp/build
2649 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2652 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2653 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2654 For example to treat all compiler warnings as errors:
2656 make KCFLAGS=-Werror
2658 Please be aware that the Makefiles assume you are using GNU make, so
2659 for instance on NetBSD you might need to use "gmake" instead of
2663 If the system board that you have is not listed, then you will need
2664 to port U-Boot to your hardware platform. To do this, follow these
2667 1. Create a new directory to hold your board specific code. Add any
2668 files you need. In your board directory, you will need at least
2669 the "Makefile" and a "<board>.c".
2670 2. Create a new configuration file "include/configs/<board>.h" for
2672 3. If you're porting U-Boot to a new CPU, then also create a new
2673 directory to hold your CPU specific code. Add any files you need.
2674 4. Run "make <board>_defconfig" with your new name.
2675 5. Type "make", and you should get a working "u-boot.srec" file
2676 to be installed on your target system.
2677 6. Debug and solve any problems that might arise.
2678 [Of course, this last step is much harder than it sounds.]
2681 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2682 ==============================================================
2684 If you have modified U-Boot sources (for instance added a new board
2685 or support for new devices, a new CPU, etc.) you are expected to
2686 provide feedback to the other developers. The feedback normally takes
2687 the form of a "patch", i.e. a context diff against a certain (latest
2688 official or latest in the git repository) version of U-Boot sources.
2690 But before you submit such a patch, please verify that your modifi-
2691 cation did not break existing code. At least make sure that *ALL* of
2692 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2693 just run the buildman script (tools/buildman/buildman), which will
2694 configure and build U-Boot for ALL supported system. Be warned, this
2695 will take a while. Please see the buildman README, or run 'buildman -H'
2699 See also "U-Boot Porting Guide" below.
2702 Monitor Commands - Overview:
2703 ============================
2705 go - start application at address 'addr'
2706 run - run commands in an environment variable
2707 bootm - boot application image from memory
2708 bootp - boot image via network using BootP/TFTP protocol
2709 bootz - boot zImage from memory
2710 tftpboot- boot image via network using TFTP protocol
2711 and env variables "ipaddr" and "serverip"
2712 (and eventually "gatewayip")
2713 tftpput - upload a file via network using TFTP protocol
2714 rarpboot- boot image via network using RARP/TFTP protocol
2715 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2716 loads - load S-Record file over serial line
2717 loadb - load binary file over serial line (kermit mode)
2719 mm - memory modify (auto-incrementing)
2720 nm - memory modify (constant address)
2721 mw - memory write (fill)
2724 cmp - memory compare
2725 crc32 - checksum calculation
2726 i2c - I2C sub-system
2727 sspi - SPI utility commands
2728 base - print or set address offset
2729 printenv- print environment variables
2730 pwm - control pwm channels
2731 setenv - set environment variables
2732 saveenv - save environment variables to persistent storage
2733 protect - enable or disable FLASH write protection
2734 erase - erase FLASH memory
2735 flinfo - print FLASH memory information
2736 nand - NAND memory operations (see doc/README.nand)
2737 bdinfo - print Board Info structure
2738 iminfo - print header information for application image
2739 coninfo - print console devices and informations
2740 ide - IDE sub-system
2741 loop - infinite loop on address range
2742 loopw - infinite write loop on address range
2743 mtest - simple RAM test
2744 icache - enable or disable instruction cache
2745 dcache - enable or disable data cache
2746 reset - Perform RESET of the CPU
2747 echo - echo args to console
2748 version - print monitor version
2749 help - print online help
2750 ? - alias for 'help'
2753 Monitor Commands - Detailed Description:
2754 ========================================
2758 For now: just type "help <command>".
2761 Note for Redundant Ethernet Interfaces:
2762 =======================================
2764 Some boards come with redundant Ethernet interfaces; U-Boot supports
2765 such configurations and is capable of automatic selection of a
2766 "working" interface when needed. MAC assignment works as follows:
2768 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2769 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2770 "eth1addr" (=>eth1), "eth2addr", ...
2772 If the network interface stores some valid MAC address (for instance
2773 in SROM), this is used as default address if there is NO correspon-
2774 ding setting in the environment; if the corresponding environment
2775 variable is set, this overrides the settings in the card; that means:
2777 o If the SROM has a valid MAC address, and there is no address in the
2778 environment, the SROM's address is used.
2780 o If there is no valid address in the SROM, and a definition in the
2781 environment exists, then the value from the environment variable is
2784 o If both the SROM and the environment contain a MAC address, and
2785 both addresses are the same, this MAC address is used.
