Re: [RFC] adding a generic QAPI event for failed device hotunplug

[David Gibson]

On Mon, Mar 22, 2021 at 01:06:53PM +0100, Paolo Bonzini wrote:
> On 22/03/21 07:39, David Gibson wrote:
> > > QEMU doesn't really keep track of "in flight" unplug requests, and as
> > > long as that's the case, its timeout even will have the same issue.
> > Not generically, maybe.  In the PAPR code we effectively do, by means
> > of the 'unplug_requested' boolean in the DRC structure.  Maybe that's
> > a mistake, but at the time I couldn't see how else to handle things.
> 
> No, that's good.  x86 also tracks it in some registers that are accessible
> from the ACPI firmware.  See "PCI slot removal notification" in
> docs/specs/acpi_pci_hotplug.txt.
> 
> > Currently we will resolve all "in flight" requests at machine reset
> > time, effectively completing those requests.  Does that differ from
> > x86 behaviour?
> 
> IIRC on x86 the requests are instead cancelled, but I'm not 100%
> sure.

Ah... we'd better check that and try to make ppc consistent with
whatever it does.

-- 
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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