1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see https://lists.denx.de/pipermail/u-boot and
55 https://marc.info/?l=u-boot
57 Where to get source code:
58 =========================
60 The U-Boot source code is maintained in the Git repository at
61 https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
62 https://source.denx.de/u-boot/u-boot
64 The "Tags" links on this page allow you to download tarballs of
65 any version you might be interested in. Official releases are also
66 available from the DENX file server through HTTPS or FTP.
67 https://ftp.denx.de/pub/u-boot/
68 ftp://ftp.denx.de/pub/u-boot/
74 - start from 8xxrom sources
75 - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
77 - make it easier to add custom boards
78 - make it possible to add other [PowerPC] CPUs
79 - extend functions, especially:
80 * Provide extended interface to Linux boot loader
83 * ATA disk / SCSI ... boot
84 - create ARMBoot project (https://sourceforge.net/projects/armboot)
85 - add other CPU families (starting with ARM)
86 - create U-Boot project (https://sourceforge.net/projects/u-boot)
87 - current project page: see https://www.denx.de/wiki/U-Boot
93 The "official" name of this project is "Das U-Boot". The spelling
94 "U-Boot" shall be used in all written text (documentation, comments
95 in source files etc.). Example:
97 This is the README file for the U-Boot project.
99 File names etc. shall be based on the string "u-boot". Examples:
101 include/asm-ppc/u-boot.h
103 #include <asm/u-boot.h>
105 Variable names, preprocessor constants etc. shall be either based on
106 the string "u_boot" or on "U_BOOT". Example:
108 U_BOOT_VERSION u_boot_logo
109 IH_OS_U_BOOT u_boot_hush_start
115 Starting with the release in October 2008, the names of the releases
116 were changed from numerical release numbers without deeper meaning
117 into a time stamp based numbering. Regular releases are identified by
118 names consisting of the calendar year and month of the release date.
119 Additional fields (if present) indicate release candidates or bug fix
120 releases in "stable" maintenance trees.
123 U-Boot v2009.11 - Release November 2009
124 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
125 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 /arch Architecture-specific files
132 /arc Files generic to ARC architecture
133 /arm Files generic to ARM architecture
134 /m68k Files generic to m68k architecture
135 /microblaze Files generic to microblaze architecture
136 /mips Files generic to MIPS architecture
137 /nds32 Files generic to NDS32 architecture
138 /nios2 Files generic to Altera NIOS2 architecture
139 /powerpc Files generic to PowerPC architecture
140 /riscv Files generic to RISC-V architecture
141 /sandbox Files generic to HW-independent "sandbox"
142 /sh Files generic to SH architecture
143 /x86 Files generic to x86 architecture
144 /xtensa Files generic to Xtensa architecture
145 /api Machine/arch-independent API for external apps
146 /board Board-dependent files
147 /boot Support for images and booting
148 /cmd U-Boot commands functions
149 /common Misc architecture-independent functions
150 /configs Board default configuration files
151 /disk Code for disk drive partition handling
152 /doc Documentation (a mix of ReST and READMEs)
153 /drivers Device drivers
154 /dts Makefile for building internal U-Boot fdt.
155 /env Environment support
156 /examples Example code for standalone applications, etc.
157 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
158 /include Header Files
159 /lib Library routines generic to all architectures
160 /Licenses Various license files
162 /post Power On Self Test
163 /scripts Various build scripts and Makefiles
164 /test Various unit test files
165 /tools Tools to build and sign FIT images, etc.
167 Software Configuration:
168 =======================
170 Configuration is usually done using C preprocessor defines; the
171 rationale behind that is to avoid dead code whenever possible.
173 There are two classes of configuration variables:
175 * Configuration _OPTIONS_:
176 These are selectable by the user and have names beginning with
179 * Configuration _SETTINGS_:
180 These depend on the hardware etc. and should not be meddled with if
181 you don't know what you're doing; they have names beginning with
184 Previously, all configuration was done by hand, which involved creating
185 symbolic links and editing configuration files manually. More recently,
186 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
187 allowing you to use the "make menuconfig" command to configure your
191 Selection of Processor Architecture and Board Type:
192 ---------------------------------------------------
194 For all supported boards there are ready-to-use default
195 configurations available; just type "make <board_name>_defconfig".
197 Example: For a TQM823L module type:
200 make TQM823L_defconfig
202 Note: If you're looking for the default configuration file for a board
203 you're sure used to be there but is now missing, check the file
204 doc/README.scrapyard for a list of no longer supported boards.
209 U-Boot can be built natively to run on a Linux host using the 'sandbox'
210 board. This allows feature development which is not board- or architecture-
211 specific to be undertaken on a native platform. The sandbox is also used to
212 run some of U-Boot's tests.
214 See doc/arch/sandbox.rst for more details.
217 Board Initialisation Flow:
218 --------------------------
220 This is the intended start-up flow for boards. This should apply for both
221 SPL and U-Boot proper (i.e. they both follow the same rules).
223 Note: "SPL" stands for "Secondary Program Loader," which is explained in
224 more detail later in this file.
226 At present, SPL mostly uses a separate code path, but the function names
227 and roles of each function are the same. Some boards or architectures
228 may not conform to this. At least most ARM boards which use
229 CONFIG_SPL_FRAMEWORK conform to this.
231 Execution typically starts with an architecture-specific (and possibly
232 CPU-specific) start.S file, such as:
234 - arch/arm/cpu/armv7/start.S
235 - arch/powerpc/cpu/mpc83xx/start.S
236 - arch/mips/cpu/start.S
238 and so on. From there, three functions are called; the purpose and
239 limitations of each of these functions are described below.
242 - purpose: essential init to permit execution to reach board_init_f()
243 - no global_data or BSS
244 - there is no stack (ARMv7 may have one but it will soon be removed)
245 - must not set up SDRAM or use console
246 - must only do the bare minimum to allow execution to continue to
248 - this is almost never needed
249 - return normally from this function
252 - purpose: set up the machine ready for running board_init_r():
253 i.e. SDRAM and serial UART
254 - global_data is available
256 - BSS is not available, so you cannot use global/static variables,
257 only stack variables and global_data
259 Non-SPL-specific notes:
260 - dram_init() is called to set up DRAM. If already done in SPL this
264 - you can override the entire board_init_f() function with your own
266 - preloader_console_init() can be called here in extremis
267 - should set up SDRAM, and anything needed to make the UART work
268 - there is no need to clear BSS, it will be done by crt0.S
269 - for specific scenarios on certain architectures an early BSS *can*
270 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
271 of BSS prior to entering board_init_f()) but doing so is discouraged.
272 Instead it is strongly recommended to architect any code changes
273 or additions such to not depend on the availability of BSS during
274 board_init_f() as indicated in other sections of this README to
275 maintain compatibility and consistency across the entire code base.
276 - must return normally from this function (don't call board_init_r()
279 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
280 this point the stack and global_data are relocated to below
281 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
285 - purpose: main execution, common code
286 - global_data is available
288 - BSS is available, all static/global variables can be used
289 - execution eventually continues to main_loop()
291 Non-SPL-specific notes:
292 - U-Boot is relocated to the top of memory and is now running from
296 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
297 CONFIG_SPL_STACK_R_ADDR points into SDRAM
298 - preloader_console_init() can be called here - typically this is
299 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
300 spl_board_init() function containing this call
301 - loads U-Boot or (in falcon mode) Linux
304 Configuration Options:
305 ----------------------
307 Configuration depends on the combination of board and CPU type; all
308 such information is kept in a configuration file
309 "include/configs/<board_name>.h".
311 Example: For a TQM823L module, all configuration settings are in
312 "include/configs/TQM823L.h".
315 Many of the options are named exactly as the corresponding Linux
316 kernel configuration options. The intention is to make it easier to
317 build a config tool - later.
319 - ARM Platform Bus Type(CCI):
320 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
321 provides full cache coherency between two clusters of multi-core
322 CPUs and I/O coherency for devices and I/O masters
324 CONFIG_SYS_FSL_HAS_CCI400
326 Defined For SoC that has cache coherent interconnect
329 CONFIG_SYS_FSL_HAS_CCN504
331 Defined for SoC that has cache coherent interconnect CCN-504
333 The following options need to be configured:
335 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
337 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
342 Specifies that the core is a 64-bit PowerPC implementation (implements
343 the "64" category of the Power ISA). This is necessary for ePAPR
344 compliance, among other possible reasons.
346 CONFIG_SYS_FSL_TBCLK_DIV
348 Defines the core time base clock divider ratio compared to the
349 system clock. On most PQ3 devices this is 8, on newer QorIQ
350 devices it can be 16 or 32. The ratio varies from SoC to Soc.
352 CONFIG_SYS_FSL_PCIE_COMPAT
354 Defines the string to utilize when trying to match PCIe device
355 tree nodes for the given platform.
357 CONFIG_SYS_FSL_ERRATUM_A004510
359 Enables a workaround for erratum A004510. If set,
360 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
361 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
364 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
366 Defines one or two SoC revisions (low 8 bits of SVR)
367 for which the A004510 workaround should be applied.
369 The rest of SVR is either not relevant to the decision
370 of whether the erratum is present (e.g. p2040 versus
371 p2041) or is implied by the build target, which controls
372 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
374 See Freescale App Note 4493 for more information about
377 CONFIG_A003399_NOR_WORKAROUND
378 Enables a workaround for IFC erratum A003399. It is only
379 required during NOR boot.
381 CONFIG_A008044_WORKAROUND
382 Enables a workaround for T1040/T1042 erratum A008044. It is only
383 required during NAND boot and valid for Rev 1.0 SoC revision
385 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
387 This is the value to write into CCSR offset 0x18600
388 according to the A004510 workaround.
390 CONFIG_SYS_FSL_DSP_DDR_ADDR
391 This value denotes start offset of DDR memory which is
392 connected exclusively to the DSP cores.
394 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
395 This value denotes start offset of M2 memory
396 which is directly connected to the DSP core.
398 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
399 This value denotes start offset of M3 memory which is directly
400 connected to the DSP core.
402 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
403 This value denotes start offset of DSP CCSR space.
405 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
406 Single Source Clock is clocking mode present in some of FSL SoC's.
407 In this mode, a single differential clock is used to supply
408 clocks to the sysclock, ddrclock and usbclock.
410 CONFIG_SYS_CPC_REINIT_F
411 This CONFIG is defined when the CPC is configured as SRAM at the
412 time of U-Boot entry and is required to be re-initialized.
415 Indicates this SoC supports deep sleep feature. If deep sleep is
416 supported, core will start to execute uboot when wakes up.
418 - Generic CPU options:
419 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
421 Defines the endianess of the CPU. Implementation of those
422 values is arch specific.
425 Freescale DDR driver in use. This type of DDR controller is
426 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
428 CONFIG_SYS_FSL_DDR_ADDR
429 Freescale DDR memory-mapped register base.
431 CONFIG_SYS_FSL_DDR_EMU
432 Specify emulator support for DDR. Some DDR features such as
433 deskew training are not available.
435 CONFIG_SYS_FSL_DDRC_GEN1
436 Freescale DDR1 controller.
438 CONFIG_SYS_FSL_DDRC_GEN2
439 Freescale DDR2 controller.
441 CONFIG_SYS_FSL_DDRC_GEN3
442 Freescale DDR3 controller.
444 CONFIG_SYS_FSL_DDRC_GEN4
445 Freescale DDR4 controller.
447 CONFIG_SYS_FSL_DDRC_ARM_GEN3
448 Freescale DDR3 controller for ARM-based SoCs.
451 Board config to use DDR1. It can be enabled for SoCs with
452 Freescale DDR1 or DDR2 controllers, depending on the board
456 Board config to use DDR2. It can be enabled for SoCs with
457 Freescale DDR2 or DDR3 controllers, depending on the board
461 Board config to use DDR3. It can be enabled for SoCs with
462 Freescale DDR3 or DDR3L controllers.
465 Board config to use DDR3L. It can be enabled for SoCs with
468 CONFIG_SYS_FSL_IFC_BE
469 Defines the IFC controller register space as Big Endian
471 CONFIG_SYS_FSL_IFC_LE
472 Defines the IFC controller register space as Little Endian
474 CONFIG_SYS_FSL_IFC_CLK_DIV
475 Defines divider of platform clock(clock input to IFC controller).
477 CONFIG_SYS_FSL_LBC_CLK_DIV
478 Defines divider of platform clock(clock input to eLBC controller).
480 CONFIG_SYS_FSL_DDR_BE
481 Defines the DDR controller register space as Big Endian
483 CONFIG_SYS_FSL_DDR_LE
484 Defines the DDR controller register space as Little Endian
486 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
487 Physical address from the view of DDR controllers. It is the
488 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
489 it could be different for ARM SoCs.
491 CONFIG_SYS_FSL_DDR_INTLV_256B
492 DDR controller interleaving on 256-byte. This is a special
493 interleaving mode, handled by Dickens for Freescale layerscape
496 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
497 Number of controllers used as main memory.
499 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
500 Number of controllers used for other than main memory.
502 CONFIG_SYS_FSL_HAS_DP_DDR
503 Defines the SoC has DP-DDR used for DPAA.
505 CONFIG_SYS_FSL_SEC_BE
506 Defines the SEC controller register space as Big Endian
508 CONFIG_SYS_FSL_SEC_LE
509 Defines the SEC controller register space as Little Endian
512 CONFIG_SYS_INIT_SP_OFFSET
514 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
515 pointer. This is needed for the temporary stack before
518 CONFIG_XWAY_SWAP_BYTES
520 Enable compilation of tools/xway-swap-bytes needed for Lantiq
521 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
522 be swapped if a flash programmer is used.
525 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
527 Select high exception vectors of the ARM core, e.g., do not
528 clear the V bit of the c1 register of CP15.
531 Generic timer clock source frequency.
533 COUNTER_FREQUENCY_REAL
534 Generic timer clock source frequency if the real clock is
535 different from COUNTER_FREQUENCY, and can only be determined
539 CONFIG_TEGRA_SUPPORT_NON_SECURE
541 Support executing U-Boot in non-secure (NS) mode. Certain
542 impossible actions will be skipped if the CPU is in NS mode,
543 such as ARM architectural timer initialization.
545 - Linux Kernel Interface:
546 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
548 When transferring memsize parameter to Linux, some versions
549 expect it to be in bytes, others in MB.
