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Genimage - The Image Creation Tool

genimage is a tool to generate multiple filesystem and flash/disk images
from a given root filesystem tree. genimage is intended to be run
in a fakeroot environment.
It also supports creating flash/disk images out of different file-system images and files.

Configuration is done in a config file parsed by libconfuse. Options
like the path to tools can be given via environment variables, the config
file or from commandline switches.

The Configuration File

The config file of genimage uses a simple configuration language, provided by libconfuse_.
This supports nested sections, as well as simple key-value pairs.

.. _libconfuse: https://github.com/martinh/libconfuse

Single-line comments can be introduced with # or //,
multi-line comments look like /* … */ (as in C).

The config file is separated into the main sections image, flash and config,
and provides an include primitive.

The image section

An image section describes a single filesystem or disk image to be built. It can be given
multiple times to generate multiple images. An image can also have multiple
partitions which refer to images themselves.
Each image must have a type which can have different suboptions depending on
the type.

Let's have a look at an example::

image nand-pcm038.img {
flash {
}
flashtype = "nand-64M-512"
partition barebox {
image = "barebox-pcm038.bin"
size = 512K
}
partition root {
image = "root-nand.jffs2"
size = 24M
}
}

This would generate a nand-pcm038.img which is a flash of type "nand-64M-512"
The image contains two partitions, "barebox-pcm038.bin" and "root-nand.jffs2"
which must refer to images described elsewhere in the config file. For example
"root-nand.jffs2" partition could be described like this::

image root-nand.jffs2 {
name = "root"
jffs2 {}
size = 24M
mountpoint = "/"
}

In this case a single jffs2 image is generated from the root mountpoint.

Here are all options for images:

:name: The name of this image. This is used for some image types
to set the name of the image.
:size: Size of this image in bytes. 'k', 'M' or 'G' can be used as suffix to
specify the size in multiple of 1024 etc. If the image if filled from
a mountpoint then '%' as suffix indicates a percentage. '200%' means
the resulting filesystem should be about 50% filled. Note that is is
only a rough estimate based on the original size of the content.
:mountpoint: mountpoint if image refers to a filesystem image. The
default is "/". The content of "${rootpath}${mountpoint}"
will be used used fill the filesystem.
:empty: If this is set to true, then the specified rootpath and
mountpoint are ignored for this image and an empty
filesystem is created. This option is only used for
writeable filesystem types, such as extX, vfat, ubifs and
jffs2. This defaults to false.
:exec-pre: Custom command to run before generating the image.
:exec-post: Custom command to run after generating the image.
:flashtype: refers to a flash section. Optional for non flash like images
like hd images
:partition: can be given multiple times and refers to a partition described
below

Additionally each image can have one of the following sections describing the
type of the image:

cpio, cramfs, ext2, ext3, ext4, file, flash, hdimage, iso, jffs2, qemu, squashfs,
tar, ubi, ubifs, vfat.

Partition options:

:offset: The offset of this partition as a total offset to the beginning
of the device.
:size: The size of this partition in bytes. If the size and
autoresize are both not set then the size of the partition
image is used.
:partition-type: Used by dos partition tables to specify the partition type.
:image: The image file this partition shall be filled with
:autoresize: Boolean specifying that the partition should be resized
automatically. For UBI volumes this means that the
autoresize flag is set. Only one volume can have this flag.
For hd images this can be used for the last partition. If set
the partition will fill the remaining space of the image.
:bootable: Boolean specifying whether to set the bootable flag.
:in-partition-table: Boolean specifying whether to include this partition in
the partition table.
:partition-uuid: UUID string used by GPT partition tables to specify the partition
id. Defaults to a random value.
:partition-type-uuid: String used by GPT partition tables to specify the partition type.
Either a UUID or a shortcut:
* L: Linux filesystem (0fc63daf-8483-4772-8e79-3d69d8477de4)
* S: Swap (0657fd6d-a4ab-43c4-84e5-0933c84b4f4f)
* H: Home (933ac7e1-2eb4-4f13-b844-0e14e2aef915)
* U: EFI System (c12a7328-f81f-11d2-ba4b-00a0c93ec93b)
* R: Linux RAID (a19d880f-05fc-4d3b-a006-743f0f84911e)
* V: Linux LVM (e6d6d379-f507-44c2-a23c-238f2a3df928)
* F: FAT32 / Basic Data Partition (ebd0a0a2-b9e5-4433-87c0-68b6b72699c7)
Defaults to L.

