[libvirt] [PATCH] qemu: use 'bochs' video type by default for UEFI domains

[Fabiano Fidêncio]

On Thu, Aug 29, 2019 at 12:21 PM Gerd Hoffmann <kraxel at redhat.com> wrote:
>
>   Hi,
>
> > Incidentally, and I haven't followed this closely so apologies if I'm
> > asking a silly question, if the point of bochs-display is to have a
> > video device without legacy VGA emulation then why aren't we using
> > the existing virtio-gpu, which has been around a lot longer and has
> > better support throughout the stack, instead?
>
> Well, virtio-gpu (on x86) actually is "-device virtio-vga".  That comes
> with legacy VGA emulation, for the boot display ...
>
> For UEFI guests with virtio-gpu support it is possible to use "-display
> virtio-gpu-pci" instead (simliar to arm).  Only drawback is that you
> can't have a EFI GOB with virtio-gpu-pci, so efifb doesn't work.  Linux
> kernel console shows up after the virtio-gpu driver loads, which is
> rather late compared to efifb.
>
> For UEFI guests without virtio-gpu support "-device virtio-gpu-pci" will
> not work due to the lack of EFI GOB support.  For these guests
> "-display bochs-display" should preferred over "-device VGA", to get rid
> of the unused legacy VGA emulation (and thereby reduce the attack
> surface).
>
> Also note that bochs-display can be plugged into pcie slots (that is
> true for virtio-gpu-pci too btw).
>
> Not sure whenever implementing this works better in libvirt or
> libosinfo.

I do believe this piece should go to libosinfo.
However, the decision of what exactly to use due to lack of this or
that device, should be done in the management apps, in a similar way
of what was done for the q35 work.

>
> cheers,
>   Gerd
>
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