Create Loop-Device for complex Image

[killermoehre]

Hi,

I need to create my own disk image with a base in LVM for real hardware machines. As systemd-repart has no support for this, I create my own disk in mkosi.finalize and give it an appropriate GPT with sgdisk, to be a rsync target of $BUILDROOT after mounting all the partitions.

Now the problem is that I can't loop-mount this disk with losetup, because in the mkosi.finalize name space there are no loop devices (ls /dev/loop* is empty).

Even if I mknod -m0777 "$LOOP_DEVICE" b 7 0; losetup "$LOOP_DEVICE" "$RAW_DISK" I get Permission denied inside mkosi.finalize.

Any idea? mkosi.prepare is probably already to late for this setup. Also, this setup worked with mkosi@v14.

[killermoehre]

Hmm … containers/bubblewrap#523 looks unfortunate in this regard. Seems like loop devices are not namespace'able. I'm open for suggestions on how to solve this within mkosi.

[DaanDeMeyer]

@killermoehre This is never going to work within mkosi. See test_initrd_lvm() in test_initrd.py for how we test LVM. Just write a wrapper script that builds the image and then copies the result over into the LVM stuff.

[killermoehre]

Bummer. But ok. So this will become a multistep setup. Thanks for the heads-up.