1 Binman Entry Documentation
2 ===========================
4 This file describes the entry types supported by binman. These entry types can
5 be placed in an image one by one to build up a final firmware image. It is
6 fairly easy to create new entry types. Just add a new file to the 'etype'
7 directory. You can use the existing entries as examples.
9 Note that some entries are subclasses of others, using and extending their
10 features to produce new behaviours.
14 Entry: blob: Entry containing an arbitrary binary blob
15 ------------------------------------------------------
17 Note: This should not be used by itself. It is normally used as a parent
18 class by other entry types.
20 Properties / Entry arguments:
21 - filename: Filename of file to read into entry
22 - compress: Compression algorithm to use:
24 lz4: Use lz4 compression (via 'lz4' command-line utility)
26 This entry reads data from a file and places it in the entry. The
27 default filename is often specified specified by the subclass. See for
28 example the 'u_boot' entry which provides the filename 'u-boot.bin'.
30 If compression is enabled, an extra 'uncomp-size' property is written to
31 the node (if enabled with -u) which provides the uncompressed size of the
36 Entry: blob-dtb: A blob that holds a device tree
37 ------------------------------------------------
39 This is a blob containing a device tree. The contents of the blob are
40 obtained from the list of available device-tree files, managed by the
45 Entry: blob-named-by-arg: A blob entry which gets its filename property from its subclass
46 -----------------------------------------------------------------------------------------
48 Properties / Entry arguments:
49 - <xxx>-path: Filename containing the contents of this entry (optional,
52 where <xxx> is the blob_fname argument to the constructor.
54 This entry cannot be used directly. Instead, it is used as a parent class
55 for another entry, which defined blob_fname. This parameter is used to
56 set the entry-arg or property containing the filename. The entry-arg or
57 property is in turn used to set the actual filename.
59 See cros_ec_rw for an example of this.
63 Entry: cbfs: Entry containing a Coreboot Filesystem (CBFS)
64 ----------------------------------------------------------
66 A CBFS provides a way to group files into a group. It has a simple directory
67 structure and allows the position of individual files to be set, since it is
68 designed to support execute-in-place in an x86 SPI-flash device. Where XIP
69 is not used, it supports compression and storing ELF files.
71 CBFS is used by coreboot as its way of orgnanising SPI-flash contents.
73 The contents of the CBFS are defined by subnodes of the cbfs entry, e.g.:
85 This creates a CBFS 1MB in size two files in it: u-boot.bin and u-boot.dtb.
86 Note that the size is required since binman does not support calculating it.
87 The contents of each entry is just what binman would normally provide if it
88 were not a CBFS node. A blob type can be used to import arbitrary files as
89 with the second subnode below:
100 filename = "u-boot.dtb";
102 cbfs-compress = "lz4";
103 cbfs-offset = <0x100000>;
107 This creates a CBFS 1MB in size with u-boot.bin (named "BOOT") and
108 u-boot.dtb (named "dtb") and compressed with the lz4 algorithm.
111 Properties supported in the top-level CBFS node:
114 Defaults to "x86", but you can specify the architecture if needed.
117 Properties supported in the CBFS entry subnodes:
120 This is the name of the file created in CBFS. It defaults to the entry
121 name (which is the node name), but you can override it with this
125 This is the CBFS file type. The following are supported:
128 This is a 'raw' file, although compression is supported. It can be
129 used to store any file in CBFS.
132 This is an ELF file that has been loaded (i.e. mapped to memory), so
133 appears in the CBFS as a flat binary. The input file must be an ELF
134 image, for example this puts "u-boot" (the ELF image) into a 'stage'
145 You can use your own ELF file with something like:
151 filename = "cbfs-stage.elf";
156 As mentioned, the file is converted to a flat binary, so it is
157 equivalent to adding "u-boot.bin", for example, but with the load and
158 start addresses specified by the ELF. At present there is no option
159 to add a flat binary with a load/start address, similar to the
160 'add-flat-binary' option in cbfstool.