550 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
554 New kernel versions are expecting firmware settings to be
555 passed using flattened device trees (based on open firmware
559 * New libfdt-based support
560 * Adds the "fdt" command
561 * The bootm command automatically updates the fdt
563 OF_TBCLK - The timebase frequency.
565 boards with QUICC Engines require OF_QE to set UCC MAC
568 CONFIG_OF_SYSTEM_SETUP
570 Other code has addition modification that it wants to make
571 to the flat device tree before handing it off to the kernel.
572 This causes ft_system_setup() to be called before booting
577 U-Boot can detect if an IDE device is present or not.
578 If not, and this new config option is activated, U-Boot
579 removes the ATA node from the DTS before booting Linux,
580 so the Linux IDE driver does not probe the device and
581 crash. This is needed for buggy hardware (uc101) where
582 no pull down resistor is connected to the signal IDE5V_DD7.
584 - vxWorks boot parameters:
586 bootvx constructs a valid bootline using the following
587 environments variables: bootdev, bootfile, ipaddr, netmask,
588 serverip, gatewayip, hostname, othbootargs.
589 It loads the vxWorks image pointed bootfile.
591 Note: If a "bootargs" environment is defined, it will override
592 the defaults discussed just above.
594 - Cache Configuration for ARM:
595 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
597 CONFIG_SYS_PL310_BASE - Physical base address of PL310
598 controller register space
603 If you have Amba PrimeCell PL011 UARTs, set this variable to
604 the clock speed of the UARTs.
608 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
609 define this to a list of base addresses for each (supported)
610 port. See e.g. include/configs/versatile.h
612 CONFIG_SERIAL_HW_FLOW_CONTROL
614 Define this variable to enable hw flow control in serial driver.
615 Current user of this option is drivers/serial/nsl16550.c driver
617 - Serial Download Echo Mode:
619 If defined to 1, all characters received during a
620 serial download (using the "loads" command) are
621 echoed back. This might be needed by some terminal
622 emulations (like "cu"), but may as well just take
623 time on others. This setting #define's the initial
624 value of the "loads_echo" environment variable.
626 - Removal of commands
627 If no commands are needed to boot, you can disable
628 CONFIG_CMDLINE to remove them. In this case, the command line
629 will not be available, and when U-Boot wants to execute the
630 boot command (on start-up) it will call board_run_command()
631 instead. This can reduce image size significantly for very
632 simple boot procedures.
634 - Regular expression support:
636 If this variable is defined, U-Boot is linked against
637 the SLRE (Super Light Regular Expression) library,
638 which adds regex support to some commands, as for
639 example "env grep" and "setexpr".
642 CONFIG_SYS_WATCHDOG_FREQ
643 Some platforms automatically call WATCHDOG_RESET()
644 from the timer interrupt handler every
645 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
646 board configuration file, a default of CONFIG_SYS_HZ/2
647 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
648 to 0 disables calling WATCHDOG_RESET() from the timer
653 When CONFIG_CMD_DATE is selected, the type of the RTC
654 has to be selected, too. Define exactly one of the
657 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
658 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
659 CONFIG_RTC_MC146818 - use MC146818 RTC
660 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
661 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
662 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
663 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
664 CONFIG_RTC_DS164x - use Dallas DS164x RTC
665 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
666 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
667 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
668 CONFIG_SYS_RV3029_TCR - enable trickle charger on
671 Note that if the RTC uses I2C, then the I2C interface
672 must also be configured. See I2C Support, below.
675 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
677 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
678 chip-ngpio pairs that tell the PCA953X driver the number of
679 pins supported by a particular chip.
681 Note that if the GPIO device uses I2C, then the I2C interface
682 must also be configured. See I2C Support, below.
685 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
686 accesses and can checksum them or write a list of them out
687 to memory. See the 'iotrace' command for details. This is
688 useful for testing device drivers since it can confirm that
689 the driver behaves the same way before and after a code
690 change. Currently this is supported on sandbox and arm. To
691 add support for your architecture, add '#include <iotrace.h>'
692 to the bottom of arch/<arch>/include/asm/io.h and test.
694 Example output from the 'iotrace stats' command is below.
695 Note that if the trace buffer is exhausted, the checksum will
696 still continue to operate.
699 Start: 10000000 (buffer start address)
700 Size: 00010000 (buffer size)
701 Offset: 00000120 (current buffer offset)
702 Output: 10000120 (start + offset)
703 Count: 00000018 (number of trace records)
704 CRC32: 9526fb66 (CRC32 of all trace records)
708 When CONFIG_TIMESTAMP is selected, the timestamp
709 (date and time) of an image is printed by image
710 commands like bootm or iminfo. This option is
711 automatically enabled when you select CONFIG_CMD_DATE .
713 - Partition Labels (disklabels) Supported:
714 Zero or more of the following:
715 CONFIG_MAC_PARTITION Apple's MacOS partition table.
716 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
717 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
718 bootloader. Note 2TB partition limit; see
720 CONFIG_SCSI) you must configure support for at
721 least one non-MTD partition type as well.
724 CONFIG_IDE_RESET - is this is defined, IDE Reset will
725 be performed by calling the function
726 ide_set_reset(int reset)
727 which has to be defined in a board specific file
732 Set this to enable ATAPI support.
737 Set this to enable support for disks larger than 137GB
738 Also look at CONFIG_SYS_64BIT_LBA.
739 Whithout these , LBA48 support uses 32bit variables and will 'only'
740 support disks up to 2.1TB.
742 CONFIG_SYS_64BIT_LBA:
743 When enabled, makes the IDE subsystem use 64bit sector addresses.
747 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
748 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
749 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
750 maximum numbers of LUNs, SCSI ID's and target
753 The environment variable 'scsidevs' is set to the number of
754 SCSI devices found during the last scan.
756 - NETWORK Support (PCI):
758 Utility code for direct access to the SPI bus on Intel 8257x.
759 This does not do anything useful unless you set at least one
760 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
763 Support for National dp83815 chips.
766 Support for National dp8382[01] gigabit chips.
768 - NETWORK Support (other):
770 Support for the Calxeda XGMAC device
773 Support for SMSC's LAN91C96 chips.
775 CONFIG_LAN91C96_USE_32_BIT
776 Define this to enable 32 bit addressing
779 Support for SMSC's LAN91C111 chip
782 Define this to hold the physical address
783 of the device (I/O space)
785 CONFIG_SMC_USE_32_BIT
786 Define this if data bus is 32 bits
788 CONFIG_SMC_USE_IOFUNCS
789 Define this to use i/o functions instead of macros
790 (some hardware wont work with macros)
792 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
793 Define this if you have more then 3 PHYs.
796 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
798 CONFIG_FTGMAC100_EGIGA
799 Define this to use GE link update with gigabit PHY.
800 Define this if FTGMAC100 is connected to gigabit PHY.
801 If your system has 10/100 PHY only, it might not occur
802 wrong behavior. Because PHY usually return timeout or
803 useless data when polling gigabit status and gigabit
804 control registers. This behavior won't affect the
805 correctnessof 10/100 link speed update.
808 Support for Renesas on-chip Ethernet controller
810 CONFIG_SH_ETHER_USE_PORT
811 Define the number of ports to be used
813 CONFIG_SH_ETHER_PHY_ADDR
814 Define the ETH PHY's address
816 CONFIG_SH_ETHER_CACHE_WRITEBACK
817 If this option is set, the driver enables cache flush.
823 CONFIG_TPM_TIS_INFINEON
824 Support for Infineon i2c bus TPM devices. Only one device
825 per system is supported at this time.
827 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
828 Define the burst count bytes upper limit
831 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
833 CONFIG_TPM_ST33ZP24_I2C
834 Support for STMicroelectronics ST33ZP24 I2C devices.
835 Requires TPM_ST33ZP24 and I2C.
837 CONFIG_TPM_ST33ZP24_SPI
838 Support for STMicroelectronics ST33ZP24 SPI devices.
839 Requires TPM_ST33ZP24 and SPI.
842 Support for Atmel TWI TPM device. Requires I2C support.
845 Support for generic parallel port TPM devices. Only one device
846 per system is supported at this time.
848 CONFIG_TPM_TIS_BASE_ADDRESS
849 Base address where the generic TPM device is mapped
850 to. Contemporary x86 systems usually map it at
854 Define this to enable the TPM support library which provides
855 functional interfaces to some TPM commands.
856 Requires support for a TPM device.
858 CONFIG_TPM_AUTH_SESSIONS
859 Define this to enable authorized functions in the TPM library.
860 Requires CONFIG_TPM and CONFIG_SHA1.
863 At the moment only the UHCI host controller is
864 supported (PIP405, MIP405); define
865 CONFIG_USB_UHCI to enable it.
866 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
867 and define CONFIG_USB_STORAGE to enable the USB
870 Supported are USB Keyboards and USB Floppy drives
873 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
874 txfilltuning field in the EHCI controller on reset.
876 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
880 Define the below if you wish to use the USB console.
881 Once firmware is rebuilt from a serial console issue the
882 command "setenv stdin usbtty; setenv stdout usbtty" and
883 attach your USB cable. The Unix command "dmesg" should print
884 it has found a new device. The environment variable usbtty
885 can be set to gserial or cdc_acm to enable your device to
886 appear to a USB host as a Linux gserial device or a
887 Common Device Class Abstract Control Model serial device.
888 If you select usbtty = gserial you should be able to enumerate
890 # modprobe usbserial vendor=0xVendorID product=0xProductID
891 else if using cdc_acm, simply setting the environment
892 variable usbtty to be cdc_acm should suffice. The following
893 might be defined in YourBoardName.h
896 Define this to build a UDC device
899 Define this to have a tty type of device available to
900 talk to the UDC device
903 Define this to enable the high speed support for usb
904 device and usbtty. If this feature is enabled, a routine
905 int is_usbd_high_speed(void)
906 also needs to be defined by the driver to dynamically poll
907 whether the enumeration has succeded at high speed or full
910 If you have a USB-IF assigned VendorID then you may wish to
911 define your own vendor specific values either in BoardName.h
912 or directly in usbd_vendor_info.h. If you don't define
913 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
914 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
915 should pretend to be a Linux device to it's target host.
917 CONFIG_USBD_MANUFACTURER
918 Define this string as the name of your company for
919 - CONFIG_USBD_MANUFACTURER "my company"
921 CONFIG_USBD_PRODUCT_NAME
922 Define this string as the name of your product
923 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
926 Define this as your assigned Vendor ID from the USB
927 Implementors Forum. This *must* be a genuine Vendor ID
928 to avoid polluting the USB namespace.
929 - CONFIG_USBD_VENDORID 0xFFFF
931 CONFIG_USBD_PRODUCTID
932 Define this as the unique Product ID
934 - CONFIG_USBD_PRODUCTID 0xFFFF
936 - ULPI Layer Support:
937 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
938 the generic ULPI layer. The generic layer accesses the ULPI PHY
939 via the platform viewport, so you need both the genric layer and
940 the viewport enabled. Currently only Chipidea/ARC based
941 viewport is supported.
942 To enable the ULPI layer support, define CONFIG_USB_ULPI and
943 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
944 If your ULPI phy needs a different reference clock than the
945 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
946 the appropriate value in Hz.
949 The MMC controller on the Intel PXA is supported. To
950 enable this define CONFIG_MMC. The MMC can be
951 accessed from the boot prompt by mapping the device
952 to physical memory similar to flash. Command line is
953 enabled with CONFIG_CMD_MMC. The MMC driver also works with
954 the FAT fs. This is enabled with CONFIG_CMD_FAT.
957 Support for Renesas on-chip MMCIF controller
960 Define the base address of MMCIF registers
963 Define the clock frequency for MMCIF
965 - USB Device Firmware Update (DFU) class support:
967 This enables the USB portion of the DFU USB class
970 This enables support for exposing NAND devices via DFU.
973 This enables support for exposing RAM via DFU.
974 Note: DFU spec refer to non-volatile memory usage, but
975 allow usages beyond the scope of spec - here RAM usage,
976 one that would help mostly the developer.
978 CONFIG_SYS_DFU_DATA_BUF_SIZE
979 Dfu transfer uses a buffer before writing data to the
980 raw storage device. Make the size (in bytes) of this buffer
981 configurable. The size of this buffer is also configurable
982 through the "dfu_bufsiz" environment variable.
984 CONFIG_SYS_DFU_MAX_FILE_SIZE
985 When updating files rather than the raw storage device,
986 we use a static buffer to copy the file into and then write
987 the buffer once we've been given the whole file. Define
988 this to the maximum filesize (in bytes) for the buffer.
989 Default is 4 MiB if undefined.
991 DFU_DEFAULT_POLL_TIMEOUT
992 Poll timeout [ms], is the timeout a device can send to the
993 host. The host must wait for this timeout before sending
994 a subsequent DFU_GET_STATUS request to the device.
996 DFU_MANIFEST_POLL_TIMEOUT
997 Poll timeout [ms], which the device sends to the host when
998 entering dfuMANIFEST state. Host waits this timeout, before
999 sending again an USB request to the device.
1001 - Journaling Flash filesystem support:
1003 Define these for a default partition on a NAND device
1005 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1006 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1007 Define these for a default partition on a NOR device
1010 See Kconfig help for available keyboard drivers.
1014 Enable the Freescale DIU video driver. Reference boards for
1015 SOCs that have a DIU should define this macro to enable DIU
1016 support, and should also define these other macros:
1021 CONFIG_VIDEO_SW_CURSOR
1022 CONFIG_VGA_AS_SINGLE_DEVICE
1024 CONFIG_VIDEO_BMP_LOGO
1026 The DIU driver will look for the 'video-mode' environment
1027 variable, and if defined, enable the DIU as a console during
1028 boot. See the documentation file doc/README.video for a
1029 description of this variable.
1031 - LCD Support: CONFIG_LCD
1033 Define this to enable LCD support (for output to LCD
1034 display); also select one of the supported displays
1035 by defining one of these:
1039 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1041 CONFIG_NEC_NL6448AC33:
1043 NEC NL6448AC33-18. Active, color, single scan.
1045 CONFIG_NEC_NL6448BC20
1047 NEC NL6448BC20-08. 6.5", 640x480.
1048 Active, color, single scan.
1050 CONFIG_NEC_NL6448BC33_54
1052 NEC NL6448BC33-54. 10.4", 640x480.
1053 Active, color, single scan.
1057 Sharp 320x240. Active, color, single scan.
1058 It isn't 16x9, and I am not sure what it is.
1060 CONFIG_SHARP_LQ64D341
1062 Sharp LQ64D341 display, 640x480.
1063 Active, color, single scan.
1067 HLD1045 display, 640x480.
1068 Active, color, single scan.
1072 Optrex CBL50840-2 NF-FW 99 22 M5
1074 Hitachi LMG6912RPFC-00T
1078 320x240. Black & white.
