1 # SPDX-License-Identifier: GPL-2.0+
2 # Copyright (c) 2016 Google, Inc
7 Firmware often consists of several components which must be packaged together.
8 For example, we may have SPL, U-Boot, a device tree and an environment area
9 grouped together and placed in MMC flash. When the system starts, it must be
10 able to find these pieces.
12 So far U-Boot has not provided a way to handle creating such images in a
13 general way. Each SoC does what it needs to build an image, often packing or
14 concatenating images in the U-Boot build system.
16 Binman aims to provide a mechanism for building images, from simple
17 SPL + U-Boot combinations, to more complex arrangements with many parts.
23 Binman reads your board's device tree and finds a node which describes the
24 required image layout. It uses this to work out what to place where. The
25 output file normally contains the device tree, so it is in principle possible
26 to read an image and extract its constituent parts.
32 So far binman is pretty simple. It supports binary blobs, such as 'u-boot',
33 'spl' and 'fdt'. It supports empty entries (such as setting to 0xff). It can
34 place entries at a fixed location in the image, or fit them together with
35 suitable padding and alignment. It provides a way to process binaries before
36 they are included, by adding a Python plug-in. The device tree is available
37 to U-Boot at run-time so that the images can be interpreted.
39 Binman can update the device tree with the final location of everything when it
40 is done. Entry positions can be provided to U-Boot SPL as run-time symbols,
41 avoiding device-tree code overhead.
43 Binman can also support incorporating filesystems in the image if required.
44 For example x86 platforms may use CBFS in some cases.
46 Binman is intended for use with U-Boot but is designed to be general enough
47 to be useful in other image-packaging situations.
53 Packaging of firmware is quite a different task from building the various
54 parts. In many cases the various binaries which go into the image come from
55 separate build systems. For example, ARM Trusted Firmware is used on ARMv8
56 devices but is not built in the U-Boot tree. If a Linux kernel is included
57 in the firmware image, it is built elsewhere.
59 It is of course possible to add more and more build rules to the U-Boot
60 build system to cover these cases. It can shell out to other Makefiles and
61 build scripts. But it seems better to create a clear divide between building
62 software and packaging it.
64 At present this is handled by manual instructions, different for each board,
65 on how to create images that will boot. By turning these instructions into a
66 standard format, we can support making valid images for any board without
67 manual effort, lots of READMEs, etc.
70 - Each binary can have its own build system and tool chain without creating
71 any dependencies between them
72 - Avoids the need for a single-shot build: individual parts can be updated
73 and brought in as needed
74 - Provides for a standard image description available in the build and at
76 - SoC-specific image-signing tools can be accomodated
77 - Avoids cluttering the U-Boot build system with image-building code
78 - The image description is automatically available at run-time in U-Boot,
79 SPL. It can be made available to other software also
80 - The image description is easily readable (it's a text file in device-tree
81 format) and permits flexible packing of binaries
87 Binman uses the following terms:
89 - image - an output file containing a firmware image
90 - binary - an input binary that goes into the image
96 FIT is U-Boot's official image format. It supports multiple binaries with
97 load / execution addresses, compression. It also supports verification
98 through hashing and RSA signatures.
100 FIT was originally designed to support booting a Linux kernel (with an
101 optional ramdisk) and device tree chosen from various options in the FIT.
102 Now that U-Boot supports configuration via device tree, it is possible to
103 load U-Boot from a FIT, with the device tree chosen by SPL.
105 Binman considers FIT to be one of the binaries it can place in the image.
107 Where possible it is best to put as much as possible in the FIT, with binman
108 used to deal with cases not covered by FIT. Examples include initial
109 execution (since FIT itself does not have an executable header) and dealing
110 with device boundaries, such as the read-only/read-write separation in SPI
113 For U-Boot, binman should not be used to create ad-hoc images in place of
117 Relationship to mkimage
118 -----------------------
120 The mkimage tool provides a means to create a FIT. Traditionally it has
121 needed an image description file: a device tree, like binman, but in a
122 different format. More recently it has started to support a '-f auto' mode
123 which can generate that automatically.