163 This is the offset of the file's data within the CBFS. It is used to
164 specify where the file should be placed in cases where a fixed position
165 is needed. Typical uses are for code which is not relocatable and must
166 execute in-place from a particular address. This works because SPI flash
167 is generally mapped into memory on x86 devices. The file header is
168 placed before this offset so that the data start lines up exactly with
169 the chosen offset. If this property is not provided, then the file is
170 placed in the next available spot.
172 The current implementation supports only a subset of CBFS features. It does
173 not support other file types (e.g. payload), adding multiple files (like the
174 'files' entry with a pattern supported by binman), putting files at a
175 particular offset in the CBFS and a few other things.
177 Of course binman can create images containing multiple CBFSs, simply by
178 defining these in the binman config:
205 filename = "image.jpg";
210 This creates an 8MB image with two CBFSs, one at offset 1MB, one at 7MB,
215 Entry: cros-ec-rw: A blob entry which contains a Chromium OS read-write EC image
216 --------------------------------------------------------------------------------
218 Properties / Entry arguments:
219 - cros-ec-rw-path: Filename containing the EC image
221 This entry holds a Chromium OS EC (embedded controller) image, for use in
222 updating the EC on startup via software sync.
226 Entry: fdtmap: An entry which contains an FDT map
227 -------------------------------------------------
229 Properties / Entry arguments:
232 An FDT map is just a header followed by an FDT containing a list of all the
233 entries in the image. The root node corresponds to the image node in the
234 original FDT, and an image-name property indicates the image name in that
237 The header is the string _FDTMAP_ followed by 8 unused bytes.
239 When used, this entry will be populated with an FDT map which reflects the
240 entries in the current image. Hierarchy is preserved, and all offsets and
243 Note that the -u option must be provided to ensure that binman updates the
244 FDT with the position of each entry.
246 Example output for a simple image with U-Boot and an FDT map:
249 image-name = "binman";
251 image-pos = <0x00000000>;
252 offset = <0x00000000>;
255 image-pos = <0x00000000>;
256 offset = <0x00000000>;
260 image-pos = <0x00000004>;
261 offset = <0x00000004>;
265 If allow-repack is used then 'orig-offset' and 'orig-size' properties are
266 added as necessary. See the binman README.
270 Entry: files: Entry containing a set of files
271 ---------------------------------------------
273 Properties / Entry arguments:
274 - pattern: Filename pattern to match the files to include
275 - compress: Compression algorithm to use:
277 lz4: Use lz4 compression (via 'lz4' command-line utility)
279 This entry reads a number of files and places each in a separate sub-entry
280 within this entry. To access these you need to enable device-tree updates
281 at run-time so you can obtain the file positions.
285 Entry: fill: An entry which is filled to a particular byte value
286 ----------------------------------------------------------------
288 Properties / Entry arguments:
289 - fill-byte: Byte to use to fill the entry
291 Note that the size property must be set since otherwise this entry does not
292 know how large it should be.
294 You can often achieve the same effect using the pad-byte property of the
295 overall image, in that the space between entries will then be padded with
296 that byte. But this entry is sometimes useful for explicitly setting the
297 byte value of a region.
301 Entry: fmap: An entry which contains an Fmap section
302 ----------------------------------------------------
304 Properties / Entry arguments:
307 FMAP is a simple format used by flashrom, an open-source utility for
308 reading and writing the SPI flash, typically on x86 CPUs. The format
309 provides flashrom with a list of areas, so it knows what it in the flash.
310 It can then read or write just a single area, instead of the whole flash.
312 The format is defined by the flashrom project, in the file lib/fmap.h -
313 see www.flashrom.org/Flashrom for more information.