1080 CONFIG_LCD_ALIGNMENT
1082 Normally the LCD is page-aligned (typically 4KB). If this is
1083 defined then the LCD will be aligned to this value instead.
1084 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1085 here, since it is cheaper to change data cache settings on
1086 a per-section basis.
1091 Sometimes, for example if the display is mounted in portrait
1092 mode or even if it's mounted landscape but rotated by 180degree,
1093 we need to rotate our content of the display relative to the
1094 framebuffer, so that user can read the messages which are
1096 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1097 initialized with a given rotation from "vl_rot" out of
1098 "vidinfo_t" which is provided by the board specific code.
1099 The value for vl_rot is coded as following (matching to
1100 fbcon=rotate:<n> linux-kernel commandline):
1101 0 = no rotation respectively 0 degree
1102 1 = 90 degree rotation
1103 2 = 180 degree rotation
1104 3 = 270 degree rotation
1106 If CONFIG_LCD_ROTATION is not defined, the console will be
1107 initialized with 0degree rotation.
1111 Support drawing of RLE8-compressed bitmaps on the LCD.
1114 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1116 The clock frequency of the MII bus
1118 CONFIG_PHY_RESET_DELAY
1120 Some PHY like Intel LXT971A need extra delay after
1121 reset before any MII register access is possible.
1122 For such PHY, set this option to the usec delay
1123 required. (minimum 300usec for LXT971A)
1125 CONFIG_PHY_CMD_DELAY (ppc4xx)
1127 Some PHY like Intel LXT971A need extra delay after
1128 command issued before MII status register can be read
1133 Define a default value for the IP address to use for
1134 the default Ethernet interface, in case this is not
1135 determined through e.g. bootp.
1136 (Environment variable "ipaddr")
1138 - Server IP address:
1141 Defines a default value for the IP address of a TFTP
1142 server to contact when using the "tftboot" command.
1143 (Environment variable "serverip")
1145 CONFIG_KEEP_SERVERADDR
1147 Keeps the server's MAC address, in the env 'serveraddr'
1148 for passing to bootargs (like Linux's netconsole option)
1150 - Gateway IP address:
1153 Defines a default value for the IP address of the
1154 default router where packets to other networks are
1156 (Environment variable "gatewayip")
1161 Defines a default value for the subnet mask (or
1162 routing prefix) which is used to determine if an IP
1163 address belongs to the local subnet or needs to be
1164 forwarded through a router.
1165 (Environment variable "netmask")
1167 - BOOTP Recovery Mode:
1168 CONFIG_BOOTP_RANDOM_DELAY
1170 If you have many targets in a network that try to
1171 boot using BOOTP, you may want to avoid that all
1172 systems send out BOOTP requests at precisely the same
1173 moment (which would happen for instance at recovery
1174 from a power failure, when all systems will try to
1175 boot, thus flooding the BOOTP server. Defining
1176 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1177 inserted before sending out BOOTP requests. The
1178 following delays are inserted then:
1180 1st BOOTP request: delay 0 ... 1 sec
1181 2nd BOOTP request: delay 0 ... 2 sec
1182 3rd BOOTP request: delay 0 ... 4 sec
1184 BOOTP requests: delay 0 ... 8 sec
1186 CONFIG_BOOTP_ID_CACHE_SIZE
1188 BOOTP packets are uniquely identified using a 32-bit ID. The
1189 server will copy the ID from client requests to responses and
1190 U-Boot will use this to determine if it is the destination of
1191 an incoming response. Some servers will check that addresses
1192 aren't in use before handing them out (usually using an ARP
1193 ping) and therefore take up to a few hundred milliseconds to
1194 respond. Network congestion may also influence the time it
1195 takes for a response to make it back to the client. If that
1196 time is too long, U-Boot will retransmit requests. In order
1197 to allow earlier responses to still be accepted after these
1198 retransmissions, U-Boot's BOOTP client keeps a small cache of
1199 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1200 cache. The default is to keep IDs for up to four outstanding
1201 requests. Increasing this will allow U-Boot to accept offers
1202 from a BOOTP client in networks with unusually high latency.
1204 - DHCP Advanced Options:
1205 You can fine tune the DHCP functionality by defining
1206 CONFIG_BOOTP_* symbols:
1208 CONFIG_BOOTP_NISDOMAIN
1209 CONFIG_BOOTP_BOOTFILESIZE
1210 CONFIG_BOOTP_NTPSERVER
1211 CONFIG_BOOTP_TIMEOFFSET
1212 CONFIG_BOOTP_VENDOREX
1213 CONFIG_BOOTP_MAY_FAIL
1215 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1216 environment variable, not the BOOTP server.
1218 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1219 after the configured retry count, the call will fail
1220 instead of starting over. This can be used to fail over
1221 to Link-local IP address configuration if the DHCP server
1224 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1226 A 32bit value in microseconds for a delay between
1227 receiving a "DHCP Offer" and sending the "DHCP Request".
1228 This fixes a problem with certain DHCP servers that don't
1229 respond 100% of the time to a "DHCP request". E.g. On an
1230 AT91RM9200 processor running at 180MHz, this delay needed
1231 to be *at least* 15,000 usec before a Windows Server 2003
1232 DHCP server would reply 100% of the time. I recommend at
1233 least 50,000 usec to be safe. The alternative is to hope
1234 that one of the retries will be successful but note that
1235 the DHCP timeout and retry process takes a longer than
1238 - Link-local IP address negotiation:
1239 Negotiate with other link-local clients on the local network
1240 for an address that doesn't require explicit configuration.
1241 This is especially useful if a DHCP server cannot be guaranteed
1242 to exist in all environments that the device must operate.
1244 See doc/README.link-local for more information.
1246 - MAC address from environment variables
1248 FDT_SEQ_MACADDR_FROM_ENV
1250 Fix-up device tree with MAC addresses fetched sequentially from
1251 environment variables. This config work on assumption that
1252 non-usable ethernet node of device-tree are either not present
1253 or their status has been marked as "disabled".
1256 CONFIG_CDP_DEVICE_ID
1258 The device id used in CDP trigger frames.
1260 CONFIG_CDP_DEVICE_ID_PREFIX
1262 A two character string which is prefixed to the MAC address
1267 A printf format string which contains the ascii name of
1268 the port. Normally is set to "eth%d" which sets
1269 eth0 for the first Ethernet, eth1 for the second etc.
1271 CONFIG_CDP_CAPABILITIES
1273 A 32bit integer which indicates the device capabilities;
1274 0x00000010 for a normal host which does not forwards.
1278 An ascii string containing the version of the software.
1282 An ascii string containing the name of the platform.
1286 A 32bit integer sent on the trigger.
1288 CONFIG_CDP_POWER_CONSUMPTION
1290 A 16bit integer containing the power consumption of the
1291 device in .1 of milliwatts.
1293 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1295 A byte containing the id of the VLAN.
1297 - Status LED: CONFIG_LED_STATUS
1299 Several configurations allow to display the current
1300 status using a LED. For instance, the LED will blink
1301 fast while running U-Boot code, stop blinking as
1302 soon as a reply to a BOOTP request was received, and
1303 start blinking slow once the Linux kernel is running
1304 (supported by a status LED driver in the Linux
1305 kernel). Defining CONFIG_LED_STATUS enables this
1310 CONFIG_LED_STATUS_GPIO
1311 The status LED can be connected to a GPIO pin.
1312 In such cases, the gpio_led driver can be used as a
1313 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1314 to include the gpio_led driver in the U-Boot binary.
1316 CONFIG_GPIO_LED_INVERTED_TABLE
1317 Some GPIO connected LEDs may have inverted polarity in which
1318 case the GPIO high value corresponds to LED off state and
1319 GPIO low value corresponds to LED on state.
1320 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1321 with a list of GPIO LEDs that have inverted polarity.
1324 CONFIG_SYS_NUM_I2C_BUSES
1325 Hold the number of i2c buses you want to use.
1327 CONFIG_SYS_I2C_DIRECT_BUS
1328 define this, if you don't use i2c muxes on your hardware.
1329 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1332 CONFIG_SYS_I2C_MAX_HOPS
1333 define how many muxes are maximal consecutively connected
1334 on one i2c bus. If you not use i2c muxes, omit this
1337 CONFIG_SYS_I2C_BUSES
1338 hold a list of buses you want to use, only used if
1339 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1340 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1341 CONFIG_SYS_NUM_I2C_BUSES = 9:
1343 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1344 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1345 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1346 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1347 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1348 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1349 {1, {I2C_NULL_HOP}}, \
1350 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1351 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1355 bus 0 on adapter 0 without a mux
1356 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1357 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1358 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1359 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1360 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1361 bus 6 on adapter 1 without a mux
1362 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1363 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1365 If you do not have i2c muxes on your board, omit this define.
1367 - Legacy I2C Support:
1368 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1369 then the following macros need to be defined (examples are
1370 from include/configs/lwmon.h):
1374 (Optional). Any commands necessary to enable the I2C
1375 controller or configure ports.
1377 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1381 The code necessary to make the I2C data line active
1382 (driven). If the data line is open collector, this
1385 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1389 The code necessary to make the I2C data line tri-stated
1390 (inactive). If the data line is open collector, this
1393 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1397 Code that returns true if the I2C data line is high,
1400 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1404 If <bit> is true, sets the I2C data line high. If it
1405 is false, it clears it (low).
1407 eg: #define I2C_SDA(bit) \
1408 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1409 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1413 If <bit> is true, sets the I2C clock line high. If it
1414 is false, it clears it (low).
1416 eg: #define I2C_SCL(bit) \
1417 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1418 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1422 This delay is invoked four times per clock cycle so this
1423 controls the rate of data transfer. The data rate thus
1424 is 1 / (I2C_DELAY * 4). Often defined to be something
1427 #define I2C_DELAY udelay(2)
1429 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1431 If your arch supports the generic GPIO framework (asm/gpio.h),
1432 then you may alternatively define the two GPIOs that are to be
1433 used as SCL / SDA. Any of the previous I2C_xxx macros will
1434 have GPIO-based defaults assigned to them as appropriate.
1436 You should define these to the GPIO value as given directly to
1437 the generic GPIO functions.
1439 CONFIG_SYS_I2C_INIT_BOARD
1441 When a board is reset during an i2c bus transfer
1442 chips might think that the current transfer is still
1443 in progress. On some boards it is possible to access
1444 the i2c SCLK line directly, either by using the
1445 processor pin as a GPIO or by having a second pin
1446 connected to the bus. If this option is defined a
1447 custom i2c_init_board() routine in boards/xxx/board.c
1448 is run early in the boot sequence.
1450 CONFIG_I2C_MULTI_BUS
1452 This option allows the use of multiple I2C buses, each of which
1453 must have a controller. At any point in time, only one bus is
1454 active. To switch to a different bus, use the 'i2c dev' command.
1455 Note that bus numbering is zero-based.
1457 CONFIG_SYS_I2C_NOPROBES
1459 This option specifies a list of I2C devices that will be skipped
1460 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1461 is set, specify a list of bus-device pairs. Otherwise, specify
1462 a 1D array of device addresses
1465 #undef CONFIG_I2C_MULTI_BUS
1466 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1468 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1470 #define CONFIG_I2C_MULTI_BUS
1471 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1473 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1475 CONFIG_SYS_SPD_BUS_NUM
1477 If defined, then this indicates the I2C bus number for DDR SPD.
1478 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1480 CONFIG_SYS_RTC_BUS_NUM
1482 If defined, then this indicates the I2C bus number for the RTC.
1483 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1485 CONFIG_SOFT_I2C_READ_REPEATED_START
1487 defining this will force the i2c_read() function in
1488 the soft_i2c driver to perform an I2C repeated start
1489 between writing the address pointer and reading the
1490 data. If this define is omitted the default behaviour
1491 of doing a stop-start sequence will be used. Most I2C
1492 devices can use either method, but some require one or
1495 - SPI Support: CONFIG_SPI
1497 Enables SPI driver (so far only tested with
1498 SPI EEPROM, also an instance works with Crystal A/D and
1499 D/As on the SACSng board)
1501 CONFIG_SYS_SPI_MXC_WAIT
1502 Timeout for waiting until spi transfer completed.
1503 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1505 - FPGA Support: CONFIG_FPGA
1507 Enables FPGA subsystem.
1509 CONFIG_FPGA_<vendor>
1511 Enables support for specific chip vendors.
1514 CONFIG_FPGA_<family>
1516 Enables support for FPGA family.
1517 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1521 Specify the number of FPGA devices to support.
1523 CONFIG_SYS_FPGA_PROG_FEEDBACK
1525 Enable printing of hash marks during FPGA configuration.
1527 CONFIG_SYS_FPGA_CHECK_BUSY
1529 Enable checks on FPGA configuration interface busy
1530 status by the configuration function. This option
1531 will require a board or device specific function to
1536 If defined, a function that provides delays in the FPGA
1537 configuration driver.
1539 CONFIG_SYS_FPGA_CHECK_CTRLC
1540 Allow Control-C to interrupt FPGA configuration
1542 CONFIG_SYS_FPGA_CHECK_ERROR
1544 Check for configuration errors during FPGA bitfile
1545 loading. For example, abort during Virtex II
1546 configuration if the INIT_B line goes low (which
1547 indicated a CRC error).
1549 CONFIG_SYS_FPGA_WAIT_INIT
1551 Maximum time to wait for the INIT_B line to de-assert
1552 after PROB_B has been de-asserted during a Virtex II
1553 FPGA configuration sequence. The default time is 500
1556 CONFIG_SYS_FPGA_WAIT_BUSY
1558 Maximum time to wait for BUSY to de-assert during
1559 Virtex II FPGA configuration. The default is 5 ms.
1561 CONFIG_SYS_FPGA_WAIT_CONFIG
1563 Time to wait after FPGA configuration. The default is
1566 - Vendor Parameter Protection:
1568 U-Boot considers the values of the environment
1569 variables "serial#" (Board Serial Number) and
1570 "ethaddr" (Ethernet Address) to be parameters that
1571 are set once by the board vendor / manufacturer, and
1572 protects these variables from casual modification by
1573 the user. Once set, these variables are read-only,
1574 and write or delete attempts are rejected. You can
1575 change this behaviour:
1577 If CONFIG_ENV_OVERWRITE is #defined in your config
1578 file, the write protection for vendor parameters is
1579 completely disabled. Anybody can change or delete
1582 Alternatively, if you define _both_ an ethaddr in the
1583 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1584 Ethernet address is installed in the environment,
1585 which can be changed exactly ONCE by the user. [The
1586 serial# is unaffected by this, i. e. it remains
1589 The same can be accomplished in a more flexible way
1590 for any variable by configuring the type of access
1591 to allow for those variables in the ".flags" variable
1592 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1597 Define this variable to enable the reservation of
1598 "protected RAM", i. e. RAM which is not overwritten
1599 by U-Boot. Define CONFIG_PRAM to hold the number of
1600 kB you want to reserve for pRAM. You can overwrite
1601 this default value by defining an environment
1602 variable "pram" to the number of kB you want to
1603 reserve. Note that the board info structure will
1604 still show the full amount of RAM. If pRAM is
1605 reserved, a new environment variable "mem" will
1606 automatically be defined to hold the amount of
1607 remaining RAM in a form that can be passed as boot
1608 argument to Linux, for instance like that:
1610 setenv bootargs ... mem=\${mem}
1613 This way you can tell Linux not to use this memory,
1614 either, which results in a memory region that will
1615 not be affected by reboots.
