# SPDX-License-Identifier: GPL-2.0+
# Copyright (c) 2016 Google, Inc

Introduction
------------

Firmware often consists of several components which must be packaged together.
For example, we may have SPL, U-Boot, a device tree and an environment area
grouped together and placed in MMC flash. When the system starts, it must be
able to find these pieces.

So far U-Boot has not provided a way to handle creating such images in a
general way. Each SoC does what it needs to build an image, often packing or
concatenating images in the U-Boot build system.

Binman aims to provide a mechanism for building images, from simple
SPL + U-Boot combinations, to more complex arrangements with many parts.


What it does
------------

Binman reads your board's device tree and finds a node which describes the
required image layout. It uses this to work out what to place where. The
output file normally contains the device tree, so it is in principle possible
to read an image and extract its constituent parts.


Features
--------

So far binman is pretty simple. It supports binary blobs, such as 'u-boot',
'spl' and 'fdt'. It supports empty entries (such as setting to 0xff). It can
place entries at a fixed location in the image, or fit them together with
suitable padding and alignment. It provides a way to process binaries before
they are included, by adding a Python plug-in. The device tree is available
to U-Boot at run-time so that the images can be interpreted.

Binman can update the device tree with the final location of everything when it
is done. Entry positions can be provided to U-Boot SPL as run-time symbols,
avoiding device-tree code overhead.

Binman can also support incorporating filesystems in the image if required.
For example x86 platforms may use CBFS in some cases.

Binman is intended for use with U-Boot but is designed to be general enough
to be useful in other image-packaging situations.


Motivation
----------

Packaging of firmware is quite a different task from building the various
parts. In many cases the various binaries which go into the image come from
separate build systems. For example, ARM Trusted Firmware is used on ARMv8
devices but is not built in the U-Boot tree. If a Linux kernel is included
in the firmware image, it is built elsewhere.

It is of course possible to add more and more build rules to the U-Boot
build system to cover these cases. It can shell out to other Makefiles and
build scripts. But it seems better to create a clear divide between building
software and packaging it.

At present this is handled by manual instructions, different for each board,
on how to create images that will boot. By turning these instructions into a
standard format, we can support making valid images for any board without
manual effort, lots of READMEs, etc.

Benefits:
- Each binary can have its own build system and tool chain without creating
any dependencies between them
- Avoids the need for a single-shot build: individual parts can be updated
and brought in as needed
- Provides for a standard image description available in the build and at
run-time
- SoC-specific image-signing tools can be accommodated
- Avoids cluttering the U-Boot build system with image-building code
- The image description is automatically available at run-time in U-Boot,
SPL. It can be made available to other software also
- The image description is easily readable (it's a text file in device-tree
format) and permits flexible packing of binaries


Terminology
-----------

Binman uses the following terms:

- image - an output file containing a firmware image
- binary - an input binary that goes into the image


Relationship to FIT
-------------------

FIT is U-Boot's official image format. It supports multiple binaries with
load / execution addresses, compression. It also supports verification
through hashing and RSA signatures.

FIT was originally designed to support booting a Linux kernel (with an
optional ramdisk) and device tree chosen from various options in the FIT.
Now that U-Boot supports configuration via device tree, it is possible to
load U-Boot from a FIT, with the device tree chosen by SPL.

Binman considers FIT to be one of the binaries it can place in the image.

Where possible it is best to put as much as possible in the FIT, with binman
used to deal with cases not covered by FIT. Examples include initial
execution (since FIT itself does not have an executable header) and dealing
with device boundaries, such as the read-only/read-write separation in SPI
flash.

For U-Boot, binman should not be used to create ad-hoc images in place of
FIT.


Relationship to mkimage
-----------------------

The mkimage tool provides a means to create a FIT. Traditionally it has
needed an image description file: a device tree, like binman, but in a
different format. More recently it has started to support a '-f auto' mode
which can generate that automatically.

More relevant to binman, mkimage also permits creation of many SoC-specific
image types. These can be listed by running 'mkimage -T list'. Examples
include 'rksd', the Rockchip SD/MMC boot format. The mkimage tool is often
called from the U-Boot build system for this reason.

Binman considers the output files created by mkimage to be binary blobs
which it can place in an image. Binman does not replace the mkimage tool or
this purpose. It would be possible in some situations to create a new entry
type for the images in mkimage, but this would not add functionality. It
seems better to use the mkimage tool to generate binaries and avoid blurring
the boundaries between building input files (mkimage) and packaging then
into a final image (binman).


Example use of binman in U-Boot
-------------------------------

Binman aims to replace some of the ad-hoc image creation in the U-Boot
build system.

Consider sunxi. It has the following steps:

1. It uses a custom mksunxiboot tool to build an SPL image called
sunxi-spl.bin. This should probably move into mkimage.

2. It uses mkimage to package U-Boot into a legacy image file (so that it can
hold the load and execution address) called u-boot.img.

3. It builds a final output image called u-boot-sunxi-with-spl.bin which
consists of sunxi-spl.bin, some padding and u-boot.img.

Binman is intended to replace the last step. The U-Boot build system builds
u-boot.bin and sunxi-spl.bin. Binman can then take over creation of
sunxi-spl.bin (by calling mksunxiboot, or hopefully one day mkimage). In any
case, it would then create the image from the component parts.

This simplifies the U-Boot Makefile somewhat, since various pieces of logic
can be replaced by a call to binman.


Example use of binman for x86
-----------------------------

In most cases x86 images have a lot of binary blobs, 'black-box' code
provided by Intel which must be run for the platform to work. Typically
these blobs are not relocatable and must be placed at fixed areas in the
firmware image.

Currently this is handled by ifdtool, which places microcode, FSP, MRC, VGA
BIOS, reference code and Intel ME binaries into a u-boot.rom file.

Binman is intended to replace all of this, with ifdtool left to handle only
the configuration of the Intel-format descriptor.


Running binman
--------------

First install prerequisites, e.g.

	sudo apt-get install python-pyelftools python3-pyelftools lzma-alone \
		liblz4-tool

Type:

	binman build -b <board_name>

to build an image for a board. The board name is the same name used when
configuring U-Boot (e.g. for sandbox_defconfig the board name is 'sandbox').
Binman assumes that the input files for the build are in ../b/<board_name>.

Or you can specify this explicitly:

	binman build -I <build_path>

where <build_path> is the build directory containing the output of the U-Boot
build.

(Future work will make this more configurable)

In either case, binman picks up the device tree file (u-boot.dtb) and looks
for its instructions in the 'binman' node.

Binman has a few other options which you can see by running 'binman -h'.


Enabling binman for a board
---------------------------

At present binman is invoked from a rule in the main Makefile. Typically you
will have a rule like:

ifneq ($(CONFIG_ARCH_<something>),)
u-boot-<your_suffix>.bin: <input_file_1> <input_file_2> checkbinman FORCE
	$(call if_changed,binman)
endif

This assumes that u-boot-<your_suffix>.bin is a target, and is the final file
that you need to produce. You can make it a target by adding it to ALL-y
either in the main Makefile or in a config.mk file in your arch subdirectory.

Once binman is executed it will pick up its instructions from a device-tree
file, typically <soc>-u-boot.dtsi, where <soc> is your CONFIG_SYS_SOC value.
You can use other, more specific CONFIG options - see 'Automatic .dtsi
inclusion' below.


Image description format
------------------------

The binman node is called 'binman'. An example image description is shown
below:

	binman {
		filename = "u-boot-sunxi-with-spl.bin";
		pad-byte = <0xff>;
		blob {
			filename = "spl/sunxi-spl.bin";
		};
		u-boot {
			offset = <CONFIG_SPL_PAD_TO>;
		};
	};


This requests binman to create an image file called u-boot-sunxi-with-spl.bin
consisting of a specially formatted SPL (spl/sunxi-spl.bin, built by the
normal U-Boot Makefile), some 0xff padding, and a U-Boot legacy image. The
padding comes from the fact that the second binary is placed at
CONFIG_SPL_PAD_TO. If that line were omitted then the U-Boot binary would
immediately follow the SPL binary.