315 When used, this entry will be populated with an FMAP which reflects the
316 entries in the current image. Note that any hierarchy is squashed, since
317 FMAP does not support this. Also, CBFS entries appear as a single entry -
318 the sub-entries are ignored.
322 Entry: gbb: An entry which contains a Chromium OS Google Binary Block
323 ---------------------------------------------------------------------
325 Properties / Entry arguments:
326 - hardware-id: Hardware ID to use for this build (a string)
327 - keydir: Directory containing the public keys to use
328 - bmpblk: Filename containing images used by recovery
330 Chromium OS uses a GBB to store various pieces of information, in particular
331 the root and recovery keys that are used to verify the boot process. Some
332 more details are here:
334 https://www.chromium.org/chromium-os/firmware-porting-guide/2-concepts
336 but note that the page dates from 2013 so is quite out of date. See
337 README.chromium for how to obtain the required keys and tools.
341 Entry: image-header: An entry which contains a pointer to the FDT map
342 ---------------------------------------------------------------------
344 Properties / Entry arguments:
345 location: Location of header ("start" or "end" of image). This is
346 optional. If omitted then the entry must have an offset property.
348 This adds an 8-byte entry to the start or end of the image, pointing to the
349 location of the FDT map. The format is a magic number followed by an offset
350 from the start or end of the image, in twos-compliment format.
352 This entry must be in the top-level part of the image.
354 NOTE: If the location is at the start/end, you will probably need to specify
355 sort-by-offset for the image, unless you actually put the image header
356 first/last in the entry list.
360 Entry: intel-cmc: Entry containing an Intel Chipset Micro Code (CMC) file
361 -------------------------------------------------------------------------
363 Properties / Entry arguments:
364 - filename: Filename of file to read into entry
366 This file contains microcode for some devices in a special format. An
367 example filename is 'Microcode/C0_22211.BIN'.
369 See README.x86 for information about x86 binary blobs.
373 Entry: intel-descriptor: Intel flash descriptor block (4KB)
374 -----------------------------------------------------------
376 Properties / Entry arguments:
377 filename: Filename of file containing the descriptor. This is typically
378 a 4KB binary file, sometimes called 'descriptor.bin'
380 This entry is placed at the start of flash and provides information about
381 the SPI flash regions. In particular it provides the base address and
382 size of the ME (Management Engine) region, allowing us to place the ME
383 binary in the right place.
385 With this entry in your image, the position of the 'intel-me' entry will be
386 fixed in the image, which avoids you needed to specify an offset for that
387 region. This is useful, because it is not possible to change the position
388 of the ME region without updating the descriptor.
390 See README.x86 for information about x86 binary blobs.
394 Entry: intel-fsp: Entry containing an Intel Firmware Support Package (FSP) file
395 -------------------------------------------------------------------------------
397 Properties / Entry arguments:
398 - filename: Filename of file to read into entry
400 This file contains binary blobs which are used on some devices to make the
401 platform work. U-Boot executes this code since it is not possible to set up
402 the hardware using U-Boot open-source code. Documentation is typically not
403 available in sufficient detail to allow this.
405 An example filename is 'FSP/QUEENSBAY_FSP_GOLD_001_20-DECEMBER-2013.fd'
407 See README.x86 for information about x86 binary blobs.
411 Entry: intel-ifwi: Entry containing an Intel Integrated Firmware Image (IFWI) file
412 ----------------------------------------------------------------------------------
414 Properties / Entry arguments:
415 - filename: Filename of file to read into entry. This is either the
416 IFWI file itself, or a file that can be converted into one using a
418 - convert-fit: If present this indicates that the ifwitool should be
419 used to convert the provided file into a IFWI.
421 This file contains code and data used by the SoC that is required to make
422 it work. It includes U-Boot TPL, microcode, things related to the CSE
423 (Converged Security Engine, the microcontroller that loads all the firmware)
424 and other items beyond the wit of man.