2787 o If both the SROM and the environment contain a MAC address, and the
2788 addresses differ, the value from the environment is used and a
2791 o If neither SROM nor the environment contain a MAC address, an error
2792 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2793 a random, locally-assigned MAC is used.
2795 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2796 will be programmed into hardware as part of the initialization process. This
2797 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2798 The naming convention is as follows:
2799 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2804 U-Boot is capable of booting (and performing other auxiliary operations on)
2805 images in two formats:
2807 New uImage format (FIT)
2808 -----------------------
2810 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2811 to Flattened Device Tree). It allows the use of images with multiple
2812 components (several kernels, ramdisks, etc.), with contents protected by
2813 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2819 Old image format is based on binary files which can be basically anything,
2820 preceded by a special header; see the definitions in include/image.h for
2821 details; basically, the header defines the following image properties:
2823 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2824 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2825 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2826 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2827 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2828 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2829 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
2830 * Compression Type (uncompressed, gzip, bzip2)
2836 The header is marked by a special Magic Number, and both the header
2837 and the data portions of the image are secured against corruption by
2844 Although U-Boot should support any OS or standalone application
2845 easily, the main focus has always been on Linux during the design of
2848 U-Boot includes many features that so far have been part of some
2849 special "boot loader" code within the Linux kernel. Also, any
2850 "initrd" images to be used are no longer part of one big Linux image;
2851 instead, kernel and "initrd" are separate images. This implementation
2852 serves several purposes:
2854 - the same features can be used for other OS or standalone
2855 applications (for instance: using compressed images to reduce the
2856 Flash memory footprint)
2858 - it becomes much easier to port new Linux kernel versions because
2859 lots of low-level, hardware dependent stuff are done by U-Boot
2861 - the same Linux kernel image can now be used with different "initrd"
2862 images; of course this also means that different kernel images can
2863 be run with the same "initrd". This makes testing easier (you don't
2864 have to build a new "zImage.initrd" Linux image when you just
2865 change a file in your "initrd"). Also, a field-upgrade of the
2866 software is easier now.
2872 Porting Linux to U-Boot based systems:
2873 ---------------------------------------
2875 U-Boot cannot save you from doing all the necessary modifications to
2876 configure the Linux device drivers for use with your target hardware
2877 (no, we don't intend to provide a full virtual machine interface to
2880 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2882 Just make sure your machine specific header file (for instance
2883 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2884 Information structure as we define in include/asm-<arch>/u-boot.h,
2885 and make sure that your definition of IMAP_ADDR uses the same value
2886 as your U-Boot configuration in CONFIG_SYS_IMMR.
2888 Note that U-Boot now has a driver model, a unified model for drivers.
2889 If you are adding a new driver, plumb it into driver model. If there
2890 is no uclass available, you are encouraged to create one. See
2894 Configuring the Linux kernel:
2895 -----------------------------
2897 No specific requirements for U-Boot. Make sure you have some root
2898 device (initial ramdisk, NFS) for your target system.
2901 Building a Linux Image:
2902 -----------------------
2904 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2905 not used. If you use recent kernel source, a new build target
2906 "uImage" will exist which automatically builds an image usable by
2907 U-Boot. Most older kernels also have support for a "pImage" target,
2908 which was introduced for our predecessor project PPCBoot and uses a
2909 100% compatible format.
2913 make TQM850L_defconfig
2918 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2919 encapsulate a compressed Linux kernel image with header information,
2920 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2922 * build a standard "vmlinux" kernel image (in ELF binary format):
2924 * convert the kernel into a raw binary image:
2926 ${CROSS_COMPILE}-objcopy -O binary \
2927 -R .note -R .comment \
2928 -S vmlinux linux.bin
2930 * compress the binary image:
2934 * package compressed binary image for U-Boot:
2936 mkimage -A ppc -O linux -T kernel -C gzip \
2937 -a 0 -e 0 -n "Linux Kernel Image" \
2938 -d linux.bin.gz uImage
2941 The "mkimage" tool can also be used to create ramdisk images for use
2942 with U-Boot, either separated from the Linux kernel image, or
2943 combined into one file. "mkimage" encapsulates the images with a 64
2944 byte header containing information about target architecture,
2945 operating system, image type, compression method, entry points, time
2946 stamp, CRC32 checksums, etc.
2948 "mkimage" can be called in two ways: to verify existing images and
2949 print the header information, or to build new images.
