1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see https://lists.denx.de/pipermail/u-boot and
55 https://marc.info/?l=u-boot
57 Where to get source code:
58 =========================
60 The U-Boot source code is maintained in the Git repository at
61 https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
62 https://source.denx.de/u-boot/u-boot
64 The "Tags" links on this page allow you to download tarballs of
65 any version you might be interested in. Official releases are also
66 available from the DENX file server through HTTPS or FTP.
67 https://ftp.denx.de/pub/u-boot/
68 ftp://ftp.denx.de/pub/u-boot/
74 - start from 8xxrom sources
75 - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
77 - make it easier to add custom boards
78 - make it possible to add other [PowerPC] CPUs
79 - extend functions, especially:
80 * Provide extended interface to Linux boot loader
83 * ATA disk / SCSI ... boot
84 - create ARMBoot project (https://sourceforge.net/projects/armboot)
85 - add other CPU families (starting with ARM)
86 - create U-Boot project (https://sourceforge.net/projects/u-boot)
87 - current project page: see https://www.denx.de/wiki/U-Boot
93 The "official" name of this project is "Das U-Boot". The spelling
94 "U-Boot" shall be used in all written text (documentation, comments
95 in source files etc.). Example:
97 This is the README file for the U-Boot project.
99 File names etc. shall be based on the string "u-boot". Examples:
101 include/asm-ppc/u-boot.h
103 #include <asm/u-boot.h>
105 Variable names, preprocessor constants etc. shall be either based on
106 the string "u_boot" or on "U_BOOT". Example:
108 U_BOOT_VERSION u_boot_logo
109 IH_OS_U_BOOT u_boot_hush_start
115 Starting with the release in October 2008, the names of the releases
116 were changed from numerical release numbers without deeper meaning
117 into a time stamp based numbering. Regular releases are identified by
118 names consisting of the calendar year and month of the release date.
119 Additional fields (if present) indicate release candidates or bug fix
120 releases in "stable" maintenance trees.
123 U-Boot v2009.11 - Release November 2009
124 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
125 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 /arch Architecture-specific files
132 /arc Files generic to ARC architecture
133 /arm Files generic to ARM architecture
134 /m68k Files generic to m68k architecture
135 /microblaze Files generic to microblaze architecture
136 /mips Files generic to MIPS architecture
137 /nios2 Files generic to Altera NIOS2 architecture
138 /powerpc Files generic to PowerPC architecture
139 /riscv Files generic to RISC-V architecture
140 /sandbox Files generic to HW-independent "sandbox"
141 /sh Files generic to SH architecture
142 /x86 Files generic to x86 architecture
143 /xtensa Files generic to Xtensa architecture
144 /api Machine/arch-independent API for external apps
145 /board Board-dependent files
146 /boot Support for images and booting
147 /cmd U-Boot commands functions
148 /common Misc architecture-independent functions
149 /configs Board default configuration files
150 /disk Code for disk drive partition handling
151 /doc Documentation (a mix of ReST and READMEs)
152 /drivers Device drivers
153 /dts Makefile for building internal U-Boot fdt.
154 /env Environment support
155 /examples Example code for standalone applications, etc.
156 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
157 /include Header Files
158 /lib Library routines generic to all architectures
159 /Licenses Various license files
161 /post Power On Self Test
162 /scripts Various build scripts and Makefiles
163 /test Various unit test files
164 /tools Tools to build and sign FIT images, etc.
166 Software Configuration:
167 =======================
169 Selection of Processor Architecture and Board Type:
170 ---------------------------------------------------
172 For all supported boards there are ready-to-use default
173 configurations available; just type "make <board_name>_defconfig".
175 Example: For a TQM823L module type:
178 make TQM823L_defconfig
180 Note: If you're looking for the default configuration file for a board
181 you're sure used to be there but is now missing, check the file
182 doc/README.scrapyard for a list of no longer supported boards.
187 U-Boot can be built natively to run on a Linux host using the 'sandbox'
188 board. This allows feature development which is not board- or architecture-
189 specific to be undertaken on a native platform. The sandbox is also used to
190 run some of U-Boot's tests.
192 See doc/arch/sandbox.rst for more details.
195 Board Initialisation Flow:
196 --------------------------
198 This is the intended start-up flow for boards. This should apply for both
199 SPL and U-Boot proper (i.e. they both follow the same rules).
201 Note: "SPL" stands for "Secondary Program Loader," which is explained in
202 more detail later in this file.
204 At present, SPL mostly uses a separate code path, but the function names
205 and roles of each function are the same. Some boards or architectures
206 may not conform to this. At least most ARM boards which use
207 CONFIG_SPL_FRAMEWORK conform to this.
209 Execution typically starts with an architecture-specific (and possibly
210 CPU-specific) start.S file, such as:
212 - arch/arm/cpu/armv7/start.S
213 - arch/powerpc/cpu/mpc83xx/start.S
214 - arch/mips/cpu/start.S
216 and so on. From there, three functions are called; the purpose and
217 limitations of each of these functions are described below.
220 - purpose: essential init to permit execution to reach board_init_f()
221 - no global_data or BSS
222 - there is no stack (ARMv7 may have one but it will soon be removed)
223 - must not set up SDRAM or use console
224 - must only do the bare minimum to allow execution to continue to
226 - this is almost never needed
227 - return normally from this function
230 - purpose: set up the machine ready for running board_init_r():
231 i.e. SDRAM and serial UART
232 - global_data is available
234 - BSS is not available, so you cannot use global/static variables,
235 only stack variables and global_data
237 Non-SPL-specific notes:
238 - dram_init() is called to set up DRAM. If already done in SPL this
242 - you can override the entire board_init_f() function with your own
244 - preloader_console_init() can be called here in extremis
245 - should set up SDRAM, and anything needed to make the UART work
246 - there is no need to clear BSS, it will be done by crt0.S
247 - for specific scenarios on certain architectures an early BSS *can*
248 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
249 of BSS prior to entering board_init_f()) but doing so is discouraged.
250 Instead it is strongly recommended to architect any code changes
251 or additions such to not depend on the availability of BSS during
252 board_init_f() as indicated in other sections of this README to
253 maintain compatibility and consistency across the entire code base.
254 - must return normally from this function (don't call board_init_r()
257 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
258 this point the stack and global_data are relocated to below
259 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
263 - purpose: main execution, common code
264 - global_data is available
266 - BSS is available, all static/global variables can be used
267 - execution eventually continues to main_loop()
269 Non-SPL-specific notes:
270 - U-Boot is relocated to the top of memory and is now running from
274 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
275 CONFIG_SYS_FSL_HAS_CCI400
277 Defined For SoC that has cache coherent interconnect
280 CONFIG_SYS_FSL_HAS_CCN504
282 Defined for SoC that has cache coherent interconnect CCN-504
284 The following options need to be configured:
286 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
288 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
293 Specifies that the core is a 64-bit PowerPC implementation (implements
294 the "64" category of the Power ISA). This is necessary for ePAPR
295 compliance, among other possible reasons.
297 CONFIG_SYS_FSL_ERRATUM_A004510
299 Enables a workaround for erratum A004510. If set,
300 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
301 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
303 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
304 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
306 Defines one or two SoC revisions (low 8 bits of SVR)
307 for which the A004510 workaround should be applied.
309 The rest of SVR is either not relevant to the decision
310 of whether the erratum is present (e.g. p2040 versus
311 p2041) or is implied by the build target, which controls
312 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
314 See Freescale App Note 4493 for more information about
317 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
319 This is the value to write into CCSR offset 0x18600
320 according to the A004510 workaround.
322 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
323 Single Source Clock is clocking mode present in some of FSL SoC's.
324 In this mode, a single differential clock is used to supply
325 clocks to the sysclock, ddrclock and usbclock.
327 - Generic CPU options:
330 Freescale DDR driver in use. This type of DDR controller is
331 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
333 CONFIG_SYS_FSL_DDR_ADDR
334 Freescale DDR memory-mapped register base.
336 CONFIG_SYS_FSL_IFC_CLK_DIV
337 Defines divider of platform clock(clock input to IFC controller).
339 CONFIG_SYS_FSL_LBC_CLK_DIV
340 Defines divider of platform clock(clock input to eLBC controller).
342 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
343 Physical address from the view of DDR controllers. It is the
344 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
345 it could be different for ARM SoCs.
348 CONFIG_XWAY_SWAP_BYTES
350 Enable compilation of tools/xway-swap-bytes needed for Lantiq
351 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
352 be swapped if a flash programmer is used.
355 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
357 Select high exception vectors of the ARM core, e.g., do not
358 clear the V bit of the c1 register of CP15.
361 Generic timer clock source frequency.
363 COUNTER_FREQUENCY_REAL
364 Generic timer clock source frequency if the real clock is
365 different from COUNTER_FREQUENCY, and can only be determined
369 CONFIG_TEGRA_SUPPORT_NON_SECURE
371 Support executing U-Boot in non-secure (NS) mode. Certain
372 impossible actions will be skipped if the CPU is in NS mode,
373 such as ARM architectural timer initialization.
375 - Linux Kernel Interface:
376 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
378 When transferring memsize parameter to Linux, some versions
379 expect it to be in bytes, others in MB.
380 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
384 New kernel versions are expecting firmware settings to be
385 passed using flattened device trees (based on open firmware
389 * New libfdt-based support
390 * Adds the "fdt" command
391 * The bootm command automatically updates the fdt
393 OF_TBCLK - The timebase frequency.
395 boards with QUICC Engines require OF_QE to set UCC MAC
400 U-Boot can detect if an IDE device is present or not.
401 If not, and this new config option is activated, U-Boot
402 removes the ATA node from the DTS before booting Linux,
403 so the Linux IDE driver does not probe the device and
404 crash. This is needed for buggy hardware (uc101) where
405 no pull down resistor is connected to the signal IDE5V_DD7.
407 - vxWorks boot parameters:
409 bootvx constructs a valid bootline using the following
410 environments variables: bootdev, bootfile, ipaddr, netmask,
411 serverip, gatewayip, hostname, othbootargs.
412 It loads the vxWorks image pointed bootfile.
414 Note: If a "bootargs" environment is defined, it will override
415 the defaults discussed just above.
417 - Cache Configuration for ARM:
418 CONFIG_SYS_PL310_BASE - Physical base address of PL310
419 controller register space
424 If you have Amba PrimeCell PL011 UARTs, set this variable to
425 the clock speed of the UARTs.
429 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
430 define this to a list of base addresses for each (supported)
431 port. See e.g. include/configs/versatile.h
433 CONFIG_SERIAL_HW_FLOW_CONTROL
435 Define this variable to enable hw flow control in serial driver.
436 Current user of this option is drivers/serial/nsl16550.c driver
438 - Serial Download Echo Mode:
440 If defined to 1, all characters received during a
441 serial download (using the "loads" command) are
442 echoed back. This might be needed by some terminal
443 emulations (like "cu"), but may as well just take
444 time on others. This setting #define's the initial
445 value of the "loads_echo" environment variable.
447 - Removal of commands
448 If no commands are needed to boot, you can disable
449 CONFIG_CMDLINE to remove them. In this case, the command line
450 will not be available, and when U-Boot wants to execute the
451 boot command (on start-up) it will call board_run_command()
452 instead. This can reduce image size significantly for very
453 simple boot procedures.
455 - Regular expression support:
457 If this variable is defined, U-Boot is linked against
458 the SLRE (Super Light Regular Expression) library,
459 which adds regex support to some commands, as for
460 example "env grep" and "setexpr".
