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 config file of genimage uses a simple configuration language, provided by libconfuse. This supports nested sections, as well as simple key-value pairs.
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.
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. The suffix 's' specifies a multiple of the (traditional) sector size of 512. 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. |
| temporary: | If this is set to true, the image is created in
tmppath rather than outputpath. This can be
useful for intermediate images defined in the
configuration file which are not needed by themselves
after the main image is created. 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. |
| align: | Alignment value to use for automatic computation of |
| 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
|
| bootable: | Boolean specifying whether to set the bootable flag. |
| in-partition-table: | Boolean specifying whether to include this partition in the partition table. Defaults to true. |
| 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:
Defaults to L. |
For each partition, its final alignment, offset and size are determined as follows:
- If the
alignoption is not present, it defaults to the value of the image'salignoption if the partition is in the partition table, otherwise to 1. - If the
offsetoption is absent or zero, andin-partition-tableis true, the partition is placed after the end of all previously defined partitions, with the final offset rounded up to the partition'salignvalue. - Otherwise, the
offsetoption is used as-is. Note that if absent, that option defaults to 0, so in practice one must specify anoffsetfor any partition that is not in the partition table (with at most one exception, e.g. a bootloader). - If the partition has the
autoresizeflag set, its size is computed as the space remaining in the image from its offset (for a GPT image, space is reserved at the end for the backup GPT table), rounded down to the partition'salignvalue. If the partition also has asizeoption, it is ensured that the computed value is not less than that size. - Otherwise, if the
sizeoption is present and non-zero, its value is used as-is. - Otherwise, if the partition has an
imageoption, the size of that image, rounded up to the partition'salignvalue, is used to determine the size of the partition.
The following sanity checks are done on these final values (in many cases, these will automatically be satisfied when the value has been determined via one of the above rules rather than given explicitly):
- For a partition in the partition table, the partition's
alignvalue must be greater than or equal to the image'salignvalue. - The partition's
offsetandsizemust both be multiples of itsalign. - The size must not be 0.
- The partition must not overlap any other partition, or the areas occupied by the partition table.
Generate android sparse images. The are typically used by fastboot. Sparse images encode "don't care" areas and areas that are filled with a single 32 bit value. As a result, they are often much smaller than raw disk images. Genimage assumes that all 'holes' in the input file are "don't care" areas. This is a reasonable assumption: Tools to generate filesystems typically operate on devices. So they only create holes in areas they don't care about. Genimage itself operates the same way when generating HD images.
Options:
| image: | The source image that will be converted. |
|---|---|
| block-size: | The granularity that the sparse image uses to find "don't care" or "fill" blocks. The supported block sizes depend on the user. The default is 4k. |
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. |
Generates cramfs images.
Options:
| extraargs: | Extra arguments passed to mkcramfs |
|---|
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. |
This represents a pre-existing image which will be used as-is. When a
partition section references an image that is not defined elsewhere in
the configuration file, a file rule is implicitly generated. It is
up to the user to ensure that the image exists in the input directory,
or to use an absolute path to the image.
It is possible to add a file image explicitly, which allows one to
provide genimage with some information about the image which can
not be deduced automatically. Currently, one such option exists:
| holes: | A list of "(<start>;<end>)" pairs specifying ranges of the
file that do not contain meaningful data, and which can therefore
be allowed to overlap other partitions or image metadata. |
|---|
For example:
image foo {
hdimage {
gpt = true
gpt-location = 64K
}
partition bootloader {
in-partition-table = false
offset = 0
image = "/path/to/bootloader.img"
}
partition rootfs {
offset = 1M
image = "rootfs.ext4"
}
}
image /path/to/bootloader.img {
file {
holes = {"(440; 1K)", "(64K; 80K)"}
}
}
This tells genimage that despite the bootloader partition
overlapping both the last 72 bytes of the MBR (where the DOS partition
table is located) and the GPT header occupying the sector starting at
offset 512, this is all OK because bootloader.img does not contain
useful data in that range. Further, in this example, the bootloader
image has been carefully crafted to also allow placing the GPT array
at offset 64K (the GPT header is always at offset 512).
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. |
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.
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.
Deprecated: use |
| partition-table-type: | Define what kind of partition table should be used. Valid options are:
|
| 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 |
| gpt: | Boolean. If true, a GPT type partition table is written. If false
a DOS type partition table is written. Defaults to false.
Deprecated: use |
| 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). |
| gpt-no-backup: | Boolean. If true, then the backup partition table at the end of the image is not written. |
| disk-uuid: | UUID string used as disk id in GPT partitioning. Defaults to a random value. |
| fill: | If this is set to true, then the image file will be filled up to the end of the last partition. This might make the file bigger. This is necessary if the image will be processed by such tools as libvirt, libguestfs or parted. |
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 |
Generates a JFFS image. Needs a valid flashtype where the flash parameters are read from.
Options:
| extraargs: | Extra arguments passed to mkfs.jffs2 |
|---|
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 |
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. |
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 or PKCS#11 URI. Passed to the --key option of
RAUC |
| cert: | Path to the certificate file or PKCS#11 URI. Passed to the --cert
option of RAUC |
| keyring: | Optional path to the keyring file. Passed to the --keyring
option of RAUC |
| manifest: | content of the manifest file |
Generates a tar image. The image will be compressed as defined by the filename suffix.
Generates an UBI image. Needs a valid flashtype where the flash parameters are read from.
Options:
| extraargs: | Extra arguments passed to ubinize |
|---|
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 |
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 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"
}
In this section the global behaviour of the program is
described. Except as noted below, 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. |
| includepath: | Colon-separated list of directories to search for files included via the ``include'' function. The current directory is searched after these. Thus, if this option is not given, only the current directory is searched. This has no effect when given in the config file. |
| 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) |
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.