2951 In the first form (with "-l" option) mkimage lists the information
2952 contained in the header of an existing U-Boot image; this includes
2953 checksum verification:
2955 tools/mkimage -l image
2956 -l ==> list image header information
2958 The second form (with "-d" option) is used to build a U-Boot image
2959 from a "data file" which is used as image payload:
2961 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2962 -n name -d data_file image
2963 -A ==> set architecture to 'arch'
2964 -O ==> set operating system to 'os'
2965 -T ==> set image type to 'type'
2966 -C ==> set compression type 'comp'
2967 -a ==> set load address to 'addr' (hex)
2968 -e ==> set entry point to 'ep' (hex)
2969 -n ==> set image name to 'name'
2970 -d ==> use image data from 'datafile'
2972 Right now, all Linux kernels for PowerPC systems use the same load
2973 address (0x00000000), but the entry point address depends on the
2976 - 2.2.x kernels have the entry point at 0x0000000C,
2977 - 2.3.x and later kernels have the entry point at 0x00000000.
2979 So a typical call to build a U-Boot image would read:
2981 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2982 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2983 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2984 > examples/uImage.TQM850L
2985 Image Name: 2.4.4 kernel for TQM850L
2986 Created: Wed Jul 19 02:34:59 2000
2987 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2988 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2989 Load Address: 0x00000000
2990 Entry Point: 0x00000000
2992 To verify the contents of the image (or check for corruption):
2994 -> tools/mkimage -l examples/uImage.TQM850L
2995 Image Name: 2.4.4 kernel for TQM850L
2996 Created: Wed Jul 19 02:34:59 2000
2997 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2998 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2999 Load Address: 0x00000000
3000 Entry Point: 0x00000000
3002 NOTE: for embedded systems where boot time is critical you can trade
3003 speed for memory and install an UNCOMPRESSED image instead: this
3004 needs more space in Flash, but boots much faster since it does not
3005 need to be uncompressed:
3007 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3008 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3009 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3010 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3011 > examples/uImage.TQM850L-uncompressed
3012 Image Name: 2.4.4 kernel for TQM850L
3013 Created: Wed Jul 19 02:34:59 2000
3014 Image Type: PowerPC Linux Kernel Image (uncompressed)
3015 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3016 Load Address: 0x00000000
3017 Entry Point: 0x00000000
3020 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3021 when your kernel is intended to use an initial ramdisk:
3023 -> tools/mkimage -n 'Simple Ramdisk Image' \
3024 > -A ppc -O linux -T ramdisk -C gzip \
3025 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3026 Image Name: Simple Ramdisk Image
3027 Created: Wed Jan 12 14:01:50 2000
3028 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3029 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3030 Load Address: 0x00000000
3031 Entry Point: 0x00000000
3033 The "dumpimage" tool can be used to disassemble or list the contents of images
3034 built by mkimage. See dumpimage's help output (-h) for details.
3036 Installing a Linux Image:
3037 -------------------------
3039 To downloading a U-Boot image over the serial (console) interface,
3040 you must convert the image to S-Record format:
3042 objcopy -I binary -O srec examples/image examples/image.srec
3044 The 'objcopy' does not understand the information in the U-Boot
3045 image header, so the resulting S-Record file will be relative to
3046 address 0x00000000. To load it to a given address, you need to
3047 specify the target address as 'offset' parameter with the 'loads'
3050 Example: install the image to address 0x40100000 (which on the
3051 TQM8xxL is in the first Flash bank):
3053 => erase 40100000 401FFFFF
3059 ## Ready for S-Record download ...
3060 ~>examples/image.srec
3061 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3063 15989 15990 15991 15992
3064 [file transfer complete]
3066 ## Start Addr = 0x00000000
3069 You can check the success of the download using the 'iminfo' command;
3070 this includes a checksum verification so you can be sure no data
3071 corruption happened:
3075 ## Checking Image at 40100000 ...
3076 Image Name: 2.2.13 for initrd on TQM850L
3077 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3078 Data Size: 335725 Bytes = 327 kB = 0 MB
3079 Load Address: 00000000
3080 Entry Point: 0000000c
3081 Verifying Checksum ... OK
3087 The "bootm" command is used to boot an application that is stored in
3088 memory (RAM or Flash). In case of a Linux kernel image, the contents
3089 of the "bootargs" environment variable is passed to the kernel as
3090 parameters. You can check and modify this variable using the
3091 "printenv" and "setenv" commands:
3094 => printenv bootargs
3095 bootargs=root=/dev/ram
3097 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3099 => printenv bootargs
3100 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3103 ## Booting Linux kernel at 40020000 ...