463 CONFIG_SYS_WATCHDOG_FREQ
464 Some platforms automatically call WATCHDOG_RESET()
465 from the timer interrupt handler every
466 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
467 board configuration file, a default of CONFIG_SYS_HZ/2
468 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
469 to 0 disables calling WATCHDOG_RESET() from the timer
474 When CONFIG_CMD_DATE is selected, the type of the RTC
475 has to be selected, too. Define exactly one of the
478 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
479 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
480 CONFIG_RTC_MC146818 - use MC146818 RTC
481 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
482 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
483 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
484 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
485 CONFIG_RTC_DS164x - use Dallas DS164x RTC
486 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
487 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
488 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
489 CONFIG_SYS_RV3029_TCR - enable trickle charger on
492 Note that if the RTC uses I2C, then the I2C interface
493 must also be configured. See I2C Support, below.
496 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
498 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
499 chip-ngpio pairs that tell the PCA953X driver the number of
500 pins supported by a particular chip.
502 Note that if the GPIO device uses I2C, then the I2C interface
503 must also be configured. See I2C Support, below.
506 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
507 accesses and can checksum them or write a list of them out
508 to memory. See the 'iotrace' command for details. This is
509 useful for testing device drivers since it can confirm that
510 the driver behaves the same way before and after a code
511 change. Currently this is supported on sandbox and arm. To
512 add support for your architecture, add '#include <iotrace.h>'
513 to the bottom of arch/<arch>/include/asm/io.h and test.
515 Example output from the 'iotrace stats' command is below.
516 Note that if the trace buffer is exhausted, the checksum will
517 still continue to operate.
520 Start: 10000000 (buffer start address)
521 Size: 00010000 (buffer size)
522 Offset: 00000120 (current buffer offset)
523 Output: 10000120 (start + offset)
524 Count: 00000018 (number of trace records)
525 CRC32: 9526fb66 (CRC32 of all trace records)
529 When CONFIG_TIMESTAMP is selected, the timestamp
530 (date and time) of an image is printed by image
531 commands like bootm or iminfo. This option is
532 automatically enabled when you select CONFIG_CMD_DATE .
534 - Partition Labels (disklabels) Supported:
535 Zero or more of the following:
536 CONFIG_MAC_PARTITION Apple's MacOS partition table.
537 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
538 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
539 bootloader. Note 2TB partition limit; see
541 CONFIG_SCSI) you must configure support for at
542 least one non-MTD partition type as well.
544 - NETWORK Support (PCI):
546 Utility code for direct access to the SPI bus on Intel 8257x.
547 This does not do anything useful unless you set at least one
548 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
551 Support for National dp83815 chips.
554 Support for National dp8382[01] gigabit chips.
556 - NETWORK Support (other):
558 Support for the Calxeda XGMAC device
561 Support for SMSC's LAN91C96 chips.
563 CONFIG_LAN91C96_USE_32_BIT
564 Define this to enable 32 bit addressing
566 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
567 Define this if you have more then 3 PHYs.
570 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
572 CONFIG_FTGMAC100_EGIGA
573 Define this to use GE link update with gigabit PHY.
574 Define this if FTGMAC100 is connected to gigabit PHY.
575 If your system has 10/100 PHY only, it might not occur
576 wrong behavior. Because PHY usually return timeout or
577 useless data when polling gigabit status and gigabit
578 control registers. This behavior won't affect the
579 correctnessof 10/100 link speed update.
582 Support for Renesas on-chip Ethernet controller
584 CONFIG_SH_ETHER_USE_PORT
585 Define the number of ports to be used
587 CONFIG_SH_ETHER_PHY_ADDR
588 Define the ETH PHY's address
590 CONFIG_SH_ETHER_CACHE_WRITEBACK
591 If this option is set, the driver enables cache flush.
597 CONFIG_TPM_TIS_INFINEON
598 Support for Infineon i2c bus TPM devices. Only one device
599 per system is supported at this time.
601 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
602 Define the burst count bytes upper limit
605 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
607 CONFIG_TPM_ST33ZP24_I2C
608 Support for STMicroelectronics ST33ZP24 I2C devices.
609 Requires TPM_ST33ZP24 and I2C.
611 CONFIG_TPM_ST33ZP24_SPI
612 Support for STMicroelectronics ST33ZP24 SPI devices.
613 Requires TPM_ST33ZP24 and SPI.
616 Support for Atmel TWI TPM device. Requires I2C support.
619 Support for generic parallel port TPM devices. Only one device
620 per system is supported at this time.
622 CONFIG_TPM_TIS_BASE_ADDRESS
623 Base address where the generic TPM device is mapped
624 to. Contemporary x86 systems usually map it at
628 Define this to enable the TPM support library which provides
629 functional interfaces to some TPM commands.
630 Requires support for a TPM device.
632 CONFIG_TPM_AUTH_SESSIONS
633 Define this to enable authorized functions in the TPM library.
634 Requires CONFIG_TPM and CONFIG_SHA1.
637 At the moment only the UHCI host controller is
638 supported (PIP405, MIP405); define
639 CONFIG_USB_UHCI to enable it.
640 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
641 and define CONFIG_USB_STORAGE to enable the USB
644 Supported are USB Keyboards and USB Floppy drives
647 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
651 Define the below if you wish to use the USB console.
652 Once firmware is rebuilt from a serial console issue the
653 command "setenv stdin usbtty; setenv stdout usbtty" and
654 attach your USB cable. The Unix command "dmesg" should print
655 it has found a new device. The environment variable usbtty
656 can be set to gserial or cdc_acm to enable your device to
657 appear to a USB host as a Linux gserial device or a
658 Common Device Class Abstract Control Model serial device.
659 If you select usbtty = gserial you should be able to enumerate
661 # modprobe usbserial vendor=0xVendorID product=0xProductID
662 else if using cdc_acm, simply setting the environment
663 variable usbtty to be cdc_acm should suffice. The following
664 might be defined in YourBoardName.h
667 Define this to build a UDC device
670 Define this to have a tty type of device available to
671 talk to the UDC device
674 Define this to enable the high speed support for usb
675 device and usbtty. If this feature is enabled, a routine
676 int is_usbd_high_speed(void)
677 also needs to be defined by the driver to dynamically poll
678 whether the enumeration has succeded at high speed or full
681 If you have a USB-IF assigned VendorID then you may wish to
682 define your own vendor specific values either in BoardName.h
683 or directly in usbd_vendor_info.h. If you don't define
684 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
685 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
686 should pretend to be a Linux device to it's target host.
688 CONFIG_USBD_MANUFACTURER
689 Define this string as the name of your company for
690 - CONFIG_USBD_MANUFACTURER "my company"
692 CONFIG_USBD_PRODUCT_NAME
693 Define this string as the name of your product
694 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
697 Define this as your assigned Vendor ID from the USB
698 Implementors Forum. This *must* be a genuine Vendor ID
699 to avoid polluting the USB namespace.
700 - CONFIG_USBD_VENDORID 0xFFFF
702 CONFIG_USBD_PRODUCTID
703 Define this as the unique Product ID
705 - CONFIG_USBD_PRODUCTID 0xFFFF
707 - ULPI Layer Support:
708 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
709 the generic ULPI layer. The generic layer accesses the ULPI PHY
710 via the platform viewport, so you need both the genric layer and
711 the viewport enabled. Currently only Chipidea/ARC based
712 viewport is supported.
713 To enable the ULPI layer support, define CONFIG_USB_ULPI and
714 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
715 If your ULPI phy needs a different reference clock than the
716 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
717 the appropriate value in Hz.
721 Support for Renesas on-chip MMCIF controller
724 Define the base address of MMCIF registers
727 Define the clock frequency for MMCIF
729 - USB Device Firmware Update (DFU) class support:
731 This enables the USB portion of the DFU USB class
734 This enables support for exposing NAND devices via DFU.
737 This enables support for exposing RAM via DFU.
738 Note: DFU spec refer to non-volatile memory usage, but
739 allow usages beyond the scope of spec - here RAM usage,
740 one that would help mostly the developer.
742 CONFIG_SYS_DFU_DATA_BUF_SIZE
743 Dfu transfer uses a buffer before writing data to the
744 raw storage device. Make the size (in bytes) of this buffer
745 configurable. The size of this buffer is also configurable
746 through the "dfu_bufsiz" environment variable.
748 CONFIG_SYS_DFU_MAX_FILE_SIZE
749 When updating files rather than the raw storage device,
750 we use a static buffer to copy the file into and then write
751 the buffer once we've been given the whole file. Define
752 this to the maximum filesize (in bytes) for the buffer.
753 Default is 4 MiB if undefined.
755 DFU_DEFAULT_POLL_TIMEOUT
756 Poll timeout [ms], is the timeout a device can send to the
757 host. The host must wait for this timeout before sending
758 a subsequent DFU_GET_STATUS request to the device.
760 DFU_MANIFEST_POLL_TIMEOUT
761 Poll timeout [ms], which the device sends to the host when
762 entering dfuMANIFEST state. Host waits this timeout, before
763 sending again an USB request to the device.
766 See Kconfig help for available keyboard drivers.
769 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
771 The clock frequency of the MII bus
773 CONFIG_PHY_CMD_DELAY (ppc4xx)
775 Some PHY like Intel LXT971A need extra delay after
776 command issued before MII status register can be read
781 Define a default value for the IP address to use for
782 the default Ethernet interface, in case this is not
783 determined through e.g. bootp.
784 (Environment variable "ipaddr")
789 Defines a default value for the IP address of a TFTP
790 server to contact when using the "tftboot" command.
791 (Environment variable "serverip")
793 - Gateway IP address:
796 Defines a default value for the IP address of the
797 default router where packets to other networks are
799 (Environment variable "gatewayip")
804 Defines a default value for the subnet mask (or
805 routing prefix) which is used to determine if an IP
806 address belongs to the local subnet or needs to be
807 forwarded through a router.
808 (Environment variable "netmask")
810 - BOOTP Recovery Mode:
811 CONFIG_BOOTP_RANDOM_DELAY
813 If you have many targets in a network that try to
814 boot using BOOTP, you may want to avoid that all
815 systems send out BOOTP requests at precisely the same
816 moment (which would happen for instance at recovery
817 from a power failure, when all systems will try to
818 boot, thus flooding the BOOTP server. Defining
819 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
820 inserted before sending out BOOTP requests. The
821 following delays are inserted then:
823 1st BOOTP request: delay 0 ... 1 sec
824 2nd BOOTP request: delay 0 ... 2 sec
825 3rd BOOTP request: delay 0 ... 4 sec
827 BOOTP requests: delay 0 ... 8 sec
829 CONFIG_BOOTP_ID_CACHE_SIZE
831 BOOTP packets are uniquely identified using a 32-bit ID. The
832 server will copy the ID from client requests to responses and
833 U-Boot will use this to determine if it is the destination of
834 an incoming response. Some servers will check that addresses
835 aren't in use before handing them out (usually using an ARP
836 ping) and therefore take up to a few hundred milliseconds to
837 respond. Network congestion may also influence the time it
838 takes for a response to make it back to the client. If that
839 time is too long, U-Boot will retransmit requests. In order
840 to allow earlier responses to still be accepted after these
841 retransmissions, U-Boot's BOOTP client keeps a small cache of
842 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
843 cache. The default is to keep IDs for up to four outstanding
844 requests. Increasing this will allow U-Boot to accept offers
845 from a BOOTP client in networks with unusually high latency.
847 - DHCP Advanced Options:
849 - Link-local IP address negotiation:
850 Negotiate with other link-local clients on the local network
851 for an address that doesn't require explicit configuration.
852 This is especially useful if a DHCP server cannot be guaranteed
853 to exist in all environments that the device must operate.
855 See doc/README.link-local for more information.
857 - MAC address from environment variables
859 FDT_SEQ_MACADDR_FROM_ENV
861 Fix-up device tree with MAC addresses fetched sequentially from
862 environment variables. This config work on assumption that
863 non-usable ethernet node of device-tree are either not present
864 or their status has been marked as "disabled".