The binman node describes an image. The sub-nodes describe entries in the
image. Each entry represents a region within the overall image. The name of
the entry (blob, u-boot) tells binman what to put there. For 'blob' we must
provide a filename. For 'u-boot', binman knows that this means 'u-boot.bin'.

Entries are normally placed into the image sequentially, one after the other.
The image size is the total size of all entries. As you can see, you can
specify the start offset of an entry using the 'offset' property.

Note that due to a device tree requirement, all entries must have a unique
name. If you want to put the same binary in the image multiple times, you can
use any unique name, with the 'type' property providing the type.

The attributes supported for entries are described below.

offset:
	This sets the offset of an entry within the image or section containing
	it. The first byte of the image is normally at offset 0. If 'offset' is
	not provided, binman sets it to the end of the previous region, or the
	start of the image's entry area (normally 0) if there is no previous
	region.

align:
	This sets the alignment of the entry. The entry offset is adjusted
	so that the entry starts on an aligned boundary within the image. For
	example 'align = <16>' means that the entry will start on a 16-byte
	boundary. Alignment shold be a power of 2. If 'align' is not
	provided, no alignment is performed.

size:
	This sets the size of the entry. The contents will be padded out to
	this size. If this is not provided, it will be set to the size of the
	contents.

pad-before:
	Padding before the contents of the entry. Normally this is 0, meaning
	that the contents start at the beginning of the entry. This can be
	offset the entry contents a little. Defaults to 0.

pad-after:
	Padding after the contents of the entry. Normally this is 0, meaning
	that the entry ends at the last byte of content (unless adjusted by
	other properties). This allows room to be created in the image for
	this entry to expand later. Defaults to 0.

align-size:
	This sets the alignment of the entry size. For example, to ensure
	that the size of an entry is a multiple of 64 bytes, set this to 64.
	If 'align-size' is not provided, no alignment is performed.

align-end:
	This sets the alignment of the end of an entry. Some entries require
	that they end on an alignment boundary, regardless of where they
	start. This does not move the start of the entry, so the contents of
	the entry will still start at the beginning. But there may be padding
	at the end. If 'align-end' is not provided, no alignment is performed.

filename:
	For 'blob' types this provides the filename containing the binary to
	put into the entry. If binman knows about the entry type (like
	u-boot-bin), then there is no need to specify this.

type:
	Sets the type of an entry. This defaults to the entry name, but it is
	possible to use any name, and then add (for example) 'type = "u-boot"'
	to specify the type.

offset-unset:
	Indicates that the offset of this entry should not be set by placing
	it immediately after the entry before. Instead, is set by another
	entry which knows where this entry should go. When this boolean
	property is present, binman will give an error if another entry does
	not set the offset (with the GetOffsets() method).

image-pos:
	This cannot be set on entry (or at least it is ignored if it is), but
	with the -u option, binman will set it to the absolute image position
	for each entry. This makes it easy to find out exactly where the entry
	ended up in the image, regardless of parent sections, etc.

expand-size:
	Expand the size of this entry to fit available space. This space is only
	limited by the size of the image/section and the position of the next
	entry.

compress:
	Sets the compression algortihm to use (for blobs only). See the entry
	documentation for details.

The attributes supported for images and sections are described below. Several
are similar to those for entries.

size:
	Sets the image size in bytes, for example 'size = <0x100000>' for a
	1MB image.

offset:
	This is similar to 'offset' in entries, setting the offset of a section
	within the image or section containing it. The first byte of the section
	is normally at offset 0. If 'offset' is not provided, binman sets it to
	the end of the previous region, or the start of the image's entry area
	(normally 0) if there is no previous region.

align-size:
	This sets the alignment of the image size. For example, to ensure
	that the image ends on a 512-byte boundary, use 'align-size = <512>'.
	If 'align-size' is not provided, no alignment is performed.

pad-before:
	This sets the padding before the image entries. The first entry will
	be positioned after the padding. This defaults to 0.

pad-after:
	This sets the padding after the image entries. The padding will be
	placed after the last entry. This defaults to 0.

pad-byte:
	This specifies the pad byte to use when padding in the image. It
	defaults to 0. To use 0xff, you would add 'pad-byte = <0xff>'.

filename:
	This specifies the image filename. It defaults to 'image.bin'.

sort-by-offset:
	This causes binman to reorder the entries as needed to make sure they
	are in increasing positional order. This can be used when your entry
	order may not match the positional order. A common situation is where
	the 'offset' properties are set by CONFIG options, so their ordering is
	not known a priori.

	This is a boolean property so needs no value. To enable it, add a
	line 'sort-by-offset;' to your description.

multiple-images:
	Normally only a single image is generated. To create more than one
	image, put this property in the binman node. For example, this will
	create image1.bin containing u-boot.bin, and image2.bin containing
	both spl/u-boot-spl.bin and u-boot.bin:

	binman {
		multiple-images;
		image1 {
			u-boot {
			};
		};

		image2 {
			spl {
			};
			u-boot {
			};
		};
	};

end-at-4gb:
	For x86 machines the ROM offsets start just before 4GB and extend
	up so that the image finished at the 4GB boundary. This boolean
	option can be enabled to support this. The image size must be
	provided so that binman knows when the image should start. For an
	8MB ROM, the offset of the first entry would be 0xfff80000 with
	this option, instead of 0 without this option.

skip-at-start:
	This property specifies the entry offset of the first entry.

	For PowerPC mpc85xx based CPU, CONFIG_SYS_TEXT_BASE is the entry
	offset of the first entry. It can be 0xeff40000 or 0xfff40000 for
	nor flash boot, 0x201000 for sd boot etc.

	'end-at-4gb' property is not applicable where CONFIG_SYS_TEXT_BASE +
	Image size != 4gb.

Examples of the above options can be found in the tests. See the
tools/binman/test directory.

It is possible to have the same binary appear multiple times in the image,
either by using a unit number suffix (u-boot@0, u-boot@1) or by using a
different name for each and specifying the type with the 'type' attribute.


Sections and hierachical images
-------------------------------

Sometimes it is convenient to split an image into several pieces, each of which
contains its own set of binaries. An example is a flash device where part of
the image is read-only and part is read-write. We can set up sections for each
of these, and place binaries in them independently. The image is still produced
as a single output file.

This feature provides a way of creating hierarchical images. For example here
is an example image with two copies of U-Boot. One is read-only (ro), intended
to be written only in the factory. Another is read-write (rw), so that it can be
upgraded in the field. The sizes are fixed so that the ro/rw boundary is known
and can be programmed:

	binman {
		section@0 {
			read-only;
			name-prefix = "ro-";
			size = <0x100000>;
			u-boot {
			};
		};
		section@1 {
			name-prefix = "rw-";
			size = <0x100000>;
			u-boot {
			};
		};
	};

This image could be placed into a SPI flash chip, with the protection boundary
set at 1MB.

A few special properties are provided for sections:

read-only:
	Indicates that this section is read-only. This has no impact on binman's
	operation, but his property can be read at run time.

name-prefix:
	This string is prepended to all the names of the binaries in the
	section. In the example above, the 'u-boot' binaries which actually be
	renamed to 'ro-u-boot' and 'rw-u-boot'. This can be useful to
	distinguish binaries with otherwise identical names.


Image Properties
----------------

Image nodes act like sections but also have a few extra properties:

filename:
	Output filename for the image. This defaults to image.bin (or in the
	case of multiple images <nodename>.bin where <nodename> is the name of
	the image node.

allow-repack:
	Create an image that can be repacked. With this option it is possible
	to change anything in the image after it is created, including updating
	the position and size of image components. By default this is not
	permitted since it is not possibly to know whether this might violate a
	constraint in the image description. For example, if a section has to
	increase in size to hold a larger binary, that might cause the section
	to fall out of its allow region (e.g. read-only portion of flash).

