Re: Debian 11 installer crashed and reboot

[Chuck Zmudzinski <brchuckz@netscape.net>]

On 8/16/2021 4:25 AM, Andrew M.A. Cater wrote:
> On Mon, Aug 16, 2021 at 02:30:33PM +0800, John Mok wrote:
> > Hi all,
> >
> > Tried to install Debian 11 guest using netinst, but the installer
> > crashed and reboot automatically.
> >
> >   Host: Xen 4.11.4 on Debian 10
> > Guest: Debian 11 (kernel 5.10)
> >
> > Here is the steps to reproduce the problem:-
> > 1) Either guest BIOS or OVMF boot
> > 2) Select "Expert install" on installation menu
> >
> > Then, the guest crashed and reboot.
> >
> > Another try with the installer on Debian Live 11, it immediately
> > crashed and reboot.
> >
> > Is it a installer bug or something ?
> >
> > Thanks a lot.
> >
> > John Mok
> I think people would need many more details as to exactly what happens and
> when it reboots.
>
> So: You boot the installer - from just a .iso file / from the .iso flashed
> to a USB? Can you show what works and at what point it fails?
>
> The quick suggestion would be that it's something to do with Xen hypervisor
> but I'm not in any better position than to guess, since I don't use Xen here.
>
> I do know that none of the tests the media team do involve booting on Xen:
> in most cases we prefer to run on real hardware. Occasionally, some of the
> tests have to be run on KVM/QEMU. Xen as DomU  is untested then.
>
> All the very best, as ever,
>
> Andy Cater


After some testing of the Debian 11 installer on Xen
(using the debian-11.0.0-amd64-netinst.iso), I find that
this image only supports installation into a Xen PV guest,
the guest always crashes and reboots for either a BIOS
or OVMF boot into an HVM Xen guest.

I also found that the device model fails to start if one
tries to run the xen built-in vnc server for graphical
output. The only solution is to connect to the
Xen console using the xl console command. The -c
switch to xl create did not work to connect to the
Xen console when creating the guest; it could not
find the pty device, so it is necessary to let the guest
complete the startup and then run xl console <dom_id>
to connect to the console once the VM is running.
This will display the first page of the debian installer
where the language is selected, and from there
Debian 11 can be installed onto a virtual disk.

The following lines in the xl.cfg file enabled the VM
to boot the debian-11.0.0-amd64-netinst.iso as a
PV Xen guest:

bootloader = 'pygrub'
bootloader_args= [ 
'--kernel=install.amd/xen/vmlinuz','--ramdisk=install.amd/xen/initrd.gz' ]

Once installed and booting from the virtual disk, the
bootloader_args setting can be commented out.

After booting from the virtual disk, the grub-pc package can
be added to boot into a Xen HVM guest with BIOS booting,
and if space is left for an efi partition, the grub-efi package
can be installed to boot with OVMF after converting
the partition table of the virtual disk from MBR to GPT.

Also, the vnc server can be used for graphical output
after booting from the virtual disk to run a desktop
environment.

All in all, it is a big pain to install Debian 11 on the Xen
hypervisor using the debian installer, as it seems
supporting Xen installations is not a priority for Debian.

But once it is installed, it works very well on Xen, and
I find I can use the same bullseye image to boot it
as a Xen PV guest, a Xen HVM guest using BIOS boot,
or as a Xen HVM guest using OVMF boot just by tweaking
the xl.cfg configuration file after getting the image configured
for such a setup. I can even boot the same image on
the bare hardware by tweaking the initramfs-tools
configuration in the installed bullseye image.

Chuck Zmudzinski