869 The device id used in CDP trigger frames.
871 CONFIG_CDP_DEVICE_ID_PREFIX
873 A two character string which is prefixed to the MAC address
878 A printf format string which contains the ascii name of
879 the port. Normally is set to "eth%d" which sets
880 eth0 for the first Ethernet, eth1 for the second etc.
882 CONFIG_CDP_CAPABILITIES
884 A 32bit integer which indicates the device capabilities;
885 0x00000010 for a normal host which does not forwards.
889 An ascii string containing the version of the software.
893 An ascii string containing the name of the platform.
897 A 32bit integer sent on the trigger.
899 CONFIG_CDP_POWER_CONSUMPTION
901 A 16bit integer containing the power consumption of the
902 device in .1 of milliwatts.
904 CONFIG_CDP_APPLIANCE_VLAN_TYPE
906 A byte containing the id of the VLAN.
908 - Status LED: CONFIG_LED_STATUS
910 Several configurations allow to display the current
911 status using a LED. For instance, the LED will blink
912 fast while running U-Boot code, stop blinking as
913 soon as a reply to a BOOTP request was received, and
914 start blinking slow once the Linux kernel is running
915 (supported by a status LED driver in the Linux
916 kernel). Defining CONFIG_LED_STATUS enables this
921 CONFIG_LED_STATUS_GPIO
922 The status LED can be connected to a GPIO pin.
923 In such cases, the gpio_led driver can be used as a
924 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
925 to include the gpio_led driver in the U-Boot binary.
927 CONFIG_GPIO_LED_INVERTED_TABLE
928 Some GPIO connected LEDs may have inverted polarity in which
929 case the GPIO high value corresponds to LED off state and
930 GPIO low value corresponds to LED on state.
931 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
932 with a list of GPIO LEDs that have inverted polarity.
935 CONFIG_SYS_NUM_I2C_BUSES
936 Hold the number of i2c buses you want to use.
938 CONFIG_SYS_I2C_DIRECT_BUS
939 define this, if you don't use i2c muxes on your hardware.
940 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
943 CONFIG_SYS_I2C_MAX_HOPS
944 define how many muxes are maximal consecutively connected
945 on one i2c bus. If you not use i2c muxes, omit this
949 hold a list of buses you want to use, only used if
950 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
951 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
952 CONFIG_SYS_NUM_I2C_BUSES = 9:
954 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
955 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
956 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
957 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
958 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
959 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
960 {1, {I2C_NULL_HOP}}, \
961 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
962 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
966 bus 0 on adapter 0 without a mux
967 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
968 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
969 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
970 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
971 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
972 bus 6 on adapter 1 without a mux
973 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
974 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
976 If you do not have i2c muxes on your board, omit this define.
978 - Legacy I2C Support:
979 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
980 then the following macros need to be defined (examples are
981 from include/configs/lwmon.h):
985 (Optional). Any commands necessary to enable the I2C
986 controller or configure ports.
988 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
992 The code necessary to make the I2C data line active
993 (driven). If the data line is open collector, this
996 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1000 The code necessary to make the I2C data line tri-stated
1001 (inactive). If the data line is open collector, this
1004 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1008 Code that returns true if the I2C data line is high,
1011 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1015 If <bit> is true, sets the I2C data line high. If it
1016 is false, it clears it (low).
1018 eg: #define I2C_SDA(bit) \
1019 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1020 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1024 If <bit> is true, sets the I2C clock line high. If it
1025 is false, it clears it (low).
1027 eg: #define I2C_SCL(bit) \
1028 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1029 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1033 This delay is invoked four times per clock cycle so this
1034 controls the rate of data transfer. The data rate thus
1035 is 1 / (I2C_DELAY * 4). Often defined to be something
1038 #define I2C_DELAY udelay(2)
1040 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1042 If your arch supports the generic GPIO framework (asm/gpio.h),
1043 then you may alternatively define the two GPIOs that are to be
1044 used as SCL / SDA. Any of the previous I2C_xxx macros will
1045 have GPIO-based defaults assigned to them as appropriate.
1047 You should define these to the GPIO value as given directly to
1048 the generic GPIO functions.
1050 CONFIG_I2C_MULTI_BUS
1052 This option allows the use of multiple I2C buses, each of which
1053 must have a controller. At any point in time, only one bus is
1054 active. To switch to a different bus, use the 'i2c dev' command.
1055 Note that bus numbering is zero-based.
1057 CONFIG_SYS_I2C_NOPROBES
1059 This option specifies a list of I2C devices that will be skipped
1060 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1061 is set, specify a list of bus-device pairs. Otherwise, specify
1062 a 1D array of device addresses
1065 #undef CONFIG_I2C_MULTI_BUS
1066 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1068 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1070 #define CONFIG_I2C_MULTI_BUS
1071 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1073 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1075 CONFIG_SYS_RTC_BUS_NUM
1077 If defined, then this indicates the I2C bus number for the RTC.
1078 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1080 CONFIG_SOFT_I2C_READ_REPEATED_START
1082 defining this will force the i2c_read() function in
1083 the soft_i2c driver to perform an I2C repeated start
1084 between writing the address pointer and reading the
1085 data. If this define is omitted the default behaviour
1086 of doing a stop-start sequence will be used. Most I2C
1087 devices can use either method, but some require one or
1090 - SPI Support: CONFIG_SPI
1092 Enables SPI driver (so far only tested with
1093 SPI EEPROM, also an instance works with Crystal A/D and
1094 D/As on the SACSng board)
1096 CONFIG_SYS_SPI_MXC_WAIT
1097 Timeout for waiting until spi transfer completed.
1098 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1100 - FPGA Support: CONFIG_FPGA
1102 Enables FPGA subsystem.
1104 CONFIG_FPGA_<vendor>
1106 Enables support for specific chip vendors.
1109 CONFIG_FPGA_<family>
1111 Enables support for FPGA family.
1112 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1114 CONFIG_SYS_FPGA_CHECK_BUSY
1116 Enable checks on FPGA configuration interface busy
1117 status by the configuration function. This option
1118 will require a board or device specific function to
1123 If defined, a function that provides delays in the FPGA
1124 configuration driver.
1126 CONFIG_SYS_FPGA_CHECK_ERROR
1128 Check for configuration errors during FPGA bitfile
1129 loading. For example, abort during Virtex II
1130 configuration if the INIT_B line goes low (which
1131 indicated a CRC error).
1133 CONFIG_SYS_FPGA_WAIT_INIT
1135 Maximum time to wait for the INIT_B line to de-assert
1136 after PROB_B has been de-asserted during a Virtex II
1137 FPGA configuration sequence. The default time is 500
1140 CONFIG_SYS_FPGA_WAIT_BUSY
1142 Maximum time to wait for BUSY to de-assert during
1143 Virtex II FPGA configuration. The default is 5 ms.
1145 CONFIG_SYS_FPGA_WAIT_CONFIG
1147 Time to wait after FPGA configuration. The default is
1150 - Vendor Parameter Protection:
1152 U-Boot considers the values of the environment
1153 variables "serial#" (Board Serial Number) and
1154 "ethaddr" (Ethernet Address) to be parameters that
1155 are set once by the board vendor / manufacturer, and
1156 protects these variables from casual modification by
1157 the user. Once set, these variables are read-only,
1158 and write or delete attempts are rejected. You can
1159 change this behaviour:
1161 If CONFIG_ENV_OVERWRITE is #defined in your config
1162 file, the write protection for vendor parameters is
1163 completely disabled. Anybody can change or delete
1166 Alternatively, if you define _both_ an ethaddr in the
1167 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1168 Ethernet address is installed in the environment,
1169 which can be changed exactly ONCE by the user. [The
1170 serial# is unaffected by this, i. e. it remains
1173 The same can be accomplished in a more flexible way
1174 for any variable by configuring the type of access
1175 to allow for those variables in the ".flags" variable
1176 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1181 Define this variable to enable the reservation of
1182 "protected RAM", i. e. RAM which is not overwritten
1183 by U-Boot. Define CONFIG_PRAM to hold the number of
1184 kB you want to reserve for pRAM. You can overwrite
1185 this default value by defining an environment
1186 variable "pram" to the number of kB you want to
1187 reserve. Note that the board info structure will
1188 still show the full amount of RAM. If pRAM is
1189 reserved, a new environment variable "mem" will
1190 automatically be defined to hold the amount of
1191 remaining RAM in a form that can be passed as boot
1192 argument to Linux, for instance like that:
1194 setenv bootargs ... mem=\${mem}
1197 This way you can tell Linux not to use this memory,
1198 either, which results in a memory region that will
1199 not be affected by reboots.
1201 *WARNING* If your board configuration uses automatic
1202 detection of the RAM size, you must make sure that
1203 this memory test is non-destructive. So far, the
1204 following board configurations are known to be
1207 IVMS8, IVML24, SPD8xx,
1208 HERMES, IP860, RPXlite, LWMON,
1214 In the current implementation, the local variables
1215 space and global environment variables space are
1216 separated. Local variables are those you define by
1217 simply typing `name=value'. To access a local
1218 variable later on, you have write `$name' or
1219 `${name}'; to execute the contents of a variable
1220 directly type `$name' at the command prompt.
1222 Global environment variables are those you use
1223 setenv/printenv to work with. To run a command stored
1224 in such a variable, you need to use the run command,
1225 and you must not use the '$' sign to access them.
1227 To store commands and special characters in a
1228 variable, please use double quotation marks
1229 surrounding the whole text of the variable, instead
1230 of the backslashes before semicolons and special
1233 - Default Environment:
1234 CONFIG_EXTRA_ENV_SETTINGS
1236 Define this to contain any number of null terminated
1237 strings (variable = value pairs) that will be part of
1238 the default environment compiled into the boot image.
1240 For example, place something like this in your
1241 board's config file:
1243 #define CONFIG_EXTRA_ENV_SETTINGS \
1247 Warning: This method is based on knowledge about the
1248 internal format how the environment is stored by the
1249 U-Boot code. This is NOT an official, exported
1250 interface! Although it is unlikely that this format
1251 will change soon, there is no guarantee either.
1252 You better know what you are doing here.
1254 Note: overly (ab)use of the default environment is
1255 discouraged. Make sure to check other ways to preset
1256 the environment like the "source" command or the
1259 CONFIG_DELAY_ENVIRONMENT
1261 Normally the environment is loaded when the board is
1262 initialised so that it is available to U-Boot. This inhibits
1263 that so that the environment is not available until
1264 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1265 this is instead controlled by the value of
1266 /config/load-environment.
1268 CONFIG_STANDALONE_LOAD_ADDR
1270 This option defines a board specific value for the
1271 address where standalone program gets loaded, thus
1272 overwriting the architecture dependent default
1275 - Automatic software updates via TFTP server
1277 CONFIG_UPDATE_TFTP_CNT_MAX
1278 CONFIG_UPDATE_TFTP_MSEC_MAX
1280 These options enable and control the auto-update feature;
1281 for a more detailed description refer to doc/README.update.
1283 - MTD Support (mtdparts command, UBI support)
1284 CONFIG_MTD_UBI_WL_THRESHOLD
1285 This parameter defines the maximum difference between the highest
1286 erase counter value and the lowest erase counter value of eraseblocks
1287 of UBI devices. When this threshold is exceeded, UBI starts performing
1288 wear leveling by means of moving data from eraseblock with low erase
1289 counter to eraseblocks with high erase counter.
1291 The default value should be OK for SLC NAND flashes, NOR flashes and
1292 other flashes which have eraseblock life-cycle 100000 or more.
1293 However, in case of MLC NAND flashes which typically have eraseblock
1294 life-cycle less than 10000, the threshold should be lessened (e.g.,
1295 to 128 or 256, although it does not have to be power of 2).
