Re: [PATCH v3 3/9] vfio: add quirk device write method

[Alex Williamson]

On Fri, 17 Jul 2020 16:57:40 +0100
Peter Maydell <peter.maydell@linaro.org> wrote:

> On Fri, 17 Jul 2020 at 16:54, Alex Williamson
> <alex.williamson@redhat.com> wrote:
> >
> > On Thu, 16 Jul 2020 18:46:33 +0100
> > Peter Maydell <peter.maydell@linaro.org> wrote:
> >  
> > > Alex (Williamson) -- as the vfio maintainer, do you have a view
> > > on whether we should be logging write accesses to port 0x3c3
> > > here as guest-errors or unimplemented-QEMU-functionality?
> > >
> > > Guest-error seems plausible to me, anyway.  
> >
> > I believe the intention was that writes would be dropped, so if this
> > generates logging that is going to cause users to file bugs, that would
> > be undesirable.  Thanks,  
> 
> It will only log if the user explicitly turns on "log things the
> guest does which are bugs in it, like writing to read-only
> registers" (with the '-d guest_errors' option).

IIRC, this quirk is based on observation more so than an actual spec,
so whether a log of such an event is interpreted as a guest error or an
emulation error might be up for debate.  Aside from that nit, and lack
of bandwidth to research how hardware handles writes,

Acked-by: Alex Williamson <alex.williamson@redhat.com>

Thanks,
Alex