	Adding this property causes the original offset and size values in the
	image description to be stored in the FDT and fdtmap.


Entry Documentation
-------------------

For details on the various entry types supported by binman and how to use them,
see README.entries. This is generated from the source code using:

	binman entry-docs >tools/binman/README.entries


Listing images
--------------

It is possible to list the entries in an existing firmware image created by
binman, provided that there is an 'fdtmap' entry in the image. For example:

    $ binman ls -i image.bin
    Name              Image-pos  Size  Entry-type    Offset  Uncomp-size
    ----------------------------------------------------------------------
    main-section                  c00  section            0
      u-boot                  0     4  u-boot             0
      section                     5fc  section            4
        cbfs                100   400  cbfs               0
          u-boot            138     4  u-boot            38
          u-boot-dtb        180   108  u-boot-dtb        80          3b5
        u-boot-dtb          500   1ff  u-boot-dtb       400          3b5
      fdtmap                6fc   381  fdtmap           6fc
      image-header          bf8     8  image-header     bf8

This shows the hierarchy of the image, the position, size and type of each
entry, the offset of each entry within its parent and the uncompressed size if
the entry is compressed.

It is also possible to list just some files in an image, e.g.

    $ binman ls -i image.bin section/cbfs
    Name              Image-pos  Size  Entry-type  Offset  Uncomp-size
    --------------------------------------------------------------------
        cbfs                100   400  cbfs             0
          u-boot            138     4  u-boot          38
          u-boot-dtb        180   108  u-boot-dtb      80          3b5

or with wildcards:

    $ binman ls -i image.bin "*cb*" "*head*"
    Name              Image-pos  Size  Entry-type    Offset  Uncomp-size
    ----------------------------------------------------------------------
        cbfs                100   400  cbfs               0
          u-boot            138     4  u-boot            38
          u-boot-dtb        180   108  u-boot-dtb        80          3b5
      image-header          bf8     8  image-header     bf8


Extracting files from images
----------------------------

You can extract files from an existing firmware image created by binman,
provided that there is an 'fdtmap' entry in the image. For example:

    $ binman extract -i image.bin section/cbfs/u-boot

which will write the uncompressed contents of that entry to the file 'u-boot' in
the current directory. You can also extract to a particular file, in this case
u-boot.bin:

    $ binman extract -i image.bin section/cbfs/u-boot -f u-boot.bin

It is possible to extract all files into a destination directory, which will
put files in subdirectories matching the entry hierarchy:

    $ binman extract -i image.bin -O outdir

or just a selection:

    $ binman extract -i image.bin "*u-boot*" -O outdir


Replacing files in an image
---------------------------

You can replace files in an existing firmware image created by binman, provided
that there is an 'fdtmap' entry in the image. For example:

    $ binman replace -i image.bin section/cbfs/u-boot

which will write the contents of the file 'u-boot' from the current directory
to the that entry, compressing if necessary. If the entry size changes, you must
add the 'allow-repack' property to the original image before generating it (see
above), otherwise you will get an error.

You can also use a particular file, in this case u-boot.bin:

    $ binman replace -i image.bin section/cbfs/u-boot -f u-boot.bin

It is possible to replace all files from a source directory which uses the same
hierarchy as the entries:

    $ binman replace -i image.bin -I indir

Files that are missing will generate a warning.

You can also replace just a selection of entries:

    $ binman replace -i image.bin "*u-boot*" -I indir


Logging
-------

Binman normally operates silently unless there is an error, in which case it
just displays the error. The -D/--debug option can be used to create a full
backtrace when errors occur.

Internally binman logs some output while it is running. This can be displayed
by increasing the -v/--verbosity from the default of 1:

   0: silent
   1: warnings only
   2: notices (important messages)
   3: info about major operations
   4: detailed information about each operation
   5: debug (all output)


Hashing Entries
---------------

It is possible to ask binman to hash the contents of an entry and write that
value back to the device-tree node. For example:

	binman {
		u-boot {
			hash {
				algo = "sha256";
			};
		};
	};

Here, a new 'value' property will be written to the 'hash' node containing
the hash of the 'u-boot' entry. Only SHA256 is supported at present. Whole
sections can be hased if desired, by adding the 'hash' node to the section.

The has value can be chcked at runtime by hashing the data actually read and
comparing this has to the value in the device tree.


Order of image creation
-----------------------

Image creation proceeds in the following order, for each entry in the image.

1. AddMissingProperties() - binman can add calculated values to the device
tree as part of its processing, for example the offset and size of each
entry. This method adds any properties associated with this, expanding the
device tree as needed. These properties can have placeholder values which are
set later by SetCalculatedProperties(). By that stage the size of sections
cannot be changed (since it would cause the images to need to be repacked),
but the correct values can be inserted.

2. ProcessFdt() - process the device tree information as required by the
particular entry. This may involve adding or deleting properties. If the
processing is complete, this method should return True. If the processing
cannot complete because it needs the ProcessFdt() method of another entry to
run first, this method should return False, in which case it will be called
again later.

3. GetEntryContents() - the contents of each entry are obtained, normally by
reading from a file. This calls the Entry.ObtainContents() to read the
contents. The default version of Entry.ObtainContents() calls
Entry.GetDefaultFilename() and then reads that file. So a common mechanism
to select a file to read is to override that function in the subclass. The
functions must return True when they have read the contents. Binman will
retry calling the functions a few times if False is returned, allowing
dependencies between the contents of different entries.

4. GetEntryOffsets() - calls Entry.GetOffsets() for each entry. This can
return a dict containing entries that need updating. The key should be the
entry name and the value is a tuple (offset, size). This allows an entry to
provide the offset and size for other entries. The default implementation
of GetEntryOffsets() returns {}.

5. PackEntries() - calls Entry.Pack() which figures out the offset and
size of an entry. The 'current' image offset is passed in, and the function
returns the offset immediately after the entry being packed. The default
implementation of Pack() is usually sufficient.

6. CheckSize() - checks that the contents of all the entries fits within
the image size. If the image does not have a defined size, the size is set
large enough to hold all the entries.

7. CheckEntries() - checks that the entries do not overlap, nor extend
outside the image.

8. SetImagePos() - sets the image position of every entry. This is the absolute
position 'image-pos', as opposed to 'offset' which is relative to the containing
section. This must be done after all offsets are known, which is why it is quite
late in the ordering.

9. SetCalculatedProperties() - update any calculated properties in the device
tree. This sets the correct 'offset' and 'size' vaues, for example.

10. ProcessEntryContents() - this calls Entry.ProcessContents() on each entry.
The default implementatoin does nothing. This can be overriden to adjust the
contents of an entry in some way. For example, it would be possible to create
an entry containing a hash of the contents of some other entries. At this
stage the offset and size of entries should not be adjusted unless absolutely
necessary, since it requires a repack (going back to PackEntries()).

11. ResetForPack() - if the ProcessEntryContents() step failed, in that an entry
has changed its size, then there is no alternative but to go back to step 5 and
try again, repacking the entries with the updated size. ResetForPack() removes
the fixed offset/size values added by binman, so that the packing can start from
scratch.

12. WriteSymbols() - write the value of symbols into the U-Boot SPL binary.
See 'Access to binman entry offsets at run time' below for a description of
what happens in this stage.

13. BuildImage() - builds the image and writes it to a file

14. WriteMap() - writes a text file containing a map of the image. This is the
final step.


Automatic .dtsi inclusion
-------------------------

It is sometimes inconvenient to add a 'binman' node to the .dts file for each
board. This can be done by using #include to bring in a common file. Another
approach supported by the U-Boot build system is to automatically include
a common header. You can then put the binman node (and anything else that is
specific to U-Boot, such as u-boot,dm-pre-reloc properies) in that header
file.