125 More relevant to binman, mkimage also permits creation of many SoC-specific
126 image types. These can be listed by running 'mkimage -T list'. Examples
127 include 'rksd', the Rockchip SD/MMC boot format. The mkimage tool is often
128 called from the U-Boot build system for this reason.
130 Binman considers the output files created by mkimage to be binary blobs
131 which it can place in an image. Binman does not replace the mkimage tool or
132 this purpose. It would be possible in some situations to create a new entry
133 type for the images in mkimage, but this would not add functionality. It
134 seems better to use the mkimage tool to generate binaries and avoid blurring
135 the boundaries between building input files (mkimage) and packaging then
136 into a final image (binman).
139 Example use of binman in U-Boot
140 -------------------------------
142 Binman aims to replace some of the ad-hoc image creation in the U-Boot
145 Consider sunxi. It has the following steps:
147 1. It uses a custom mksunxiboot tool to build an SPL image called
148 sunxi-spl.bin. This should probably move into mkimage.
150 2. It uses mkimage to package U-Boot into a legacy image file (so that it can
151 hold the load and execution address) called u-boot.img.
153 3. It builds a final output image called u-boot-sunxi-with-spl.bin which
154 consists of sunxi-spl.bin, some padding and u-boot.img.
156 Binman is intended to replace the last step. The U-Boot build system builds
157 u-boot.bin and sunxi-spl.bin. Binman can then take over creation of
158 sunxi-spl.bin (by calling mksunxiboot, or hopefully one day mkimage). In any
159 case, it would then create the image from the component parts.
161 This simplifies the U-Boot Makefile somewhat, since various pieces of logic
162 can be replaced by a call to binman.
165 Example use of binman for x86
166 -----------------------------
168 In most cases x86 images have a lot of binary blobs, 'black-box' code
169 provided by Intel which must be run for the platform to work. Typically
170 these blobs are not relocatable and must be placed at fixed areas in the
173 Currently this is handled by ifdtool, which places microcode, FSP, MRC, VGA
174 BIOS, reference code and Intel ME binaries into a u-boot.rom file.
176 Binman is intended to replace all of this, with ifdtool left to handle only
177 the configuration of the Intel-format descriptor.
183 First install prerequisites, e.g.
185 sudo apt-get install python-pyelftools python3-pyelftools lzma-alone \
190 binman build -b <board_name>
192 to build an image for a board. The board name is the same name used when
193 configuring U-Boot (e.g. for sandbox_defconfig the board name is 'sandbox').
194 Binman assumes that the input files for the build are in ../b/<board_name>.
196 Or you can specify this explicitly:
198 binman build -I <build_path>
200 where <build_path> is the build directory containing the output of the U-Boot
203 (Future work will make this more configurable)
205 In either case, binman picks up the device tree file (u-boot.dtb) and looks
206 for its instructions in the 'binman' node.
208 Binman has a few other options which you can see by running 'binman -h'.
211 Enabling binman for a board
212 ---------------------------
214 At present binman is invoked from a rule in the main Makefile. Typically you
215 will have a rule like:
217 ifneq ($(CONFIG_ARCH_<something>),)
218 u-boot-<your_suffix>.bin: <input_file_1> <input_file_2> checkbinman FORCE
219 $(call if_changed,binman)
222 This assumes that u-boot-<your_suffix>.bin is a target, and is the final file
223 that you need to produce. You can make it a target by adding it to ALL-y
224 either in the main Makefile or in a config.mk file in your arch subdirectory.
226 Once binman is executed it will pick up its instructions from a device-tree
227 file, typically <soc>-u-boot.dtsi, where <soc> is your CONFIG_SYS_SOC value.
228 You can use other, more specific CONFIG options - see 'Automatic .dtsi
232 Image description format
233 ------------------------
235 The binman node is called 'binman'. An example image description is shown
239 filename = "u-boot-sunxi-with-spl.bin";
242 filename = "spl/sunxi-spl.bin";
245 offset = <CONFIG_SPL_PAD_TO>;
250 This requests binman to create an image file called u-boot-sunxi-with-spl.bin
251 consisting of a specially formatted SPL (spl/sunxi-spl.bin, built by the
252 normal U-Boot Makefile), some 0xff padding, and a U-Boot legacy image. The
253 padding comes from the fact that the second binary is placed at
254 CONFIG_SPL_PAD_TO. If that line were omitted then the U-Boot binary would
255 immediately follow the SPL binary.