1617 *WARNING* If your board configuration uses automatic
1618 detection of the RAM size, you must make sure that
1619 this memory test is non-destructive. So far, the
1620 following board configurations are known to be
1623 IVMS8, IVML24, SPD8xx,
1624 HERMES, IP860, RPXlite, LWMON,
1628 CONFIG_NET_RETRY_COUNT
1630 This variable defines the number of retries for
1631 network operations like ARP, RARP, TFTP, or BOOTP
1632 before giving up the operation. If not defined, a
1633 default value of 5 is used.
1637 Timeout waiting for an ARP reply in milliseconds.
1641 Timeout in milliseconds used in NFS protocol.
1642 If you encounter "ERROR: Cannot umount" in nfs command,
1643 try longer timeout such as
1644 #define CONFIG_NFS_TIMEOUT 10000UL
1648 In the current implementation, the local variables
1649 space and global environment variables space are
1650 separated. Local variables are those you define by
1651 simply typing `name=value'. To access a local
1652 variable later on, you have write `$name' or
1653 `${name}'; to execute the contents of a variable
1654 directly type `$name' at the command prompt.
1656 Global environment variables are those you use
1657 setenv/printenv to work with. To run a command stored
1658 in such a variable, you need to use the run command,
1659 and you must not use the '$' sign to access them.
1661 To store commands and special characters in a
1662 variable, please use double quotation marks
1663 surrounding the whole text of the variable, instead
1664 of the backslashes before semicolons and special
1667 - Command Line Editing and History:
1668 CONFIG_CMDLINE_PS_SUPPORT
1670 Enable support for changing the command prompt string
1671 at run-time. Only static string is supported so far.
1672 The string is obtained from environment variables PS1
1675 - Default Environment:
1676 CONFIG_EXTRA_ENV_SETTINGS
1678 Define this to contain any number of null terminated
1679 strings (variable = value pairs) that will be part of
1680 the default environment compiled into the boot image.
1682 For example, place something like this in your
1683 board's config file:
1685 #define CONFIG_EXTRA_ENV_SETTINGS \
1689 Warning: This method is based on knowledge about the
1690 internal format how the environment is stored by the
1691 U-Boot code. This is NOT an official, exported
1692 interface! Although it is unlikely that this format
1693 will change soon, there is no guarantee either.
1694 You better know what you are doing here.
1696 Note: overly (ab)use of the default environment is
1697 discouraged. Make sure to check other ways to preset
1698 the environment like the "source" command or the
1701 CONFIG_DELAY_ENVIRONMENT
1703 Normally the environment is loaded when the board is
1704 initialised so that it is available to U-Boot. This inhibits
1705 that so that the environment is not available until
1706 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1707 this is instead controlled by the value of
1708 /config/load-environment.
1710 - TFTP Fixed UDP Port:
1713 If this is defined, the environment variable tftpsrcp
1714 is used to supply the TFTP UDP source port value.
1715 If tftpsrcp isn't defined, the normal pseudo-random port
1716 number generator is used.
1718 Also, the environment variable tftpdstp is used to supply
1719 the TFTP UDP destination port value. If tftpdstp isn't
1720 defined, the normal port 69 is used.
1722 The purpose for tftpsrcp is to allow a TFTP server to
1723 blindly start the TFTP transfer using the pre-configured
1724 target IP address and UDP port. This has the effect of
1725 "punching through" the (Windows XP) firewall, allowing
1726 the remainder of the TFTP transfer to proceed normally.
1727 A better solution is to properly configure the firewall,
1728 but sometimes that is not allowed.
1730 CONFIG_STANDALONE_LOAD_ADDR
1732 This option defines a board specific value for the
1733 address where standalone program gets loaded, thus
1734 overwriting the architecture dependent default
1737 - Frame Buffer Address:
1740 Define CONFIG_FB_ADDR if you want to use specific
1741 address for frame buffer. This is typically the case
1742 when using a graphics controller has separate video
1743 memory. U-Boot will then place the frame buffer at
1744 the given address instead of dynamically reserving it
1745 in system RAM by calling lcd_setmem(), which grabs
1746 the memory for the frame buffer depending on the
1747 configured panel size.
1749 Please see board_init_f function.
1751 - Automatic software updates via TFTP server
1753 CONFIG_UPDATE_TFTP_CNT_MAX
1754 CONFIG_UPDATE_TFTP_MSEC_MAX
1756 These options enable and control the auto-update feature;
1757 for a more detailed description refer to doc/README.update.
1759 - MTD Support (mtdparts command, UBI support)
1760 CONFIG_MTD_UBI_WL_THRESHOLD
1761 This parameter defines the maximum difference between the highest
1762 erase counter value and the lowest erase counter value of eraseblocks
1763 of UBI devices. When this threshold is exceeded, UBI starts performing
1764 wear leveling by means of moving data from eraseblock with low erase
1765 counter to eraseblocks with high erase counter.
1767 The default value should be OK for SLC NAND flashes, NOR flashes and
1768 other flashes which have eraseblock life-cycle 100000 or more.
1769 However, in case of MLC NAND flashes which typically have eraseblock
1770 life-cycle less than 10000, the threshold should be lessened (e.g.,
1771 to 128 or 256, although it does not have to be power of 2).
1775 CONFIG_MTD_UBI_BEB_LIMIT
1776 This option specifies the maximum bad physical eraseblocks UBI
1777 expects on the MTD device (per 1024 eraseblocks). If the
1778 underlying flash does not admit of bad eraseblocks (e.g. NOR
1779 flash), this value is ignored.
1781 NAND datasheets often specify the minimum and maximum NVM
1782 (Number of Valid Blocks) for the flashes' endurance lifetime.
1783 The maximum expected bad eraseblocks per 1024 eraseblocks
1784 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1785 which gives 20 for most NANDs (MaxNVB is basically the total
1786 count of eraseblocks on the chip).
1788 To put it differently, if this value is 20, UBI will try to
1789 reserve about 1.9% of physical eraseblocks for bad blocks
1790 handling. And that will be 1.9% of eraseblocks on the entire
1791 NAND chip, not just the MTD partition UBI attaches. This means
1792 that if you have, say, a NAND flash chip admits maximum 40 bad
1793 eraseblocks, and it is split on two MTD partitions of the same
1794 size, UBI will reserve 40 eraseblocks when attaching a
1799 CONFIG_MTD_UBI_FASTMAP
1800 Fastmap is a mechanism which allows attaching an UBI device
1801 in nearly constant time. Instead of scanning the whole MTD device it
1802 only has to locate a checkpoint (called fastmap) on the device.
1803 The on-flash fastmap contains all information needed to attach
1804 the device. Using fastmap makes only sense on large devices where
1805 attaching by scanning takes long. UBI will not automatically install
1806 a fastmap on old images, but you can set the UBI parameter
1807 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1808 that fastmap-enabled images are still usable with UBI implementations
1809 without fastmap support. On typical flash devices the whole fastmap
1810 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1812 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1813 Set this parameter to enable fastmap automatically on images
1817 CONFIG_MTD_UBI_FM_DEBUG
1818 Enable UBI fastmap debug
1823 Enable building of SPL globally.
1825 CONFIG_SPL_MAX_FOOTPRINT
1826 Maximum size in memory allocated to the SPL, BSS included.
1827 When defined, the linker checks that the actual memory
1828 used by SPL from _start to __bss_end does not exceed it.
1829 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1830 must not be both defined at the same time.
1833 Maximum size of the SPL image (text, data, rodata, and
1834 linker lists sections), BSS excluded.
1835 When defined, the linker checks that the actual size does
1838 CONFIG_SPL_RELOC_TEXT_BASE
1839 Address to relocate to. If unspecified, this is equal to
1840 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1842 CONFIG_SPL_BSS_START_ADDR
1843 Link address for the BSS within the SPL binary.
1845 CONFIG_SPL_BSS_MAX_SIZE
1846 Maximum size in memory allocated to the SPL BSS.
1847 When defined, the linker checks that the actual memory used
1848 by SPL from __bss_start to __bss_end does not exceed it.
1849 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1850 must not be both defined at the same time.
1853 Adress of the start of the stack SPL will use
1855 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1856 When defined, SPL will panic() if the image it has
1857 loaded does not have a signature.
1858 Defining this is useful when code which loads images
1859 in SPL cannot guarantee that absolutely all read errors
1861 An example is the LPC32XX MLC NAND driver, which will
1862 consider that a completely unreadable NAND block is bad,
1863 and thus should be skipped silently.
1865 CONFIG_SPL_RELOC_STACK
1866 Adress of the start of the stack SPL will use after
1867 relocation. If unspecified, this is equal to
1870 CONFIG_SYS_SPL_MALLOC_START
1871 Starting address of the malloc pool used in SPL.
1872 When this option is set the full malloc is used in SPL and
1873 it is set up by spl_init() and before that, the simple malloc()
1874 can be used if CONFIG_SYS_MALLOC_F is defined.
1876 CONFIG_SYS_SPL_MALLOC_SIZE
1877 The size of the malloc pool used in SPL.
1879 CONFIG_SPL_DISPLAY_PRINT
1880 For ARM, enable an optional function to print more information
1881 about the running system.
1883 CONFIG_SPL_INIT_MINIMAL
1884 Arch init code should be built for a very small image
1886 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
1887 Sector to load kernel uImage from when MMC is being
1888 used in raw mode (for Falcon mode)
1890 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
1891 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
1892 Sector and number of sectors to load kernel argument
1893 parameters from when MMC is being used in raw mode
1896 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
1897 Filename to read to load U-Boot when reading from filesystem
1899 CONFIG_SPL_FS_LOAD_KERNEL_NAME
1900 Filename to read to load kernel uImage when reading
1901 from filesystem (for Falcon mode)
1903 CONFIG_SPL_FS_LOAD_ARGS_NAME
1904 Filename to read to load kernel argument parameters
1905 when reading from filesystem (for Falcon mode)
1907 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1908 Set this for NAND SPL on PPC mpc83xx targets, so that
1909 start.S waits for the rest of the SPL to load before
1910 continuing (the hardware starts execution after just
1911 loading the first page rather than the full 4K).
1913 CONFIG_SPL_SKIP_RELOCATE
1914 Avoid SPL relocation
1916 CONFIG_SPL_NAND_IDENT
1917 SPL uses the chip ID list to identify the NAND flash.
1918 Requires CONFIG_SPL_NAND_BASE.
1921 Support for a lightweight UBI (fastmap) scanner and
1924 CONFIG_SPL_NAND_RAW_ONLY
1925 Support to boot only raw u-boot.bin images. Use this only
1926 if you need to save space.
1928 CONFIG_SPL_COMMON_INIT_DDR
1929 Set for common ddr init with serial presence detect in
1932 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1933 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1934 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1935 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1936 CONFIG_SYS_NAND_ECCBYTES
1937 Defines the size and behavior of the NAND that SPL uses
1940 CONFIG_SYS_NAND_U_BOOT_DST
1941 Location in memory to load U-Boot to
1943 CONFIG_SYS_NAND_U_BOOT_SIZE
1944 Size of image to load
1946 CONFIG_SYS_NAND_U_BOOT_START
1947 Entry point in loaded image to jump to
1949 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1950 Define this if you need to first read the OOB and then the
1951 data. This is used, for example, on davinci platforms.
1953 CONFIG_SPL_RAM_DEVICE
1954 Support for running image already present in ram, in SPL binary
1957 Image offset to which the SPL should be padded before appending
1958 the SPL payload. By default, this is defined as
1959 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1960 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1961 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1964 Final target image containing SPL and payload. Some SPLs
1965 use an arch-specific makefile fragment instead, for
1966 example if more than one image needs to be produced.
1968 CONFIG_SPL_FIT_PRINT
1969 Printing information about a FIT image adds quite a bit of
1970 code to SPL. So this is normally disabled in SPL. Use this
1971 option to re-enable it. This will affect the output of the
1972 bootm command when booting a FIT image.
1976 Enable building of TPL globally.
1979 Image offset to which the TPL should be padded before appending
1980 the TPL payload. By default, this is defined as
1981 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1982 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1983 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1985 - Interrupt support (PPC):
1987 There are common interrupt_init() and timer_interrupt()
1988 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1989 for CPU specific initialization. interrupt_init_cpu()
1990 should set decrementer_count to appropriate value. If
1991 CPU resets decrementer automatically after interrupt
1992 (ppc4xx) it should set decrementer_count to zero.
1993 timer_interrupt() calls timer_interrupt_cpu() for CPU
1994 specific handling. If board has watchdog / status_led
1995 / other_activity_monitor it works automatically from
1996 general timer_interrupt().
1999 Board initialization settings:
2000 ------------------------------
2002 During Initialization u-boot calls a number of board specific functions
2003 to allow the preparation of board specific prerequisites, e.g. pin setup
2004 before drivers are initialized. To enable these callbacks the
2005 following configuration macros have to be defined. Currently this is
2006 architecture specific, so please check arch/your_architecture/lib/board.c
2007 typically in board_init_f() and board_init_r().
2009 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2010 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2011 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2012 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2014 Configuration Settings:
2015 -----------------------
2017 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2018 Optionally it can be defined to support 64-bit memory commands.
2020 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2021 undefine this when you're short of memory.
2023 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2024 width of the commands listed in the 'help' command output.
2026 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2027 prompt for user input.
2029 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2031 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2033 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2035 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2036 the application (usually a Linux kernel) when it is
2039 - CONFIG_SYS_BAUDRATE_TABLE:
2040 List of legal baudrate settings for this board.
2042 - CONFIG_SYS_MEM_RESERVE_SECURE
2043 Only implemented for ARMv8 for now.
2044 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2045 is substracted from total RAM and won't be reported to OS.