1299 CONFIG_MTD_UBI_BEB_LIMIT
1300 This option specifies the maximum bad physical eraseblocks UBI
1301 expects on the MTD device (per 1024 eraseblocks). If the
1302 underlying flash does not admit of bad eraseblocks (e.g. NOR
1303 flash), this value is ignored.
1305 NAND datasheets often specify the minimum and maximum NVM
1306 (Number of Valid Blocks) for the flashes' endurance lifetime.
1307 The maximum expected bad eraseblocks per 1024 eraseblocks
1308 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1309 which gives 20 for most NANDs (MaxNVB is basically the total
1310 count of eraseblocks on the chip).
1312 To put it differently, if this value is 20, UBI will try to
1313 reserve about 1.9% of physical eraseblocks for bad blocks
1314 handling. And that will be 1.9% of eraseblocks on the entire
1315 NAND chip, not just the MTD partition UBI attaches. This means
1316 that if you have, say, a NAND flash chip admits maximum 40 bad
1317 eraseblocks, and it is split on two MTD partitions of the same
1318 size, UBI will reserve 40 eraseblocks when attaching a
1323 CONFIG_MTD_UBI_FASTMAP
1324 Fastmap is a mechanism which allows attaching an UBI device
1325 in nearly constant time. Instead of scanning the whole MTD device it
1326 only has to locate a checkpoint (called fastmap) on the device.
1327 The on-flash fastmap contains all information needed to attach
1328 the device. Using fastmap makes only sense on large devices where
1329 attaching by scanning takes long. UBI will not automatically install
1330 a fastmap on old images, but you can set the UBI parameter
1331 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1332 that fastmap-enabled images are still usable with UBI implementations
1333 without fastmap support. On typical flash devices the whole fastmap
1334 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1336 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1337 Set this parameter to enable fastmap automatically on images
1341 CONFIG_MTD_UBI_FM_DEBUG
1342 Enable UBI fastmap debug
1347 Enable building of SPL globally.
1349 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1350 When defined, SPL will panic() if the image it has
1351 loaded does not have a signature.
1352 Defining this is useful when code which loads images
1353 in SPL cannot guarantee that absolutely all read errors
1355 An example is the LPC32XX MLC NAND driver, which will
1356 consider that a completely unreadable NAND block is bad,
1357 and thus should be skipped silently.
1359 CONFIG_SPL_DISPLAY_PRINT
1360 For ARM, enable an optional function to print more information
1361 about the running system.
1363 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1364 Set this for NAND SPL on PPC mpc83xx targets, so that
1365 start.S waits for the rest of the SPL to load before
1366 continuing (the hardware starts execution after just
1367 loading the first page rather than the full 4K).
1370 Support for a lightweight UBI (fastmap) scanner and
1373 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1374 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1375 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1376 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1377 CONFIG_SYS_NAND_ECCBYTES
1378 Defines the size and behavior of the NAND that SPL uses
1381 CONFIG_SYS_NAND_U_BOOT_DST
1382 Location in memory to load U-Boot to
1384 CONFIG_SYS_NAND_U_BOOT_SIZE
1385 Size of image to load
1387 CONFIG_SYS_NAND_U_BOOT_START
1388 Entry point in loaded image to jump to
1390 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1391 Define this if you need to first read the OOB and then the
1392 data. This is used, for example, on davinci platforms.
1394 CONFIG_SPL_RAM_DEVICE
1395 Support for running image already present in ram, in SPL binary
1397 CONFIG_SPL_FIT_PRINT
1398 Printing information about a FIT image adds quite a bit of
1399 code to SPL. So this is normally disabled in SPL. Use this
1400 option to re-enable it. This will affect the output of the
1401 bootm command when booting a FIT image.
1403 - Interrupt support (PPC):
1405 There are common interrupt_init() and timer_interrupt()
1406 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1407 for CPU specific initialization. interrupt_init_cpu()
1408 should set decrementer_count to appropriate value. If
1409 CPU resets decrementer automatically after interrupt
1410 (ppc4xx) it should set decrementer_count to zero.
1411 timer_interrupt() calls timer_interrupt_cpu() for CPU
1412 specific handling. If board has watchdog / status_led
1413 / other_activity_monitor it works automatically from
1414 general timer_interrupt().
1417 Board initialization settings:
1418 ------------------------------
1420 During Initialization u-boot calls a number of board specific functions
1421 to allow the preparation of board specific prerequisites, e.g. pin setup
1422 before drivers are initialized. To enable these callbacks the
1423 following configuration macros have to be defined. Currently this is
1424 architecture specific, so please check arch/your_architecture/lib/board.c
1425 typically in board_init_f() and board_init_r().
1427 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1428 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1429 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1431 Configuration Settings:
1432 -----------------------
1434 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1435 Optionally it can be defined to support 64-bit memory commands.
1437 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1438 undefine this when you're short of memory.
1440 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1441 width of the commands listed in the 'help' command output.
1443 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1444 prompt for user input.
1446 - CONFIG_SYS_BAUDRATE_TABLE:
1447 List of legal baudrate settings for this board.
1449 - CONFIG_SYS_MEM_RESERVE_SECURE
1450 Only implemented for ARMv8 for now.
1451 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1452 is substracted from total RAM and won't be reported to OS.
1453 This memory can be used as secure memory. A variable
1454 gd->arch.secure_ram is used to track the location. In systems
1455 the RAM base is not zero, or RAM is divided into banks,
1456 this variable needs to be recalcuated to get the address.
1458 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1459 Enable temporary baudrate change while serial download
1461 - CONFIG_SYS_SDRAM_BASE:
1462 Physical start address of SDRAM. _Must_ be 0 here.
1464 - CONFIG_SYS_FLASH_BASE:
1465 Physical start address of Flash memory.
1467 - CONFIG_SYS_MONITOR_LEN:
1468 Size of memory reserved for monitor code, used to
1469 determine _at_compile_time_ (!) if the environment is
1470 embedded within the U-Boot image, or in a separate
1473 - CONFIG_SYS_MALLOC_LEN:
1474 Size of DRAM reserved for malloc() use.
1476 - CONFIG_SYS_MALLOC_F_LEN
1477 Size of the malloc() pool for use before relocation. If
1478 this is defined, then a very simple malloc() implementation
1479 will become available before relocation. The address is just
1480 below the global data, and the stack is moved down to make
1483 This feature allocates regions with increasing addresses
1484 within the region. calloc() is supported, but realloc()
1485 is not available. free() is supported but does nothing.
1486 The memory will be freed (or in fact just forgotten) when
1487 U-Boot relocates itself.
1489 - CONFIG_SYS_MALLOC_SIMPLE
1490 Provides a simple and small malloc() and calloc() for those
1491 boards which do not use the full malloc in SPL (which is
1492 enabled with CONFIG_SYS_SPL_MALLOC).
1494 - CONFIG_SYS_NONCACHED_MEMORY:
1495 Size of non-cached memory area. This area of memory will be
1496 typically located right below the malloc() area and mapped
1497 uncached in the MMU. This is useful for drivers that would
1498 otherwise require a lot of explicit cache maintenance. For
1499 some drivers it's also impossible to properly maintain the
1500 cache. For example if the regions that need to be flushed
1501 are not a multiple of the cache-line size, *and* padding
1502 cannot be allocated between the regions to align them (i.e.
1503 if the HW requires a contiguous array of regions, and the
1504 size of each region is not cache-aligned), then a flush of
1505 one region may result in overwriting data that hardware has
1506 written to another region in the same cache-line. This can
1507 happen for example in network drivers where descriptors for
1508 buffers are typically smaller than the CPU cache-line (e.g.
1509 16 bytes vs. 32 or 64 bytes).
1511 Non-cached memory is only supported on 32-bit ARM at present.
1513 - CONFIG_SYS_BOOTMAPSZ:
1514 Maximum size of memory mapped by the startup code of
1515 the Linux kernel; all data that must be processed by
1516 the Linux kernel (bd_info, boot arguments, FDT blob if
1517 used) must be put below this limit, unless "bootm_low"
1518 environment variable is defined and non-zero. In such case
1519 all data for the Linux kernel must be between "bootm_low"
1520 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
1521 variable "bootm_mapsize" will override the value of
1522 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
1523 then the value in "bootm_size" will be used instead.
1525 - CONFIG_SYS_BOOT_GET_CMDLINE:
1526 Enables allocating and saving kernel cmdline in space between
1527 "bootm_low" and "bootm_low" + BOOTMAPSZ.
1529 - CONFIG_SYS_BOOT_GET_KBD:
1530 Enables allocating and saving a kernel copy of the bd_info in
1531 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
1533 - CONFIG_SYS_FLASH_PROTECTION
1534 If defined, hardware flash sectors protection is used
1535 instead of U-Boot software protection.
1537 - CONFIG_SYS_FLASH_CFI:
1538 Define if the flash driver uses extra elements in the
1539 common flash structure for storing flash geometry.
1541 - CONFIG_FLASH_CFI_DRIVER
1542 This option also enables the building of the cfi_flash driver
1543 in the drivers directory
1545 - CONFIG_FLASH_CFI_MTD
1546 This option enables the building of the cfi_mtd driver
1547 in the drivers directory. The driver exports CFI flash
1550 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
1551 Use buffered writes to flash.
1553 - CONFIG_FLASH_SPANSION_S29WS_N
1554 s29ws-n MirrorBit flash has non-standard addresses for buffered
1557 - CONFIG_FLASH_SHOW_PROGRESS
1558 If defined (must be an integer), print out countdown
1559 digits and dots. Recommended value: 45 (9..1) for 80
1560 column displays, 15 (3..1) for 40 column displays.
1562 - CONFIG_FLASH_VERIFY
1563 If defined, the content of the flash (destination) is compared
1564 against the source after the write operation. An error message
1565 will be printed when the contents are not identical.
1566 Please note that this option is useless in nearly all cases,
1567 since such flash programming errors usually are detected earlier
1568 while unprotecting/erasing/programming. Please only enable
1569 this option if you really know what you are doing.
1571 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1572 - CONFIG_ENV_FLAGS_LIST_STATIC
1573 Enable validation of the values given to environment variables when
1574 calling env set. Variables can be restricted to only decimal,
1575 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
1576 the variables can also be restricted to IP address or MAC address.
1578 The format of the list is:
1579 type_attribute = [s|d|x|b|i|m]
1580 access_attribute = [a|r|o|c]
1581 attributes = type_attribute[access_attribute]
1582 entry = variable_name[:attributes]
1585 The type attributes are:
1586 s - String (default)
1589 b - Boolean ([1yYtT|0nNfF])
1593 The access attributes are:
1599 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1600 Define this to a list (string) to define the ".flags"
1601 environment variable in the default or embedded environment.
1603 - CONFIG_ENV_FLAGS_LIST_STATIC
1604 Define this to a list (string) to define validation that
1605 should be done if an entry is not found in the ".flags"
1606 environment variable. To override a setting in the static
1607 list, simply add an entry for the same variable name to the
1610 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
1611 regular expression. This allows multiple variables to define the same
1612 flags without explicitly listing them for each variable.
1614 The following definitions that deal with the placement and management
1615 of environment data (variable area); in general, we support the
1616 following configurations:
1618 - CONFIG_BUILD_ENVCRC:
1620 Builds up envcrc with the target environment so that external utils
1621 may easily extract it and embed it in final U-Boot images.
1623 BE CAREFUL! The first access to the environment happens quite early
1624 in U-Boot initialization (when we try to get the setting of for the
1625 console baudrate). You *MUST* have mapped your NVRAM area then, or
1628 Please note that even with NVRAM we still use a copy of the
1629 environment in RAM: we could work on NVRAM directly, but we want to
1630 keep settings there always unmodified except somebody uses "saveenv"
1631 to save the current settings.