257 The binman node describes an image. The sub-nodes describe entries in the
258 image. Each entry represents a region within the overall image. The name of
259 the entry (blob, u-boot) tells binman what to put there. For 'blob' we must
260 provide a filename. For 'u-boot', binman knows that this means 'u-boot.bin'.
262 Entries are normally placed into the image sequentially, one after the other.
263 The image size is the total size of all entries. As you can see, you can
264 specify the start offset of an entry using the 'offset' property.
266 Note that due to a device tree requirement, all entries must have a unique
267 name. If you want to put the same binary in the image multiple times, you can
268 use any unique name, with the 'type' property providing the type.
270 The attributes supported for entries are described below.
273 This sets the offset of an entry within the image or section containing
274 it. The first byte of the image is normally at offset 0. If 'offset' is
275 not provided, binman sets it to the end of the previous region, or the
276 start of the image's entry area (normally 0) if there is no previous
280 This sets the alignment of the entry. The entry offset is adjusted
281 so that the entry starts on an aligned boundary within the image. For
282 example 'align = <16>' means that the entry will start on a 16-byte
283 boundary. Alignment shold be a power of 2. If 'align' is not
284 provided, no alignment is performed.
287 This sets the size of the entry. The contents will be padded out to
288 this size. If this is not provided, it will be set to the size of the
292 Padding before the contents of the entry. Normally this is 0, meaning
293 that the contents start at the beginning of the entry. This can be
294 offset the entry contents a little. Defaults to 0.
297 Padding after the contents of the entry. Normally this is 0, meaning
298 that the entry ends at the last byte of content (unless adjusted by
299 other properties). This allows room to be created in the image for
300 this entry to expand later. Defaults to 0.
303 This sets the alignment of the entry size. For example, to ensure
304 that the size of an entry is a multiple of 64 bytes, set this to 64.
305 If 'align-size' is not provided, no alignment is performed.
308 This sets the alignment of the end of an entry. Some entries require
309 that they end on an alignment boundary, regardless of where they
310 start. This does not move the start of the entry, so the contents of
311 the entry will still start at the beginning. But there may be padding
312 at the end. If 'align-end' is not provided, no alignment is performed.
315 For 'blob' types this provides the filename containing the binary to
316 put into the entry. If binman knows about the entry type (like
317 u-boot-bin), then there is no need to specify this.
320 Sets the type of an entry. This defaults to the entry name, but it is
321 possible to use any name, and then add (for example) 'type = "u-boot"'
325 Indicates that the offset of this entry should not be set by placing
326 it immediately after the entry before. Instead, is set by another
327 entry which knows where this entry should go. When this boolean
328 property is present, binman will give an error if another entry does
329 not set the offset (with the GetOffsets() method).
332 This cannot be set on entry (or at least it is ignored if it is), but
333 with the -u option, binman will set it to the absolute image position
334 for each entry. This makes it easy to find out exactly where the entry
335 ended up in the image, regardless of parent sections, etc.
338 Expand the size of this entry to fit available space. This space is only
339 limited by the size of the image/section and the position of the next
343 Sets the compression algortihm to use (for blobs only). See the entry
344 documentation for details.
346 The attributes supported for images and sections are described below. Several
347 are similar to those for entries.
350 Sets the image size in bytes, for example 'size = <0x100000>' for a
354 This is similar to 'offset' in entries, setting the offset of a section
355 within the image or section containing it. The first byte of the section
356 is normally at offset 0. If 'offset' is not provided, binman sets it to
357 the end of the previous region, or the start of the image's entry area
358 (normally 0) if there is no previous region.
361 This sets the alignment of the image size. For example, to ensure
362 that the image ends on a 512-byte boundary, use 'align-size = <512>'.
