Re: No display in Xen PV guests: "This VM has no graphic display device."

[Akihiko Odaki]

On 2024/12/12 0:27, Dario Faggioli wrote:
> Hello everyone,
>
> We've found an issue that manifests in Xen PV guests. We have
> encountered it when testing our (SUSE and openSUSE) packaged version of
> 9.1.x, but I've been able to reproduce it even using the upstream
> master branch.
>
> QEMU 8.2.8 works fine, so something happened during 9.0 or 9.1
> development (and not backported to stable).
>
> Basically, it's enough to try to create a Xen PV guest with virt-
> manager and the only output of the virt-manager window will be "This VM
> has no graphic display device" (while, e.g., `xl console <domid>` works
> fine).
>
> There is some additional info in this bug, but not all of that makes
> sense (we were in a hurry for a fix, and this is not my area :-/):
>
> https://bugzilla.suse.com/show_bug.cgi?id=1232712
>
> However, what I eventually figured out though (through a couple of
> bisections), is that if I revert _both_:
>
> - 6ece1df966 hw/xen: Register framebuffer backend via xen_backend_init()
> - e99441a379 ui/curses: Do not use console_select().
>
> Things work again.
>
> As I said, this is not my field, so there's not much more that I can
> say for now. Nevertheless, I'm happy to try to help as much as I can
> (e.g., testing theories, trying patches, etc)... So let me know what I
> can do. :-)

Hi,

I tried to run Xen on QEMU to debug this but it doesn't boot. The 
command line I used is:
qemu-system-x86_64 -nographic -kernel var/xen -initrd 
var/xtf/tests/example/test-pv64-example -append 'loglvl=all 
com1=115200,,8n1 console=com1 noreboot console_timestamps=boot' -m 512

It gives no console output. Do you have an idea how to fix this?

Regards,
Akihiko Odaki