1633 BE CAREFUL! For some special cases, the local device can not use
1634 "saveenv" command. For example, the local device will get the
1635 environment stored in a remote NOR flash by SRIO or PCIE link,
1636 but it can not erase, write this NOR flash by SRIO or PCIE interface.
1638 - CONFIG_NAND_ENV_DST
1640 Defines address in RAM to which the nand_spl code should copy the
1641 environment. If redundant environment is used, it will be copied to
1642 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
1644 Please note that the environment is read-only until the monitor
1645 has been relocated to RAM and a RAM copy of the environment has been
1646 created; also, when using EEPROM you will have to use env_get_f()
1647 until then to read environment variables.
1649 The environment is protected by a CRC32 checksum. Before the monitor
1650 is relocated into RAM, as a result of a bad CRC you will be working
1651 with the compiled-in default environment - *silently*!!! [This is
1652 necessary, because the first environment variable we need is the
1653 "baudrate" setting for the console - if we have a bad CRC, we don't
1654 have any device yet where we could complain.]
1656 Note: once the monitor has been relocated, then it will complain if
1657 the default environment is used; a new CRC is computed as soon as you
1658 use the "saveenv" command to store a valid environment.
1660 - CONFIG_SYS_FAULT_MII_ADDR:
1661 MII address of the PHY to check for the Ethernet link state.
1663 - CONFIG_NS16550_MIN_FUNCTIONS:
1664 Define this if you desire to only have use of the NS16550_init
1665 and NS16550_putc functions for the serial driver located at
1666 drivers/serial/ns16550.c. This option is useful for saving
1667 space for already greatly restricted images, including but not
1668 limited to NAND_SPL configurations.
1670 - CONFIG_DISPLAY_BOARDINFO
1671 Display information about the board that U-Boot is running on
1672 when U-Boot starts up. The board function checkboard() is called
1675 - CONFIG_DISPLAY_BOARDINFO_LATE
1676 Similar to the previous option, but display this information
1677 later, once stdio is running and output goes to the LCD, if
1680 Low Level (hardware related) configuration options:
1681 ---------------------------------------------------
1683 - CONFIG_SYS_CACHELINE_SIZE:
1684 Cache Line Size of the CPU.
1686 - CONFIG_SYS_CCSRBAR_DEFAULT:
1687 Default (power-on reset) physical address of CCSR on Freescale
1690 - CONFIG_SYS_CCSRBAR:
1691 Virtual address of CCSR. On a 32-bit build, this is typically
1692 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
1694 - CONFIG_SYS_CCSRBAR_PHYS:
1695 Physical address of CCSR. CCSR can be relocated to a new
1696 physical address, if desired. In this case, this macro should
1697 be set to that address. Otherwise, it should be set to the
1698 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
1699 is typically relocated on 36-bit builds. It is recommended
1700 that this macro be defined via the _HIGH and _LOW macros:
1702 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
1703 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
1705 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
1706 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
1707 either 0 (32-bit build) or 0xF (36-bit build). This macro is
1708 used in assembly code, so it must not contain typecasts or
1709 integer size suffixes (e.g. "ULL").
1711 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
1712 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
1713 used in assembly code, so it must not contain typecasts or
1714 integer size suffixes (e.g. "ULL").
1716 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
1717 DO NOT CHANGE unless you know exactly what you're
1718 doing! (11-4) [MPC8xx systems only]
1720 - CONFIG_SYS_INIT_RAM_ADDR:
1722 Start address of memory area that can be used for
1723 initial data and stack; please note that this must be
1724 writable memory that is working WITHOUT special
1725 initialization, i. e. you CANNOT use normal RAM which
1726 will become available only after programming the
1727 memory controller and running certain initialization
1730 U-Boot uses the following memory types:
1731 - MPC8xx: IMMR (internal memory of the CPU)
1733 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
1735 - CONFIG_SYS_OR_TIMING_SDRAM:
1739 Chip has SRIO or not
1742 Board has SRIO 1 port available
1745 Board has SRIO 2 port available
1747 - CONFIG_SRIO_PCIE_BOOT_MASTER
1748 Board can support master function for Boot from SRIO and PCIE
1750 - CONFIG_SYS_SRIOn_MEM_VIRT:
1751 Virtual Address of SRIO port 'n' memory region
1753 - CONFIG_SYS_SRIOn_MEM_PHYxS:
1754 Physical Address of SRIO port 'n' memory region
1756 - CONFIG_SYS_SRIOn_MEM_SIZE:
1757 Size of SRIO port 'n' memory region
1759 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
1760 Defined to tell the NAND controller that the NAND chip is using
1762 Not all NAND drivers use this symbol.
1763 Example of drivers that use it:
1764 - drivers/mtd/nand/raw/ndfc.c
1765 - drivers/mtd/nand/raw/mxc_nand.c
1767 - CONFIG_SYS_NDFC_EBC0_CFG
1768 Sets the EBC0_CFG register for the NDFC. If not defined
1769 a default value will be used.
1772 Get DDR timing information from an I2C EEPROM. Common
1773 with pluggable memory modules such as SODIMMs
1776 I2C address of the SPD EEPROM
1778 - CONFIG_SYS_SPD_BUS_NUM
1779 If SPD EEPROM is on an I2C bus other than the first
1780 one, specify here. Note that the value must resolve
1781 to something your driver can deal with.
1783 - CONFIG_FSL_DDR_INTERACTIVE
1784 Enable interactive DDR debugging. See doc/README.fsl-ddr.
1786 - CONFIG_FSL_DDR_SYNC_REFRESH
1787 Enable sync of refresh for multiple controllers.
1789 - CONFIG_FSL_DDR_BIST
1790 Enable built-in memory test for Freescale DDR controllers.
1793 Enable RMII mode for all FECs.
1794 Note that this is a global option, we can't
1795 have one FEC in standard MII mode and another in RMII mode.
1797 - CONFIG_CRC32_VERIFY
1798 Add a verify option to the crc32 command.
1801 => crc32 -v <address> <count> <crc32>
1803 Where address/count indicate a memory area
1804 and crc32 is the correct crc32 which the
1808 Add the "loopw" memory command. This only takes effect if
1809 the memory commands are activated globally (CONFIG_CMD_MEMORY).
1811 - CONFIG_CMD_MX_CYCLIC
1812 Add the "mdc" and "mwc" memory commands. These are cyclic
1817 This command will print 4 bytes (10,11,12,13) each 500 ms.
1819 => mwc.l 100 12345678 10
1820 This command will write 12345678 to address 100 all 10 ms.
1822 This only takes effect if the memory commands are activated
1823 globally (CONFIG_CMD_MEMORY).
1826 Set when the currently-running compilation is for an artifact
1827 that will end up in the SPL (as opposed to the TPL or U-Boot
1828 proper). Code that needs stage-specific behavior should check
1832 Set when the currently-running compilation is for an artifact
1833 that will end up in the TPL (as opposed to the SPL or U-Boot
1834 proper). Code that needs stage-specific behavior should check
1837 - CONFIG_ARCH_MAP_SYSMEM
1838 Generally U-Boot (and in particular the md command) uses
1839 effective address. It is therefore not necessary to regard
1840 U-Boot address as virtual addresses that need to be translated
1841 to physical addresses. However, sandbox requires this, since
1842 it maintains its own little RAM buffer which contains all
1843 addressable memory. This option causes some memory accesses
1844 to be mapped through map_sysmem() / unmap_sysmem().
1846 - CONFIG_X86_RESET_VECTOR
1847 If defined, the x86 reset vector code is included. This is not
1848 needed when U-Boot is running from Coreboot.
1850 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
1851 Option to disable subpage write in NAND driver
1852 driver that uses this:
1853 drivers/mtd/nand/raw/davinci_nand.c
1855 Freescale QE/FMAN Firmware Support:
1856 -----------------------------------
1858 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
1859 loading of "firmware", which is encoded in the QE firmware binary format.
1860 This firmware often needs to be loaded during U-Boot booting, so macros
1861 are used to identify the storage device (NOR flash, SPI, etc) and the address
1864 - CONFIG_SYS_FMAN_FW_ADDR
1865 The address in the storage device where the FMAN microcode is located. The
1866 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
1869 - CONFIG_SYS_QE_FW_ADDR
1870 The address in the storage device where the QE microcode is located. The
1871 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
1874 - CONFIG_SYS_QE_FMAN_FW_LENGTH
1875 The maximum possible size of the firmware. The firmware binary format
1876 has a field that specifies the actual size of the firmware, but it
1877 might not be possible to read any part of the firmware unless some
1878 local storage is allocated to hold the entire firmware first.
1880 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
1881 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
1882 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
1883 virtual address in NOR flash.
1885 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
1886 Specifies that QE/FMAN firmware is located in NAND flash.
1887 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
1889 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
1890 Specifies that QE/FMAN firmware is located on the primary SD/MMC
1891 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
1893 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
1894 Specifies that QE/FMAN firmware is located in the remote (master)
1895 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
1896 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
1897 window->master inbound window->master LAW->the ucode address in
1898 master's memory space.
1900 Freescale Layerscape Management Complex Firmware Support:
1901 ---------------------------------------------------------
1902 The Freescale Layerscape Management Complex (MC) supports the loading of
1904 This firmware often needs to be loaded during U-Boot booting, so macros
1905 are used to identify the storage device (NOR flash, SPI, etc) and the address
1908 - CONFIG_FSL_MC_ENET
1909 Enable the MC driver for Layerscape SoCs.
1911 Freescale Layerscape Debug Server Support:
1912 -------------------------------------------
1913 The Freescale Layerscape Debug Server Support supports the loading of
1914 "Debug Server firmware" and triggering SP boot-rom.
1915 This firmware often needs to be loaded during U-Boot booting.
1917 - CONFIG_SYS_MC_RSV_MEM_ALIGN
1918 Define alignment of reserved memory MC requires
1923 In order to achieve reproducible builds, timestamps used in the U-Boot build
1924 process have to be set to a fixed value.
1926 This is done using the SOURCE_DATE_EPOCH environment variable.
1927 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
1928 option for U-Boot or an environment variable in U-Boot.
1930 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
1932 Building the Software:
1933 ======================
1935 Building U-Boot has been tested in several native build environments
1936 and in many different cross environments. Of course we cannot support
1937 all possibly existing versions of cross development tools in all
1938 (potentially obsolete) versions. In case of tool chain problems we
1939 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
1940 which is extensively used to build and test U-Boot.
1942 If you are not using a native environment, it is assumed that you
1943 have GNU cross compiling tools available in your path. In this case,
1944 you must set the environment variable CROSS_COMPILE in your shell.
1945 Note that no changes to the Makefile or any other source files are
1946 necessary. For example using the ELDK on a 4xx CPU, please enter:
1948 $ CROSS_COMPILE=ppc_4xx-
1949 $ export CROSS_COMPILE
1951 U-Boot is intended to be simple to build. After installing the
1952 sources you must configure U-Boot for one specific board type. This
1957 where "NAME_defconfig" is the name of one of the existing configu-
1958 rations; see configs/*_defconfig for supported names.
1960 Note: for some boards special configuration names may exist; check if
1961 additional information is available from the board vendor; for
1962 instance, the TQM823L systems are available without (standard)
1963 or with LCD support. You can select such additional "features"
1964 when choosing the configuration, i. e.