3104 Image Name: 2.2.13 for NFS on TQM850L
3105 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3106 Data Size: 381681 Bytes = 372 kB = 0 MB
3107 Load Address: 00000000
3108 Entry Point: 0000000c
3109 Verifying Checksum ... OK
3110 Uncompressing Kernel Image ... OK
3111 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
3112 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3113 time_init: decrementer frequency = 187500000/60
3114 Calibrating delay loop... 49.77 BogoMIPS
3115 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3118 If you want to boot a Linux kernel with initial RAM disk, you pass
3119 the memory addresses of both the kernel and the initrd image (PPBCOOT
3120 format!) to the "bootm" command:
3122 => imi 40100000 40200000
3124 ## Checking Image at 40100000 ...
3125 Image Name: 2.2.13 for initrd on TQM850L
3126 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3127 Data Size: 335725 Bytes = 327 kB = 0 MB
3128 Load Address: 00000000
3129 Entry Point: 0000000c
3130 Verifying Checksum ... OK
3132 ## Checking Image at 40200000 ...
3133 Image Name: Simple Ramdisk Image
3134 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3135 Data Size: 566530 Bytes = 553 kB = 0 MB
3136 Load Address: 00000000
3137 Entry Point: 00000000
3138 Verifying Checksum ... OK
3140 => bootm 40100000 40200000
3141 ## Booting Linux kernel at 40100000 ...
3142 Image Name: 2.2.13 for initrd on TQM850L
3143 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3144 Data Size: 335725 Bytes = 327 kB = 0 MB
3145 Load Address: 00000000
3146 Entry Point: 0000000c
3147 Verifying Checksum ... OK
3148 Uncompressing Kernel Image ... OK
3149 ## Loading RAMDisk Image at 40200000 ...
3150 Image Name: Simple Ramdisk Image
3151 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3152 Data Size: 566530 Bytes = 553 kB = 0 MB
3153 Load Address: 00000000
3154 Entry Point: 00000000
3155 Verifying Checksum ... OK
3156 Loading Ramdisk ... OK
3157 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
3158 Boot arguments: root=/dev/ram
3159 time_init: decrementer frequency = 187500000/60
3160 Calibrating delay loop... 49.77 BogoMIPS
3162 RAMDISK: Compressed image found at block 0
3163 VFS: Mounted root (ext2 filesystem).
3167 Boot Linux and pass a flat device tree:
3170 First, U-Boot must be compiled with the appropriate defines. See the section
3171 titled "Linux Kernel Interface" above for a more in depth explanation. The
3172 following is an example of how to start a kernel and pass an updated
3178 oft=oftrees/mpc8540ads.dtb
3179 => tftp $oftaddr $oft
3180 Speed: 1000, full duplex
3182 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3183 Filename 'oftrees/mpc8540ads.dtb'.
3184 Load address: 0x300000
3187 Bytes transferred = 4106 (100a hex)
3188 => tftp $loadaddr $bootfile
3189 Speed: 1000, full duplex
3191 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3193 Load address: 0x200000
3194 Loading:############
3196 Bytes transferred = 1029407 (fb51f hex)
3201 => bootm $loadaddr - $oftaddr
3202 ## Booting image at 00200000 ...
3203 Image Name: Linux-2.6.17-dirty
3204 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3205 Data Size: 1029343 Bytes = 1005.2 kB
3206 Load Address: 00000000
3207 Entry Point: 00000000
3208 Verifying Checksum ... OK
3209 Uncompressing Kernel Image ... OK
3210 Booting using flat device tree at 0x300000
3211 Using MPC85xx ADS machine description
3212 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3216 More About U-Boot Image Types:
3217 ------------------------------
3219 U-Boot supports the following image types:
3221 "Standalone Programs" are directly runnable in the environment
3222 provided by U-Boot; it is expected that (if they behave
3223 well) you can continue to work in U-Boot after return from
3224 the Standalone Program.
3225 "OS Kernel Images" are usually images of some Embedded OS which
3226 will take over control completely. Usually these programs
3227 will install their own set of exception handlers, device
3228 drivers, set up the MMU, etc. - this means, that you cannot
3229 expect to re-enter U-Boot except by resetting the CPU.
