[Libguestfs] [PATCH v2 08/11] v2v: don't set spice display if QXL isn't supported

[Richard W.M. Jones]

On Wed, May 18, 2016 at 02:00:56PM +0200, Cédric Bosdonnat wrote:
> Setting spice display if we know the libvirt guest doesn't have QXL
> capabilities will only make the guest slower for the user. Fallback
> to VNC in such a case.
> 
> A typical use case is when v2v-ing a windows guest without having the
> windows QXL driver at hand.
> ---
>  v2v/output_libvirt.ml | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/v2v/output_libvirt.ml b/v2v/output_libvirt.ml
> index bedd6b4..1999600 100644
> --- a/v2v/output_libvirt.ml
> +++ b/v2v/output_libvirt.ml
> @@ -239,7 +239,9 @@ let create_libvirt_xml ?pool source target_buses guestcaps
>      | Some { s_display_type = VNC } ->
>         e "graphics" [ "type", "vnc" ] []
>      | Some { s_display_type = Spice } ->
> -       e "graphics" [ "type", "spice" ] [] in
> +       match guestcaps.gcaps_video with
> +       | QXL ->    e "graphics" [ "type", "spice" ] []
> +       | Cirrus -> e "graphics" [ "type", "vnc" ] [] in
>  
>    (match source.s_display with
>     | Some { s_keymap = Some km } -> append_attr ("keymap", km) graphics

I didn't have a comment on this patch before, but it doesn't
look correct to me now.

What it says is if we have a guest which originally was using SPICE
[quite unusual -- does Xen support SPICE?  if not, what kind of source
hypervisor supports SPICE?], but during conversion we didn't manage to
install a QXL driver, then we should switch the guest to use VNC.

But that's a problem for two reasons:

(a) You can use SPICE without any special drivers.  It falls back to
emulating a high resolution SVGA device.

(b) We're changing the access method from SPICE to VNC, unnecessarily.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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