426 A typical filename is 'ifwi.bin' for an IFWI file, or 'fitimage.bin' for a
427 file that will be converted to an IFWI.
429 The position of this entry is generally set by the intel-descriptor entry.
431 The contents of the IFWI are specified by the subnodes of the IFWI node.
432 Each subnode describes an entry which is placed into the IFWFI with a given
433 sub-partition (and optional entry name).
435 Properties for subnodes:
436 ifwi-subpart - sub-parition to put this entry into, e.g. "IBBP"
437 ifwi-entry - entry name t use, e.g. "IBBL"
438 ifwi-replace - if present, indicates that the item should be replaced
439 in the IFWI. Otherwise it is added.
441 See README.x86 for information about x86 binary blobs.
445 Entry: intel-me: Entry containing an Intel Management Engine (ME) file
446 ----------------------------------------------------------------------
448 Properties / Entry arguments:
449 - filename: Filename of file to read into entry
451 This file contains code used by the SoC that is required to make it work.
452 The Management Engine is like a background task that runs things that are
453 not clearly documented, but may include keyboard, deplay and network
454 access. For platform that use ME it is not possible to disable it. U-Boot
455 does not directly execute code in the ME binary.
457 A typical filename is 'me.bin'.
459 The position of this entry is generally set by the intel-descriptor entry.
461 See README.x86 for information about x86 binary blobs.
465 Entry: intel-mrc: Entry containing an Intel Memory Reference Code (MRC) file
466 ----------------------------------------------------------------------------
468 Properties / Entry arguments:
469 - filename: Filename of file to read into entry
471 This file contains code for setting up the SDRAM on some Intel systems. This
472 is executed by U-Boot when needed early during startup. A typical filename
475 See README.x86 for information about x86 binary blobs.
479 Entry: intel-refcode: Entry containing an Intel Reference Code file
480 -------------------------------------------------------------------
482 Properties / Entry arguments:
483 - filename: Filename of file to read into entry
485 This file contains code for setting up the platform on some Intel systems.
486 This is executed by U-Boot when needed early during startup. A typical
487 filename is 'refcode.bin'.
489 See README.x86 for information about x86 binary blobs.
493 Entry: intel-vbt: Entry containing an Intel Video BIOS Table (VBT) file
494 -----------------------------------------------------------------------
496 Properties / Entry arguments:
497 - filename: Filename of file to read into entry
499 This file contains code that sets up the integrated graphics subsystem on
500 some Intel SoCs. U-Boot executes this when the display is started up.
502 See README.x86 for information about Intel binary blobs.
506 Entry: intel-vga: Entry containing an Intel Video Graphics Adaptor (VGA) file
507 -----------------------------------------------------------------------------
509 Properties / Entry arguments:
510 - filename: Filename of file to read into entry
512 This file contains code that sets up the integrated graphics subsystem on
513 some Intel SoCs. U-Boot executes this when the display is started up.
515 This is similar to the VBT file but in a different format.
517 See README.x86 for information about Intel binary blobs.
521 Entry: powerpc-mpc85xx-bootpg-resetvec: PowerPC mpc85xx bootpg + resetvec code for U-Boot
522 -----------------------------------------------------------------------------------------
524 Properties / Entry arguments:
525 - filename: Filename of u-boot-br.bin (default 'u-boot-br.bin')
527 This enrty is valid for PowerPC mpc85xx cpus. This entry holds
528 'bootpg + resetvec' code for PowerPC mpc85xx CPUs which needs to be
529 placed at offset 'RESET_VECTOR_ADDRESS - 0xffc'.
533 Entry: section: Entry that contains other entries
534 -------------------------------------------------
536 Properties / Entry arguments: (see binman README for more information)
537 pad-byte: Pad byte to use when padding
538 sort-by-offset: True if entries should be sorted by offset, False if
539 they must be in-order in the device tree description
540 end-at-4gb: Used to build an x86 ROM which ends at 4GB (2^32)
541 skip-at-start: Number of bytes before the first entry starts. These
542 effectively adjust the starting offset of entries. For example,
543 if this is 16, then the first entry would start at 16. An entry
544 with offset = 20 would in fact be written at offset 4 in the image
545 file, since the first 16 bytes are skipped when writing.