The image configuration options

cpio

Generates cpio images.

Options:

:format: archive format. Passed to the -H option to the cpio command.
Valid options are bin, odc, newc, crc, tar,
ustar, hpbin and hpodc
:extraargs: Extra arguments passed to the cpio tool
:compress: If given, pipe image through compression tool. Valid options are
for example gzip, lzop or any other tool that compresses
from stdin to stdout.

cramfs

Generates cramfs images.

Options:

:extraargs: Extra arguments passed to mkcramfs

ext2, ext3, ext4

Generates ext* images.

Options:

:use-mke2fs: If set to true, then mke2fs is used to create the
image. Otherwise, genext2fs is used. Defaults to false.
:mke2fs-conf: mke2fs.conf that should be used. If unspecified, the system
default is used.
:extraargs: Extra arguments passed to genext2fs or mke2fs.
:features: Filesystem features. Passed to the -O option of tune2fs. This
is a comma separated list of enabled or disabled features. See
man ext4 for features.
For genext2fs all feature are specified. Default for ext3 images is
has_journal. Default for ext4 images is
extents,uninit_bg,dir_index,has_journal.
For mke2fs these features are added in addition to the default
features of the ext type. Already enabled features can be disabled
by prefixing the feature with ^.
:label: Specify the volume-label. Passed to the -L option of tune2fs
:fs-timestamp: Sets different timestamps in the image. Sets the given timestamp
using the debugfs commands set_current_time,
set_super_value mkfs_time and set_super_value lastcheck
:root-owner: User and group IDs for the root directory. Defaults to 0:0.
:usage-type: Specify the usage type for the filesystem. Only valid with mke2fs.
More details can be found in the mke2fs man-page.

FIT

Generates U-Boot FIT images.

Options:

:its: String option holding the path of the input its file
:keydir: String option holding the directory containing the keys
used for signing.

flash

Generates flash images. These are basically the partition contents padded to the
partition sizes concatenated together. There is no partition table. Needs a valid
flashtype where the flash parameters are read from.

hdimage

Generates DOS partition images.

Options:

:align: Partition alignment. Defaults to 512 bytes
:partition-table: Boolean. If true, writes a partition table. If false, no
partition table is generated. Defaults to true.
:extended-partition: Number of the extended partition. Contains the number of the
extended partition between 1 and 4 or 0 for automatic. Defaults
to 0.
:disk-signature: 32 bit integer used as disk signature (offset 440 in the
MBR). Using a special value random will result in
using random 32 bit number.
:gpt: Boolean. If true, a GPT type partition table is written. If false
a DOS type partition table is written. Defaults to false.
:gpt-location: Location of the GPT table. Occasionally useful for moving the GPT
table away from where a bootloader is placed due to hardware
requirements. All partitions in the table must begin after this
table. Regardless of this setting, the GPT header will still be
placed at 512 bytes (sector 1). Defaults to 1024 bytes (sector 2).
:disk-uuid: UUID string used as disk id in GPT partitioning. Defaults to a
random value.

iso

Generates an ISO image.

Options:

:boot-image: Path to the El Torito boot image. Passed to the -b option
of genisofs
:bootargs: Bootargs for the El Torito boot image. Defaults to
-no-emul-boot -boot-load-size 4 -boot-info-table -c boot.cat -hide boot.cat
:extraargs: Extra arguments passed to genisofs
:input-charset: The input charset. Passed to the -input-charset option of genisofs.
Defaults to default
:volume-id: Volume ID. Passed to the -V option of genisofs

jffs2

Generates a JFFS image. Needs a valid flashtype where the flash parameters are
read from.

Options:

:extraargs: Extra arguments passed to mkfs.jffs2

qemu

Generates a QEMU image. Needs at least one valid partition.

Options:

:format: A valid qemu-img like qcow, qcow2, parallels, vdi,
vhdx or vmdk. Check qemu-img convert --help for the complete
list of possible values. Defaults to qcow2.
:extraargs: Extra arguments passed to qemu-img convert

squashfs

Generates a squashfs image.

Options:

:extraargs: Extra arguments passed to mksquashfs
:compression: compression type for the image. Possible values are gzip
(default), lzo, xz or none
:block-size: Block size. Passed to the -b option of mksquashfs. Defaults
to 4096.

rauc

Generates a RAUC update bundle.