1966 make TQM823L_defconfig
1967 - will configure for a plain TQM823L, i. e. no LCD support
1969 make TQM823L_LCD_defconfig
1970 - will configure for a TQM823L with U-Boot console on LCD
1975 Finally, type "make all", and you should get some working U-Boot
1976 images ready for download to / installation on your system:
1978 - "u-boot.bin" is a raw binary image
1979 - "u-boot" is an image in ELF binary format
1980 - "u-boot.srec" is in Motorola S-Record format
1982 By default the build is performed locally and the objects are saved
1983 in the source directory. One of the two methods can be used to change
1984 this behavior and build U-Boot to some external directory:
1986 1. Add O= to the make command line invocations:
1988 make O=/tmp/build distclean
1989 make O=/tmp/build NAME_defconfig
1990 make O=/tmp/build all
1992 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
1994 export KBUILD_OUTPUT=/tmp/build
1999 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2002 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2003 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2004 For example to treat all compiler warnings as errors:
2006 make KCFLAGS=-Werror
2008 Please be aware that the Makefiles assume you are using GNU make, so
2009 for instance on NetBSD you might need to use "gmake" instead of
2013 If the system board that you have is not listed, then you will need
2014 to port U-Boot to your hardware platform. To do this, follow these
2017 1. Create a new directory to hold your board specific code. Add any
2018 files you need. In your board directory, you will need at least
2019 the "Makefile" and a "<board>.c".
2020 2. Create a new configuration file "include/configs/<board>.h" for
2022 3. If you're porting U-Boot to a new CPU, then also create a new
2023 directory to hold your CPU specific code. Add any files you need.
2024 4. Run "make <board>_defconfig" with your new name.
2025 5. Type "make", and you should get a working "u-boot.srec" file
2026 to be installed on your target system.
2027 6. Debug and solve any problems that might arise.
2028 [Of course, this last step is much harder than it sounds.]
2031 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2032 ==============================================================
2034 If you have modified U-Boot sources (for instance added a new board
2035 or support for new devices, a new CPU, etc.) you are expected to
2036 provide feedback to the other developers. The feedback normally takes
2037 the form of a "patch", i.e. a context diff against a certain (latest
2038 official or latest in the git repository) version of U-Boot sources.
2040 But before you submit such a patch, please verify that your modifi-
2041 cation did not break existing code. At least make sure that *ALL* of
2042 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2043 just run the buildman script (tools/buildman/buildman), which will
2044 configure and build U-Boot for ALL supported system. Be warned, this
2045 will take a while. Please see the buildman README, or run 'buildman -H'
2049 See also "U-Boot Porting Guide" below.
2052 Monitor Commands - Overview:
2053 ============================
2055 go - start application at address 'addr'
2056 run - run commands in an environment variable
2057 bootm - boot application image from memory
2058 bootp - boot image via network using BootP/TFTP protocol
2059 bootz - boot zImage from memory
2060 tftpboot- boot image via network using TFTP protocol
2061 and env variables "ipaddr" and "serverip"
2062 (and eventually "gatewayip")
2063 tftpput - upload a file via network using TFTP protocol
2064 rarpboot- boot image via network using RARP/TFTP protocol
2065 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2066 loads - load S-Record file over serial line
2067 loadb - load binary file over serial line (kermit mode)
2068 loadm - load binary blob from source address to destination address
2070 mm - memory modify (auto-incrementing)
2071 nm - memory modify (constant address)
2072 mw - memory write (fill)
2075 cmp - memory compare
2076 crc32 - checksum calculation
2077 i2c - I2C sub-system
2078 sspi - SPI utility commands
2079 base - print or set address offset
2080 printenv- print environment variables
2081 pwm - control pwm channels
2082 setenv - set environment variables
2083 saveenv - save environment variables to persistent storage
2084 protect - enable or disable FLASH write protection
2085 erase - erase FLASH memory
2086 flinfo - print FLASH memory information
2087 nand - NAND memory operations (see doc/README.nand)
2088 bdinfo - print Board Info structure
2089 iminfo - print header information for application image
2090 coninfo - print console devices and informations
2091 ide - IDE sub-system
2092 loop - infinite loop on address range
2093 loopw - infinite write loop on address range
2094 mtest - simple RAM test
2095 icache - enable or disable instruction cache
2096 dcache - enable or disable data cache
2097 reset - Perform RESET of the CPU
2098 echo - echo args to console
2099 version - print monitor version
2100 help - print online help
2101 ? - alias for 'help'
2104 Monitor Commands - Detailed Description:
2105 ========================================
2109 For now: just type "help <command>".
2112 Note for Redundant Ethernet Interfaces:
2113 =======================================
2115 Some boards come with redundant Ethernet interfaces; U-Boot supports
2116 such configurations and is capable of automatic selection of a
2117 "working" interface when needed. MAC assignment works as follows:
2119 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2120 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2121 "eth1addr" (=>eth1), "eth2addr", ...
2123 If the network interface stores some valid MAC address (for instance
2124 in SROM), this is used as default address if there is NO correspon-
2125 ding setting in the environment; if the corresponding environment
2126 variable is set, this overrides the settings in the card; that means:
2128 o If the SROM has a valid MAC address, and there is no address in the
2129 environment, the SROM's address is used.
2131 o If there is no valid address in the SROM, and a definition in the
2132 environment exists, then the value from the environment variable is
2135 o If both the SROM and the environment contain a MAC address, and
2136 both addresses are the same, this MAC address is used.
2138 o If both the SROM and the environment contain a MAC address, and the
2139 addresses differ, the value from the environment is used and a
2142 o If neither SROM nor the environment contain a MAC address, an error
2143 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2144 a random, locally-assigned MAC is used.
2146 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2147 will be programmed into hardware as part of the initialization process. This
2148 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2149 The naming convention is as follows:
2150 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2155 U-Boot is capable of booting (and performing other auxiliary operations on)
2156 images in two formats:
2158 New uImage format (FIT)
2159 -----------------------
2161 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2162 to Flattened Device Tree). It allows the use of images with multiple
2163 components (several kernels, ramdisks, etc.), with contents protected by
2164 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2170 Old image format is based on binary files which can be basically anything,
2171 preceded by a special header; see the definitions in include/image.h for
2172 details; basically, the header defines the following image properties:
2174 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2175 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2176 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2177 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2178 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2179 IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2180 Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
2181 * Compression Type (uncompressed, gzip, bzip2)
2187 The header is marked by a special Magic Number, and both the header
2188 and the data portions of the image are secured against corruption by
2195 Although U-Boot should support any OS or standalone application
2196 easily, the main focus has always been on Linux during the design of
2199 U-Boot includes many features that so far have been part of some
2200 special "boot loader" code within the Linux kernel. Also, any
2201 "initrd" images to be used are no longer part of one big Linux image;
2202 instead, kernel and "initrd" are separate images. This implementation
2203 serves several purposes:
2205 - the same features can be used for other OS or standalone
2206 applications (for instance: using compressed images to reduce the
2207 Flash memory footprint)
2209 - it becomes much easier to port new Linux kernel versions because
2210 lots of low-level, hardware dependent stuff are done by U-Boot
2212 - the same Linux kernel image can now be used with different "initrd"
2213 images; of course this also means that different kernel images can
2214 be run with the same "initrd". This makes testing easier (you don't
2215 have to build a new "zImage.initrd" Linux image when you just
2216 change a file in your "initrd"). Also, a field-upgrade of the
2217 software is easier now.
2223 Porting Linux to U-Boot based systems:
2224 ---------------------------------------
2226 U-Boot cannot save you from doing all the necessary modifications to
2227 configure the Linux device drivers for use with your target hardware
2228 (no, we don't intend to provide a full virtual machine interface to
2231 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2233 Just make sure your machine specific header file (for instance
2234 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2235 Information structure as we define in include/asm-<arch>/u-boot.h,
2236 and make sure that your definition of IMAP_ADDR uses the same value
2237 as your U-Boot configuration in CONFIG_SYS_IMMR.
2239 Note that U-Boot now has a driver model, a unified model for drivers.
2240 If you are adding a new driver, plumb it into driver model. If there
2241 is no uclass available, you are encouraged to create one. See
2245 Configuring the Linux kernel:
2246 -----------------------------
2248 No specific requirements for U-Boot. Make sure you have some root
2249 device (initial ramdisk, NFS) for your target system.
2252 Building a Linux Image:
2253 -----------------------
2255 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2256 not used. If you use recent kernel source, a new build target
2257 "uImage" will exist which automatically builds an image usable by
2258 U-Boot. Most older kernels also have support for a "pImage" target,
2259 which was introduced for our predecessor project PPCBoot and uses a
2260 100% compatible format.
2264 make TQM850L_defconfig
2269 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2270 encapsulate a compressed Linux kernel image with header information,
2271 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2273 * build a standard "vmlinux" kernel image (in ELF binary format):
2275 * convert the kernel into a raw binary image:
2277 ${CROSS_COMPILE}-objcopy -O binary \
2278 -R .note -R .comment \
2279 -S vmlinux linux.bin
2281 * compress the binary image:
2285 * package compressed binary image for U-Boot:
2287 mkimage -A ppc -O linux -T kernel -C gzip \
2288 -a 0 -e 0 -n "Linux Kernel Image" \
2289 -d linux.bin.gz uImage
2292 The "mkimage" tool can also be used to create ramdisk images for use
2293 with U-Boot, either separated from the Linux kernel image, or
2294 combined into one file. "mkimage" encapsulates the images with a 64
2295 byte header containing information about target architecture,
2296 operating system, image type, compression method, entry points, time
2297 stamp, CRC32 checksums, etc.
2299 "mkimage" can be called in two ways: to verify existing images and
2300 print the header information, or to build new images.
2302 In the first form (with "-l" option) mkimage lists the information
2303 contained in the header of an existing U-Boot image; this includes
2304 checksum verification:
2306 tools/mkimage -l image
2307 -l ==> list image header information
2309 The second form (with "-d" option) is used to build a U-Boot image
2310 from a "data file" which is used as image payload:
2312 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2313 -n name -d data_file image
2314 -A ==> set architecture to 'arch'
2315 -O ==> set operating system to 'os'
2316 -T ==> set image type to 'type'
2317 -C ==> set compression type 'comp'
2318 -a ==> set load address to 'addr' (hex)
2319 -e ==> set entry point to 'ep' (hex)
2320 -n ==> set image name to 'name'
2321 -d ==> use image data from 'datafile'
2323 Right now, all Linux kernels for PowerPC systems use the same load
2324 address (0x00000000), but the entry point address depends on the
2327 - 2.2.x kernels have the entry point at 0x0000000C,
2328 - 2.3.x and later kernels have the entry point at 0x00000000.
2330 So a typical call to build a U-Boot image would read:
2332 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2333 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2334 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2335 > examples/uImage.TQM850L
2336 Image Name: 2.4.4 kernel for TQM850L
2337 Created: Wed Jul 19 02:34:59 2000
2338 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2339 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2340 Load Address: 0x00000000
2341 Entry Point: 0x00000000
2343 To verify the contents of the image (or check for corruption):
2345 -> tools/mkimage -l examples/uImage.TQM850L
2346 Image Name: 2.4.4 kernel for TQM850L
2347 Created: Wed Jul 19 02:34:59 2000
2348 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2349 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2350 Load Address: 0x00000000
2351 Entry Point: 0x00000000
2353 NOTE: for embedded systems where boot time is critical you can trade
2354 speed for memory and install an UNCOMPRESSED image instead: this
2355 needs more space in Flash, but boots much faster since it does not
2356 need to be uncompressed:
2358 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2359 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2360 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2361 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2362 > examples/uImage.TQM850L-uncompressed
2363 Image Name: 2.4.4 kernel for TQM850L
2364 Created: Wed Jul 19 02:34:59 2000
2365 Image Type: PowerPC Linux Kernel Image (uncompressed)
2366 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2367 Load Address: 0x00000000
2368 Entry Point: 0x00000000
2371 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2372 when your kernel is intended to use an initial ramdisk:
2374 -> tools/mkimage -n 'Simple Ramdisk Image' \
2375 > -A ppc -O linux -T ramdisk -C gzip \
2376 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2377 Image Name: Simple Ramdisk Image
2378 Created: Wed Jan 12 14:01:50 2000
2379 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2380 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2381 Load Address: 0x00000000
2382 Entry Point: 0x00000000
2384 The "dumpimage" tool can be used to disassemble or list the contents of images
2385 built by mkimage. See dumpimage's help output (-h) for details.
