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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Mon, 17 Mar 2014 15:50:39 +0100
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Subject: Re: [Qemu-devel] virtio device error reporting best practice?
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To: Dave Airlie <airlied@gmail.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

On Mo, 2014-03-17 at 16:02 +1000, Dave Airlie wrote:
> So I'm looking at how best to do virtio gpu device error reporting,
> and how to deal with illegal stuff,
> 
> I've two levels of errors I want to support,
> 
> a) unrecoverable or bad guest kernel programming errors,
> 
> b) per 3D context errors from the renderer backend,

What you find in modern real hardware (xhci for example) and which would
also make sense for virtio is:

 * stick an error message into a event queue (for non-fatal errors),
   which would be a good fit for (b)
 * set a bit in a error status register, maybe raise IRQ, stop
   processing until reset (for fatal errors, i.e. your (a) case).
   such a register can live in config space for virtio.

cheers,
  Gerd