Re: video/GPU passthrough, second monitor, shared keyboard/mouse

[Alex Williamson <alex.williamson@redhat.com>]

On Wed, 2015-07-29 at 12:59 +0200, Daniel Pocock wrote:
> 
> Hi all,
> 
> I'm looking at a setup that involves a Linux host and a non-Linux VM
> under KVM, on a workstation for a power-user.
> 
> The non-Linux VM would have a dedicated video card/GPU, to maximize
> compatibility and performance for certain applications.
> 
> It may be possible to interact with the VM using SPICE but it is
> possible to just have a second monitor for it too.
> 
> So my questions are:
> 
> - Does all this make sense?

Yes, though your last point about using spice is a bit off.  With an
assigned GPU, the content of the display is owned by the guest, the
spice server in the host does not have access to it.  The spice
connection is therefore limited to any emulated graphics that may also
be attached to the VM.  It's possible to mirror the display between
physical and emulated graphics, if the guest supports it, but
performance will suffer substantially.  It's best to consider only
guest-based remote access mechanisms for GPU assignment VMs (ex.
guest-based VNC server).

> - How to share the keyboard and mouse between the host and the VM?  E.g.
> should I just use Synergy or x2vnc or is there a nicer solution with KVM
> or qemu?

Synergy works.  Any mechanism you would use to control a separate
physical system works.  It's also possible to assign a USB controller to
the VM and use a KVM switch between host and guest as well.  USB
"passthrough" (vs assignment) is also possible for individual USB
endpoints.

> - are any other free software solutions (e.g. VirtualBox, Xen) likely to
> be better or worse for such a project?

You're asking this to the kvm list, obviously we want kvm to be the best
solution for this.  Thanks,

Alex