2387 Installing a Linux Image:
2388 -------------------------
2390 To downloading a U-Boot image over the serial (console) interface,
2391 you must convert the image to S-Record format:
2393 objcopy -I binary -O srec examples/image examples/image.srec
2395 The 'objcopy' does not understand the information in the U-Boot
2396 image header, so the resulting S-Record file will be relative to
2397 address 0x00000000. To load it to a given address, you need to
2398 specify the target address as 'offset' parameter with the 'loads'
2401 Example: install the image to address 0x40100000 (which on the
2402 TQM8xxL is in the first Flash bank):
2404 => erase 40100000 401FFFFF
2410 ## Ready for S-Record download ...
2411 ~>examples/image.srec
2412 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2414 15989 15990 15991 15992
2415 [file transfer complete]
2417 ## Start Addr = 0x00000000
2420 You can check the success of the download using the 'iminfo' command;
2421 this includes a checksum verification so you can be sure no data
2422 corruption happened:
2426 ## Checking Image at 40100000 ...
2427 Image Name: 2.2.13 for initrd on TQM850L
2428 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2429 Data Size: 335725 Bytes = 327 kB = 0 MB
2430 Load Address: 00000000
2431 Entry Point: 0000000c
2432 Verifying Checksum ... OK
2438 The "bootm" command is used to boot an application that is stored in
2439 memory (RAM or Flash). In case of a Linux kernel image, the contents
2440 of the "bootargs" environment variable is passed to the kernel as
2441 parameters. You can check and modify this variable using the
2442 "printenv" and "setenv" commands:
2445 => printenv bootargs
2446 bootargs=root=/dev/ram
2448 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2450 => printenv bootargs
2451 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2454 ## Booting Linux kernel at 40020000 ...
2455 Image Name: 2.2.13 for NFS on TQM850L
2456 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2457 Data Size: 381681 Bytes = 372 kB = 0 MB
2458 Load Address: 00000000
2459 Entry Point: 0000000c
2460 Verifying Checksum ... OK
2461 Uncompressing Kernel Image ... OK
2462 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
2463 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2464 time_init: decrementer frequency = 187500000/60
2465 Calibrating delay loop... 49.77 BogoMIPS
2466 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2469 If you want to boot a Linux kernel with initial RAM disk, you pass
2470 the memory addresses of both the kernel and the initrd image (PPBCOOT
2471 format!) to the "bootm" command:
2473 => imi 40100000 40200000
2475 ## Checking Image at 40100000 ...
2476 Image Name: 2.2.13 for initrd on TQM850L
2477 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2478 Data Size: 335725 Bytes = 327 kB = 0 MB
2479 Load Address: 00000000
2480 Entry Point: 0000000c
2481 Verifying Checksum ... OK
2483 ## Checking Image at 40200000 ...
2484 Image Name: Simple Ramdisk Image
2485 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2486 Data Size: 566530 Bytes = 553 kB = 0 MB
2487 Load Address: 00000000
2488 Entry Point: 00000000
2489 Verifying Checksum ... OK
2491 => bootm 40100000 40200000
2492 ## Booting Linux kernel at 40100000 ...
2493 Image Name: 2.2.13 for initrd on TQM850L
2494 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2495 Data Size: 335725 Bytes = 327 kB = 0 MB
2496 Load Address: 00000000
2497 Entry Point: 0000000c
2498 Verifying Checksum ... OK
2499 Uncompressing Kernel Image ... OK
2500 ## Loading RAMDisk Image at 40200000 ...
2501 Image Name: Simple Ramdisk Image
2502 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2503 Data Size: 566530 Bytes = 553 kB = 0 MB
2504 Load Address: 00000000
2505 Entry Point: 00000000
2506 Verifying Checksum ... OK
2507 Loading Ramdisk ... OK
2508 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
2509 Boot arguments: root=/dev/ram
2510 time_init: decrementer frequency = 187500000/60
2511 Calibrating delay loop... 49.77 BogoMIPS
2513 RAMDISK: Compressed image found at block 0
2514 VFS: Mounted root (ext2 filesystem).
2518 Boot Linux and pass a flat device tree:
2521 First, U-Boot must be compiled with the appropriate defines. See the section
2522 titled "Linux Kernel Interface" above for a more in depth explanation. The
2523 following is an example of how to start a kernel and pass an updated
2529 oft=oftrees/mpc8540ads.dtb
2530 => tftp $oftaddr $oft
2531 Speed: 1000, full duplex
2533 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
2534 Filename 'oftrees/mpc8540ads.dtb'.
2535 Load address: 0x300000
2538 Bytes transferred = 4106 (100a hex)
2539 => tftp $loadaddr $bootfile
2540 Speed: 1000, full duplex
2542 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
2544 Load address: 0x200000
2545 Loading:############
2547 Bytes transferred = 1029407 (fb51f hex)
2552 => bootm $loadaddr - $oftaddr
2553 ## Booting image at 00200000 ...
2554 Image Name: Linux-2.6.17-dirty
2555 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2556 Data Size: 1029343 Bytes = 1005.2 kB
2557 Load Address: 00000000
2558 Entry Point: 00000000
2559 Verifying Checksum ... OK
2560 Uncompressing Kernel Image ... OK
2561 Booting using flat device tree at 0x300000
2562 Using MPC85xx ADS machine description
2563 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
2567 More About U-Boot Image Types:
2568 ------------------------------
2570 U-Boot supports the following image types:
2572 "Standalone Programs" are directly runnable in the environment
2573 provided by U-Boot; it is expected that (if they behave
2574 well) you can continue to work in U-Boot after return from
2575 the Standalone Program.
2576 "OS Kernel Images" are usually images of some Embedded OS which
2577 will take over control completely. Usually these programs
2578 will install their own set of exception handlers, device
2579 drivers, set up the MMU, etc. - this means, that you cannot
2580 expect to re-enter U-Boot except by resetting the CPU.
2581 "RAMDisk Images" are more or less just data blocks, and their
2582 parameters (address, size) are passed to an OS kernel that is
2584 "Multi-File Images" contain several images, typically an OS
2585 (Linux) kernel image and one or more data images like
2586 RAMDisks. This construct is useful for instance when you want
2587 to boot over the network using BOOTP etc., where the boot
2588 server provides just a single image file, but you want to get
2589 for instance an OS kernel and a RAMDisk image.
2591 "Multi-File Images" start with a list of image sizes, each
2592 image size (in bytes) specified by an "uint32_t" in network
2593 byte order. This list is terminated by an "(uint32_t)0".
2594 Immediately after the terminating 0 follow the images, one by
2595 one, all aligned on "uint32_t" boundaries (size rounded up to
2596 a multiple of 4 bytes).
2598 "Firmware Images" are binary images containing firmware (like
2599 U-Boot or FPGA images) which usually will be programmed to
2602 "Script files" are command sequences that will be executed by
2603 U-Boot's command interpreter; this feature is especially
2604 useful when you configure U-Boot to use a real shell (hush)
2605 as command interpreter.
2607 Booting the Linux zImage:
2608 -------------------------
2610 On some platforms, it's possible to boot Linux zImage. This is done
2611 using the "bootz" command. The syntax of "bootz" command is the same
2612 as the syntax of "bootm" command.
2614 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
2615 kernel with raw initrd images. The syntax is slightly different, the
2616 address of the initrd must be augmented by it's size, in the following
2617 format: "<initrd addres>:<initrd size>".
2623 One of the features of U-Boot is that you can dynamically load and
2624 run "standalone" applications, which can use some resources of
2625 U-Boot like console I/O functions or interrupt services.
2627 Two simple examples are included with the sources:
2632 'examples/hello_world.c' contains a small "Hello World" Demo
2633 application; it is automatically compiled when you build U-Boot.
2634 It's configured to run at address 0x00040004, so you can play with it
2638 ## Ready for S-Record download ...
2639 ~>examples/hello_world.srec
2640 1 2 3 4 5 6 7 8 9 10 11 ...
2641 [file transfer complete]
2643 ## Start Addr = 0x00040004
2645 => go 40004 Hello World! This is a test.
2646 ## Starting application at 0x00040004 ...
2657 Hit any key to exit ...
2659 ## Application terminated, rc = 0x0
2661 Another example, which demonstrates how to register a CPM interrupt
2662 handler with the U-Boot code, can be found in 'examples/timer.c'.
2663 Here, a CPM timer is set up to generate an interrupt every second.
2664 The interrupt service routine is trivial, just printing a '.'
2665 character, but this is just a demo program. The application can be
2666 controlled by the following keys:
2668 ? - print current values og the CPM Timer registers
2669 b - enable interrupts and start timer
2670 e - stop timer and disable interrupts
2671 q - quit application
2674 ## Ready for S-Record download ...
2675 ~>examples/timer.srec
2676 1 2 3 4 5 6 7 8 9 10 11 ...
2677 [file transfer complete]
2679 ## Start Addr = 0x00040004
2682 ## Starting application at 0x00040004 ...
2685 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2688 [q, b, e, ?] Set interval 1000000 us
2691 [q, b, e, ?] ........
2692 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2695 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2698 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2701 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2703 [q, b, e, ?] ...Stopping timer
2705 [q, b, e, ?] ## Application terminated, rc = 0x0
2711 Over time, many people have reported problems when trying to use the
2712 "minicom" terminal emulation program for serial download. I (wd)
2713 consider minicom to be broken, and recommend not to use it. Under
2714 Unix, I recommend to use C-Kermit for general purpose use (and
2715 especially for kermit binary protocol download ("loadb" command), and
2716 use "cu" for S-Record download ("loads" command). See
2717 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
2718 for help with kermit.
2721 Nevertheless, if you absolutely want to use it try adding this
2722 configuration to your "File transfer protocols" section:
2724 Name Program Name U/D FullScr IO-Red. Multi
2725 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
2726 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
2732 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2733 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2735 Building requires a cross environment; it is known to work on
2736 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2737 need gmake since the Makefiles are not compatible with BSD make).
2738 Note that the cross-powerpc package does not install include files;
2739 attempting to build U-Boot will fail because <machine/ansi.h> is
2740 missing. This file has to be installed and patched manually:
2742 # cd /usr/pkg/cross/powerpc-netbsd/include
2744 # ln -s powerpc machine
2745 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2746 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2748 Native builds *don't* work due to incompatibilities between native
2749 and U-Boot include files.
2751 Booting assumes that (the first part of) the image booted is a
2752 stage-2 loader which in turn loads and then invokes the kernel
2753 proper. Loader sources will eventually appear in the NetBSD source
2754 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2755 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
2758 Implementation Internals:
2759 =========================
2761 The following is not intended to be a complete description of every
2762 implementation detail. However, it should help to understand the
2763 inner workings of U-Boot and make it easier to port it to custom
2767 Initial Stack, Global Data:
2768 ---------------------------
2770 The implementation of U-Boot is complicated by the fact that U-Boot
2771 starts running out of ROM (flash memory), usually without access to
2772 system RAM (because the memory controller is not initialized yet).
2773 This means that we don't have writable Data or BSS segments, and BSS
2774 is not initialized as zero. To be able to get a C environment working
2775 at all, we have to allocate at least a minimal stack. Implementation
2776 options for this are defined and restricted by the CPU used: Some CPU
2777 models provide on-chip memory (like the IMMR area on MPC8xx and
2778 MPC826x processors), on others (parts of) the data cache can be
2779 locked as (mis-) used as memory, etc.
