UBIFS root file systems differ between builds, e.g. the one of the
Microchip SAMA7G5-EK: the superblock gets a random UUID, the inodes get
the ctime of the build host, which can't be reset with touch, and the
entries of each directory are added in readdir() order, which depends on
the host file system and decides inode numbers and layout.
Add a patch that, when SOURCE_DATE_EPOCH is set, uses a time-based
(version 1) UUID with that time and clamps all inode times to it. The
node ID of the UUID is taken from the new --uuid-node option, which the
image build sets from IMG_PART_DISKGUID, itself derived from
SOURCE_DATE_EPOCH and the kernel vermagic.
Directory entries are added sorted by name. Two trees with the same
contents but different ctimes and readdir() order now give identical
images; without SOURCE_DATE_EPOCH the UUID stays random.
Link: https://github.com/openwrt/openwrt/pull/25430
Signed-off-by: Paul Spooren <mail@aparcar.org>
Paul Spooren
1eaea67aef