Binman will search for the following files in arch/<arch>/dts:

   <dts>-u-boot.dtsi where <dts> is the base name of the .dts file
   <CONFIG_SYS_SOC>-u-boot.dtsi
   <CONFIG_SYS_CPU>-u-boot.dtsi
   <CONFIG_SYS_VENDOR>-u-boot.dtsi
   u-boot.dtsi

U-Boot will only use the first one that it finds. If you need to include a
more general file you can do that from the more specific file using #include.
If you are having trouble figuring out what is going on, you can uncomment
the 'warning' line in scripts/Makefile.lib to see what it has found:

   # Uncomment for debugging
   # This shows all the files that were considered and the one that we chose.
   # u_boot_dtsi_options_debug = $(u_boot_dtsi_options_raw)


Access to binman entry offsets at run time (symbols)
----------------------------------------------------

Binman assembles images and determines where each entry is placed in the image.
This information may be useful to U-Boot at run time. For example, in SPL it
is useful to be able to find the location of U-Boot so that it can be executed
when SPL is finished.

Binman allows you to declare symbols in the SPL image which are filled in
with their correct values during the build. For example:

    binman_sym_declare(ulong, u_boot_any, image_pos);

declares a ulong value which will be assigned to the image-pos of any U-Boot
image (u-boot.bin, u-boot.img, u-boot-nodtb.bin) that is present in the image.
You can access this value with something like:

    ulong u_boot_offset = binman_sym(ulong, u_boot_any, image_pos);

Thus u_boot_offset will be set to the image-pos of U-Boot in memory, assuming
that the whole image has been loaded, or is available in flash. You can then
jump to that address to start U-Boot.

At present this feature is only supported in SPL and TPL. In principle it is
possible to fill in such symbols in U-Boot proper, as well, but a future C
library is planned for this instead, to read from the device tree.

As well as image-pos, it is possible to read the size of an entry and its
offset (which is the start position of the entry within its parent).

A small technical note: Binman automatically adds the base address of the image
(i.e. __image_copy_start) to the value of the image-pos symbol, so that when the
image is loaded to its linked address, the value will be correct and actually
point into the image.

For example, say SPL is at the start of the image and linked to start at address
80108000. If U-Boot's image-pos is 0x8000 then binman will write an image-pos
for U-Boot of 80110000 into the SPL binary, since it assumes the image is loaded
to 80108000, with SPL at 80108000 and U-Boot at 80110000.

For x86 devices (with the end-at-4gb property) this base address is not added
since it is assumed that images are XIP and the offsets already include the
address.


Access to binman entry offsets at run time (fdt)
------------------------------------------------

Binman can update the U-Boot FDT to include the final position and size of
each entry in the images it processes. The option to enable this is -u and it
causes binman to make sure that the 'offset', 'image-pos' and 'size' properties
are set correctly for every entry. Since it is not necessary to specify these in
the image definition, binman calculates the final values and writes these to
the device tree. These can be used by U-Boot at run-time to find the location
of each entry.

Alternatively, an FDT map entry can be used to add a special FDT containing
just the information about the image. This is preceded by a magic string so can
be located anywhere in the image. An image header (typically at the start or end
of the image) can be used to point to the FDT map. See fdtmap and image-header
entries for more information.


Compression
-----------

Binman support compression for 'blob' entries (those of type 'blob' and
derivatives). To enable this for an entry, add a 'compress' property:

    blob {
        filename = "datafile";
        compress = "lz4";
    };

The entry will then contain the compressed data, using the 'lz4' compression
algorithm. Currently this is the only one that is supported. The uncompressed
size is written to the node in an 'uncomp-size' property, if -u is used.



Map files
---------

The -m option causes binman to output a .map file for each image that it
generates. This shows the offset and size of each entry. For example:

      Offset      Size  Name
    00000000  00000028  main-section
     00000000  00000010  section@0
      00000000  00000004  u-boot
     00000010  00000010  section@1
      00000000  00000004  u-boot

This shows a hierarchical image with two sections, each with a single entry. The
offsets of the sections are absolute hex byte offsets within the image. The
offsets of the entries are relative to their respective sections. The size of
each entry is also shown, in bytes (hex). The indentation shows the entries
nested inside their sections.


Passing command-line arguments to entries
-----------------------------------------

Sometimes it is useful to pass binman the value of an entry property from the
command line. For example some entries need access to files and it is not
always convenient to put these filenames in the image definition (device tree).

The-a option supports this:

    -a<prop>=<value>

where

    <prop> is the property to set
    <value> is the value to set it to

Not all properties can be provided this way. Only some entries support it,
typically for filenames.


External tools
--------------

Binman can make use of external command-line tools to handle processing of
entry contents or to generate entry contents. These tools are executed using
the 'tools' module's Run() method. The tools generally must exist on the PATH,
but the --toolpath option can be used to specify additional search paths to
use. This option can be specified multiple times to add more than one path.


Code coverage
-------------

Binman is a critical tool and is designed to be very testable. Entry
implementations target 100% test coverage. Run 'binman test -T' to check this.

To enable Python test coverage on Debian-type distributions (e.g. Ubuntu):

   $ sudo apt-get install python-coverage python3-coverage python-pytest


Concurrent tests
----------------

Binman tries to run tests concurrently. This means that the tests make use of
all available CPUs to run.

 To enable this:

   $ sudo apt-get install python-subunit python3-subunit

Use '-P 1' to disable this. It is automatically disabled when code coverage is
being used (-T) since they are incompatible.


Debugging tests
---------------

Sometimes when debugging tests it is useful to keep the input and output
directories so they can be examined later. Use -X or --test-preserve-dirs for
this.


Advanced Features / Technical docs
----------------------------------

The behaviour of entries is defined by the Entry class. All other entries are
a subclass of this. An important subclass is Entry_blob which takes binary
data from a file and places it in the entry. In fact most entry types are
subclasses of Entry_blob.

Each entry type is a separate file in the tools/binman/etype directory. Each
file contains a class called Entry_<type> where <type> is the entry type.
New entry types can be supported by adding new files in that directory.
These will automatically be detected by binman when needed.

Entry properties are documented in entry.py. The entry subclasses are free
to change the values of properties to support special behaviour. For example,
when Entry_blob loads a file, it sets content_size to the size of the file.
Entry classes can adjust other entries. For example, an entry that knows
where other entries should be positioned can set up those entries' offsets
so they don't need to be set in the binman decription. It can also adjust
entry contents.

Most of the time such essoteric behaviour is not needed, but it can be
essential for complex images.

If you need to specify a particular device-tree compiler to use, you can define
the DTC environment variable. This can be useful when the system dtc is too
old.

To enable a full backtrace and other debugging features in binman, pass
BINMAN_DEBUG=1 to your build:

   make qemu-x86_defconfig
   make BINMAN_DEBUG=1

To enable verbose logging from binman, base BINMAN_VERBOSE to your build, which
adds a -v<level> option to the call to binman:

   make qemu-x86_defconfig
   make BINMAN_VERBOSE=5


History / Credits
-----------------

Binman takes a lot of inspiration from a Chrome OS tool called
'cros_bundle_firmware', which I wrote some years ago. That tool was based on
a reasonably simple and sound design but has expanded greatly over the
years. In particular its handling of x86 images is convoluted.

Quite a few lessons have been learned which are hopefully applied here.


Design notes
------------

On the face of it, a tool to create firmware images should be fairly simple:
just find all the input binaries and place them at the right place in the
image. The difficulty comes from the wide variety of input types (simple
flat binaries containing code, packaged data with various headers), packing
requirments (alignment, spacing, device boundaries) and other required
features such as hierarchical images.

The design challenge is to make it easy to create simple images, while
allowing the more complex cases to be supported. For example, for most
images we don't much care exactly where each binary ends up, so we should
not have to specify that unnecessarily.

New entry types should aim to provide simple usage where possible. If new
core features are needed, they can be added in the Entry base class.