546 name-prefix: Adds a prefix to the name of every entry in the section
547 when writing out the map
549 Since a section is also an entry, it inherits all the properies of entries
552 A section is an entry which can contain other entries, thus allowing
553 hierarchical images to be created. See 'Sections and hierarchical images'
554 in the binman README for more information.
558 Entry: text: An entry which contains text
559 -----------------------------------------
561 The text can be provided either in the node itself or by a command-line
562 argument. There is a level of indirection to allow multiple text strings
565 Properties / Entry arguments:
566 text-label: The value of this string indicates the property / entry-arg
567 that contains the string to place in the entry
568 <xxx> (actual name is the value of text-label): contains the string to
570 <text>: The text to place in the entry (overrides the above mechanism).
571 This is useful when the text is constant.
577 text-label = "message";
582 binman -amessage="this is my message"
584 and binman will insert that string into the entry.
586 It is also possible to put the string directly in the node:
590 text-label = "message";
591 message = "a message directly in the node"
598 text = "some text directly in the node"
601 The text is not itself nul-terminated. This can be achieved, if required,
602 by setting the size of the entry to something larger than the text.
606 Entry: u-boot: U-Boot flat binary
607 ---------------------------------
609 Properties / Entry arguments:
610 - filename: Filename of u-boot.bin (default 'u-boot.bin')
612 This is the U-Boot binary, containing relocation information to allow it
613 to relocate itself at runtime. The binary typically includes a device tree
614 blob at the end of it. Use u_boot_nodtb if you want to package the device
617 U-Boot can access binman symbols at runtime. See:
619 'Access to binman entry offsets at run time (fdt)'
621 in the binman README for more information.
625 Entry: u-boot-dtb: U-Boot device tree
626 -------------------------------------
628 Properties / Entry arguments:
629 - filename: Filename of u-boot.dtb (default 'u-boot.dtb')
631 This is the U-Boot device tree, containing configuration information for
632 U-Boot. U-Boot needs this to know what devices are present and which drivers
635 Note: This is mostly an internal entry type, used by others. This allows
636 binman to know which entries contain a device tree.
640 Entry: u-boot-dtb-with-ucode: A U-Boot device tree file, with the microcode removed
641 -----------------------------------------------------------------------------------
643 Properties / Entry arguments:
644 - filename: Filename of u-boot.dtb (default 'u-boot.dtb')
646 See Entry_u_boot_ucode for full details of the three entries involved in
647 this process. This entry provides the U-Boot device-tree file, which
648 contains the microcode. If the microcode is not being collated into one
649 place then the offset and size of the microcode is recorded by this entry,
650 for use by u_boot_with_ucode_ptr. If it is being collated, then this
651 entry deletes the microcode from the device tree (to save space) and makes
652 it available to u_boot_ucode.
656 Entry: u-boot-elf: U-Boot ELF image
657 -----------------------------------
659 Properties / Entry arguments:
660 - filename: Filename of u-boot (default 'u-boot')
662 This is the U-Boot ELF image. It does not include a device tree but can be
663 relocated to any address for execution.
667 Entry: u-boot-img: U-Boot legacy image
668 --------------------------------------
670 Properties / Entry arguments:
671 - filename: Filename of u-boot.img (default 'u-boot.img')
673 This is the U-Boot binary as a packaged image, in legacy format. It has a
674 header which allows it to be loaded at the correct address for execution.