3230 "RAMDisk Images" are more or less just data blocks, and their
3231 parameters (address, size) are passed to an OS kernel that is
3233 "Multi-File Images" contain several images, typically an OS
3234 (Linux) kernel image and one or more data images like
3235 RAMDisks. This construct is useful for instance when you want
3236 to boot over the network using BOOTP etc., where the boot
3237 server provides just a single image file, but you want to get
3238 for instance an OS kernel and a RAMDisk image.
3240 "Multi-File Images" start with a list of image sizes, each
3241 image size (in bytes) specified by an "uint32_t" in network
3242 byte order. This list is terminated by an "(uint32_t)0".
3243 Immediately after the terminating 0 follow the images, one by
3244 one, all aligned on "uint32_t" boundaries (size rounded up to
3245 a multiple of 4 bytes).
3247 "Firmware Images" are binary images containing firmware (like
3248 U-Boot or FPGA images) which usually will be programmed to
3251 "Script files" are command sequences that will be executed by
3252 U-Boot's command interpreter; this feature is especially
3253 useful when you configure U-Boot to use a real shell (hush)
3254 as command interpreter.
3256 Booting the Linux zImage:
3257 -------------------------
3259 On some platforms, it's possible to boot Linux zImage. This is done
3260 using the "bootz" command. The syntax of "bootz" command is the same
3261 as the syntax of "bootm" command.
3263 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3264 kernel with raw initrd images. The syntax is slightly different, the
3265 address of the initrd must be augmented by it's size, in the following
3266 format: "<initrd addres>:<initrd size>".
3272 One of the features of U-Boot is that you can dynamically load and
3273 run "standalone" applications, which can use some resources of
3274 U-Boot like console I/O functions or interrupt services.
3276 Two simple examples are included with the sources:
3281 'examples/hello_world.c' contains a small "Hello World" Demo
3282 application; it is automatically compiled when you build U-Boot.
3283 It's configured to run at address 0x00040004, so you can play with it
3287 ## Ready for S-Record download ...
3288 ~>examples/hello_world.srec
3289 1 2 3 4 5 6 7 8 9 10 11 ...
3290 [file transfer complete]
3292 ## Start Addr = 0x00040004
3294 => go 40004 Hello World! This is a test.
3295 ## Starting application at 0x00040004 ...
3306 Hit any key to exit ...
3308 ## Application terminated, rc = 0x0
3310 Another example, which demonstrates how to register a CPM interrupt
3311 handler with the U-Boot code, can be found in 'examples/timer.c'.
3312 Here, a CPM timer is set up to generate an interrupt every second.
3313 The interrupt service routine is trivial, just printing a '.'
3314 character, but this is just a demo program. The application can be
3315 controlled by the following keys:
3317 ? - print current values og the CPM Timer registers
3318 b - enable interrupts and start timer
3319 e - stop timer and disable interrupts
3320 q - quit application
3323 ## Ready for S-Record download ...
3324 ~>examples/timer.srec
3325 1 2 3 4 5 6 7 8 9 10 11 ...
3326 [file transfer complete]
3328 ## Start Addr = 0x00040004
3331 ## Starting application at 0x00040004 ...
3334 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3337 [q, b, e, ?] Set interval 1000000 us
3340 [q, b, e, ?] ........
3341 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3344 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3347 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3350 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3352 [q, b, e, ?] ...Stopping timer
3354 [q, b, e, ?] ## Application terminated, rc = 0x0
3360 Over time, many people have reported problems when trying to use the
3361 "minicom" terminal emulation program for serial download. I (wd)
3362 consider minicom to be broken, and recommend not to use it. Under
3363 Unix, I recommend to use C-Kermit for general purpose use (and
3364 especially for kermit binary protocol download ("loadb" command), and
3365 use "cu" for S-Record download ("loads" command). See
3366 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3367 for help with kermit.
3370 Nevertheless, if you absolutely want to use it try adding this
3371 configuration to your "File transfer protocols" section:
3373 Name Program Name U/D FullScr IO-Red. Multi
3374 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3375 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3381 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3382 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3384 Building requires a cross environment; it is known to work on
3385 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3386 need gmake since the Makefiles are not compatible with BSD make).
3387 Note that the cross-powerpc package does not install include files;
3388 attempting to build U-Boot will fail because <machine/ansi.h> is
3389 missing. This file has to be installed and patched manually:
3391 # cd /usr/pkg/cross/powerpc-netbsd/include
3393 # ln -s powerpc machine
3394 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3395 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3397 Native builds *don't* work due to incompatibilities between native
3398 and U-Boot include files.
