Re: [PATCH] qrap: Pass PCI device numbers to qemu in base 10, not in base 16

[Andrea Bolognani <abologna@redhat.com>]

On Thu, Feb 23, 2023 at 09:27:14AM +1100, David Gibson wrote:
> On Wed, Feb 22, 2023 at 02:40:32AM -0800, Andrea Bolognani wrote:
> > I don't think this is going to work.
> >
> > The problem is that, while PCI buses are indeed named with increasing
> > numbers in integer format (pci.9, pci.10 and so on), PCI slots are
> > addressed using hexadecimal format (0x9, 0xa and so on). libvirt uses
> > this naming convention because it matches QEMU's.
>
> Actually, I think we're ok.  PCI slots are addressed in hex by
> convention, but AFAICT if you *just* give a slot number, it will
> accept either decimal or hex (so addr=10 and addr=0xa are equivalent).
> That's *not* true if you use SS.F format to include the function
> number - then it expects hex only.  But we're not doing that, so so
> always using decimal should be ok here.
>
> Source: set_pci_devfn() in the qemu source
>
> Obviously that's a pretty fragile hack, but that's 'qrap' for you.

Yeah, even if that happens to work I'd rather not rely on it,
especially since a proper solution doesn't look like it would be a
lot of additional effort.

I've managed to reproduce the original issue in the context of
KubeVirt. I'll hopefully have a patch ready soon.

-- 
Andrea Bolognani / Red Hat / Virtualization