genimage is a tool to generate multiple filesystem and flash images
from a given root filesystem tree. genimage is intended to be run
in a fakeroot environment.

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

The configuration file
======================

The config file is separated into the 'flash', 'image' and 'config' sections,
and the 'include' primitive.

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

    include("foo.cfg")

The top-level sections are described below.

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.

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
}


The image section
-----------------

An image section describes a single image to be built. it can be given
multiple times to generate multiple images. Also an image can 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
mountpoint	mountpoint if image refers to a filesystem image.
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, ext2, ext3, ext4, file, flash, hdimage, iso, jffs2, 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. The last partition may have
		size 0 to make this partition use the rest of the available space
		on the device.
partition-type	Used by dos partition tables to specify the partition type.
image		The image file this partition shall be filled with
autoresize	used by ubi (FIXME: do we need this? isn't size = 0 enough)	
bootable	Boolean specifying whether to set the bootable flag.
in-partition-table	Boolean specifying whether to include this partition in
			the partition table.

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)
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)
tar		path to the tar program (default tar)
tune2fs		path to the tune2fs program (default tune2fs)
ubinize		path to the ubinize program (default ubinize)