2781 Chris Hallinan posted a good summary of these issues to the
2782 U-Boot mailing list:
2784 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2785 From: "Chris Hallinan" <clh@net1plus.com>
2786 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2789 Correct me if I'm wrong, folks, but the way I understand it
2790 is this: Using DCACHE as initial RAM for Stack, etc, does not
2791 require any physical RAM backing up the cache. The cleverness
2792 is that the cache is being used as a temporary supply of
2793 necessary storage before the SDRAM controller is setup. It's
2794 beyond the scope of this list to explain the details, but you
2795 can see how this works by studying the cache architecture and
2796 operation in the architecture and processor-specific manuals.
2798 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2799 is another option for the system designer to use as an
2800 initial stack/RAM area prior to SDRAM being available. Either
2801 option should work for you. Using CS 4 should be fine if your
2802 board designers haven't used it for something that would
2803 cause you grief during the initial boot! It is frequently not
2806 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
2807 with your processor/board/system design. The default value
2808 you will find in any recent u-boot distribution in
2809 walnut.h should work for you. I'd set it to a value larger
2810 than your SDRAM module. If you have a 64MB SDRAM module, set
2811 it above 400_0000. Just make sure your board has no resources
2812 that are supposed to respond to that address! That code in
2813 start.S has been around a while and should work as is when
2814 you get the config right.
2819 It is essential to remember this, since it has some impact on the C
2820 code for the initialization procedures:
2822 * Initialized global data (data segment) is read-only. Do not attempt
2825 * Do not use any uninitialized global data (or implicitly initialized
2826 as zero data - BSS segment) at all - this is undefined, initiali-
2827 zation is performed later (when relocating to RAM).
2829 * Stack space is very limited. Avoid big data buffers or things like
2832 Having only the stack as writable memory limits means we cannot use
2833 normal global data to share information between the code. But it
2834 turned out that the implementation of U-Boot can be greatly
2835 simplified by making a global data structure (gd_t) available to all
2836 functions. We could pass a pointer to this data as argument to _all_
2837 functions, but this would bloat the code. Instead we use a feature of
2838 the GCC compiler (Global Register Variables) to share the data: we
2839 place a pointer (gd) to the global data into a register which we
2840 reserve for this purpose.
2842 When choosing a register for such a purpose we are restricted by the
2843 relevant (E)ABI specifications for the current architecture, and by
2844 GCC's implementation.
2846 For PowerPC, the following registers have specific use:
2848 R2: reserved for system use
2849 R3-R4: parameter passing and return values
2850 R5-R10: parameter passing
2851 R13: small data area pointer
2855 (U-Boot also uses R12 as internal GOT pointer. r12
2856 is a volatile register so r12 needs to be reset when
2857 going back and forth between asm and C)
2859 ==> U-Boot will use R2 to hold a pointer to the global data
2861 Note: on PPC, we could use a static initializer (since the
2862 address of the global data structure is known at compile time),
2863 but it turned out that reserving a register results in somewhat
2864 smaller code - although the code savings are not that big (on
2865 average for all boards 752 bytes for the whole U-Boot image,
2866 624 text + 127 data).
2868 On ARM, the following registers are used:
2870 R0: function argument word/integer result
2871 R1-R3: function argument word
2872 R9: platform specific
2873 R10: stack limit (used only if stack checking is enabled)
2874 R11: argument (frame) pointer
2875 R12: temporary workspace
2878 R15: program counter
2880 ==> U-Boot will use R9 to hold a pointer to the global data
2882 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
2884 On Nios II, the ABI is documented here:
2885 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
2887 ==> U-Boot will use gp to hold a pointer to the global data
2889 Note: on Nios II, we give "-G0" option to gcc and don't use gp
2890 to access small data sections, so gp is free.
2892 On RISC-V, the following registers are used:
2894 x0: hard-wired zero (zero)
2895 x1: return address (ra)
2896 x2: stack pointer (sp)
2897 x3: global pointer (gp)
2898 x4: thread pointer (tp)
2899 x5: link register (t0)
2900 x8: frame pointer (fp)
2901 x10-x11: arguments/return values (a0-1)
2902 x12-x17: arguments (a2-7)
2903 x28-31: temporaries (t3-6)
2904 pc: program counter (pc)
2906 ==> U-Boot will use gp to hold a pointer to the global data
2911 U-Boot runs in system state and uses physical addresses, i.e. the
2912 MMU is not used either for address mapping nor for memory protection.
2914 The available memory is mapped to fixed addresses using the memory
2915 controller. In this process, a contiguous block is formed for each
2916 memory type (Flash, SDRAM, SRAM), even when it consists of several
2917 physical memory banks.
2919 U-Boot is installed in the first 128 kB of the first Flash bank (on
2920 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2921 booting and sizing and initializing DRAM, the code relocates itself
2922 to the upper end of DRAM. Immediately below the U-Boot code some
2923 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
2924 configuration setting]. Below that, a structure with global Board
2925 Info data is placed, followed by the stack (growing downward).
2927 Additionally, some exception handler code is copied to the low 8 kB
2928 of DRAM (0x00000000 ... 0x00001FFF).
2930 So a typical memory configuration with 16 MB of DRAM could look like
2933 0x0000 0000 Exception Vector code
2936 0x0000 2000 Free for Application Use
2942 0x00FB FF20 Monitor Stack (Growing downward)
2943 0x00FB FFAC Board Info Data and permanent copy of global data
2944 0x00FC 0000 Malloc Arena
2947 0x00FE 0000 RAM Copy of Monitor Code
2948 ... eventually: LCD or video framebuffer
2949 ... eventually: pRAM (Protected RAM - unchanged by reset)
2950 0x00FF FFFF [End of RAM]
2953 System Initialization:
2954 ----------------------
2956 In the reset configuration, U-Boot starts at the reset entry point
2957 (on most PowerPC systems at address 0x00000100). Because of the reset
2958 configuration for CS0# this is a mirror of the on board Flash memory.
2959 To be able to re-map memory U-Boot then jumps to its link address.
2960 To be able to implement the initialization code in C, a (small!)
2961 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2962 which provide such a feature like), or in a locked part of the data
2963 cache. After that, U-Boot initializes the CPU core, the caches and
2966 Next, all (potentially) available memory banks are mapped using a
2967 preliminary mapping. For example, we put them on 512 MB boundaries
2968 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2969 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2970 programmed for SDRAM access. Using the temporary configuration, a
2971 simple memory test is run that determines the size of the SDRAM
2974 When there is more than one SDRAM bank, and the banks are of
2975 different size, the largest is mapped first. For equal size, the first
2976 bank (CS2#) is mapped first. The first mapping is always for address
2977 0x00000000, with any additional banks following immediately to create
2978 contiguous memory starting from 0.
2980 Then, the monitor installs itself at the upper end of the SDRAM area
2981 and allocates memory for use by malloc() and for the global Board
2982 Info data; also, the exception vector code is copied to the low RAM
2983 pages, and the final stack is set up.
2985 Only after this relocation will you have a "normal" C environment;
2986 until that you are restricted in several ways, mostly because you are
2987 running from ROM, and because the code will have to be relocated to a
2991 U-Boot Porting Guide:
2992 ----------------------
2994 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
2998 int main(int argc, char *argv[])
3000 sighandler_t no_more_time;
3002 signal(SIGALRM, no_more_time);
3003 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3005 if (available_money > available_manpower) {
3006 Pay consultant to port U-Boot;
3010 Download latest U-Boot source;
3012 Subscribe to u-boot mailing list;
3015 email("Hi, I am new to U-Boot, how do I get started?");
3018 Read the README file in the top level directory;
3019 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3020 Read applicable doc/README.*;
3021 Read the source, Luke;
3022 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3025 if (available_money > toLocalCurrency ($2500))
3028 Add a lot of aggravation and time;
3030 if (a similar board exists) { /* hopefully... */
3031 cp -a board/<similar> board/<myboard>
3032 cp include/configs/<similar>.h include/configs/<myboard>.h
3034 Create your own board support subdirectory;
3035 Create your own board include/configs/<myboard>.h file;
3037 Edit new board/<myboard> files
3038 Edit new include/configs/<myboard>.h
3043 Add / modify source code;
3047 email("Hi, I am having problems...");
3049 Send patch file to the U-Boot email list;
3050 if (reasonable critiques)
3051 Incorporate improvements from email list code review;
3053 Defend code as written;
3059 void no_more_time (int sig)
3068 All contributions to U-Boot should conform to the Linux kernel
3069 coding style; see the kernel coding style guide at
3070 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3071 script "scripts/Lindent" in your Linux kernel source directory.
3073 Source files originating from a different project (for example the
3074 MTD subsystem) are generally exempt from these guidelines and are not
3075 reformatted to ease subsequent migration to newer versions of those
3078 Please note that U-Boot is implemented in C (and to some small parts in
3079 Assembler); no C++ is used, so please do not use C++ style comments (//)
3082 Please also stick to the following formatting rules:
3083 - remove any trailing white space
3084 - use TAB characters for indentation and vertical alignment, not spaces
3085 - make sure NOT to use DOS '\r\n' line feeds
3086 - do not add more than 2 consecutive empty lines to source files
3087 - do not add trailing empty lines to source files
3089 Submissions which do not conform to the standards may be returned
3090 with a request to reformat the changes.
3096 Since the number of patches for U-Boot is growing, we need to
3097 establish some rules. Submissions which do not conform to these rules
3098 may be rejected, even when they contain important and valuable stuff.
3100 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3102 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3103 see https://lists.denx.de/listinfo/u-boot
3105 When you send a patch, please include the following information with
3108 * For bug fixes: a description of the bug and how your patch fixes
3109 this bug. Please try to include a way of demonstrating that the
3110 patch actually fixes something.
3112 * For new features: a description of the feature and your
3115 * For major contributions, add a MAINTAINERS file with your
3116 information and associated file and directory references.
3118 * When you add support for a new board, don't forget to add a
3119 maintainer e-mail address to the boards.cfg file, too.
3121 * If your patch adds new configuration options, don't forget to
3122 document these in the README file.
3124 * The patch itself. If you are using git (which is *strongly*
3125 recommended) you can easily generate the patch using the
3126 "git format-patch". If you then use "git send-email" to send it to
3127 the U-Boot mailing list, you will avoid most of the common problems
3128 with some other mail clients.
3130 If you cannot use git, use "diff -purN OLD NEW". If your version of
3131 diff does not support these options, then get the latest version of
3134 The current directory when running this command shall be the parent
3135 directory of the U-Boot source tree (i. e. please make sure that
3136 your patch includes sufficient directory information for the
3139 We prefer patches as plain text. MIME attachments are discouraged,
3140 and compressed attachments must not be used.
3142 * If one logical set of modifications affects or creates several
3143 files, all these changes shall be submitted in a SINGLE patch file.
3145 * Changesets that contain different, unrelated modifications shall be
3146 submitted as SEPARATE patches, one patch per changeset.
3151 * Before sending the patch, run the buildman script on your patched
3152 source tree and make sure that no errors or warnings are reported
3153 for any of the boards.
3155 * Keep your modifications to the necessary minimum: A patch
3156 containing several unrelated changes or arbitrary reformats will be
3157 returned with a request to re-formatting / split it.
3159 * If you modify existing code, make sure that your new code does not
3160 add to the memory footprint of the code ;-) Small is beautiful!
3161 When adding new features, these should compile conditionally only
3162 (using #ifdef), and the resulting code with the new feature
3163 disabled must not need more memory than the old code without your
3166 * Remember that there is a size limit of 100 kB per message on the
3167 u-boot mailing list. Bigger patches will be moderated. If they are
3168 reasonable and not too big, they will be acknowledged. But patches
3169 bigger than the size limit should be avoided.