To do
-----

Some ideas:
- Use of-platdata to make the information available to code that is unable
  to use device tree (such as a very small SPL image)
- Allow easy building of images by specifying just the board name
- Support building an image for a board (-b) more completely, with a
  configurable build directory
- Support adding FITs to an image
- Support for ARM Trusted Firmware (ATF)
- Detect invalid properties in nodes
- Sort the fdtmap by offset

--
Simon Glass <sjg@chromium.org>
7/7/2016

Binman Entry Documentation
===========================

This file describes the entry types supported by binman. These entry types can
be placed in an image one by one to build up a final firmware image. It is
fairly easy to create new entry types. Just add a new file to the 'etype'
directory. You can use the existing entries as examples.

Note that some entries are subclasses of others, using and extending their
features to produce new behaviours.



Entry: blob: Entry containing an arbitrary binary blob
------------------------------------------------------

Note: This should not be used by itself. It is normally used as a parent
class by other entry types.

Properties / Entry arguments:
    - filename: Filename of file to read into entry
    - compress: Compression algorithm to use:
        none: No compression
        lz4: Use lz4 compression (via 'lz4' command-line utility)

This entry reads data from a file and places it in the entry. The
default filename is often specified specified by the subclass. See for
example the 'u_boot' entry which provides the filename 'u-boot.bin'.

If compression is enabled, an extra 'uncomp-size' property is written to
the node (if enabled with -u) which provides the uncompressed size of the
data.



Entry: blob-dtb: A blob that holds a device tree
------------------------------------------------

This is a blob containing a device tree. The contents of the blob are
obtained from the list of available device-tree files, managed by the
'state' module.



Entry: blob-named-by-arg: A blob entry which gets its filename property from its subclass
-----------------------------------------------------------------------------------------

Properties / Entry arguments:
    - <xxx>-path: Filename containing the contents of this entry (optional,
        defaults to 0)

where <xxx> is the blob_fname argument to the constructor.

This entry cannot be used directly. Instead, it is used as a parent class
for another entry, which defined blob_fname. This parameter is used to
set the entry-arg or property containing the filename. The entry-arg or
property is in turn used to set the actual filename.

See cros_ec_rw for an example of this.



Entry: cbfs: Entry containing a Coreboot Filesystem (CBFS)
----------------------------------------------------------

A CBFS provides a way to group files into a group. It has a simple directory
structure and allows the position of individual files to be set, since it is
designed to support execute-in-place in an x86 SPI-flash device. Where XIP
is not used, it supports compression and storing ELF files.

CBFS is used by coreboot as its way of orgnanising SPI-flash contents.

The contents of the CBFS are defined by subnodes of the cbfs entry, e.g.:

    cbfs {
        size = <0x100000>;
        u-boot {
            cbfs-type = "raw";
        };
        u-boot-dtb {
            cbfs-type = "raw";
        };
    };

This creates a CBFS 1MB in size two files in it: u-boot.bin and u-boot.dtb.
Note that the size is required since binman does not support calculating it.
The contents of each entry is just what binman would normally provide if it
were not a CBFS node. A blob type can be used to import arbitrary files as
with the second subnode below:

    cbfs {
        size = <0x100000>;
        u-boot {
            cbfs-name = "BOOT";
            cbfs-type = "raw";
        };

        dtb {
            type = "blob";
            filename = "u-boot.dtb";
            cbfs-type = "raw";
            cbfs-compress = "lz4";
            cbfs-offset = <0x100000>;
        };
    };

This creates a CBFS 1MB in size with u-boot.bin (named "BOOT") and
u-boot.dtb (named "dtb") and compressed with the lz4 algorithm.


Properties supported in the top-level CBFS node:

cbfs-arch:
    Defaults to "x86", but you can specify the architecture if needed.


Properties supported in the CBFS entry subnodes:

cbfs-name:
    This is the name of the file created in CBFS. It defaults to the entry
    name (which is the node name), but you can override it with this
    property.

cbfs-type:
    This is the CBFS file type. The following are supported:

    raw:
        This is a 'raw' file, although compression is supported. It can be
        used to store any file in CBFS.

    stage:
        This is an ELF file that has been loaded (i.e. mapped to memory), so
        appears in the CBFS as a flat binary. The input file must be an ELF
        image, for example this puts "u-boot" (the ELF image) into a 'stage'
        entry:

            cbfs {
                size = <0x100000>;
                u-boot-elf {
                    cbfs-name = "BOOT";
                    cbfs-type = "stage";
                };
            };

        You can use your own ELF file with something like:

            cbfs {
                size = <0x100000>;
                something {
                    type = "blob";
                    filename = "cbfs-stage.elf";
                    cbfs-type = "stage";
                };
            };

        As mentioned, the file is converted to a flat binary, so it is
        equivalent to adding "u-boot.bin", for example, but with the load and
        start addresses specified by the ELF. At present there is no option
        to add a flat binary with a load/start address, similar to the
        'add-flat-binary' option in cbfstool.

cbfs-offset:
    This is the offset of the file's data within the CBFS. It is used to
    specify where the file should be placed in cases where a fixed position
    is needed. Typical uses are for code which is not relocatable and must
    execute in-place from a particular address. This works because SPI flash
    is generally mapped into memory on x86 devices. The file header is
    placed before this offset so that the data start lines up exactly with
    the chosen offset. If this property is not provided, then the file is
    placed in the next available spot.

The current implementation supports only a subset of CBFS features. It does
not support other file types (e.g. payload), adding multiple files (like the
'files' entry with a pattern supported by binman), putting files at a
particular offset in the CBFS and a few other things.

Of course binman can create images containing multiple CBFSs, simply by
defining these in the binman config:


    binman {
        size = <0x800000>;
        cbfs {
            offset = <0x100000>;
            size = <0x100000>;
            u-boot {
                cbfs-type = "raw";
            };
            u-boot-dtb {
                cbfs-type = "raw";
            };
        };

        cbfs2 {
            offset = <0x700000>;
            size = <0x100000>;
            u-boot {
                cbfs-type = "raw";
            };
            u-boot-dtb {
                cbfs-type = "raw";
            };
            image {
                type = "blob";
                filename = "image.jpg";
            };
        };
    };

This creates an 8MB image with two CBFSs, one at offset 1MB, one at 7MB,
both of size 1MB.



Entry: cros-ec-rw: A blob entry which contains a Chromium OS read-write EC image
--------------------------------------------------------------------------------

Properties / Entry arguments:
    - cros-ec-rw-path: Filename containing the EC image

This entry holds a Chromium OS EC (embedded controller) image, for use in
updating the EC on startup via software sync.



Entry: fdtmap: An entry which contains an FDT map
-------------------------------------------------

Properties / Entry arguments:
    None

An FDT map is just a header followed by an FDT containing a list of all the
entries in the image. The root node corresponds to the image node in the
original FDT, and an image-name property indicates the image name in that
original tree.

The header is the string _FDTMAP_ followed by 8 unused bytes.

When used, this entry will be populated with an FDT map which reflects the
entries in the current image. Hierarchy is preserved, and all offsets and
sizes are included.

Note that the -u option must be provided to ensure that binman updates the
FDT with the position of each entry.

Example output for a simple image with U-Boot and an FDT map:

/ {
    image-name = "binman";
    size = <0x00000112>;
    image-pos = <0x00000000>;
    offset = <0x00000000>;
    u-boot {
        size = <0x00000004>;
        image-pos = <0x00000000>;
        offset = <0x00000000>;
    };
    fdtmap {
        size = <0x0000010e>;
        image-pos = <0x00000004>;
        offset = <0x00000004>;
    };
};

If allow-repack is used then 'orig-offset' and 'orig-size' properties are
added as necessary. See the binman README.



Entry: files: Entry containing a set of files
---------------------------------------------

Properties / Entry arguments:
    - pattern: Filename pattern to match the files to include
    - compress: Compression algorithm to use:
        none: No compression
        lz4: Use lz4 compression (via 'lz4' command-line utility)

This entry reads a number of files and places each in a separate sub-entry
within this entry. To access these you need to enable device-tree updates
at run-time so you can obtain the file positions.



Entry: fill: An entry which is filled to a particular byte value
----------------------------------------------------------------

Properties / Entry arguments:
    - fill-byte: Byte to use to fill the entry

Note that the size property must be set since otherwise this entry does not
know how large it should be.

