On Wed, Jan 9, 2013 at 2:32 AM, Ronen B <bronen@xxxxxxxxx> wrote:
>
> Hi,
> I would like to use the --overlay-size-mb parameter to make a one time chance and than lock the image.
> In other words, i want to boot the image that is placed on a SD card to make some changes in the OS (on the first boot) and then lock it so no other changes can be made in further boots.
> Any idea based on the --overlay-size-mb parameter would be appreciate (including boot parameters, kernel tweaks and so on...)
>
> Thanks
> Ronen
The boot parameter rd.live.overlay.readonly would seem to fit your
need, but with it, a Fedora LiveOS image fails to boot completely to a
graphical desktop.
The following patch to /usr/sbin/dmsquash-live-root in the initramfs
achieves your objective:
commit 8850fc92a9b7eb9a6f0c20d6971094668493aea1
Author: Frederick Grose <fgrose@xxxxxxxxxxxxx>
Date: Sat Jan 26 15:09:12 2013 -0500
Provide devices to enable booting with rd.live.overlay.readonly=1
diff --git a/modules.d/90dmsquash-live/dmsquash-live-root.sh
b/modules.d/90dmsquash-live/dmsquash-live-root.sh
index f302d44..0b1ed20 100755
--- a/modules.d/90dmsquash-live/dmsquash-live-root.sh
+++ b/modules.d/90dmsquash-live/dmsquash-live-root.sh
@@ -110,18 +110,34 @@ do_live_overlay() {
umount -l /run/initramfs/overlayfs || :
fi
- if [ -z "$setup" ]; then
- if [ -n "$devspec" -a -n "$pathspec" ]; then
+ if [ -z "$setup" -o -n "$readonly_overlay" ]; then
+ if [ -n "$setup" ]; then
+ warn "Using temporary overlay."
+ elif [ -n "$devspec" -a -n "$pathspec" ]; then
warn "Unable to find persistent overlay; using temporary"
sleep 5
fi
dd if=/dev/null of=/overlay bs=1024 count=1
seek=$((512*1024)) 2> /dev/null
- losetup $OVERLAY_LOOPDEV /overlay
+ if [ -n "$setup" -a -n "$readonly_overlay" ]; then
+ RO_OVERLAY_LOOPDEV=$( losetup -f )
+ losetup $RO_OVERLAY_LOOPDEV /overlay
+ else
+ losetup $OVERLAY_LOOPDEV /overlay
+ fi
fi
# set up the snapshot
- echo 0 `blockdev --getsz $BASE_LOOPDEV` snapshot $BASE_LOOPDEV
$OVERLAY_LOOPDEV p 8 | dmsetup create $readonly_overlay live-rw
+ sz=$(blockdev --getsz $BASE_LOOPDEV)
+ if [ -n "$readonly_overlay" ]; then
+ echo 0 $sz snapshot $BASE_LOOPDEV $OVERLAY_LOOPDEV p 8 |
dmsetup create $readonly_overlay live-ro
+ base="/dev/mapper/live-ro"
+ over=$RO_OVERLAY_LOOPDEV
+ else
+ base=$BASE_LOOPDEV
+ over=$OVERLAY_LOOPDEV
+ fi
+ echo 0 $sz snapshot $base $over p 8 | dmsetup create live-rw
}
# live cd helper function
(Here are some instructions for changing files in the initramfs,
http://gyanip.blogspot.com/2010/12/procedure-to-insert-module-into-initrd.html
that I found helpful.)
Alternatively, you could merge the changes in your overlay with the
script on this wiki page:
https://fedoraproject.org/wiki/LiveOS_image#Merge_overlay_into_new_image
Following the merge, if the overlay file in the USB/SD device
filesystem at /LiveOS/overlay-LIVE-xxxx-xxxx is deleted or renamed, a
normal boot of the device will fail to find it and will generate a
temporary overlay for that single, non-persistent boot.
If you need to distribute your customized image, the edit-livecd
script of the the livecd-tools package was designed for rebuilding an
install .iso file from a customized image.
The edit-livecd script is behind on maintenance though and fails.
The editliveos.py script is a replacement available here,
http://git.sugarlabs.org/~FGrose/soas/sugar-clone-extensions/trees/master/editliveos
editliveos.py will run in a folder that also contains the fs.py,
live.py, creator.py, and util.py files, which have been modified to
support editliveos.py. (livecd-tools need not be installed.)
For instructions, run editliveos.py --help, or see this wiki section
(expand the [show] frame link),
http://wiki.sugarlabs.org/go/Sugar_on_a_Stick/Sugar_Clone#editliveos.help
--Fred
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