-U-boot new uImage source file format (bindings definition)
+U-Boot new uImage source file format (bindings definition)
==========================================================
Author: Marian Balakowicz <m8@semihalf.com>
+External data additions, 25/1/16 Simon Glass <sjg@chromium.org>
1) Introduction
---------------
replace direct passing of 'struct bd_info' which was used to boot pre-FDT
kernels.
-However, U-boot needs to support both techniques to provide backward
+However, U-Boot needs to support both techniques to provide backward
compatibility for platforms which are not FDT ready. Number of elements
playing role in the booting process has increased and now includes the FDT
blob. Kernel image, FDT blob and possibly ramdisk image - all must be placed
Libfdt has been selected for the new uImage format implementation as (1) it
provides needed functionality, (2) is actively maintained and developed and
-(3) increases code reuse as it is already part of the U-boot source tree.
+(3) increases code reuse as it is already part of the U-Boot source tree.
b) Terminology
This document defines new uImage structure by providing FDT bindings for new
-uImage internals. Bindings are defined from U-boot perspective, i.e. describe
-final form of the uImage at the moment when it reaches U-boot. User
+uImage internals. Bindings are defined from U-Boot perspective, i.e. describe
+final form of the uImage at the moment when it reaches U-Boot. User
perspective may be simpler, as some of the properties (like timestamps and
-hashes) will need to be filled in automatically by the U-boot mkimage tool.
+hashes) will need to be filled in automatically by the U-Boot mkimage tool.
To avoid confusion with the kernel FDT the following naming convention is
proposed for the new uImage format related terms:
conforms to bindings defined in this document.
.its - image tree source
-.fit - flattened image tree blob
+.itb - flattened image tree blob
c) Image building procedure
The following picture shows how the new uImage is prepared. Input consists of
image source file (.its) and a set of data files. Image is created with the
-help of standard U-boot mkimage tool which in turn uses dtc (device tree
+help of standard U-Boot mkimage tool which in turn uses dtc (device tree
compiler) to produce image tree blob (.itb). Resulting .itb file is the
actual binary of a new uImage.
|
o images
| |
- | o image@1 {...}
- | o image@2 {...}
+ | o image-1 {...}
+ | o image-2 {...}
| ...
|
o configurations
- |- default = "conf@1"
+ |- default = "conf-1"
|
- o conf@1 {...}
- o conf@2 {...}
+ o conf-1 {...}
+ o conf-2 {...}
...
This node is a container node for component sub-image nodes. Each sub-node of
the '/images' node should have the following layout:
- o image@1
+ o image-1
|- description = "component sub-image description"
|- data = /incbin/("path/to/data/file.bin")
|- type = "sub-image type name"
|- load = <00000000>
|- entry = <00000000>
|
- o hash@1 {...}
- o hash@2 {...}
+ o hash-1 {...}
+ o hash-2 {...}
...
Mandatory properties:
- description : Textual description of the component sub-image
- type : Name of component sub-image type, supported types are:
- "standalone", "kernel", "ramdisk", "firmware", "script", "filesystem",
- "flat_dt" and others (see uimage_type in common/images.c).
+ "standalone", "kernel", "kernel_noload", "ramdisk", "firmware", "script",
+ "filesystem", "flat_dt" and others (see uimage_type in common/image.c).
- data : Path to the external file which contains this node's binary data.
- compression : Compression used by included data. Supported compressions
are "gzip" and "bzip2". If no compression is used compression property
- should be set to "none".
+ should be set to "none". If the data is compressed but it should not be
+ uncompressed by U-Boot (e.g. compressed ramdisk), this should also be set
+ to "none".
Conditionally mandatory property:
- - os : OS name, mandatory for type="kernel", valid OS names are: "openbsd",
- "netbsd", "freebsd", "4_4bsd", "linux", "svr4", "esix", "solaris", "irix",
- "sco", "dell", "ncr", "lynxos", "vxworks", "psos", "qnx", "u_boot",
- "rtems", "unity", "integrity".
+ - os : OS name, mandatory for types "kernel" and "ramdisk". Valid OS names
+ are: "openbsd", "netbsd", "freebsd", "4_4bsd", "linux", "svr4", "esix",
+ "solaris", "irix", "sco", "dell", "ncr", "lynxos", "vxworks", "psos", "qnx",
+ "u_boot", "rtems", "unity", "integrity".