You can often achieve the same effect using the pad-byte property of the
overall image, in that the space between entries will then be padded with
that byte. But this entry is sometimes useful for explicitly setting the
byte value of a region.



Entry: fmap: An entry which contains an Fmap section
----------------------------------------------------

Properties / Entry arguments:
    None

FMAP is a simple format used by flashrom, an open-source utility for
reading and writing the SPI flash, typically on x86 CPUs. The format
provides flashrom with a list of areas, so it knows what it in the flash.
It can then read or write just a single area, instead of the whole flash.

The format is defined by the flashrom project, in the file lib/fmap.h -
see www.flashrom.org/Flashrom for more information.

When used, this entry will be populated with an FMAP which reflects the
entries in the current image. Note that any hierarchy is squashed, since
FMAP does not support this. Also, CBFS entries appear as a single entry -
the sub-entries are ignored.



Entry: gbb: An entry which contains a Chromium OS Google Binary Block
---------------------------------------------------------------------

Properties / Entry arguments:
    - hardware-id: Hardware ID to use for this build (a string)
    - keydir: Directory containing the public keys to use
    - bmpblk: Filename containing images used by recovery

Chromium OS uses a GBB to store various pieces of information, in particular
the root and recovery keys that are used to verify the boot process. Some
more details are here:

    https://www.chromium.org/chromium-os/firmware-porting-guide/2-concepts

but note that the page dates from 2013 so is quite out of date. See
README.chromium for how to obtain the required keys and tools.



Entry: image-header: An entry which contains a pointer to the FDT map
---------------------------------------------------------------------

Properties / Entry arguments:
    location: Location of header ("start" or "end" of image). This is
        optional. If omitted then the entry must have an offset property.

This adds an 8-byte entry to the start or end of the image, pointing to the
location of the FDT map. The format is a magic number followed by an offset
from the start or end of the image, in twos-compliment format.

This entry must be in the top-level part of the image.

NOTE: If the location is at the start/end, you will probably need to specify
sort-by-offset for the image, unless you actually put the image header
first/last in the entry list.



Entry: intel-cmc: Entry containing an Intel Chipset Micro Code (CMC) file
-------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains microcode for some devices in a special format. An
example filename is 'Microcode/C0_22211.BIN'.

See README.x86 for information about x86 binary blobs.



Entry: intel-descriptor: Intel flash descriptor block (4KB)
-----------------------------------------------------------

Properties / Entry arguments:
    filename: Filename of file containing the descriptor. This is typically
        a 4KB binary file, sometimes called 'descriptor.bin'

This entry is placed at the start of flash and provides information about
the SPI flash regions. In particular it provides the base address and
size of the ME (Management Engine) region, allowing us to place the ME
binary in the right place.

With this entry in your image, the position of the 'intel-me' entry will be
fixed in the image, which avoids you needed to specify an offset for that
region. This is useful, because it is not possible to change the position
of the ME region without updating the descriptor.

See README.x86 for information about x86 binary blobs.



Entry: intel-fit: Intel Firmware Image Table (FIT)
--------------------------------------------------

This entry contains a dummy FIT as required by recent Intel CPUs. The FIT
contains information about the firmware and microcode available in the
image.

At present binman only supports a basic FIT with no microcode.



Entry: intel-fit-ptr: Intel Firmware Image Table (FIT) pointer
--------------------------------------------------------------

This entry contains a pointer to the FIT. It is required to be at address
0xffffffc0 in the image.



Entry: intel-fsp: Entry containing an Intel Firmware Support Package (FSP) file
-------------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains binary blobs which are used on some devices to make the
platform work. U-Boot executes this code since it is not possible to set up
the hardware using U-Boot open-source code. Documentation is typically not
available in sufficient detail to allow this.

An example filename is 'FSP/QUEENSBAY_FSP_GOLD_001_20-DECEMBER-2013.fd'

See README.x86 for information about x86 binary blobs.



Entry: intel-fsp-m: Entry containing Intel Firmware Support Package (FSP) memory init
-------------------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains a binary blob which is used on some devices to set up
SDRAM. U-Boot executes this code in SPL so that it can make full use of
memory. Documentation is typically not available in sufficient detail to
allow U-Boot do this this itself..

An example filename is 'fsp_m.bin'

See README.x86 for information about x86 binary blobs.



Entry: intel-fsp-s: Entry containing Intel Firmware Support Package (FSP) silicon init
--------------------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains a binary blob which is used on some devices to set up
the silicon. U-Boot executes this code in U-Boot proper after SDRAM is
running, so that it can make full use of memory. Documentation is typically
not available in sufficient detail to allow U-Boot do this this itself.

An example filename is 'fsp_s.bin'

See README.x86 for information about x86 binary blobs.



Entry: intel-fsp-t: Entry containing Intel Firmware Support Package (FSP) temp ram init
---------------------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains a binary blob which is used on some devices to set up
temporary memory (Cache-as-RAM or CAR). U-Boot executes this code in TPL so
that it has access to memory for its stack and initial storage.

An example filename is 'fsp_t.bin'

See README.x86 for information about x86 binary blobs.



Entry: intel-ifwi: Entry containing an Intel Integrated Firmware Image (IFWI) file
----------------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry. This is either the
        IFWI file itself, or a file that can be converted into one using a
        tool
    - convert-fit: If present this indicates that the ifwitool should be
        used to convert the provided file into a IFWI.

This file contains code and data used by the SoC that is required to make
it work. It includes U-Boot TPL, microcode, things related to the CSE
(Converged Security Engine, the microcontroller that loads all the firmware)
and other items beyond the wit of man.

A typical filename is 'ifwi.bin' for an IFWI file, or 'fitimage.bin' for a
file that will be converted to an IFWI.

The position of this entry is generally set by the intel-descriptor entry.

The contents of the IFWI are specified by the subnodes of the IFWI node.
Each subnode describes an entry which is placed into the IFWFI with a given
sub-partition (and optional entry name).

Properties for subnodes:
    ifwi-subpart - sub-parition to put this entry into, e.g. "IBBP"
    ifwi-entry - entry name t use, e.g. "IBBL"
    ifwi-replace - if present, indicates that the item should be replaced
        in the IFWI. Otherwise it is added.

See README.x86 for information about x86 binary blobs.



Entry: intel-me: Entry containing an Intel Management Engine (ME) file
----------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains code used by the SoC that is required to make it work.
The Management Engine is like a background task that runs things that are
not clearly documented, but may include keyboard, display and network
access. For platform that use ME it is not possible to disable it. U-Boot
does not directly execute code in the ME binary.

A typical filename is 'me.bin'.

The position of this entry is generally set by the intel-descriptor entry.

See README.x86 for information about x86 binary blobs.



Entry: intel-mrc: Entry containing an Intel Memory Reference Code (MRC) file
----------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains code for setting up the SDRAM on some Intel systems. This
is executed by U-Boot when needed early during startup. A typical filename
is 'mrc.bin'.

See README.x86 for information about x86 binary blobs.



Entry: intel-refcode: Entry containing an Intel Reference Code file
-------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains code for setting up the platform on some Intel systems.
This is executed by U-Boot when needed early during startup. A typical
filename is 'refcode.bin'.

See README.x86 for information about x86 binary blobs.



Entry: intel-vbt: Entry containing an Intel Video BIOS Table (VBT) file
-----------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains code that sets up the integrated graphics subsystem on
some Intel SoCs. U-Boot executes this when the display is started up.

See README.x86 for information about Intel binary blobs.



Entry: intel-vga: Entry containing an Intel Video Graphics Adaptor (VGA) file
-----------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of file to read into entry

This file contains code that sets up the integrated graphics subsystem on
some Intel SoCs. U-Boot executes this when the display is started up.

This is similar to the VBT file but in a different format.

See README.x86 for information about Intel binary blobs.



