docs/manual: add genimage.cfg file coding style standard

This patch adds the explanation for the genimage.cfg files coding standard.
A real standard is not defined upstream by the genimage utility
developers[1], but I try to give one here in Buildroot for consistency.

[1]: https://github.com/pengutronix/genimage

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
This commit is contained in:
Giulio Benetti 2021-11-08 20:51:30 +01:00 committed by Arnout Vandecappelle (Essensium/Mind)
parent d828e5245a
commit e9c3541bad

View File

@ -136,6 +136,68 @@ LIBFOO_POST_INSTALL_TARGET_HOOKS += LIBFOO_REMOVE_DATA
endif
---------------------
[[writing-genimage-cfg]]
=== The +genimage.cfg+ file
+genimage.cfg+ files contain the output image layout that genimage utility
uses to create final .img file.
An example follows:
---------------------
image efi-part.vfat {
vfat {
file EFI {
image = "efi-part/EFI"
}
file Image {
image = "Image"
}
}
size = 32M
}
image sdimage.img {
hdimage {
}
partition u-boot {
image = "efi-part.vfat"
offset = 8K
}
partition root {
image = "rootfs.ext2"
size = 512M
}
}
---------------------
* Every +section+(i.e. hdimage, vfat etc.), +partition+ must be indented
with one tab.
* Every +file+ or other +subnode+ must be indented with two tabs.
* Every node(+section+, +partition+, +file+, +subnode+) must have an open
curly bracket on the same line of the node's name, while the closing one
must be on a newline and after it a newline must be added except for the
last one node. Same goes for its option, for example option +size = +.
* Every +option+(i.e. +image+, +offset+, +size+) must have the +=+
assignment one space from it and one space from the value specified.
* Filename must at least begin with genimage prefix and have the .cfg
extension to be easy to recognize.
The +genimage.cfg+ files are the input for the genimage tool used in
Buildroot to generate the final image file(i.e. sdcard.img). For further
details about the _genimage_ language, refer to
https://github.com/pengutronix/genimage/blob/master/README.rst[].
=== The documentation
The documentation uses the