Re: [PATCH v2] spapr/xive: Use the xics flag to check for XIVE-only IRQ backends

[David Gibson]

On Fri, Aug 21, 2020 at 07:39:34AM +0200, Cédric Le Goater wrote:
> On 8/21/20 1:22 AM, David Gibson wrote:
> > On Thu, Aug 20, 2020 at 04:01:06PM +0200, Cédric Le Goater wrote:
> >> The sPAPR machine has four different IRQ backends, each implementing
> >> the XICS or XIVE interrupt mode or both in the case of the 'dual'
> >> backend.
> >>
> >> If a machine is started in P8 compat mode, QEMU should necessarily
> >> support the XICS interrupt mode and in that case, the XIVE-only IRQ
> >> backend is invalid. Currently, spapr_irq_check() tests the pointer
> >> value to the IRQ backend to check for this condition, instead use the
> >> 'xics' flag. It's equivalent and it will ease the introduction of new
> >> XIVE-only IRQ backends if needed.
> >>
> >> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> > 
> > Thanks, applied to ppc-for-5.2.
> > 
> > I still kind of want to remove the last vestiges of those
> > "backends", but I'm unlikely to have time to do so soon.
> 
> What did you have in mind ? 
> 
> Move the 'xics' and 'xive' flags directly under the spapr machine ? 
> It would add state.

Looking at my draft patches, looks like I was planning to replace the
flags with spapr caps.  IIRC there was migration breakage with my
draft, though, can't remember what would be needed to fix it.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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