3400 Booting assumes that (the first part of) the image booted is a
3401 stage-2 loader which in turn loads and then invokes the kernel
3402 proper. Loader sources will eventually appear in the NetBSD source
3403 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3404 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3407 Implementation Internals:
3408 =========================
3410 The following is not intended to be a complete description of every
3411 implementation detail. However, it should help to understand the
3412 inner workings of U-Boot and make it easier to port it to custom
3416 Initial Stack, Global Data:
3417 ---------------------------
3419 The implementation of U-Boot is complicated by the fact that U-Boot
3420 starts running out of ROM (flash memory), usually without access to
3421 system RAM (because the memory controller is not initialized yet).
3422 This means that we don't have writable Data or BSS segments, and BSS
3423 is not initialized as zero. To be able to get a C environment working
3424 at all, we have to allocate at least a minimal stack. Implementation
3425 options for this are defined and restricted by the CPU used: Some CPU
3426 models provide on-chip memory (like the IMMR area on MPC8xx and
3427 MPC826x processors), on others (parts of) the data cache can be
3428 locked as (mis-) used as memory, etc.
3430 Chris Hallinan posted a good summary of these issues to the
3431 U-Boot mailing list:
3433 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3434 From: "Chris Hallinan" <clh@net1plus.com>
3435 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3438 Correct me if I'm wrong, folks, but the way I understand it
3439 is this: Using DCACHE as initial RAM for Stack, etc, does not
3440 require any physical RAM backing up the cache. The cleverness
3441 is that the cache is being used as a temporary supply of
3442 necessary storage before the SDRAM controller is setup. It's
3443 beyond the scope of this list to explain the details, but you
3444 can see how this works by studying the cache architecture and
3445 operation in the architecture and processor-specific manuals.
3447 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3448 is another option for the system designer to use as an
3449 initial stack/RAM area prior to SDRAM being available. Either
3450 option should work for you. Using CS 4 should be fine if your
3451 board designers haven't used it for something that would
3452 cause you grief during the initial boot! It is frequently not
3455 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3456 with your processor/board/system design. The default value
3457 you will find in any recent u-boot distribution in
3458 walnut.h should work for you. I'd set it to a value larger
3459 than your SDRAM module. If you have a 64MB SDRAM module, set
3460 it above 400_0000. Just make sure your board has no resources
3461 that are supposed to respond to that address! That code in
3462 start.S has been around a while and should work as is when
3463 you get the config right.
3468 It is essential to remember this, since it has some impact on the C
3469 code for the initialization procedures:
3471 * Initialized global data (data segment) is read-only. Do not attempt
3474 * Do not use any uninitialized global data (or implicitly initialized
3475 as zero data - BSS segment) at all - this is undefined, initiali-
3476 zation is performed later (when relocating to RAM).
3478 * Stack space is very limited. Avoid big data buffers or things like
3481 Having only the stack as writable memory limits means we cannot use
3482 normal global data to share information between the code. But it
3483 turned out that the implementation of U-Boot can be greatly
3484 simplified by making a global data structure (gd_t) available to all
3485 functions. We could pass a pointer to this data as argument to _all_
3486 functions, but this would bloat the code. Instead we use a feature of
3487 the GCC compiler (Global Register Variables) to share the data: we
3488 place a pointer (gd) to the global data into a register which we
3489 reserve for this purpose.
3491 When choosing a register for such a purpose we are restricted by the
3492 relevant (E)ABI specifications for the current architecture, and by
3493 GCC's implementation.
3495 For PowerPC, the following registers have specific use:
3497 R2: reserved for system use
3498 R3-R4: parameter passing and return values
3499 R5-R10: parameter passing
3500 R13: small data area pointer
3504 (U-Boot also uses R12 as internal GOT pointer. r12
3505 is a volatile register so r12 needs to be reset when
3506 going back and forth between asm and C)
3508 ==> U-Boot will use R2 to hold a pointer to the global data
3510 Note: on PPC, we could use a static initializer (since the
3511 address of the global data structure is known at compile time),
3512 but it turned out that reserving a register results in somewhat
3513 smaller code - although the code savings are not that big (on
3514 average for all boards 752 bytes for the whole U-Boot image,
3515 624 text + 127 data).
3517 On ARM, the following registers are used:
3519 R0: function argument word/integer result
3520 R1-R3: function argument word
3521 R9: platform specific
3522 R10: stack limit (used only if stack checking is enabled)
3523 R11: argument (frame) pointer
3524 R12: temporary workspace
3527 R15: program counter
3529 ==> U-Boot will use R9 to hold a pointer to the global data
3531 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3533 On Nios II, the ABI is documented here:
3534 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3536 ==> U-Boot will use gp to hold a pointer to the global data
3538 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3539 to access small data sections, so gp is free.