363 If 'align-size' is not provided, no alignment is performed.
366 This sets the padding before the image entries. The first entry will
367 be positioned after the padding. This defaults to 0.
370 This sets the padding after the image entries. The padding will be
371 placed after the last entry. This defaults to 0.
374 This specifies the pad byte to use when padding in the image. It
375 defaults to 0. To use 0xff, you would add 'pad-byte = <0xff>'.
378 This specifies the image filename. It defaults to 'image.bin'.
381 This causes binman to reorder the entries as needed to make sure they
382 are in increasing positional order. This can be used when your entry
383 order may not match the positional order. A common situation is where
384 the 'offset' properties are set by CONFIG options, so their ordering is
387 This is a boolean property so needs no value. To enable it, add a
388 line 'sort-by-offset;' to your description.
391 Normally only a single image is generated. To create more than one
392 image, put this property in the binman node. For example, this will
393 create image1.bin containing u-boot.bin, and image2.bin containing
394 both spl/u-boot-spl.bin and u-boot.bin:
412 For x86 machines the ROM offsets start just before 4GB and extend
413 up so that the image finished at the 4GB boundary. This boolean
414 option can be enabled to support this. The image size must be
415 provided so that binman knows when the image should start. For an
416 8MB ROM, the offset of the first entry would be 0xfff80000 with
417 this option, instead of 0 without this option.
420 This property specifies the entry offset of the first entry.
422 For PowerPC mpc85xx based CPU, CONFIG_SYS_TEXT_BASE is the entry
423 offset of the first entry. It can be 0xeff40000 or 0xfff40000 for
424 nor flash boot, 0x201000 for sd boot etc.
426 'end-at-4gb' property is not applicable where CONFIG_SYS_TEXT_BASE +
429 Examples of the above options can be found in the tests. See the
430 tools/binman/test directory.
432 It is possible to have the same binary appear multiple times in the image,
433 either by using a unit number suffix (u-boot@0, u-boot@1) or by using a
434 different name for each and specifying the type with the 'type' attribute.
437 Sections and hierachical images
438 -------------------------------
440 Sometimes it is convenient to split an image into several pieces, each of which
441 contains its own set of binaries. An example is a flash device where part of
442 the image is read-only and part is read-write. We can set up sections for each
443 of these, and place binaries in them independently. The image is still produced
444 as a single output file.
446 This feature provides a way of creating hierarchical images. For example here
447 is an example image with two copies of U-Boot. One is read-only (ro), intended
448 to be written only in the factory. Another is read-write (rw), so that it can be
449 upgraded in the field. The sizes are fixed so that the ro/rw boundary is known
450 and can be programmed:
468 This image could be placed into a SPI flash chip, with the protection boundary
471 A few special properties are provided for sections:
474 Indicates that this section is read-only. This has no impact on binman's
475 operation, but his property can be read at run time.
478 This string is prepended to all the names of the binaries in the
479 section. In the example above, the 'u-boot' binaries which actually be
480 renamed to 'ro-u-boot' and 'rw-u-boot'. This can be useful to
481 distinguish binaries with otherwise identical names.
487 For details on the various entry types supported by binman and how to use them,
488 see README.entries. This is generated from the source code using:
490 binman entry-docs >tools/binman/README.entries
496 It is possible to list the entries in an existing firmware image created by
497 binman, provided that there is an 'fdtmap' entry in the image. For example:
499 $ binman ls -i image.bin
500 Name Image-pos Size Entry-type Offset Uncomp-size
501 ----------------------------------------------------------------------
502 main-section c00 section 0
504 section 5fc section 4
506 u-boot 138 4 u-boot 38
507 u-boot-dtb 180 108 u-boot-dtb 80 3b5
508 u-boot-dtb 500 1ff u-boot-dtb 400 3b5
509 fdtmap 6fc 381 fdtmap 6fc
510 image-header bf8 8 image-header bf8
512 This shows the hierarchy of the image, the position, size and type of each
513 entry, the offset of each entry within its parent and the uncompressed size if
514 the entry is compressed.
