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

[Stefano Brivio <sbrivio@redhat.com>]

On Thu, 23 Feb 2023 06:06:17 -0800
Andrea Bolognani <abologna@redhat.com> wrote:

> 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, allow me to do this: I would push this patch meanwhile, along
with the changes for the DNS issue you reported, because that one might
impact many users, and I think it makes sense to have a fix out soon.

I start thinking it's also part of the issue Paul reported for Podman
with pasta here:
  https://github.com/containers/podman/issues/17074

This patch itself can't hurt, and it changes exactly two letters.

As soon as you have something less qrappy we'll go with that (you don't
even need to rebase, I'll revert this one on the tree first).

-- 
Stefano