2046 This memory can be used as secure memory. A variable
2047 gd->arch.secure_ram is used to track the location. In systems
2048 the RAM base is not zero, or RAM is divided into banks,
2049 this variable needs to be recalcuated to get the address.
2051 - CONFIG_SYS_MEM_TOP_HIDE:
2052 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2053 this specified memory area will get subtracted from the top
2054 (end) of RAM and won't get "touched" at all by U-Boot. By
2055 fixing up gd->ram_size the Linux kernel should gets passed
2056 the now "corrected" memory size and won't touch it either.
2057 This should work for arch/ppc and arch/powerpc. Only Linux
2058 board ports in arch/powerpc with bootwrapper support that
2059 recalculate the memory size from the SDRAM controller setup
2060 will have to get fixed in Linux additionally.
2062 This option can be used as a workaround for the 440EPx/GRx
2063 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2066 WARNING: Please make sure that this value is a multiple of
2067 the Linux page size (normally 4k). If this is not the case,
2068 then the end address of the Linux memory will be located at a
2069 non page size aligned address and this could cause major
2072 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2073 Enable temporary baudrate change while serial download
2075 - CONFIG_SYS_SDRAM_BASE:
2076 Physical start address of SDRAM. _Must_ be 0 here.
2078 - CONFIG_SYS_FLASH_BASE:
2079 Physical start address of Flash memory.
2081 - CONFIG_SYS_MONITOR_BASE:
2082 Physical start address of boot monitor code (set by
2083 make config files to be same as the text base address
2084 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2085 CONFIG_SYS_FLASH_BASE when booting from flash.
2087 - CONFIG_SYS_MONITOR_LEN:
2088 Size of memory reserved for monitor code, used to
2089 determine _at_compile_time_ (!) if the environment is
2090 embedded within the U-Boot image, or in a separate
2093 - CONFIG_SYS_MALLOC_LEN:
2094 Size of DRAM reserved for malloc() use.
2096 - CONFIG_SYS_MALLOC_F_LEN
2097 Size of the malloc() pool for use before relocation. If
2098 this is defined, then a very simple malloc() implementation
2099 will become available before relocation. The address is just
2100 below the global data, and the stack is moved down to make
2103 This feature allocates regions with increasing addresses
2104 within the region. calloc() is supported, but realloc()
2105 is not available. free() is supported but does nothing.
2106 The memory will be freed (or in fact just forgotten) when
2107 U-Boot relocates itself.
2109 - CONFIG_SYS_MALLOC_SIMPLE
2110 Provides a simple and small malloc() and calloc() for those
2111 boards which do not use the full malloc in SPL (which is
2112 enabled with CONFIG_SYS_SPL_MALLOC_START).
2114 - CONFIG_SYS_NONCACHED_MEMORY:
2115 Size of non-cached memory area. This area of memory will be
2116 typically located right below the malloc() area and mapped
2117 uncached in the MMU. This is useful for drivers that would
2118 otherwise require a lot of explicit cache maintenance. For
2119 some drivers it's also impossible to properly maintain the
2120 cache. For example if the regions that need to be flushed
2121 are not a multiple of the cache-line size, *and* padding
2122 cannot be allocated between the regions to align them (i.e.
2123 if the HW requires a contiguous array of regions, and the
2124 size of each region is not cache-aligned), then a flush of
2125 one region may result in overwriting data that hardware has
2126 written to another region in the same cache-line. This can
2127 happen for example in network drivers where descriptors for
2128 buffers are typically smaller than the CPU cache-line (e.g.
2129 16 bytes vs. 32 or 64 bytes).
2131 Non-cached memory is only supported on 32-bit ARM at present.
2133 - CONFIG_SYS_BOOTM_LEN:
2134 Normally compressed uImages are limited to an
2135 uncompressed size of 8 MBytes. If this is not enough,
2136 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2137 to adjust this setting to your needs.
2139 - CONFIG_SYS_BOOTMAPSZ:
2140 Maximum size of memory mapped by the startup code of
2141 the Linux kernel; all data that must be processed by
2142 the Linux kernel (bd_info, boot arguments, FDT blob if
2143 used) must be put below this limit, unless "bootm_low"
2144 environment variable is defined and non-zero. In such case
2145 all data for the Linux kernel must be between "bootm_low"
2146 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2147 variable "bootm_mapsize" will override the value of
2148 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2149 then the value in "bootm_size" will be used instead.
2151 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2152 Enable initrd_high functionality. If defined then the
2153 initrd_high feature is enabled and the bootm ramdisk subcommand
2156 - CONFIG_SYS_BOOT_GET_CMDLINE:
2157 Enables allocating and saving kernel cmdline in space between
2158 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2160 - CONFIG_SYS_BOOT_GET_KBD:
2161 Enables allocating and saving a kernel copy of the bd_info in
2162 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2164 - CONFIG_SYS_MAX_FLASH_BANKS:
2165 Max number of Flash memory banks
2167 - CONFIG_SYS_MAX_FLASH_SECT:
2168 Max number of sectors on a Flash chip
2170 - CONFIG_SYS_FLASH_ERASE_TOUT:
2171 Timeout for Flash erase operations (in ms)
2173 - CONFIG_SYS_FLASH_WRITE_TOUT:
2174 Timeout for Flash write operations (in ms)
2176 - CONFIG_SYS_FLASH_LOCK_TOUT
2177 Timeout for Flash set sector lock bit operation (in ms)
2179 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2180 Timeout for Flash clear lock bits operation (in ms)
2182 - CONFIG_SYS_FLASH_PROTECTION
2183 If defined, hardware flash sectors protection is used
2184 instead of U-Boot software protection.
2186 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2188 Enable TFTP transfers directly to flash memory;
2189 without this option such a download has to be
2190 performed in two steps: (1) download to RAM, and (2)
2191 copy from RAM to flash.
2193 The two-step approach is usually more reliable, since
2194 you can check if the download worked before you erase
2195 the flash, but in some situations (when system RAM is
2196 too limited to allow for a temporary copy of the
2197 downloaded image) this option may be very useful.
2199 - CONFIG_SYS_FLASH_CFI:
2200 Define if the flash driver uses extra elements in the
2201 common flash structure for storing flash geometry.
2203 - CONFIG_FLASH_CFI_DRIVER
2204 This option also enables the building of the cfi_flash driver
2205 in the drivers directory
2207 - CONFIG_FLASH_CFI_MTD
2208 This option enables the building of the cfi_mtd driver
2209 in the drivers directory. The driver exports CFI flash
2212 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2213 Use buffered writes to flash.
2215 - CONFIG_FLASH_SPANSION_S29WS_N
2216 s29ws-n MirrorBit flash has non-standard addresses for buffered
2219 - CONFIG_SYS_FLASH_QUIET_TEST
2220 If this option is defined, the common CFI flash doesn't
2221 print it's warning upon not recognized FLASH banks. This
2222 is useful, if some of the configured banks are only
2223 optionally available.
2225 - CONFIG_FLASH_SHOW_PROGRESS
2226 If defined (must be an integer), print out countdown
2227 digits and dots. Recommended value: 45 (9..1) for 80
2228 column displays, 15 (3..1) for 40 column displays.
2230 - CONFIG_FLASH_VERIFY
2231 If defined, the content of the flash (destination) is compared
2232 against the source after the write operation. An error message
2233 will be printed when the contents are not identical.
2234 Please note that this option is useless in nearly all cases,
2235 since such flash programming errors usually are detected earlier
2236 while unprotecting/erasing/programming. Please only enable
2237 this option if you really know what you are doing.
2239 - CONFIG_SYS_RX_ETH_BUFFER:
2240 Defines the number of Ethernet receive buffers. On some
2241 Ethernet controllers it is recommended to set this value
2242 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2243 buffers can be full shortly after enabling the interface
2244 on high Ethernet traffic.
2245 Defaults to 4 if not defined.
2247 - CONFIG_ENV_MAX_ENTRIES
2249 Maximum number of entries in the hash table that is used
2250 internally to store the environment settings. The default
2251 setting is supposed to be generous and should work in most
2252 cases. This setting can be used to tune behaviour; see
2253 lib/hashtable.c for details.
2255 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2256 - CONFIG_ENV_FLAGS_LIST_STATIC
2257 Enable validation of the values given to environment variables when
2258 calling env set. Variables can be restricted to only decimal,
2259 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2260 the variables can also be restricted to IP address or MAC address.
2262 The format of the list is:
2263 type_attribute = [s|d|x|b|i|m]
2264 access_attribute = [a|r|o|c]
2265 attributes = type_attribute[access_attribute]
2266 entry = variable_name[:attributes]
2269 The type attributes are:
2270 s - String (default)
2273 b - Boolean ([1yYtT|0nNfF])
2277 The access attributes are:
2283 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2284 Define this to a list (string) to define the ".flags"
2285 environment variable in the default or embedded environment.
2287 - CONFIG_ENV_FLAGS_LIST_STATIC
2288 Define this to a list (string) to define validation that
2289 should be done if an entry is not found in the ".flags"
2290 environment variable. To override a setting in the static
2291 list, simply add an entry for the same variable name to the
2294 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2295 regular expression. This allows multiple variables to define the same
2296 flags without explicitly listing them for each variable.
2298 The following definitions that deal with the placement and management
2299 of environment data (variable area); in general, we support the
2300 following configurations:
2302 - CONFIG_BUILD_ENVCRC:
2304 Builds up envcrc with the target environment so that external utils
2305 may easily extract it and embed it in final U-Boot images.
2307 BE CAREFUL! The first access to the environment happens quite early
2308 in U-Boot initialization (when we try to get the setting of for the
2309 console baudrate). You *MUST* have mapped your NVRAM area then, or
2312 Please note that even with NVRAM we still use a copy of the
2313 environment in RAM: we could work on NVRAM directly, but we want to
2314 keep settings there always unmodified except somebody uses "saveenv"
2315 to save the current settings.
2317 BE CAREFUL! For some special cases, the local device can not use
2318 "saveenv" command. For example, the local device will get the
2319 environment stored in a remote NOR flash by SRIO or PCIE link,
2320 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2322 - CONFIG_NAND_ENV_DST
2324 Defines address in RAM to which the nand_spl code should copy the
2325 environment. If redundant environment is used, it will be copied to
2326 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2328 Please note that the environment is read-only until the monitor
2329 has been relocated to RAM and a RAM copy of the environment has been
2330 created; also, when using EEPROM you will have to use env_get_f()
2331 until then to read environment variables.
2333 The environment is protected by a CRC32 checksum. Before the monitor
2334 is relocated into RAM, as a result of a bad CRC you will be working
2335 with the compiled-in default environment - *silently*!!! [This is
2336 necessary, because the first environment variable we need is the
2337 "baudrate" setting for the console - if we have a bad CRC, we don't
2338 have any device yet where we could complain.]
2340 Note: once the monitor has been relocated, then it will complain if
2341 the default environment is used; a new CRC is computed as soon as you
2342 use the "saveenv" command to store a valid environment.
2344 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2345 Echo the inverted Ethernet link state to the fault LED.
2347 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2348 also needs to be defined.
2350 - CONFIG_SYS_FAULT_MII_ADDR:
2351 MII address of the PHY to check for the Ethernet link state.
2353 - CONFIG_NS16550_MIN_FUNCTIONS:
2354 Define this if you desire to only have use of the NS16550_init
2355 and NS16550_putc functions for the serial driver located at
2356 drivers/serial/ns16550.c. This option is useful for saving
2357 space for already greatly restricted images, including but not
2358 limited to NAND_SPL configurations.
2360 - CONFIG_DISPLAY_BOARDINFO
2361 Display information about the board that U-Boot is running on
2362 when U-Boot starts up. The board function checkboard() is called
2365 - CONFIG_DISPLAY_BOARDINFO_LATE
2366 Similar to the previous option, but display this information
2367 later, once stdio is running and output goes to the LCD, if
2370 - CONFIG_BOARD_SIZE_LIMIT:
2371 Maximum size of the U-Boot image. When defined, the
2372 build system checks that the actual size does not
2375 Low Level (hardware related) configuration options:
2376 ---------------------------------------------------
2378 - CONFIG_SYS_CACHELINE_SIZE:
2379 Cache Line Size of the CPU.
2381 - CONFIG_SYS_CCSRBAR_DEFAULT:
2382 Default (power-on reset) physical address of CCSR on Freescale
2385 - CONFIG_SYS_CCSRBAR:
2386 Virtual address of CCSR. On a 32-bit build, this is typically
2387 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2389 - CONFIG_SYS_CCSRBAR_PHYS:
2390 Physical address of CCSR. CCSR can be relocated to a new
2391 physical address, if desired. In this case, this macro should
2392 be set to that address. Otherwise, it should be set to the
2393 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2394 is typically relocated on 36-bit builds. It is recommended
2395 that this macro be defined via the _HIGH and _LOW macros:
2397 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2398 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2400 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2401 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2402 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2403 used in assembly code, so it must not contain typecasts or
2404 integer size suffixes (e.g. "ULL").
2406 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2407 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2408 used in assembly code, so it must not contain typecasts or
2409 integer size suffixes (e.g. "ULL").
2411 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2412 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2413 forced to a value that ensures that CCSR is not relocated.
2416 Most IDE controllers were designed to be connected with PCI
2417 interface. Only few of them were designed for AHB interface.
2418 When software is doing ATA command and data transfer to
2419 IDE devices through IDE-AHB controller, some additional
2420 registers accessing to these kind of IDE-AHB controller
2423 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2424 DO NOT CHANGE unless you know exactly what you're
2425 doing! (11-4) [MPC8xx systems only]
2427 - CONFIG_SYS_INIT_RAM_ADDR:
2429 Start address of memory area that can be used for
2430 initial data and stack; please note that this must be
2431 writable memory that is working WITHOUT special
2432 initialization, i. e. you CANNOT use normal RAM which
2433 will become available only after programming the
2434 memory controller and running certain initialization
2437 U-Boot uses the following memory types:
2438 - MPC8xx: IMMR (internal memory of the CPU)
2440 - CONFIG_SYS_GBL_DATA_OFFSET:
2442 Offset of the initial data structure in the memory
2443 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2444 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2445 data is located at the end of the available space
2446 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2447 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2448 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2449 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2452 On the MPC824X (or other systems that use the data
2453 cache for initial memory) the address chosen for
2454 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2455 point to an otherwise UNUSED address space between
2456 the top of RAM and the start of the PCI space.
