Updating to kernel 5.14 (Tumbleweed Sep 5 2021 snapshot) makes system
unbootable when running on top of Xen-server.

This seems like a general kernel 5.14 bug, not specific to openSuSE/Tumbleweed
as I can reproduce on Fedora 34 (by updating to 5.14 testing kernel from koji).
5.13 works perfectly.

On Tumbleweed, during boot it hangs in "starting dracut initqueue hook" and
times out waiting for /dev/disk/by-uuid/xxxx

It seems like kernel cannot identify the disks at all (working fine on 5.13)

After entering the recovery-mode, follow is observed:

- lsblk shows only the CD-rom drive
- ls /dev/disk/ only has by-path and by-id. by-uuid directory is gone.

I've reproduced the problem in cleanly installed Tumbleweed (both
MicroOS/Ignition and install from ISO), and clean installed Fedora 34.

Following kernel versions tested/are affected: 5.14.0 and 5.14.1 (5.14.1 tested
on Fedora).

Can be reproduced on Fedora with both BTRFS and XFS/LVM install, so not
specific to BTRFS.

Reproduced on two seperate XCP-ng 8.2 (xen-based) Hypervisors.

From hypervisors:
# yum info qemu
Installed Packages
Name        : qemu
Arch        : x86_64
Epoch       : 2
Version     : 2.10.2
Release     : 4.5.3.xcpng8.2
Size        : 19 M
Repo        : installed
From repo   : install
Summary     : qemu-dm device model
License     : GPL
Description : This package contains Qemu.

# uname -a
Linux hostname 4.19.0+1 #1 SMP Wed Dec 16 12:16:11 CET 2020 x86_64 x86_64
x86_64 GNU/Linux