Re: xen ovmf/uefi firmware does not save screen resolution

[Chuck Zmudzinski <brchuckz@xxxxxxxxxxxx>]

On 9/22/2022 11:25 AM, Chuck Zmudzinski wrote:
> On 9/22/2022 4:37 AM, mhbeyle@xxxxxxxx wrote:
> > Thanks for the answers.
> >
> > Chuck, I tried at the time to apply suggested patches to the software 
> > with no results. It is not clear that any of the current patches solve 
> > the problem.
> >
> > I think there are two problems here: One, the virtual machine that 
> > creates xen uses QEMU and the UEFI bios is not able to communicate the 
> > resolution data to the system. Two, this kind of problem would be easily 
> > solved by virtualizing a more modern vga instead of the current cards 
> > (cirrus etc.)
>
> Actually, this might be a bug in Xen 4.16 that was not in Xen 4.14.
>
> On Debian 11 (bullseye/stable for Dom0) booting HVM with Tiano Core
> UEFI works for me using vga = stdvga and videoram = 16:
>
> With Debian 11.x stable for dom0, the Xen version is 4.14 and the Qemu
> version is a bit old, 5.2, but booting with ovmf/uefi works:
>
> I boot Debian 11.x (stable) in a Xen HVM using ovmf using vga = stdvga in the
> xl.cfg and it seems to work in a VNC window. I can get 1920x1080 resolution
> (with videoram = 16 in the xl.cfg), but this only works on Debian stable dom0
> with Xen version 4.14.x and Qemu version 5.2 (haven't checked if Debian
> backported Qemu version 7.0 for Debian 11 also works).
>
> After login, use the gnome display settings and it gives the option of up
> to 1920x1080 resolution with videoram = 16. I presume KDE, XFCE, MATE, etc.
> also would allow this.
>
> It is true the Tiano Core UEFI boot configuration setup screen and the grub
> screen resolution is low (I think only 800x600) at the beginning of booting.
>
> Here is my xl config for ovmf (UEFI booting with vga = stdvga, videoram = 16)
> and a VNC display and Debian stable with Xen 4.14.x dom0 and Qemu 5.2 in
> dom0 on Debian stable:
>
> --- domain configuration file ---
> builder = 'hvm'
> bios = 'ovmf'
> memory = '6144'
> vcpus = '4'
> disk = ['/dev/linux/bullseye,,xvda,w']
> name = 'bullseye-hvm'
> vif = [ 'mac=<redacted>,type=vif,script=vif-route,ip=<redacted>' ]
> on_poweroff = 'destroy'
> on_reboot = 'restart'
> on_crash = 'restart'
> boot = 'c'
> acpi = '1'
> apic = '1'
> viridian = '1'
> xen_platform_pci = '1'
> serial = 'pty'
> vga = 'stdvga'
> videoram = '16'
> sdl = '0'
> vnc = '1'
> vnclisten = '0.0.0.0'
> vncdisplay = '1'
> usb = '1'
> usbdevice = 'tablet'
> --- End of domain configuration file ---
>
> But the same configuration with Xen 4.16 and Qemu 7.1 in dom0 that is in 
> Debian
> unstable, and also in Fedora 36 with Xen 4.16 and Qemu 6.2 I think, I get a 
> crash at
> boot - it does show the Tiano Core configuration screen and grub screen at 
> 800x600
> resolution but crashes soon after. When trying to boot Fedora 36 in a Xen HVM 
> with
> ovmf, I got this in the journal of the guest:

Sorry, this is from the journal of the dom0, not the guest:

>
> xen-qemu-system-i386: relocate_memory 4096 pages from GFN bf000 to GFN c1000 
> failed: Invalid argument
>
> Also, with a good boot (using seabios) I get this in the journal of the guest,
> but is missing from the boot that crashes:
>
> fedora kernel: BIOS-e820: [mem 0x00000000fc000000-0x00000000fcffffff] reserved
>
> The size of this missing entry is 4096 pages, which is probably what Qemu is 
> trying to
> relocate but cannot with ovmf/uefi boot because it is missing. 4096 pages is 
> 16 MB,
> which is probably the video shared memory.
>
> This is probably a bug/regression in Xen somewhere between Xen 4.14 and 4.16
> and I will try to bisect it when I have time.
>
> Best regards,
>
> Chuck
>
> > that are not recognized by the operating system when using 
> > UEFI and do not load specific drivers. For example, the problem is 
> > solved using qxl and a driver in Windows, but the qxl development is not 
> > complete and fails.
> >
> > With limitations, it seems that the problem in QEMU is solved by 
> > changing the parameters in the BIOS and doing a warm/soft reboot. I 
> > don't know why, this can't be done in xen. The settings are never saved 
> > and the reboot, at least in windows 10, is always a cold one (xen 
> > destroys the virtual machine and recreates it. The soft reboot parameter 
> > hangs the vm).
> >
> > Regards.
> >
> > __________
> > MhBeyle ___
> >
> >
> >
>