Options:

:extraargs: Extra arguments passed to RAUC
:file: Specify a file to be added into the RAUC bundle. Usage is:
file foo { image = "bar" } which adds a file "foo" in the
RAUC bundle from then input file "bar"
:files: A list of filenames added into the RAUC bundle. Like file
above, but without the ability to add the files under different
name.
:key: Path to the key file. Passed to the --key option of RAUC
:cert: Path to the certificate file. Passed to the --cert option
of RAUC
:manifest: content of the manifest file

tar

Generates a tar image. The image will be compressed as defined by the filename suffix.

ubi

Generates an UBI image. Needs a valid flashtype where the flash parameters are
read from.

Options:

:extraargs: Extra arguments passed to ubinize

ubifs

Generates a UBIFS image. Needs a valid flashtype where the flash parameters are
read from.

Options:

:extraargs: Extra arguments passed to mkubifs
:max-size: Maximum size of the UBIFS image

vfat

Generates a VFAT image.

Options:

:extraargs: Extra arguments passed to mkdosfs
:label: Specify the volume-label. Passed to the -n option of mkdosfs
:file: Specify a file to be added into the filesystem image. Usage is:
file foo { image = "bar" } which adds a file "foo" in the
filesystem image from the input file "bar"
:files: A list of filenames added into the filesystem image. Like file
above, but without the ability to add the files under different
name.

Note: If no content is specified with file or files then
rootpath and mountpoint are used to provide the content.

The Flash Section

The flash section can be given multiple times and each section describes a
flash chip. The option names are mostly derived from the UBI terminology.
There are the following options:

:pebsize: The size of a physical eraseblock in bytes
:lebsize: The size of a logical eraseblock in bytes (for ubifs)
:numpebs: Number of physical eraseblocks on this device. The total
size of the device is determined by pebsize * numpebs
:minimum-io-unit-size: The minimum size in bytes accessible on this device
:vid-header-offset: offset of the volume identifier header
:sub-page-size: The size of a sub page in bytes.

Several flash related image types need a valid flash section. From the image types
the flash type section is referred to using the flashtype option which contains
the name of the flash type to be used.

For more information of the meaning of these values see the ubi(fs) and mtd FAQs:

http://www.linux-mtd.infradead.org/faq/general.html

Example flash section::

flash nand-64M-512 {
pebsize = 16384
lebsize = 15360
numpebs = 4096
minimum-io-unit-size = 512
vid-header-offset = 512
sub-page-size = 512
}
...
image jffs2 {
flashtype = "nand-64M-512"
}

The config section

In this section the global behaviour of the program is described. All options
here can be given from either environment variables, the config file or
command line switches. For instance, a config option foo can be passed as a
--foo command line switch or as a GENIMAGE_FOO environment variable.

:config: default: genimage.cfg
Path to the genimage config file.

:loglevel: default: 1
genimage log level.

:outputpath: default: images
Mandatory path where all images are written to (must exist).
:inputpath: default: input
This mandatory path is searched for input images, for example
bootloader binaries, kernel images (must exist).
:rootpath: default: root
Mandatory path to the root filesystem (must exist).
:tmppath: default: tmp
Optional path to a temporary directory. There must be enough space
available here to hold a copy of the root filesystem.

:cpio: path to the cpio program (default cpio)
:dd: path to the dd program (default dd)
:e2fsck: path to the e2fsck program (default e2fsck)
:genext2fs: path to the genext2fs program (default genext2fs)
:genisoimage: path to the genisoimage program (default genisoimage)
:mcopy: path to the mcopy program (default mcopy)
:mmd: path to the mmd program (default mmd)
:mkcramfs: path to the mkcramfs program (default mkcramfs)
:mkdosfs: path to the mkdosfs program (default mkdosfs)
:mkfsjffs2: path to the mkfs.jffs2 program (default mkfs.jffs2)
:mkfsubifs: path to the mkfs.ubifs program (default mkfs.ubifs)
:mksquashfs: path to the mksquashfs program (default mksquashfs)
:qemu-img: path to the qemu-img program (default qemu-img)
:tar: path to the tar program (default tar)
:tune2fs: path to the tune2fs program (default tune2fs)
:ubinize: path to the ubinize program (default ubinize)

Include Configurations Fragments

To include a "foo.cfg" config file, use the following statement::

include("foo.cfg")

This allows to re-use, for example flash configuration files, across different image configurations.