516 It is also possible to list just some files in an image, e.g.
518 $ binman ls -i image.bin section/cbfs
519 Name Image-pos Size Entry-type Offset Uncomp-size
520 --------------------------------------------------------------------
522 u-boot 138 4 u-boot 38
523 u-boot-dtb 180 108 u-boot-dtb 80 3b5
527 $ binman ls -i image.bin "*cb*" "*head*"
528 Name Image-pos Size Entry-type Offset Uncomp-size
529 ----------------------------------------------------------------------
531 u-boot 138 4 u-boot 38
532 u-boot-dtb 180 108 u-boot-dtb 80 3b5
533 image-header bf8 8 image-header bf8
539 Binman normally operates silently unless there is an error, in which case it
540 just displays the error. The -D/--debug option can be used to create a full
541 backtrace when errors occur.
543 Internally binman logs some output while it is running. This can be displayed
544 by increasing the -v/--verbosity from the default of 1:
548 2: notices (important messages)
549 3: info about major operations
550 4: detailed information about each operation
551 5: debug (all output)
557 It is possible to ask binman to hash the contents of an entry and write that
558 value back to the device-tree node. For example:
568 Here, a new 'value' property will be written to the 'hash' node containing
569 the hash of the 'u-boot' entry. Only SHA256 is supported at present. Whole
570 sections can be hased if desired, by adding the 'hash' node to the section.
572 The has value can be chcked at runtime by hashing the data actually read and
573 comparing this has to the value in the device tree.
576 Order of image creation
577 -----------------------
579 Image creation proceeds in the following order, for each entry in the image.
581 1. AddMissingProperties() - binman can add calculated values to the device
582 tree as part of its processing, for example the offset and size of each
583 entry. This method adds any properties associated with this, expanding the
584 device tree as needed. These properties can have placeholder values which are
585 set later by SetCalculatedProperties(). By that stage the size of sections
586 cannot be changed (since it would cause the images to need to be repacked),
587 but the correct values can be inserted.
589 2. ProcessFdt() - process the device tree information as required by the
590 particular entry. This may involve adding or deleting properties. If the
591 processing is complete, this method should return True. If the processing
592 cannot complete because it needs the ProcessFdt() method of another entry to
593 run first, this method should return False, in which case it will be called
596 3. GetEntryContents() - the contents of each entry are obtained, normally by
597 reading from a file. This calls the Entry.ObtainContents() to read the
598 contents. The default version of Entry.ObtainContents() calls
599 Entry.GetDefaultFilename() and then reads that file. So a common mechanism
600 to select a file to read is to override that function in the subclass. The
601 functions must return True when they have read the contents. Binman will
602 retry calling the functions a few times if False is returned, allowing
603 dependencies between the contents of different entries.
605 4. GetEntryOffsets() - calls Entry.GetOffsets() for each entry. This can
606 return a dict containing entries that need updating. The key should be the
607 entry name and the value is a tuple (offset, size). This allows an entry to
608 provide the offset and size for other entries. The default implementation
609 of GetEntryOffsets() returns {}.
611 5. PackEntries() - calls Entry.Pack() which figures out the offset and
612 size of an entry. The 'current' image offset is passed in, and the function
613 returns the offset immediately after the entry being packed. The default
614 implementation of Pack() is usually sufficient.
616 6. CheckSize() - checks that the contents of all the entries fits within
617 the image size. If the image does not have a defined size, the size is set
618 large enough to hold all the entries.
620 7. CheckEntries() - checks that the entries do not overlap, nor extend
623 8. SetCalculatedProperties() - update any calculated properties in the device
624 tree. This sets the correct 'offset' and 'size' vaues, for example.
626 9. ProcessEntryContents() - this calls Entry.ProcessContents() on each entry.
627 The default implementatoin does nothing. This can be overriden to adjust the
628 contents of an entry in some way. For example, it would be possible to create
629 an entry containing a hash of the contents of some other entries. At this
630 stage the offset and size of entries should not be adjusted unless absolutely
631 necessary, since it requires a repack (going back to PackEntries()).
633 10. WriteSymbols() - write the value of symbols into the U-Boot SPL binary.
634 See 'Access to binman entry offsets at run time' below for a description of
635 what happens in this stage.