2458 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2460 - CONFIG_SYS_OR_TIMING_SDRAM:
2463 - CONFIG_SYS_MAMR_PTA:
2464 periodic timer for refresh
2467 Chip has SRIO or not
2470 Board has SRIO 1 port available
2473 Board has SRIO 2 port available
2475 - CONFIG_SRIO_PCIE_BOOT_MASTER
2476 Board can support master function for Boot from SRIO and PCIE
2478 - CONFIG_SYS_SRIOn_MEM_VIRT:
2479 Virtual Address of SRIO port 'n' memory region
2481 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2482 Physical Address of SRIO port 'n' memory region
2484 - CONFIG_SYS_SRIOn_MEM_SIZE:
2485 Size of SRIO port 'n' memory region
2487 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2488 Defined to tell the NAND controller that the NAND chip is using
2490 Not all NAND drivers use this symbol.
2491 Example of drivers that use it:
2492 - drivers/mtd/nand/raw/ndfc.c
2493 - drivers/mtd/nand/raw/mxc_nand.c
2495 - CONFIG_SYS_NDFC_EBC0_CFG
2496 Sets the EBC0_CFG register for the NDFC. If not defined
2497 a default value will be used.
2500 Get DDR timing information from an I2C EEPROM. Common
2501 with pluggable memory modules such as SODIMMs
2504 I2C address of the SPD EEPROM
2506 - CONFIG_SYS_SPD_BUS_NUM
2507 If SPD EEPROM is on an I2C bus other than the first
2508 one, specify here. Note that the value must resolve
2509 to something your driver can deal with.
2511 - CONFIG_SYS_DDR_RAW_TIMING
2512 Get DDR timing information from other than SPD. Common with
2513 soldered DDR chips onboard without SPD. DDR raw timing
2514 parameters are extracted from datasheet and hard-coded into
2515 header files or board specific files.
2517 - CONFIG_FSL_DDR_INTERACTIVE
2518 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2520 - CONFIG_FSL_DDR_SYNC_REFRESH
2521 Enable sync of refresh for multiple controllers.
2523 - CONFIG_FSL_DDR_BIST
2524 Enable built-in memory test for Freescale DDR controllers.
2526 - CONFIG_SYS_83XX_DDR_USES_CS0
2527 Only for 83xx systems. If specified, then DDR should
2528 be configured using CS0 and CS1 instead of CS2 and CS3.
2531 Enable RMII mode for all FECs.
2532 Note that this is a global option, we can't
2533 have one FEC in standard MII mode and another in RMII mode.
2535 - CONFIG_CRC32_VERIFY
2536 Add a verify option to the crc32 command.
2539 => crc32 -v <address> <count> <crc32>
2541 Where address/count indicate a memory area
2542 and crc32 is the correct crc32 which the
2546 Add the "loopw" memory command. This only takes effect if
2547 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2549 - CONFIG_CMD_MX_CYCLIC
2550 Add the "mdc" and "mwc" memory commands. These are cyclic
2555 This command will print 4 bytes (10,11,12,13) each 500 ms.
2557 => mwc.l 100 12345678 10
2558 This command will write 12345678 to address 100 all 10 ms.
2560 This only takes effect if the memory commands are activated
2561 globally (CONFIG_CMD_MEMORY).
2564 Set when the currently-running compilation is for an artifact
2565 that will end up in the SPL (as opposed to the TPL or U-Boot
2566 proper). Code that needs stage-specific behavior should check
2570 Set when the currently-running compilation is for an artifact
2571 that will end up in the TPL (as opposed to the SPL or U-Boot
2572 proper). Code that needs stage-specific behavior should check
2575 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2576 Only for 85xx systems. If this variable is specified, the section
2577 .resetvec is not kept and the section .bootpg is placed in the
2578 previous 4k of the .text section.
2580 - CONFIG_ARCH_MAP_SYSMEM
2581 Generally U-Boot (and in particular the md command) uses
2582 effective address. It is therefore not necessary to regard
2583 U-Boot address as virtual addresses that need to be translated
2584 to physical addresses. However, sandbox requires this, since
2585 it maintains its own little RAM buffer which contains all
2586 addressable memory. This option causes some memory accesses
2587 to be mapped through map_sysmem() / unmap_sysmem().
2589 - CONFIG_X86_RESET_VECTOR
2590 If defined, the x86 reset vector code is included. This is not
2591 needed when U-Boot is running from Coreboot.
2593 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2594 Option to disable subpage write in NAND driver
2595 driver that uses this:
2596 drivers/mtd/nand/raw/davinci_nand.c
2598 Freescale QE/FMAN Firmware Support:
2599 -----------------------------------
2601 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2602 loading of "firmware", which is encoded in the QE firmware binary format.
2603 This firmware often needs to be loaded during U-Boot booting, so macros
2604 are used to identify the storage device (NOR flash, SPI, etc) and the address
2607 - CONFIG_SYS_FMAN_FW_ADDR
2608 The address in the storage device where the FMAN microcode is located. The
2609 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2612 - CONFIG_SYS_QE_FW_ADDR
2613 The address in the storage device where the QE microcode is located. The
2614 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2617 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2618 The maximum possible size of the firmware. The firmware binary format
2619 has a field that specifies the actual size of the firmware, but it
2620 might not be possible to read any part of the firmware unless some
2621 local storage is allocated to hold the entire firmware first.
2623 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2624 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2625 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2626 virtual address in NOR flash.
2628 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2629 Specifies that QE/FMAN firmware is located in NAND flash.
2630 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2632 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2633 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2634 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2636 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2637 Specifies that QE/FMAN firmware is located in the remote (master)
2638 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2639 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2640 window->master inbound window->master LAW->the ucode address in
2641 master's memory space.
2643 Freescale Layerscape Management Complex Firmware Support:
2644 ---------------------------------------------------------
2645 The Freescale Layerscape Management Complex (MC) supports the loading of
2647 This firmware often needs to be loaded during U-Boot booting, so macros
2648 are used to identify the storage device (NOR flash, SPI, etc) and the address
2651 - CONFIG_FSL_MC_ENET
2652 Enable the MC driver for Layerscape SoCs.
2654 Freescale Layerscape Debug Server Support:
2655 -------------------------------------------
2656 The Freescale Layerscape Debug Server Support supports the loading of
2657 "Debug Server firmware" and triggering SP boot-rom.
2658 This firmware often needs to be loaded during U-Boot booting.
2660 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2661 Define alignment of reserved memory MC requires
2666 In order to achieve reproducible builds, timestamps used in the U-Boot build
2667 process have to be set to a fixed value.
2669 This is done using the SOURCE_DATE_EPOCH environment variable.
2670 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2671 option for U-Boot or an environment variable in U-Boot.
2673 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2675 Building the Software:
2676 ======================
2678 Building U-Boot has been tested in several native build environments
2679 and in many different cross environments. Of course we cannot support
2680 all possibly existing versions of cross development tools in all
2681 (potentially obsolete) versions. In case of tool chain problems we
2682 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2683 which is extensively used to build and test U-Boot.
2685 If you are not using a native environment, it is assumed that you
2686 have GNU cross compiling tools available in your path. In this case,
2687 you must set the environment variable CROSS_COMPILE in your shell.
2688 Note that no changes to the Makefile or any other source files are
2689 necessary. For example using the ELDK on a 4xx CPU, please enter:
2691 $ CROSS_COMPILE=ppc_4xx-
2692 $ export CROSS_COMPILE
2694 U-Boot is intended to be simple to build. After installing the
2695 sources you must configure U-Boot for one specific board type. This
2700 where "NAME_defconfig" is the name of one of the existing configu-
2701 rations; see configs/*_defconfig for supported names.
2703 Note: for some boards special configuration names may exist; check if
2704 additional information is available from the board vendor; for
2705 instance, the TQM823L systems are available without (standard)
2706 or with LCD support. You can select such additional "features"
2707 when choosing the configuration, i. e.
2709 make TQM823L_defconfig
2710 - will configure for a plain TQM823L, i. e. no LCD support
2712 make TQM823L_LCD_defconfig
2713 - will configure for a TQM823L with U-Boot console on LCD
2718 Finally, type "make all", and you should get some working U-Boot
2719 images ready for download to / installation on your system:
2721 - "u-boot.bin" is a raw binary image
2722 - "u-boot" is an image in ELF binary format
2723 - "u-boot.srec" is in Motorola S-Record format
2725 By default the build is performed locally and the objects are saved
2726 in the source directory. One of the two methods can be used to change
2727 this behavior and build U-Boot to some external directory:
2729 1. Add O= to the make command line invocations:
2731 make O=/tmp/build distclean
2732 make O=/tmp/build NAME_defconfig
2733 make O=/tmp/build all
2735 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2737 export KBUILD_OUTPUT=/tmp/build
2742 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2745 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2746 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2747 For example to treat all compiler warnings as errors:
2749 make KCFLAGS=-Werror
2751 Please be aware that the Makefiles assume you are using GNU make, so
2752 for instance on NetBSD you might need to use "gmake" instead of
2756 If the system board that you have is not listed, then you will need
2757 to port U-Boot to your hardware platform. To do this, follow these
2760 1. Create a new directory to hold your board specific code. Add any
2761 files you need. In your board directory, you will need at least
2762 the "Makefile" and a "<board>.c".
2763 2. Create a new configuration file "include/configs/<board>.h" for
2765 3. If you're porting U-Boot to a new CPU, then also create a new
2766 directory to hold your CPU specific code. Add any files you need.
2767 4. Run "make <board>_defconfig" with your new name.
2768 5. Type "make", and you should get a working "u-boot.srec" file
2769 to be installed on your target system.
2770 6. Debug and solve any problems that might arise.
2771 [Of course, this last step is much harder than it sounds.]
2774 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2775 ==============================================================
2777 If you have modified U-Boot sources (for instance added a new board
2778 or support for new devices, a new CPU, etc.) you are expected to
2779 provide feedback to the other developers. The feedback normally takes
2780 the form of a "patch", i.e. a context diff against a certain (latest
2781 official or latest in the git repository) version of U-Boot sources.
2783 But before you submit such a patch, please verify that your modifi-
2784 cation did not break existing code. At least make sure that *ALL* of
2785 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2786 just run the buildman script (tools/buildman/buildman), which will
2787 configure and build U-Boot for ALL supported system. Be warned, this
2788 will take a while. Please see the buildman README, or run 'buildman -H'
2792 See also "U-Boot Porting Guide" below.
2795 Monitor Commands - Overview:
2796 ============================
2798 go - start application at address 'addr'
2799 run - run commands in an environment variable
2800 bootm - boot application image from memory
2801 bootp - boot image via network using BootP/TFTP protocol
2802 bootz - boot zImage from memory
2803 tftpboot- boot image via network using TFTP protocol
2804 and env variables "ipaddr" and "serverip"
2805 (and eventually "gatewayip")
2806 tftpput - upload a file via network using TFTP protocol
2807 rarpboot- boot image via network using RARP/TFTP protocol
2808 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2809 loads - load S-Record file over serial line
2810 loadb - load binary file over serial line (kermit mode)
2812 mm - memory modify (auto-incrementing)
2813 nm - memory modify (constant address)
2814 mw - memory write (fill)
2817 cmp - memory compare
2818 crc32 - checksum calculation
2819 i2c - I2C sub-system
2820 sspi - SPI utility commands
2821 base - print or set address offset
2822 printenv- print environment variables
2823 pwm - control pwm channels
2824 setenv - set environment variables
2825 saveenv - save environment variables to persistent storage
2826 protect - enable or disable FLASH write protection
2827 erase - erase FLASH memory
2828 flinfo - print FLASH memory information
2829 nand - NAND memory operations (see doc/README.nand)
2830 bdinfo - print Board Info structure
2831 iminfo - print header information for application image
2832 coninfo - print console devices and informations
2833 ide - IDE sub-system
2834 loop - infinite loop on address range
2835 loopw - infinite write loop on address range
2836 mtest - simple RAM test
2837 icache - enable or disable instruction cache
2838 dcache - enable or disable data cache
2839 reset - Perform RESET of the CPU
2840 echo - echo args to console
2841 version - print monitor version
2842 help - print online help
2843 ? - alias for 'help'
2846 Monitor Commands - Detailed Description:
2847 ========================================
2851 For now: just type "help <command>".
2854 Note for Redundant Ethernet Interfaces:
2855 =======================================
2857 Some boards come with redundant Ethernet interfaces; U-Boot supports
2858 such configurations and is capable of automatic selection of a
2859 "working" interface when needed. MAC assignment works as follows:
2861 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2862 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2863 "eth1addr" (=>eth1), "eth2addr", ...
2865 If the network interface stores some valid MAC address (for instance
2866 in SROM), this is used as default address if there is NO correspon-
2867 ding setting in the environment; if the corresponding environment
2868 variable is set, this overrides the settings in the card; that means:
2870 o If the SROM has a valid MAC address, and there is no address in the
2871 environment, the SROM's address is used.
2873 o If there is no valid address in the SROM, and a definition in the
2874 environment exists, then the value from the environment variable is
2877 o If both the SROM and the environment contain a MAC address, and
2878 both addresses are the same, this MAC address is used.
2880 o If both the SROM and the environment contain a MAC address, and the
2881 addresses differ, the value from the environment is used and a
2884 o If neither SROM nor the environment contain a MAC address, an error
2885 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2886 a random, locally-assigned MAC is used.
2888 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2889 will be programmed into hardware as part of the initialization process. This
2890 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2891 The naming convention is as follows:
2892 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2897 U-Boot is capable of booting (and performing other auxiliary operations on)
2898 images in two formats:
2900 New uImage format (FIT)
2901 -----------------------
2903 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2904 to Flattened Device Tree). It allows the use of images with multiple
2905 components (several kernels, ramdisks, etc.), with contents protected by
2906 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2912 Old image format is based on binary files which can be basically anything,
2913 preceded by a special header; see the definitions in include/image.h for
2914 details; basically, the header defines the following image properties:
2916 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2917 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2918 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2919 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
2921 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2922 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2923 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
2924 * Compression Type (uncompressed, gzip, bzip2)
2930 The header is marked by a special Magic Number, and both the header
2931 and the data portions of the image are secured against corruption by
2938 Although U-Boot should support any OS or standalone application
2939 easily, the main focus has always been on Linux during the design of
2942 U-Boot includes many features that so far have been part of some
2943 special "boot loader" code within the Linux kernel. Also, any
2944 "initrd" images to be used are no longer part of one big Linux image;
2945 instead, kernel and "initrd" are separate images. This implementation
2946 serves several purposes:
2948 - the same features can be used for other OS or standalone
2949 applications (for instance: using compressed images to reduce the
2950 Flash memory footprint)
2952 - it becomes much easier to port new Linux kernel versions because
2953 lots of low-level, hardware dependent stuff are done by U-Boot
2955 - the same Linux kernel image can now be used with different "initrd"
2956 images; of course this also means that different kernel images can
2957 be run with the same "initrd". This makes testing easier (you don't
2958 have to build a new "zImage.initrd" Linux image when you just
2959 change a file in your "initrd"). Also, a field-upgrade of the
2960 software is easier now.