3541 On NDS32, the following registers are used:
3543 R0-R1: argument/return
3545 R15: temporary register for assembler
3546 R16: trampoline register
3547 R28: frame pointer (FP)
3548 R29: global pointer (GP)
3549 R30: link register (LP)
3550 R31: stack pointer (SP)
3551 PC: program counter (PC)
3553 ==> U-Boot will use R10 to hold a pointer to the global data
3555 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3556 or current versions of GCC may "optimize" the code too much.
3558 On RISC-V, the following registers are used:
3560 x0: hard-wired zero (zero)
3561 x1: return address (ra)
3562 x2: stack pointer (sp)
3563 x3: global pointer (gp)
3564 x4: thread pointer (tp)
3565 x5: link register (t0)
3566 x8: frame pointer (fp)
3567 x10-x11: arguments/return values (a0-1)
3568 x12-x17: arguments (a2-7)
3569 x28-31: temporaries (t3-6)
3570 pc: program counter (pc)
3572 ==> U-Boot will use gp to hold a pointer to the global data
3577 U-Boot runs in system state and uses physical addresses, i.e. the
3578 MMU is not used either for address mapping nor for memory protection.
3580 The available memory is mapped to fixed addresses using the memory
3581 controller. In this process, a contiguous block is formed for each
3582 memory type (Flash, SDRAM, SRAM), even when it consists of several
3583 physical memory banks.
3585 U-Boot is installed in the first 128 kB of the first Flash bank (on
3586 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3587 booting and sizing and initializing DRAM, the code relocates itself
3588 to the upper end of DRAM. Immediately below the U-Boot code some
3589 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3590 configuration setting]. Below that, a structure with global Board
3591 Info data is placed, followed by the stack (growing downward).
3593 Additionally, some exception handler code is copied to the low 8 kB
3594 of DRAM (0x00000000 ... 0x00001FFF).
3596 So a typical memory configuration with 16 MB of DRAM could look like
3599 0x0000 0000 Exception Vector code
3602 0x0000 2000 Free for Application Use
3608 0x00FB FF20 Monitor Stack (Growing downward)
3609 0x00FB FFAC Board Info Data and permanent copy of global data
3610 0x00FC 0000 Malloc Arena
3613 0x00FE 0000 RAM Copy of Monitor Code
3614 ... eventually: LCD or video framebuffer
3615 ... eventually: pRAM (Protected RAM - unchanged by reset)
3616 0x00FF FFFF [End of RAM]
3619 System Initialization:
3620 ----------------------
3622 In the reset configuration, U-Boot starts at the reset entry point
3623 (on most PowerPC systems at address 0x00000100). Because of the reset
3624 configuration for CS0# this is a mirror of the on board Flash memory.
3625 To be able to re-map memory U-Boot then jumps to its link address.
3626 To be able to implement the initialization code in C, a (small!)
3627 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3628 which provide such a feature like), or in a locked part of the data
3629 cache. After that, U-Boot initializes the CPU core, the caches and
3632 Next, all (potentially) available memory banks are mapped using a
3633 preliminary mapping. For example, we put them on 512 MB boundaries
3634 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3635 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3636 programmed for SDRAM access. Using the temporary configuration, a
3637 simple memory test is run that determines the size of the SDRAM
3640 When there is more than one SDRAM bank, and the banks are of
3641 different size, the largest is mapped first. For equal size, the first
3642 bank (CS2#) is mapped first. The first mapping is always for address
3643 0x00000000, with any additional banks following immediately to create
3644 contiguous memory starting from 0.
3646 Then, the monitor installs itself at the upper end of the SDRAM area
3647 and allocates memory for use by malloc() and for the global Board
3648 Info data; also, the exception vector code is copied to the low RAM
3649 pages, and the final stack is set up.