Entry: powerpc-mpc85xx-bootpg-resetvec: PowerPC mpc85xx bootpg + resetvec code for U-Boot
-----------------------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot-br.bin (default 'u-boot-br.bin')

This entry is valid for PowerPC mpc85xx cpus. This entry holds
'bootpg + resetvec' code for PowerPC mpc85xx CPUs which needs to be
placed at offset 'RESET_VECTOR_ADDRESS - 0xffc'.



Entry: section: Entry that contains other entries
-------------------------------------------------

Properties / Entry arguments: (see binman README for more information)
    pad-byte: Pad byte to use when padding
    sort-by-offset: True if entries should be sorted by offset, False if
        they must be in-order in the device tree description
    end-at-4gb: Used to build an x86 ROM which ends at 4GB (2^32)
    skip-at-start: Number of bytes before the first entry starts. These
        effectively adjust the starting offset of entries. For example,
        if this is 16, then the first entry would start at 16. An entry
        with offset = 20 would in fact be written at offset 4 in the image
        file, since the first 16 bytes are skipped when writing.
    name-prefix: Adds a prefix to the name of every entry in the section
        when writing out the map

Since a section is also an entry, it inherits all the properies of entries
too.

A section is an entry which can contain other entries, thus allowing
hierarchical images to be created. See 'Sections and hierarchical images'
in the binman README for more information.



Entry: text: An entry which contains text
-----------------------------------------

The text can be provided either in the node itself or by a command-line
argument. There is a level of indirection to allow multiple text strings
and sharing of text.

Properties / Entry arguments:
    text-label: The value of this string indicates the property / entry-arg
        that contains the string to place in the entry
    <xxx> (actual name is the value of text-label): contains the string to
        place in the entry.
    <text>: The text to place in the entry (overrides the above mechanism).
        This is useful when the text is constant.

Example node:

    text {
        size = <50>;
        text-label = "message";
    };

You can then use:

    binman -amessage="this is my message"

and binman will insert that string into the entry.

It is also possible to put the string directly in the node:

    text {
        size = <8>;
        text-label = "message";
        message = "a message directly in the node"
    };

or just:

    text {
        size = <8>;
        text = "some text directly in the node"
    };

The text is not itself nul-terminated. This can be achieved, if required,
by setting the size of the entry to something larger than the text.



Entry: u-boot: U-Boot flat binary
---------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot.bin (default 'u-boot.bin')

This is the U-Boot binary, containing relocation information to allow it
to relocate itself at runtime. The binary typically includes a device tree
blob at the end of it. Use u_boot_nodtb if you want to package the device
tree separately.

U-Boot can access binman symbols at runtime. See:

    'Access to binman entry offsets at run time (fdt)'

in the binman README for more information.



Entry: u-boot-dtb: U-Boot device tree
-------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot.dtb (default 'u-boot.dtb')

This is the U-Boot device tree, containing configuration information for
U-Boot. U-Boot needs this to know what devices are present and which drivers
to activate.

Note: This is mostly an internal entry type, used by others. This allows
binman to know which entries contain a device tree.



Entry: u-boot-dtb-with-ucode: A U-Boot device tree file, with the microcode removed
-----------------------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot.dtb (default 'u-boot.dtb')

See Entry_u_boot_ucode for full details of the three entries involved in
this process. This entry provides the U-Boot device-tree file, which
contains the microcode. If the microcode is not being collated into one
place then the offset and size of the microcode is recorded by this entry,
for use by u_boot_with_ucode_ptr. If it is being collated, then this
entry deletes the microcode from the device tree (to save space) and makes
it available to u_boot_ucode.



Entry: u-boot-elf: U-Boot ELF image
-----------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot (default 'u-boot')

This is the U-Boot ELF image. It does not include a device tree but can be
relocated to any address for execution.



Entry: u-boot-img: U-Boot legacy image
--------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot.img (default 'u-boot.img')

This is the U-Boot binary as a packaged image, in legacy format. It has a
header which allows it to be loaded at the correct address for execution.

You should use FIT (Flat Image Tree) instead of the legacy image for new
applications.



Entry: u-boot-nodtb: U-Boot flat binary without device tree appended
--------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot.bin (default 'u-boot-nodtb.bin')

This is the U-Boot binary, containing relocation information to allow it
to relocate itself at runtime. It does not include a device tree blob at
the end of it so normally cannot work without it. You can add a u_boot_dtb
entry after this one, or use a u_boot entry instead (which contains both
U-Boot and the device tree).



Entry: u-boot-spl: U-Boot SPL binary
------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot-spl.bin (default 'spl/u-boot-spl.bin')

This is the U-Boot SPL (Secondary Program Loader) binary. This is a small
binary which loads before U-Boot proper, typically into on-chip SRAM. It is
responsible for locating, loading and jumping to U-Boot. Note that SPL is
not relocatable so must be loaded to the correct address in SRAM, or written
to run from the correct address if direct flash execution is possible (e.g.
on x86 devices).

SPL can access binman symbols at runtime. See:

    'Access to binman entry offsets at run time (symbols)'

in the binman README for more information.

The ELF file 'spl/u-boot-spl' must also be available for this to work, since
binman uses that to look up symbols to write into the SPL binary.



Entry: u-boot-spl-bss-pad: U-Boot SPL binary padded with a BSS region
---------------------------------------------------------------------

Properties / Entry arguments:
    None

This is similar to u_boot_spl except that padding is added after the SPL
binary to cover the BSS (Block Started by Symbol) region. This region holds
the various used by SPL. It is set to 0 by SPL when it starts up. If you
want to append data to the SPL image (such as a device tree file), you must
pad out the BSS region to avoid the data overlapping with U-Boot variables.
This entry is useful in that case. It automatically pads out the entry size
to cover both the code, data and BSS.

The ELF file 'spl/u-boot-spl' must also be available for this to work, since
binman uses that to look up the BSS address.



Entry: u-boot-spl-dtb: U-Boot SPL device tree
---------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot.dtb (default 'spl/u-boot-spl.dtb')

This is the SPL device tree, containing configuration information for
SPL. SPL needs this to know what devices are present and which drivers
to activate.



Entry: u-boot-spl-elf: U-Boot SPL ELF image
-------------------------------------------

Properties / Entry arguments:
    - filename: Filename of SPL u-boot (default 'spl/u-boot-spl')

This is the U-Boot SPL ELF image. It does not include a device tree but can
be relocated to any address for execution.



Entry: u-boot-spl-nodtb: SPL binary without device tree appended
----------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of spl/u-boot-spl-nodtb.bin (default
        'spl/u-boot-spl-nodtb.bin')

This is the U-Boot SPL binary, It does not include a device tree blob at
the end of it so may not be able to work without it, assuming SPL needs
a device tree to operation on your platform. You can add a u_boot_spl_dtb
entry after this one, or use a u_boot_spl entry instead (which contains
both SPL and the device tree).



Entry: u-boot-spl-with-ucode-ptr: U-Boot SPL with embedded microcode pointer
----------------------------------------------------------------------------

This is used when SPL must set up the microcode for U-Boot.

See Entry_u_boot_ucode for full details of the entries involved in this
process.



Entry: u-boot-tpl: U-Boot TPL binary
------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot-tpl.bin (default 'tpl/u-boot-tpl.bin')

This is the U-Boot TPL (Tertiary Program Loader) binary. This is a small
binary which loads before SPL, typically into on-chip SRAM. It is
responsible for locating, loading and jumping to SPL, the next-stage
loader. Note that SPL is not relocatable so must be loaded to the correct
address in SRAM, or written to run from the correct address if direct
flash execution is possible (e.g. on x86 devices).

SPL can access binman symbols at runtime. See:

    'Access to binman entry offsets at run time (symbols)'

in the binman README for more information.

The ELF file 'tpl/u-boot-tpl' must also be available for this to work, since
binman uses that to look up symbols to write into the TPL binary.