2966 Porting Linux to U-Boot based systems:
2967 ---------------------------------------
2969 U-Boot cannot save you from doing all the necessary modifications to
2970 configure the Linux device drivers for use with your target hardware
2971 (no, we don't intend to provide a full virtual machine interface to
2974 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2976 Just make sure your machine specific header file (for instance
2977 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2978 Information structure as we define in include/asm-<arch>/u-boot.h,
2979 and make sure that your definition of IMAP_ADDR uses the same value
2980 as your U-Boot configuration in CONFIG_SYS_IMMR.
2982 Note that U-Boot now has a driver model, a unified model for drivers.
2983 If you are adding a new driver, plumb it into driver model. If there
2984 is no uclass available, you are encouraged to create one. See
2988 Configuring the Linux kernel:
2989 -----------------------------
2991 No specific requirements for U-Boot. Make sure you have some root
2992 device (initial ramdisk, NFS) for your target system.
2995 Building a Linux Image:
2996 -----------------------
2998 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2999 not used. If you use recent kernel source, a new build target
3000 "uImage" will exist which automatically builds an image usable by
3001 U-Boot. Most older kernels also have support for a "pImage" target,
3002 which was introduced for our predecessor project PPCBoot and uses a
3003 100% compatible format.
3007 make TQM850L_defconfig
3012 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3013 encapsulate a compressed Linux kernel image with header information,
3014 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3016 * build a standard "vmlinux" kernel image (in ELF binary format):
3018 * convert the kernel into a raw binary image:
3020 ${CROSS_COMPILE}-objcopy -O binary \
3021 -R .note -R .comment \
3022 -S vmlinux linux.bin
3024 * compress the binary image:
3028 * package compressed binary image for U-Boot:
3030 mkimage -A ppc -O linux -T kernel -C gzip \
3031 -a 0 -e 0 -n "Linux Kernel Image" \
3032 -d linux.bin.gz uImage
3035 The "mkimage" tool can also be used to create ramdisk images for use
3036 with U-Boot, either separated from the Linux kernel image, or
3037 combined into one file. "mkimage" encapsulates the images with a 64
3038 byte header containing information about target architecture,
3039 operating system, image type, compression method, entry points, time
3040 stamp, CRC32 checksums, etc.
3042 "mkimage" can be called in two ways: to verify existing images and
3043 print the header information, or to build new images.
3045 In the first form (with "-l" option) mkimage lists the information
3046 contained in the header of an existing U-Boot image; this includes
3047 checksum verification:
3049 tools/mkimage -l image
3050 -l ==> list image header information
3052 The second form (with "-d" option) is used to build a U-Boot image
3053 from a "data file" which is used as image payload:
3055 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3056 -n name -d data_file image
3057 -A ==> set architecture to 'arch'
3058 -O ==> set operating system to 'os'
3059 -T ==> set image type to 'type'
3060 -C ==> set compression type 'comp'
3061 -a ==> set load address to 'addr' (hex)
3062 -e ==> set entry point to 'ep' (hex)
3063 -n ==> set image name to 'name'
3064 -d ==> use image data from 'datafile'
3066 Right now, all Linux kernels for PowerPC systems use the same load
3067 address (0x00000000), but the entry point address depends on the
3070 - 2.2.x kernels have the entry point at 0x0000000C,
3071 - 2.3.x and later kernels have the entry point at 0x00000000.
3073 So a typical call to build a U-Boot image would read:
3075 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3076 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3077 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3078 > examples/uImage.TQM850L
3079 Image Name: 2.4.4 kernel for TQM850L
3080 Created: Wed Jul 19 02:34:59 2000
3081 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3082 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3083 Load Address: 0x00000000
3084 Entry Point: 0x00000000
3086 To verify the contents of the image (or check for corruption):
3088 -> tools/mkimage -l examples/uImage.TQM850L
3089 Image Name: 2.4.4 kernel for TQM850L
3090 Created: Wed Jul 19 02:34:59 2000
3091 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3092 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3093 Load Address: 0x00000000
3094 Entry Point: 0x00000000
3096 NOTE: for embedded systems where boot time is critical you can trade
3097 speed for memory and install an UNCOMPRESSED image instead: this
3098 needs more space in Flash, but boots much faster since it does not
3099 need to be uncompressed:
3101 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3102 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3103 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3104 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3105 > examples/uImage.TQM850L-uncompressed
3106 Image Name: 2.4.4 kernel for TQM850L
3107 Created: Wed Jul 19 02:34:59 2000
3108 Image Type: PowerPC Linux Kernel Image (uncompressed)
3109 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3110 Load Address: 0x00000000
3111 Entry Point: 0x00000000
3114 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3115 when your kernel is intended to use an initial ramdisk:
3117 -> tools/mkimage -n 'Simple Ramdisk Image' \
3118 > -A ppc -O linux -T ramdisk -C gzip \
3119 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3120 Image Name: Simple Ramdisk Image
3121 Created: Wed Jan 12 14:01:50 2000
3122 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3123 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3124 Load Address: 0x00000000
3125 Entry Point: 0x00000000
3127 The "dumpimage" tool can be used to disassemble or list the contents of images
3128 built by mkimage. See dumpimage's help output (-h) for details.
3130 Installing a Linux Image:
3131 -------------------------
3133 To downloading a U-Boot image over the serial (console) interface,
3134 you must convert the image to S-Record format:
3136 objcopy -I binary -O srec examples/image examples/image.srec
3138 The 'objcopy' does not understand the information in the U-Boot
3139 image header, so the resulting S-Record file will be relative to
3140 address 0x00000000. To load it to a given address, you need to
3141 specify the target address as 'offset' parameter with the 'loads'
3144 Example: install the image to address 0x40100000 (which on the
3145 TQM8xxL is in the first Flash bank):
3147 => erase 40100000 401FFFFF
3153 ## Ready for S-Record download ...
3154 ~>examples/image.srec
3155 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3157 15989 15990 15991 15992
3158 [file transfer complete]
3160 ## Start Addr = 0x00000000
3163 You can check the success of the download using the 'iminfo' command;
3164 this includes a checksum verification so you can be sure no data
3165 corruption happened:
3169 ## Checking Image at 40100000 ...
3170 Image Name: 2.2.13 for initrd on TQM850L
3171 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3172 Data Size: 335725 Bytes = 327 kB = 0 MB
3173 Load Address: 00000000
3174 Entry Point: 0000000c
3175 Verifying Checksum ... OK
3181 The "bootm" command is used to boot an application that is stored in
3182 memory (RAM or Flash). In case of a Linux kernel image, the contents
3183 of the "bootargs" environment variable is passed to the kernel as
3184 parameters. You can check and modify this variable using the
3185 "printenv" and "setenv" commands:
3188 => printenv bootargs
3189 bootargs=root=/dev/ram
3191 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3193 => printenv bootargs
3194 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3197 ## Booting Linux kernel at 40020000 ...
3198 Image Name: 2.2.13 for NFS on TQM850L
3199 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3200 Data Size: 381681 Bytes = 372 kB = 0 MB
3201 Load Address: 00000000
3202 Entry Point: 0000000c
3203 Verifying Checksum ... OK
3204 Uncompressing Kernel Image ... OK
3205 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
3206 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3207 time_init: decrementer frequency = 187500000/60
3208 Calibrating delay loop... 49.77 BogoMIPS
3209 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3212 If you want to boot a Linux kernel with initial RAM disk, you pass
3213 the memory addresses of both the kernel and the initrd image (PPBCOOT
3214 format!) to the "bootm" command:
3216 => imi 40100000 40200000
3218 ## Checking Image at 40100000 ...
3219 Image Name: 2.2.13 for initrd on TQM850L
3220 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3221 Data Size: 335725 Bytes = 327 kB = 0 MB
3222 Load Address: 00000000
3223 Entry Point: 0000000c
3224 Verifying Checksum ... OK
3226 ## Checking Image at 40200000 ...
3227 Image Name: Simple Ramdisk Image
3228 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3229 Data Size: 566530 Bytes = 553 kB = 0 MB
3230 Load Address: 00000000
3231 Entry Point: 00000000
3232 Verifying Checksum ... OK
3234 => bootm 40100000 40200000
3235 ## Booting Linux kernel at 40100000 ...
3236 Image Name: 2.2.13 for initrd on TQM850L
3237 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3238 Data Size: 335725 Bytes = 327 kB = 0 MB
3239 Load Address: 00000000
3240 Entry Point: 0000000c
3241 Verifying Checksum ... OK
3242 Uncompressing Kernel Image ... OK
3243 ## Loading RAMDisk Image at 40200000 ...
3244 Image Name: Simple Ramdisk Image
3245 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3246 Data Size: 566530 Bytes = 553 kB = 0 MB
3247 Load Address: 00000000
3248 Entry Point: 00000000
3249 Verifying Checksum ... OK
3250 Loading Ramdisk ... OK
3251 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
3252 Boot arguments: root=/dev/ram
3253 time_init: decrementer frequency = 187500000/60
3254 Calibrating delay loop... 49.77 BogoMIPS
3256 RAMDISK: Compressed image found at block 0
3257 VFS: Mounted root (ext2 filesystem).
3261 Boot Linux and pass a flat device tree:
3264 First, U-Boot must be compiled with the appropriate defines. See the section
3265 titled "Linux Kernel Interface" above for a more in depth explanation. The
3266 following is an example of how to start a kernel and pass an updated
3272 oft=oftrees/mpc8540ads.dtb
3273 => tftp $oftaddr $oft
3274 Speed: 1000, full duplex
3276 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3277 Filename 'oftrees/mpc8540ads.dtb'.
3278 Load address: 0x300000
3281 Bytes transferred = 4106 (100a hex)
3282 => tftp $loadaddr $bootfile
3283 Speed: 1000, full duplex
3285 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3287 Load address: 0x200000
3288 Loading:############
3290 Bytes transferred = 1029407 (fb51f hex)
3295 => bootm $loadaddr - $oftaddr
3296 ## Booting image at 00200000 ...
3297 Image Name: Linux-2.6.17-dirty
3298 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3299 Data Size: 1029343 Bytes = 1005.2 kB
3300 Load Address: 00000000
3301 Entry Point: 00000000
3302 Verifying Checksum ... OK
3303 Uncompressing Kernel Image ... OK
3304 Booting using flat device tree at 0x300000
3305 Using MPC85xx ADS machine description
3306 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3310 More About U-Boot Image Types:
3311 ------------------------------
3313 U-Boot supports the following image types:
3315 "Standalone Programs" are directly runnable in the environment
3316 provided by U-Boot; it is expected that (if they behave
3317 well) you can continue to work in U-Boot after return from
3318 the Standalone Program.
3319 "OS Kernel Images" are usually images of some Embedded OS which
3320 will take over control completely. Usually these programs
3321 will install their own set of exception handlers, device
3322 drivers, set up the MMU, etc. - this means, that you cannot
3323 expect to re-enter U-Boot except by resetting the CPU.
3324 "RAMDisk Images" are more or less just data blocks, and their
3325 parameters (address, size) are passed to an OS kernel that is
3327 "Multi-File Images" contain several images, typically an OS
3328 (Linux) kernel image and one or more data images like
3329 RAMDisks. This construct is useful for instance when you want
3330 to boot over the network using BOOTP etc., where the boot
3331 server provides just a single image file, but you want to get
3332 for instance an OS kernel and a RAMDisk image.
3334 "Multi-File Images" start with a list of image sizes, each
3335 image size (in bytes) specified by an "uint32_t" in network
3336 byte order. This list is terminated by an "(uint32_t)0".
3337 Immediately after the terminating 0 follow the images, one by
3338 one, all aligned on "uint32_t" boundaries (size rounded up to
3339 a multiple of 4 bytes).
3341 "Firmware Images" are binary images containing firmware (like
3342 U-Boot or FPGA images) which usually will be programmed to
3345 "Script files" are command sequences that will be executed by
3346 U-Boot's command interpreter; this feature is especially
3347 useful when you configure U-Boot to use a real shell (hush)
3348 as command interpreter.
3350 Booting the Linux zImage:
3351 -------------------------
3353 On some platforms, it's possible to boot Linux zImage. This is done
3354 using the "bootz" command. The syntax of "bootz" command is the same
3355 as the syntax of "bootm" command.
3357 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3358 kernel with raw initrd images. The syntax is slightly different, the
3359 address of the initrd must be augmented by it's size, in the following
3360 format: "<initrd addres>:<initrd size>".
3366 One of the features of U-Boot is that you can dynamically load and
3367 run "standalone" applications, which can use some resources of
3368 U-Boot like console I/O functions or interrupt services.
3370 Two simple examples are included with the sources:
3375 'examples/hello_world.c' contains a small "Hello World" Demo
3376 application; it is automatically compiled when you build U-Boot.
3377 It's configured to run at address 0x00040004, so you can play with it
3381 ## Ready for S-Record download ...
3382 ~>examples/hello_world.srec
3383 1 2 3 4 5 6 7 8 9 10 11 ...
3384 [file transfer complete]
3386 ## Start Addr = 0x00040004
3388 => go 40004 Hello World! This is a test.
3389 ## Starting application at 0x00040004 ...
3400 Hit any key to exit ...
3402 ## Application terminated, rc = 0x0
3404 Another example, which demonstrates how to register a CPM interrupt
3405 handler with the U-Boot code, can be found in 'examples/timer.c'.
3406 Here, a CPM timer is set up to generate an interrupt every second.
3407 The interrupt service routine is trivial, just printing a '.'
3408 character, but this is just a demo program. The application can be
3409 controlled by the following keys:
3411 ? - print current values og the CPM Timer registers
3412 b - enable interrupts and start timer
3413 e - stop timer and disable interrupts
3414 q - quit application
3417 ## Ready for S-Record download ...
3418 ~>examples/timer.srec
3419 1 2 3 4 5 6 7 8 9 10 11 ...
3420 [file transfer complete]
3422 ## Start Addr = 0x00040004
3425 ## Starting application at 0x00040004 ...