637 11. BuildImage() - builds the image and writes it to a file. This is the final
641 Automatic .dtsi inclusion
642 -------------------------
644 It is sometimes inconvenient to add a 'binman' node to the .dts file for each
645 board. This can be done by using #include to bring in a common file. Another
646 approach supported by the U-Boot build system is to automatically include
647 a common header. You can then put the binman node (and anything else that is
648 specific to U-Boot, such as u-boot,dm-pre-reloc properies) in that header
651 Binman will search for the following files in arch/<arch>/dts:
653 <dts>-u-boot.dtsi where <dts> is the base name of the .dts file
654 <CONFIG_SYS_SOC>-u-boot.dtsi
655 <CONFIG_SYS_CPU>-u-boot.dtsi
656 <CONFIG_SYS_VENDOR>-u-boot.dtsi
659 U-Boot will only use the first one that it finds. If you need to include a
660 more general file you can do that from the more specific file using #include.
661 If you are having trouble figuring out what is going on, you can uncomment
662 the 'warning' line in scripts/Makefile.lib to see what it has found:
664 # Uncomment for debugging
665 # This shows all the files that were considered and the one that we chose.
666 # u_boot_dtsi_options_debug = $(u_boot_dtsi_options_raw)
669 Access to binman entry offsets at run time (symbols)
670 ----------------------------------------------------
672 Binman assembles images and determines where each entry is placed in the image.
673 This information may be useful to U-Boot at run time. For example, in SPL it
674 is useful to be able to find the location of U-Boot so that it can be executed
675 when SPL is finished.
677 Binman allows you to declare symbols in the SPL image which are filled in
678 with their correct values during the build. For example:
680 binman_sym_declare(ulong, u_boot_any, offset);
682 declares a ulong value which will be assigned to the offset of any U-Boot
683 image (u-boot.bin, u-boot.img, u-boot-nodtb.bin) that is present in the image.
684 You can access this value with something like:
686 ulong u_boot_offset = binman_sym(ulong, u_boot_any, offset);
688 Thus u_boot_offset will be set to the offset of U-Boot in memory, assuming that
689 the whole image has been loaded, or is available in flash. You can then jump to
690 that address to start U-Boot.
692 At present this feature is only supported in SPL. In principle it is possible
693 to fill in such symbols in U-Boot proper, as well.
696 Access to binman entry offsets at run time (fdt)
697 ------------------------------------------------
699 Binman can update the U-Boot FDT to include the final position and size of
700 each entry in the images it processes. The option to enable this is -u and it
701 causes binman to make sure that the 'offset', 'image-pos' and 'size' properties
702 are set correctly for every entry. Since it is not necessary to specify these in
703 the image definition, binman calculates the final values and writes these to
704 the device tree. These can be used by U-Boot at run-time to find the location
707 Alternatively, an FDT map entry can be used to add a special FDT containing
708 just the information about the image. This is preceded by a magic string so can
709 be located anywhere in the image. An image header (typically at the start or end
710 of the image) can be used to point to the FDT map. See fdtmap and image-header
711 entries for more information.
717 Binman support compression for 'blob' entries (those of type 'blob' and
718 derivatives). To enable this for an entry, add a 'compress' property:
721 filename = "datafile";
725 The entry will then contain the compressed data, using the 'lz4' compression
726 algorithm. Currently this is the only one that is supported. The uncompressed
727 size is written to the node in an 'uncomp-size' property, if -u is used.
734 The -m option causes binman to output a .map file for each image that it
735 generates. This shows the offset and size of each entry. For example:
738 00000000 00000028 main-section
739 00000000 00000010 section@0
740 00000000 00000004 u-boot
741 00000010 00000010 section@1
742 00000000 00000004 u-boot
744 This shows a hierarchical image with two sections, each with a single entry. The
745 offsets of the sections are absolute hex byte offsets within the image. The
746 offsets of the entries are relative to their respective sections. The size of
747 each entry is also shown, in bytes (hex). The indentation shows the entries
748 nested inside their sections.
