Every image gets handled the same way regardless of filesystem, so
let's use a filesystem-neutral name (rather than adding new
lines for every fstype anyone might want to use).
We want all "/var/run" information to live in /dev/.run, until the real
root is mounted.
Therefore we mount a tmpfs on /dev/.run, which can/will be bind/move mounted
on /var/run later on.
This allows creation of initramfs images which contain a Live system.
The primary use for this is keeping very large initramfs-based systems
(e.g. anaconda, the Fedora installer) compressed in-memory, by using a
compressed filesystem image like squashfs or btrfs.
dmsquash-live-genrules.sh will initqueue dmsquash-live-root itself
(rather than making udev rules) if the given live "device" is actually
an existing, plain file.
parse-dmsquash-live.sh will only accept paths that end in ".img".
dmsquash-live-root will only handle images named "*squashfs.img",
"*ext3fs.img", or "*btrfs.img".
Adds the readonly_overlay karg for cases where the dm snapshot should be set to readonly. Use case would be a livecd that is configured to have a readonly root where filling up the dm snapshot would cause a problem.
If you're using a persistent overlay, you might want to reset it
at boot time if it has become corrupted somehow. Support using
reset_overlay as a command line optino to do so
The persistent overlay can be specified with an overlay= argument
on the command line. We'll probably try to move this into the
root= syntax soon, but this is the old way that works
Fedora/Red Hat live images are implemented as an ext3fs inside of
a squashfs. Writability is achieved with a device-mapper snapshot
on top of that.
This gives the basic support without a lot of things like persistent
overlays, iso md5sum checking, etc and also with a new basic syntax
that has to be specified as root=live:LABEL=...
Harald Hoyer