Ubuntu domU can not start after domU was upgraded from 19.04 to 19.10

[imker]

Hello,

I upgraded a Xen PV domU with Ubuntu 19.04 installed to 19.10. The domU is running on a Ubuntu 18.04 server with xen 4.9.2. The upgrade went fine, and I restarted the system as expected. But the domU want start. I use pygrub for the domU to start.

Here the config of the domU
--------------------------------------------------------------------------------------------
# Basics
name = "lisa"
memory = 2048
bootloader = "pygrub"

# Disks
disk = [
  'phy:/dev/systems/lisa-root,xvda,w',
  'phy:/dev/systems/lisa-swap,xvdb,w',
 ]

# Network Interface
vif = [
  'bridge=xenbr0, mac=00:16:34:45:1F:A2',
  'bridge=xenbr1, mac=00:16:3E:AE:D6:3F',
 ]

# Advanced
vcpus=2
--------------------------------------------------------------------------------------------

Here the output when I start the machine with xl:
--------------------------------------------------------------------------------------------
xl create /etc/xen/lisa.cfg
Parsing config from /etc/xen/lisa.cfg
xc: error: panic: xc_dom_bzimageloader.c:768: xc_dom_probe_bzimage_kernel unable to LZ4 decompress kernel
: Invalid kernel
xc: error: panic: xc_dom_core.c:702: xc_dom_find_loader: no loader found: Invalid kernel
libxl: error: libxl_dom.c:671:libxl__build_dom: xc_dom_parse_image failed: No such file or directory
libxl: error: libxl_create.c:1217:domcreate_rebuild_done: Domain 19:cannot (re-)build domain: -3
libxl: error: libxl_domain.c:1003:libxl__destroy_domid: Domain 19:Non-existant domain
libxl: error: libxl_domain.c:962:domain_destroy_callback: Domain 19:Unable to destroy guest
libxl: error: libxl_domain.c:889:domain_destroy_cb: Domain 19:Destruction of domain failed
--------------------------------------------------------------------------------------------

Thanks for your help
Imker

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xen-hypervisor-4.9-amd64 4.9.2-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-70.79-generic 4.15.18
Uname: Linux 4.15.0-70-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: amd64
Date: Sat Nov 30 15:30:19 2019
InstallationDate: Installed on 2013-05-16 (2388 days ago)
InstallationMedia: Ubuntu-Server 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130214)
SourcePackage: xen
UpgradeStatus: Upgraded to bionic on 2018-09-20 (435 days ago)

[richard ostrow (kshots)]

I've had the same problem for a while now, similar setup as described on the forums:

https://ubuntuforums.org/showthread.php?t=2431459&p=13913095#post13913095

I can boot the older 5.0.0 kernel if I'm fast enough with the console immediately upon creation of the DomU (i.e., xl create -c ...), but this makes unattended DomU start unachievable.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[imker (imker)]

Hi Richard,

I found out that I can boot the domU if I change it to a HVM.
e. g. Comment the line
# bootloader = "pygrub"

and add the line
builder = "hvm"

in the config file.

Now the domU works as expected, but it is a HVM what brings several disadvantages and cost more resources. So I really hope the Ubuntu Team can fix the problem in xen/pygrub.

Thank you