676 You should use FIT (Flat Image Tree) instead of the legacy image for new
681 Entry: u-boot-nodtb: U-Boot flat binary without device tree appended
682 --------------------------------------------------------------------
684 Properties / Entry arguments:
685 - filename: Filename of u-boot.bin (default 'u-boot-nodtb.bin')
687 This is the U-Boot binary, containing relocation information to allow it
688 to relocate itself at runtime. It does not include a device tree blob at
689 the end of it so normally cannot work without it. You can add a u_boot_dtb
690 entry after this one, or use a u_boot entry instead (which contains both
691 U-Boot and the device tree).
695 Entry: u-boot-spl: U-Boot SPL binary
696 ------------------------------------
698 Properties / Entry arguments:
699 - filename: Filename of u-boot-spl.bin (default 'spl/u-boot-spl.bin')
701 This is the U-Boot SPL (Secondary Program Loader) binary. This is a small
702 binary which loads before U-Boot proper, typically into on-chip SRAM. It is
703 responsible for locating, loading and jumping to U-Boot. Note that SPL is
704 not relocatable so must be loaded to the correct address in SRAM, or written
705 to run from the correct address if direct flash execution is possible (e.g.
708 SPL can access binman symbols at runtime. See:
710 'Access to binman entry offsets at run time (symbols)'
712 in the binman README for more information.
714 The ELF file 'spl/u-boot-spl' must also be available for this to work, since
715 binman uses that to look up symbols to write into the SPL binary.
719 Entry: u-boot-spl-bss-pad: U-Boot SPL binary padded with a BSS region
720 ---------------------------------------------------------------------
722 Properties / Entry arguments:
725 This is similar to u_boot_spl except that padding is added after the SPL
726 binary to cover the BSS (Block Started by Symbol) region. This region holds
727 the various used by SPL. It is set to 0 by SPL when it starts up. If you
728 want to append data to the SPL image (such as a device tree file), you must
729 pad out the BSS region to avoid the data overlapping with U-Boot variables.
730 This entry is useful in that case. It automatically pads out the entry size
731 to cover both the code, data and BSS.
733 The ELF file 'spl/u-boot-spl' must also be available for this to work, since
734 binman uses that to look up the BSS address.
738 Entry: u-boot-spl-dtb: U-Boot SPL device tree
739 ---------------------------------------------
741 Properties / Entry arguments:
742 - filename: Filename of u-boot.dtb (default 'spl/u-boot-spl.dtb')
744 This is the SPL device tree, containing configuration information for
745 SPL. SPL needs this to know what devices are present and which drivers
750 Entry: u-boot-spl-elf: U-Boot SPL ELF image
751 -------------------------------------------
753 Properties / Entry arguments:
754 - filename: Filename of SPL u-boot (default 'spl/u-boot-spl')
756 This is the U-Boot SPL ELF image. It does not include a device tree but can
757 be relocated to any address for execution.
761 Entry: u-boot-spl-nodtb: SPL binary without device tree appended
762 ----------------------------------------------------------------
764 Properties / Entry arguments:
765 - filename: Filename of spl/u-boot-spl-nodtb.bin (default
766 'spl/u-boot-spl-nodtb.bin')
768 This is the U-Boot SPL binary, It does not include a device tree blob at
769 the end of it so may not be able to work without it, assuming SPL needs
770 a device tree to operation on your platform. You can add a u_boot_spl_dtb
771 entry after this one, or use a u_boot_spl entry instead (which contains
772 both SPL and the device tree).
776 Entry: u-boot-spl-with-ucode-ptr: U-Boot SPL with embedded microcode pointer
777 ----------------------------------------------------------------------------
779 This is used when SPL must set up the microcode for U-Boot.
781 See Entry_u_boot_ucode for full details of the entries involved in this
786 Entry: u-boot-tpl: U-Boot TPL binary
787 ------------------------------------
789 Properties / Entry arguments:
790 - filename: Filename of u-boot-tpl.bin (default 'tpl/u-boot-tpl.bin')
792 This is the U-Boot TPL (Tertiary Program Loader) binary. This is a small
793 binary which loads before SPL, typically into on-chip SRAM. It is
794 responsible for locating, loading and jumping to SPL, the next-stage
795 loader. Note that SPL is not relocatable so must be loaded to the correct
796 address in SRAM, or written to run from the correct address if direct
797 flash execution is possible (e.g. on x86 devices).