- arch : Architecture name, mandatory for types: "standalone", "kernel",
"firmware", "ramdisk" and "fdt". Valid architecture names are: "alpha",
"arm", "i386", "ia64", "mips", "mips64", "ppc", "s390", "sh", "sparc",
property of the root node. Mandatory for types: "standalone" and "kernel".
Optional nodes:
- - hash@1 : Each hash sub-node represents separate hash or checksum
+ - hash-1 : Each hash sub-node represents separate hash or checksum
calculated for node's data according to specified algorithm.
5) Hash nodes
-------------
-o hash@1
+o hash-1
|- algo = "hash or checksum algorithm name"
|- value = [hash or checksum value]
o configurations
|- default = "default configuration sub-node unit name"
|
- o config@1 {...}
- o config@2 {...}
+ o config-1 {...}
+ o config-2 {...}
...
Each configuration has the following structure:
-o config@1
+o config-1
|- description = "configuration description"
|- kernel = "kernel sub-node unit name"
|- ramdisk = "ramdisk sub-node unit name"
- |- fdt = "fdt sub-node unit-name"
+ |- fdt = "fdt sub-node unit-name" [, "fdt overlay sub-node unit-name", ...]
+ |- fpga = "fpga sub-node unit-name"
+ |- loadables = "loadables sub-node unit-name"
+ |- compatible = "vendor,board-style device tree compatible string"
Mandatory properties:
- ramdisk : Unit name of the corresponding ramdisk image (component image
node of a "ramdisk" type).
- fdt : Unit name of the corresponding fdt blob (component image node of a
- "fdt type").
+ "fdt type"). Additional fdt overlay nodes can be supplied which signify
+ that the resulting device tree blob is generated by the first base fdt
+ blob with all subsequent overlays applied.
- setup : Unit name of the corresponding setup binary (used for booting
an x86 kernel). This contains the setup.bin file built by the kernel.
+ - fpga : Unit name of the corresponding fpga bitstream blob
+ (component image node of a "fpga type").
+ - loadables : Unit name containing a list of additional binaries to be
+ loaded at their given locations. "loadables" is a comma-separated list
+ of strings. U-Boot will load each binary at its given start-address and
+ may optionally invoke additional post-processing steps on this binary based
+ on its component image node type.
+ - compatible : The root compatible string of the U-Boot device tree that
+ this configuration shall automatically match when CONFIG_FIT_BEST_MATCH is
+ enabled. If this property is not provided, the compatible string will be
+ extracted from the fdt blob instead. This is only possible if the fdt is
+ not compressed, so images with compressed fdts that want to use compatible
+ string matching must always provide this property.
The FDT blob is required to properly boot FDT based kernel, so the minimal
configuration for 2.6 FDT kernel is (kernel, fdt) pair.
not* be specified in a configuration node.
-8) Examples
+8) External data
+----------------
+
+The above format shows a 'data' property which holds the data for each image.
+It is also possible for this data to reside outside the FIT itself. This
+allows the FIT to be quite small, so that it can be loaded and scanned
+without loading a large amount of data. Then when an image is needed it can
+be loaded from an external source.
+
+In this case the 'data' property is omitted. Instead you can use:
+
+ - data-offset : offset of the data in a separate image store. The image
+ store is placed immediately after the last byte of the device tree binary,
+ aligned to a 4-byte boundary.
+ - data-size : size of the data in bytes
+
+The 'data-offset' property can be substituted with 'data-position', which
+defines an absolute position or address as the offset. This is helpful when
+booting U-Boot proper before performing relocation. Pass '-p [offset]' to
+mkimage to enable 'data-position'.
+
+Normal kernel FIT image has data embedded within FIT structure. U-Boot image
+for SPL boot has external data. Existence of 'data-offset' can be used to
+identify which format is used.
+
+For FIT image with external data, it would be better to align each blob of data
+to block(512 byte) for block device, so that we don't need to do the copy when
+read the image data in SPL. Pass '-B 0x200' to mkimage to align the FIT
+structure and data to 512 byte, other values available for other align size.
+
+9) Examples
-----------
Please see doc/uImage.FIT/*.its for actual image source files.
projects / oweals / u-boot.git / blobdiff