Entry: u-boot-tpl-dtb: U-Boot TPL device tree
---------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot.dtb (default 'tpl/u-boot-tpl.dtb')

This is the TPL device tree, containing configuration information for
TPL. TPL needs this to know what devices are present and which drivers
to activate.



Entry: u-boot-tpl-dtb-with-ucode: U-Boot TPL with embedded microcode pointer
----------------------------------------------------------------------------

This is used when TPL must set up the microcode for U-Boot.

See Entry_u_boot_ucode for full details of the entries involved in this
process.



Entry: u-boot-tpl-elf: U-Boot TPL ELF image
-------------------------------------------

Properties / Entry arguments:
    - filename: Filename of TPL u-boot (default 'tpl/u-boot-tpl')

This is the U-Boot TPL ELF image. It does not include a device tree but can
be relocated to any address for execution.



Entry: u-boot-tpl-with-ucode-ptr: U-Boot TPL with embedded microcode pointer
----------------------------------------------------------------------------

See Entry_u_boot_ucode for full details of the entries involved in this
process.



Entry: u-boot-ucode: U-Boot microcode block
-------------------------------------------

Properties / Entry arguments:
    None

The contents of this entry are filled in automatically by other entries
which must also be in the image.

U-Boot on x86 needs a single block of microcode. This is collected from
the various microcode update nodes in the device tree. It is also unable
to read the microcode from the device tree on platforms that use FSP
(Firmware Support Package) binaries, because the API requires that the
microcode is supplied before there is any SRAM available to use (i.e.
the FSP sets up the SRAM / cache-as-RAM but does so in the call that
requires the microcode!). To keep things simple, all x86 platforms handle
microcode the same way in U-Boot (even non-FSP platforms). This is that
a table is placed at _dt_ucode_base_size containing the base address and
size of the microcode. This is either passed to the FSP (for FSP
platforms), or used to set up the microcode (for non-FSP platforms).
This all happens in the build system since it is the only way to get
the microcode into a single blob and accessible without SRAM.

There are two cases to handle. If there is only one microcode blob in
the device tree, then the ucode pointer it set to point to that. This
entry (u-boot-ucode) is empty. If there is more than one update, then
this entry holds the concatenation of all updates, and the device tree
entry (u-boot-dtb-with-ucode) is updated to remove the microcode. This
last step ensures that that the microcode appears in one contiguous
block in the image and is not unnecessarily duplicated in the device
tree. It is referred to as 'collation' here.

Entry types that have a part to play in handling microcode:

    Entry_u_boot_with_ucode_ptr:
        Contains u-boot-nodtb.bin (i.e. U-Boot without the device tree).
        It updates it with the address and size of the microcode so that
        U-Boot can find it early on start-up.
    Entry_u_boot_dtb_with_ucode:
        Contains u-boot.dtb. It stores the microcode in a
        'self.ucode_data' property, which is then read by this class to
        obtain the microcode if needed. If collation is performed, it
        removes the microcode from the device tree.
    Entry_u_boot_ucode:
        This class. If collation is enabled it reads the microcode from
        the Entry_u_boot_dtb_with_ucode entry, and uses it as the
        contents of this entry.



Entry: u-boot-with-ucode-ptr: U-Boot with embedded microcode pointer
--------------------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot-nodtb.bin (default 'u-boot-nodtb.bin')
    - optional-ucode: boolean property to make microcode optional. If the
        u-boot.bin image does not include microcode, no error will
        be generated.

See Entry_u_boot_ucode for full details of the three entries involved in
this process. This entry updates U-Boot with the offset and size of the
microcode, to allow early x86 boot code to find it without doing anything
complicated. Otherwise it is the same as the u_boot entry.



Entry: vblock: An entry which contains a Chromium OS verified boot block
------------------------------------------------------------------------

Properties / Entry arguments:
    - content: List of phandles to entries to sign
    - keydir: Directory containing the public keys to use
    - keyblock: Name of the key file to use (inside keydir)
    - signprivate: Name of provide key file to use (inside keydir)
    - version: Version number of the vblock (typically 1)
    - kernelkey: Name of the kernel key to use (inside keydir)
    - preamble-flags: Value of the vboot preamble flags (typically 0)

Output files:
    - input.<unique_name> - input file passed to futility
    - vblock.<unique_name> - output file generated by futility (which is
        used as the entry contents)

Chromium OS signs the read-write firmware and kernel, writing the signature
in this block. This allows U-Boot to verify that the next firmware stage
and kernel are genuine.



Entry: x86-reset16: x86 16-bit reset code for U-Boot
----------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot-x86-reset16.bin (default
        'u-boot-x86-reset16.bin')

x86 CPUs start up in 16-bit mode, even if they are 32-bit CPUs. This code
must be placed at a particular address. This entry holds that code. It is
typically placed at offset CONFIG_RESET_VEC_LOC. The code is responsible
for jumping to the x86-start16 code, which continues execution.

For 64-bit U-Boot, the 'x86_reset16_spl' entry type is used instead.



Entry: x86-reset16-spl: x86 16-bit reset code for U-Boot
--------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot-x86-reset16.bin (default
        'u-boot-x86-reset16.bin')

x86 CPUs start up in 16-bit mode, even if they are 32-bit CPUs. This code
must be placed at a particular address. This entry holds that code. It is
typically placed at offset CONFIG_RESET_VEC_LOC. The code is responsible
for jumping to the x86-start16 code, which continues execution.

For 32-bit U-Boot, the 'x86_reset_spl' entry type is used instead.



Entry: x86-reset16-tpl: x86 16-bit reset code for U-Boot
--------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot-x86-reset16.bin (default
        'u-boot-x86-reset16.bin')

x86 CPUs start up in 16-bit mode, even if they are 32-bit CPUs. This code
must be placed at a particular address. This entry holds that code. It is
typically placed at offset CONFIG_RESET_VEC_LOC. The code is responsible
for jumping to the x86-start16 code, which continues execution.

For 32-bit U-Boot, the 'x86_reset_tpl' entry type is used instead.



Entry: x86-start16: x86 16-bit start-up code for U-Boot
-------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of u-boot-x86-start16.bin (default
        'u-boot-x86-start16.bin')

x86 CPUs start up in 16-bit mode, even if they are 32-bit CPUs. This code
must be placed in the top 64KB of the ROM. The reset code jumps to it. This
entry holds that code. It is typically placed at offset
CONFIG_SYS_X86_START16. The code is responsible for changing to 32-bit mode
and jumping to U-Boot's entry point, which requires 32-bit mode (for 32-bit
U-Boot).

For 64-bit U-Boot, the 'x86_start16_spl' entry type is used instead.



Entry: x86-start16-spl: x86 16-bit start-up code for SPL
--------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of spl/u-boot-x86-start16-spl.bin (default
        'spl/u-boot-x86-start16-spl.bin')

x86 CPUs start up in 16-bit mode, even if they are 32-bit CPUs. This code
must be placed in the top 64KB of the ROM. The reset code jumps to it. This
entry holds that code. It is typically placed at offset
CONFIG_SYS_X86_START16. The code is responsible for changing to 32-bit mode
and jumping to U-Boot's entry point, which requires 32-bit mode (for 32-bit
U-Boot).

For 32-bit U-Boot, the 'x86-start16' entry type is used instead.



Entry: x86-start16-tpl: x86 16-bit start-up code for TPL
--------------------------------------------------------

Properties / Entry arguments:
    - filename: Filename of tpl/u-boot-x86-start16-tpl.bin (default
        'tpl/u-boot-x86-start16-tpl.bin')

x86 CPUs start up in 16-bit mode, even if they are 32-bit CPUs. This code
must be placed in the top 64KB of the ROM. The reset code jumps to it. This
entry holds that code. It is typically placed at offset
CONFIG_SYS_X86_START16. The code is responsible for changing to 32-bit mode
and jumping to U-Boot's entry point, which requires 32-bit mode (for 32-bit
U-Boot).

If TPL is not being used, the 'x86-start16-spl or 'x86-start16' entry types
may be used instead.