799 SPL can access binman symbols at runtime. See:
801 'Access to binman entry offsets at run time (symbols)'
803 in the binman README for more information.
805 The ELF file 'tpl/u-boot-tpl' must also be available for this to work, since
806 binman uses that to look up symbols to write into the TPL binary.
810 Entry: u-boot-tpl-dtb: U-Boot TPL device tree
811 ---------------------------------------------
813 Properties / Entry arguments:
814 - filename: Filename of u-boot.dtb (default 'tpl/u-boot-tpl.dtb')
816 This is the TPL device tree, containing configuration information for
817 TPL. TPL needs this to know what devices are present and which drivers
822 Entry: u-boot-tpl-dtb-with-ucode: U-Boot TPL with embedded microcode pointer
823 ----------------------------------------------------------------------------
825 This is used when TPL must set up the microcode for U-Boot.
827 See Entry_u_boot_ucode for full details of the entries involved in this
832 Entry: u-boot-tpl-elf: U-Boot TPL ELF image
833 -------------------------------------------
835 Properties / Entry arguments:
836 - filename: Filename of TPL u-boot (default 'tpl/u-boot-tpl')
838 This is the U-Boot TPL ELF image. It does not include a device tree but can
839 be relocated to any address for execution.
843 Entry: u-boot-tpl-with-ucode-ptr: U-Boot TPL with embedded microcode pointer
844 ----------------------------------------------------------------------------
846 See Entry_u_boot_ucode for full details of the entries involved in this
851 Entry: u-boot-ucode: U-Boot microcode block
852 -------------------------------------------
854 Properties / Entry arguments:
857 The contents of this entry are filled in automatically by other entries
858 which must also be in the image.
860 U-Boot on x86 needs a single block of microcode. This is collected from
861 the various microcode update nodes in the device tree. It is also unable
862 to read the microcode from the device tree on platforms that use FSP
863 (Firmware Support Package) binaries, because the API requires that the
864 microcode is supplied before there is any SRAM available to use (i.e.
865 the FSP sets up the SRAM / cache-as-RAM but does so in the call that
866 requires the microcode!). To keep things simple, all x86 platforms handle
867 microcode the same way in U-Boot (even non-FSP platforms). This is that
868 a table is placed at _dt_ucode_base_size containing the base address and
869 size of the microcode. This is either passed to the FSP (for FSP
870 platforms), or used to set up the microcode (for non-FSP platforms).
871 This all happens in the build system since it is the only way to get
872 the microcode into a single blob and accessible without SRAM.
874 There are two cases to handle. If there is only one microcode blob in
875 the device tree, then the ucode pointer it set to point to that. This
876 entry (u-boot-ucode) is empty. If there is more than one update, then
877 this entry holds the concatenation of all updates, and the device tree
878 entry (u-boot-dtb-with-ucode) is updated to remove the microcode. This
879 last step ensures that that the microcode appears in one contiguous
880 block in the image and is not unnecessarily duplicated in the device
881 tree. It is referred to as 'collation' here.
883 Entry types that have a part to play in handling microcode:
885 Entry_u_boot_with_ucode_ptr:
886 Contains u-boot-nodtb.bin (i.e. U-Boot without the device tree).
887 It updates it with the address and size of the microcode so that
888 U-Boot can find it early on start-up.
889 Entry_u_boot_dtb_with_ucode:
890 Contains u-boot.dtb. It stores the microcode in a
891 'self.ucode_data' property, which is then read by this class to
892 obtain the microcode if needed. If collation is performed, it
893 removes the microcode from the device tree.