3428 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3431 [q, b, e, ?] Set interval 1000000 us
3434 [q, b, e, ?] ........
3435 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3438 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3441 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3444 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3446 [q, b, e, ?] ...Stopping timer
3448 [q, b, e, ?] ## Application terminated, rc = 0x0
3454 Over time, many people have reported problems when trying to use the
3455 "minicom" terminal emulation program for serial download. I (wd)
3456 consider minicom to be broken, and recommend not to use it. Under
3457 Unix, I recommend to use C-Kermit for general purpose use (and
3458 especially for kermit binary protocol download ("loadb" command), and
3459 use "cu" for S-Record download ("loads" command). See
3460 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3461 for help with kermit.
3464 Nevertheless, if you absolutely want to use it try adding this
3465 configuration to your "File transfer protocols" section:
3467 Name Program Name U/D FullScr IO-Red. Multi
3468 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3469 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3475 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3476 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3478 Building requires a cross environment; it is known to work on
3479 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3480 need gmake since the Makefiles are not compatible with BSD make).
3481 Note that the cross-powerpc package does not install include files;
3482 attempting to build U-Boot will fail because <machine/ansi.h> is
3483 missing. This file has to be installed and patched manually:
3485 # cd /usr/pkg/cross/powerpc-netbsd/include
3487 # ln -s powerpc machine
3488 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3489 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3491 Native builds *don't* work due to incompatibilities between native
3492 and U-Boot include files.
3494 Booting assumes that (the first part of) the image booted is a
3495 stage-2 loader which in turn loads and then invokes the kernel
3496 proper. Loader sources will eventually appear in the NetBSD source
3497 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3498 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3501 Implementation Internals:
3502 =========================
3504 The following is not intended to be a complete description of every
3505 implementation detail. However, it should help to understand the
3506 inner workings of U-Boot and make it easier to port it to custom
3510 Initial Stack, Global Data:
3511 ---------------------------
3513 The implementation of U-Boot is complicated by the fact that U-Boot
3514 starts running out of ROM (flash memory), usually without access to
3515 system RAM (because the memory controller is not initialized yet).
3516 This means that we don't have writable Data or BSS segments, and BSS
3517 is not initialized as zero. To be able to get a C environment working
3518 at all, we have to allocate at least a minimal stack. Implementation
3519 options for this are defined and restricted by the CPU used: Some CPU
3520 models provide on-chip memory (like the IMMR area on MPC8xx and
3521 MPC826x processors), on others (parts of) the data cache can be
3522 locked as (mis-) used as memory, etc.
3524 Chris Hallinan posted a good summary of these issues to the
3525 U-Boot mailing list:
3527 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3528 From: "Chris Hallinan" <clh@net1plus.com>
3529 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3532 Correct me if I'm wrong, folks, but the way I understand it
3533 is this: Using DCACHE as initial RAM for Stack, etc, does not
3534 require any physical RAM backing up the cache. The cleverness
3535 is that the cache is being used as a temporary supply of
3536 necessary storage before the SDRAM controller is setup. It's
3537 beyond the scope of this list to explain the details, but you
3538 can see how this works by studying the cache architecture and
3539 operation in the architecture and processor-specific manuals.
3541 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3542 is another option for the system designer to use as an
3543 initial stack/RAM area prior to SDRAM being available. Either
3544 option should work for you. Using CS 4 should be fine if your
3545 board designers haven't used it for something that would
3546 cause you grief during the initial boot! It is frequently not
3549 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3550 with your processor/board/system design. The default value
3551 you will find in any recent u-boot distribution in
3552 walnut.h should work for you. I'd set it to a value larger
3553 than your SDRAM module. If you have a 64MB SDRAM module, set
3554 it above 400_0000. Just make sure your board has no resources
3555 that are supposed to respond to that address! That code in
3556 start.S has been around a while and should work as is when
3557 you get the config right.
3562 It is essential to remember this, since it has some impact on the C
3563 code for the initialization procedures:
3565 * Initialized global data (data segment) is read-only. Do not attempt
3568 * Do not use any uninitialized global data (or implicitly initialized
3569 as zero data - BSS segment) at all - this is undefined, initiali-
3570 zation is performed later (when relocating to RAM).
3572 * Stack space is very limited. Avoid big data buffers or things like
3575 Having only the stack as writable memory limits means we cannot use
3576 normal global data to share information between the code. But it
3577 turned out that the implementation of U-Boot can be greatly
3578 simplified by making a global data structure (gd_t) available to all
3579 functions. We could pass a pointer to this data as argument to _all_
3580 functions, but this would bloat the code. Instead we use a feature of
3581 the GCC compiler (Global Register Variables) to share the data: we
3582 place a pointer (gd) to the global data into a register which we
3583 reserve for this purpose.
3585 When choosing a register for such a purpose we are restricted by the
3586 relevant (E)ABI specifications for the current architecture, and by
3587 GCC's implementation.
3589 For PowerPC, the following registers have specific use:
3591 R2: reserved for system use
3592 R3-R4: parameter passing and return values
3593 R5-R10: parameter passing
3594 R13: small data area pointer
3598 (U-Boot also uses R12 as internal GOT pointer. r12
3599 is a volatile register so r12 needs to be reset when
3600 going back and forth between asm and C)
3602 ==> U-Boot will use R2 to hold a pointer to the global data
3604 Note: on PPC, we could use a static initializer (since the
3605 address of the global data structure is known at compile time),
3606 but it turned out that reserving a register results in somewhat
3607 smaller code - although the code savings are not that big (on
3608 average for all boards 752 bytes for the whole U-Boot image,
3609 624 text + 127 data).
3611 On ARM, the following registers are used:
3613 R0: function argument word/integer result
3614 R1-R3: function argument word
3615 R9: platform specific
3616 R10: stack limit (used only if stack checking is enabled)
3617 R11: argument (frame) pointer
3618 R12: temporary workspace
3621 R15: program counter
3623 ==> U-Boot will use R9 to hold a pointer to the global data
3625 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3627 On Nios II, the ABI is documented here:
3628 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3630 ==> U-Boot will use gp to hold a pointer to the global data
3632 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3633 to access small data sections, so gp is free.
3635 On NDS32, the following registers are used:
3637 R0-R1: argument/return
3639 R15: temporary register for assembler
3640 R16: trampoline register
3641 R28: frame pointer (FP)
3642 R29: global pointer (GP)
3643 R30: link register (LP)
3644 R31: stack pointer (SP)
3645 PC: program counter (PC)
3647 ==> U-Boot will use R10 to hold a pointer to the global data
3649 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3650 or current versions of GCC may "optimize" the code too much.
3652 On RISC-V, the following registers are used:
3654 x0: hard-wired zero (zero)
3655 x1: return address (ra)
3656 x2: stack pointer (sp)
3657 x3: global pointer (gp)
3658 x4: thread pointer (tp)
3659 x5: link register (t0)
3660 x8: frame pointer (fp)
3661 x10-x11: arguments/return values (a0-1)
3662 x12-x17: arguments (a2-7)
3663 x28-31: temporaries (t3-6)
3664 pc: program counter (pc)
3666 ==> U-Boot will use gp to hold a pointer to the global data
3671 U-Boot runs in system state and uses physical addresses, i.e. the
3672 MMU is not used either for address mapping nor for memory protection.
3674 The available memory is mapped to fixed addresses using the memory
3675 controller. In this process, a contiguous block is formed for each
3676 memory type (Flash, SDRAM, SRAM), even when it consists of several
3677 physical memory banks.
3679 U-Boot is installed in the first 128 kB of the first Flash bank (on
3680 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3681 booting and sizing and initializing DRAM, the code relocates itself
3682 to the upper end of DRAM. Immediately below the U-Boot code some
3683 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3684 configuration setting]. Below that, a structure with global Board
3685 Info data is placed, followed by the stack (growing downward).
3687 Additionally, some exception handler code is copied to the low 8 kB
3688 of DRAM (0x00000000 ... 0x00001FFF).
3690 So a typical memory configuration with 16 MB of DRAM could look like
3693 0x0000 0000 Exception Vector code
3696 0x0000 2000 Free for Application Use
3702 0x00FB FF20 Monitor Stack (Growing downward)
3703 0x00FB FFAC Board Info Data and permanent copy of global data
3704 0x00FC 0000 Malloc Arena
3707 0x00FE 0000 RAM Copy of Monitor Code
3708 ... eventually: LCD or video framebuffer
3709 ... eventually: pRAM (Protected RAM - unchanged by reset)
3710 0x00FF FFFF [End of RAM]
3713 System Initialization:
3714 ----------------------
3716 In the reset configuration, U-Boot starts at the reset entry point
3717 (on most PowerPC systems at address 0x00000100). Because of the reset
3718 configuration for CS0# this is a mirror of the on board Flash memory.
3719 To be able to re-map memory U-Boot then jumps to its link address.
3720 To be able to implement the initialization code in C, a (small!)
3721 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3722 which provide such a feature like), or in a locked part of the data
3723 cache. After that, U-Boot initializes the CPU core, the caches and
3726 Next, all (potentially) available memory banks are mapped using a
3727 preliminary mapping. For example, we put them on 512 MB boundaries
3728 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3729 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3730 programmed for SDRAM access. Using the temporary configuration, a
3731 simple memory test is run that determines the size of the SDRAM
3734 When there is more than one SDRAM bank, and the banks are of
3735 different size, the largest is mapped first. For equal size, the first
3736 bank (CS2#) is mapped first. The first mapping is always for address
3737 0x00000000, with any additional banks following immediately to create
3738 contiguous memory starting from 0.
3740 Then, the monitor installs itself at the upper end of the SDRAM area
3741 and allocates memory for use by malloc() and for the global Board
3742 Info data; also, the exception vector code is copied to the low RAM
3743 pages, and the final stack is set up.
3745 Only after this relocation will you have a "normal" C environment;
3746 until that you are restricted in several ways, mostly because you are
3747 running from ROM, and because the code will have to be relocated to a
3751 U-Boot Porting Guide:
3752 ----------------------
3754 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3758 int main(int argc, char *argv[])
3760 sighandler_t no_more_time;
3762 signal(SIGALRM, no_more_time);
3763 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3765 if (available_money > available_manpower) {
3766 Pay consultant to port U-Boot;
3770 Download latest U-Boot source;
3772 Subscribe to u-boot mailing list;
3775 email("Hi, I am new to U-Boot, how do I get started?");
3778 Read the README file in the top level directory;
3779 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3780 Read applicable doc/README.*;
3781 Read the source, Luke;
3782 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3785 if (available_money > toLocalCurrency ($2500))
3788 Add a lot of aggravation and time;
3790 if (a similar board exists) { /* hopefully... */
3791 cp -a board/<similar> board/<myboard>
3792 cp include/configs/<similar>.h include/configs/<myboard>.h
3794 Create your own board support subdirectory;
3795 Create your own board include/configs/<myboard>.h file;
3797 Edit new board/<myboard> files
3798 Edit new include/configs/<myboard>.h
3803 Add / modify source code;
3807 email("Hi, I am having problems...");
3809 Send patch file to the U-Boot email list;
3810 if (reasonable critiques)
3811 Incorporate improvements from email list code review;
3813 Defend code as written;
3819 void no_more_time (int sig)
3828 All contributions to U-Boot should conform to the Linux kernel
3829 coding style; see the kernel coding style guide at
3830 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3831 script "scripts/Lindent" in your Linux kernel source directory.
3833 Source files originating from a different project (for example the
3834 MTD subsystem) are generally exempt from these guidelines and are not
3835 reformatted to ease subsequent migration to newer versions of those
3838 Please note that U-Boot is implemented in C (and to some small parts in
3839 Assembler); no C++ is used, so please do not use C++ style comments (//)
3842 Please also stick to the following formatting rules:
3843 - remove any trailing white space
3844 - use TAB characters for indentation and vertical alignment, not spaces
3845 - make sure NOT to use DOS '\r\n' line feeds
3846 - do not add more than 2 consecutive empty lines to source files
3847 - do not add trailing empty lines to source files
3849 Submissions which do not conform to the standards may be returned
3850 with a request to reformat the changes.
3856 Since the number of patches for U-Boot is growing, we need to
3857 establish some rules. Submissions which do not conform to these rules
3858 may be rejected, even when they contain important and valuable stuff.
3860 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3862 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3863 see https://lists.denx.de/listinfo/u-boot
3865 When you send a patch, please include the following information with
3868 * For bug fixes: a description of the bug and how your patch fixes
3869 this bug. Please try to include a way of demonstrating that the
3870 patch actually fixes something.
3872 * For new features: a description of the feature and your
3875 * For major contributions, add a MAINTAINERS file with your
3876 information and associated file and directory references.
3878 * When you add support for a new board, don't forget to add a
3879 maintainer e-mail address to the boards.cfg file, too.
3881 * If your patch adds new configuration options, don't forget to
3882 document these in the README file.
3884 * The patch itself. If you are using git (which is *strongly*
3885 recommended) you can easily generate the patch using the
3886 "git format-patch". If you then use "git send-email" to send it to
3887 the U-Boot mailing list, you will avoid most of the common problems
3888 with some other mail clients.
3890 If you cannot use git, use "diff -purN OLD NEW". If your version of
3891 diff does not support these options, then get the latest version of
3894 The current directory when running this command shall be the parent
3895 directory of the U-Boot source tree (i. e. please make sure that
3896 your patch includes sufficient directory information for the
3899 We prefer patches as plain text. MIME attachments are discouraged,
3900 and compressed attachments must not be used.
3902 * If one logical set of modifications affects or creates several
3903 files, all these changes shall be submitted in a SINGLE patch file.
3905 * Changesets that contain different, unrelated modifications shall be
3906 submitted as SEPARATE patches, one patch per changeset.
3911 * Before sending the patch, run the buildman script on your patched
3912 source tree and make sure that no errors or warnings are reported
3913 for any of the boards.
3915 * Keep your modifications to the necessary minimum: A patch
3916 containing several unrelated changes or arbitrary reformats will be
3917 returned with a request to re-formatting / split it.
3919 * If you modify existing code, make sure that your new code does not
3920 add to the memory footprint of the code ;-) Small is beautiful!
3921 When adding new features, these should compile conditionally only
3922 (using #ifdef), and the resulting code with the new feature
3923 disabled must not need more memory than the old code without your
3926 * Remember that there is a size limit of 100 kB per message on the
3927 u-boot mailing list. Bigger patches will be moderated. If they are
3928 reasonable and not too big, they will be acknowledged. But patches
3929 bigger than the size limit should be avoided.
projects / platform / kernel / u-boot.git / blob