3651 Only after this relocation will you have a "normal" C environment;
3652 until that you are restricted in several ways, mostly because you are
3653 running from ROM, and because the code will have to be relocated to a
3657 U-Boot Porting Guide:
3658 ----------------------
3660 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3664 int main(int argc, char *argv[])
3666 sighandler_t no_more_time;
3668 signal(SIGALRM, no_more_time);
3669 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3671 if (available_money > available_manpower) {
3672 Pay consultant to port U-Boot;
3676 Download latest U-Boot source;
3678 Subscribe to u-boot mailing list;
3681 email("Hi, I am new to U-Boot, how do I get started?");
3684 Read the README file in the top level directory;
3685 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3686 Read applicable doc/README.*;
3687 Read the source, Luke;
3688 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3691 if (available_money > toLocalCurrency ($2500))
3694 Add a lot of aggravation and time;
3696 if (a similar board exists) { /* hopefully... */
3697 cp -a board/<similar> board/<myboard>
3698 cp include/configs/<similar>.h include/configs/<myboard>.h
3700 Create your own board support subdirectory;
3701 Create your own board include/configs/<myboard>.h file;
3703 Edit new board/<myboard> files
3704 Edit new include/configs/<myboard>.h
3709 Add / modify source code;
3713 email("Hi, I am having problems...");
3715 Send patch file to the U-Boot email list;
3716 if (reasonable critiques)
3717 Incorporate improvements from email list code review;
3719 Defend code as written;
3725 void no_more_time (int sig)
3734 All contributions to U-Boot should conform to the Linux kernel
3735 coding style; see the kernel coding style guide at
3736 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3737 script "scripts/Lindent" in your Linux kernel source directory.
3739 Source files originating from a different project (for example the
3740 MTD subsystem) are generally exempt from these guidelines and are not
3741 reformatted to ease subsequent migration to newer versions of those
3744 Please note that U-Boot is implemented in C (and to some small parts in
3745 Assembler); no C++ is used, so please do not use C++ style comments (//)
3748 Please also stick to the following formatting rules:
3749 - remove any trailing white space
3750 - use TAB characters for indentation and vertical alignment, not spaces
3751 - make sure NOT to use DOS '\r\n' line feeds
3752 - do not add more than 2 consecutive empty lines to source files
3753 - do not add trailing empty lines to source files
3755 Submissions which do not conform to the standards may be returned
3756 with a request to reformat the changes.
3762 Since the number of patches for U-Boot is growing, we need to
3763 establish some rules. Submissions which do not conform to these rules
3764 may be rejected, even when they contain important and valuable stuff.
3766 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3768 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3769 see https://lists.denx.de/listinfo/u-boot
3771 When you send a patch, please include the following information with
3774 * For bug fixes: a description of the bug and how your patch fixes
3775 this bug. Please try to include a way of demonstrating that the
3776 patch actually fixes something.
3778 * For new features: a description of the feature and your
3781 * For major contributions, add a MAINTAINERS file with your
3782 information and associated file and directory references.
3784 * When you add support for a new board, don't forget to add a
3785 maintainer e-mail address to the boards.cfg file, too.
3787 * If your patch adds new configuration options, don't forget to
3788 document these in the README file.
3790 * The patch itself. If you are using git (which is *strongly*
3791 recommended) you can easily generate the patch using the
3792 "git format-patch". If you then use "git send-email" to send it to
3793 the U-Boot mailing list, you will avoid most of the common problems
3794 with some other mail clients.
3796 If you cannot use git, use "diff -purN OLD NEW". If your version of
3797 diff does not support these options, then get the latest version of
3800 The current directory when running this command shall be the parent
3801 directory of the U-Boot source tree (i. e. please make sure that
3802 your patch includes sufficient directory information for the
3805 We prefer patches as plain text. MIME attachments are discouraged,
3806 and compressed attachments must not be used.
3808 * If one logical set of modifications affects or creates several
3809 files, all these changes shall be submitted in a SINGLE patch file.
3811 * Changesets that contain different, unrelated modifications shall be
3812 submitted as SEPARATE patches, one patch per changeset.
3817 * Before sending the patch, run the buildman script on your patched
3818 source tree and make sure that no errors or warnings are reported
3819 for any of the boards.
3821 * Keep your modifications to the necessary minimum: A patch
3822 containing several unrelated changes or arbitrary reformats will be
3823 returned with a request to re-formatting / split it.
3825 * If you modify existing code, make sure that your new code does not
3826 add to the memory footprint of the code ;-) Small is beautiful!
3827 When adding new features, these should compile conditionally only
3828 (using #ifdef), and the resulting code with the new feature
3829 disabled must not need more memory than the old code without your
3832 * Remember that there is a size limit of 100 kB per message on the
3833 u-boot mailing list. Bigger patches will be moderated. If they are
3834 reasonable and not too big, they will be acknowledged. But patches
3835 bigger than the size limit should be avoided.