895 This class. If collation is enabled it reads the microcode from
896 the Entry_u_boot_dtb_with_ucode entry, and uses it as the
897 contents of this entry.
901 Entry: u-boot-with-ucode-ptr: U-Boot with embedded microcode pointer
902 --------------------------------------------------------------------
904 Properties / Entry arguments:
905 - filename: Filename of u-boot-nodtb.dtb (default 'u-boot-nodtb.dtb')
906 - optional-ucode: boolean property to make microcode optional. If the
907 u-boot.bin image does not include microcode, no error will
910 See Entry_u_boot_ucode for full details of the three entries involved in
911 this process. This entry updates U-Boot with the offset and size of the
912 microcode, to allow early x86 boot code to find it without doing anything
913 complicated. Otherwise it is the same as the u_boot entry.
917 Entry: vblock: An entry which contains a Chromium OS verified boot block
918 ------------------------------------------------------------------------
920 Properties / Entry arguments:
921 - content: List of phandles to entries to sign
922 - keydir: Directory containing the public keys to use
923 - keyblock: Name of the key file to use (inside keydir)
924 - signprivate: Name of provide key file to use (inside keydir)
925 - version: Version number of the vblock (typically 1)
926 - kernelkey: Name of the kernel key to use (inside keydir)
927 - preamble-flags: Value of the vboot preamble flags (typically 0)
930 - input.<unique_name> - input file passed to futility
931 - vblock.<unique_name> - output file generated by futility (which is
932 used as the entry contents)
934 Chromium OS signs the read-write firmware and kernel, writing the signature
935 in this block. This allows U-Boot to verify that the next firmware stage
936 and kernel are genuine.
940 Entry: x86-start16: x86 16-bit start-up code for U-Boot
941 -------------------------------------------------------
943 Properties / Entry arguments:
944 - filename: Filename of u-boot-x86-16bit.bin (default
945 'u-boot-x86-16bit.bin')
947 x86 CPUs start up in 16-bit mode, even if they are 32-bit CPUs. This code
948 must be placed at a particular address. This entry holds that code. It is
949 typically placed at offset CONFIG_SYS_X86_START16. The code is responsible
950 for changing to 32-bit mode and jumping to U-Boot's entry point, which
951 requires 32-bit mode (for 32-bit U-Boot).
953 For 64-bit U-Boot, the 'x86_start16_spl' entry type is used instead.
957 Entry: x86-start16-spl: x86 16-bit start-up code for SPL
958 --------------------------------------------------------
960 Properties / Entry arguments:
961 - filename: Filename of spl/u-boot-x86-16bit-spl.bin (default
962 'spl/u-boot-x86-16bit-spl.bin')
964 x86 CPUs start up in 16-bit mode, even if they are 64-bit CPUs. This code
965 must be placed at a particular address. This entry holds that code. It is
966 typically placed at offset CONFIG_SYS_X86_START16. The code is responsible
967 for changing to 32-bit mode and starting SPL, which in turn changes to
968 64-bit mode and jumps to U-Boot (for 64-bit U-Boot).
970 For 32-bit U-Boot, the 'x86_start16' entry type is used instead.
974 Entry: x86-start16-tpl: x86 16-bit start-up code for TPL
975 --------------------------------------------------------
977 Properties / Entry arguments:
978 - filename: Filename of tpl/u-boot-x86-16bit-tpl.bin (default
979 'tpl/u-boot-x86-16bit-tpl.bin')
981 x86 CPUs start up in 16-bit mode, even if they are 64-bit CPUs. This code
982 must be placed at a particular address. This entry holds that code. It is
983 typically placed at offset CONFIG_SYS_X86_START16. The code is responsible
984 for changing to 32-bit mode and starting TPL, which in turn jumps to SPL.
986 If TPL is not being used, the 'x86_start16_spl or 'x86_start16' entry types