751 Passing command-line arguments to entries
752 -----------------------------------------
754 Sometimes it is useful to pass binman the value of an entry property from the
755 command line. For example some entries need access to files and it is not
756 always convenient to put these filenames in the image definition (device tree).
758 The-a option supports this:
764 <prop> is the property to set
765 <value> is the value to set it to
767 Not all properties can be provided this way. Only some entries support it,
768 typically for filenames.
774 Binman can make use of external command-line tools to handle processing of
775 entry contents or to generate entry contents. These tools are executed using
776 the 'tools' module's Run() method. The tools generally must exist on the PATH,
777 but the --toolpath option can be used to specify additional search paths to
778 use. This option can be specified multiple times to add more than one path.
784 Binman is a critical tool and is designed to be very testable. Entry
785 implementations target 100% test coverage. Run 'binman test -T' to check this.
787 To enable Python test coverage on Debian-type distributions (e.g. Ubuntu):
789 $ sudo apt-get install python-coverage python3-coverage python-pytest
795 Binman tries to run tests concurrently. This means that the tests make use of
796 all available CPUs to run.
800 $ sudo apt-get install python-subunit python3-subunit
802 Use '-P 1' to disable this. It is automatically disabled when code coverage is
803 being used (-T) since they are incompatible.
809 Sometimes when debugging tests it is useful to keep the input and output
810 directories so they can be examined later. Use -X or --test-preserve-dirs for
814 Advanced Features / Technical docs
815 ----------------------------------
817 The behaviour of entries is defined by the Entry class. All other entries are
818 a subclass of this. An important subclass is Entry_blob which takes binary
819 data from a file and places it in the entry. In fact most entry types are
820 subclasses of Entry_blob.
822 Each entry type is a separate file in the tools/binman/etype directory. Each
823 file contains a class called Entry_<type> where <type> is the entry type.
824 New entry types can be supported by adding new files in that directory.
825 These will automatically be detected by binman when needed.
827 Entry properties are documented in entry.py. The entry subclasses are free
828 to change the values of properties to support special behaviour. For example,
829 when Entry_blob loads a file, it sets content_size to the size of the file.
830 Entry classes can adjust other entries. For example, an entry that knows
831 where other entries should be positioned can set up those entries' offsets
832 so they don't need to be set in the binman decription. It can also adjust
835 Most of the time such essoteric behaviour is not needed, but it can be
836 essential for complex images.
838 If you need to specify a particular device-tree compiler to use, you can define
839 the DTC environment variable. This can be useful when the system dtc is too
842 To enable a full backtrace and other debugging features in binman, pass
843 BINMAN_DEBUG=1 to your build:
845 make sandbox_defconfig
852 Binman takes a lot of inspiration from a Chrome OS tool called
853 'cros_bundle_firmware', which I wrote some years ago. That tool was based on
854 a reasonably simple and sound design but has expanded greatly over the
855 years. In particular its handling of x86 images is convoluted.
857 Quite a few lessons have been learned which are hopefully applied here.
863 On the face of it, a tool to create firmware images should be fairly simple:
864 just find all the input binaries and place them at the right place in the
865 image. The difficulty comes from the wide variety of input types (simple
866 flat binaries containing code, packaged data with various headers), packing
867 requirments (alignment, spacing, device boundaries) and other required
868 features such as hierarchical images.
870 The design challenge is to make it easy to create simple images, while
871 allowing the more complex cases to be supported. For example, for most
872 images we don't much care exactly where each binary ends up, so we should
873 not have to specify that unnecessarily.
875 New entry types should aim to provide simple usage where possible. If new
876 core features are needed, they can be added in the Entry base class.
883 - Use of-platdata to make the information available to code that is unable
884 to use device tree (such as a very small SPL image)
885 - Allow easy building of images by specifying just the board name
886 - Add an option to decode an image into the constituent binaries
887 - Support building an image for a board (-b) more completely, with a
888 configurable build directory
889 - Support updating binaries in an image (with no size change / repacking)
890 - Support updating binaries in an image (with repacking)
891 - Support adding FITs to an image
892 - Support for ARM Trusted Firmware (ATF)
895 Simon Glass <sjg@chromium.org>