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dracut: mount only subdirectory of /lib/modules

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This makes is possible to modify /lib/modules content - especially
install other kernel packages, without unmounting the whole
/lib/modules. Since dom0-provided modules will no longer conflict with
VM kernel packages (assuming kernel versions are different), there is no
need for qubes-kernel-vm-placeholder anymore.

Having only one subdirectory of /lib/modules mounted is somehow tricky,
because:
1. Directory name isn't always the same - it depends on kernel version.
This means that mountpoint must be created dynamically (so $NEWROOT must
be mounted in R/W for a moment).
2. There is one-command way to mount only a subdirectory of some
filesystem. So use a trick: mount it in some temporary directory, get
interesting subdir with `mount --bind`, then unmount temporary
directory.

QubesOS/qubes-issues#1354
This commit is contained in:
Marek Marczykowski-Górecki 2015-11-08 03:46:25 +01:00
parent 42469fdbe4
commit 789e9c2549
No known key found for this signature in database
GPG Key ID: 063938BA42CFA724
2 changed files with 26 additions and 4 deletions
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15
dracut/full-modules/mount_modules.sh
View File

@ -4,11 +4,22 @@
#
if ! [ -d $NEWROOT/lib/modules/`uname -r` ]; then
kver="`uname -r`"
if ! [ -d "$NEWROOT/lib/modules/$kver/kernel" ]; then
echo "Waiting for /dev/xvdd device..."
while ! [ -e /dev/xvdd ]; do sleep 0.1; done
mount -n -t ext3 /dev/xvdd $NEWROOT/lib/modules
# Mount only `uname -r` subdirectory, to leave the rest of /lib/modules writable
mkdir -p /tmp/modules
mount -n -t ext3 /dev/xvdd /tmp/modules
if ! [ -d "$NEWROOT/lib/modules/$kver" ]; then
mount "$NEWROOT" -o remount,rw
mkdir -p "$NEWROOT/lib/modules/$kver"
mount "$NEWROOT" -o remount,ro
fi
mount --bind "/tmp/modules/$kver" "$NEWROOT/lib/modules/$kver"
umount /tmp/modules
rmdir /tmp/modules
fi
killall udevd systemd-udevd

15
dracut/simple/init.sh
View File

@ -54,11 +54,22 @@ mkdir -p /sysroot
mount /dev/mapper/dmroot /sysroot -o ro
NEWROOT=/sysroot
if ! [ -d $NEWROOT/lib/modules/`uname -r` ]; then
kver="`uname -r`"
if ! [ -d "$NEWROOT/lib/modules/$kver/kernel" ]; then
echo "Waiting for /dev/xvdd device..."
while ! [ -e /dev/xvdd ]; do sleep 0.1; done
mount -n -t ext3 /dev/xvdd $NEWROOT/lib/modules
# Mount only `uname -r` subdirectory, to leave the rest of /lib/modules writable
mkdir -p /tmp/modules
mount -n -t ext3 /dev/xvdd /tmp/modules
if ! [ -d "$NEWROOT/lib/modules/$kver" ]; then
mount "$NEWROOT" -o remount,rw
mkdir -p "$NEWROOT/lib/modules/$kver"
mount "$NEWROOT" -o remount,ro
fi
mount --bind "/tmp/modules/$kver" "$NEWROOT/lib/modules/$kver"
umount /tmp/modules
rmdir /tmp/modules
fi