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

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Feb 22, 2023 at 02:40:32AM -0800, Andrea Bolognani wrote:
> On Tue, Feb 21, 2023 at 08:24:25PM +0100, Stefano Brivio wrote:
> >  		if (!has_json) {
> >  			snprintf(dev_str, ARG_MAX,
> > -			         "%s,%s%x%s,netdev=hostnet0,x-txburst=4096",
> > +			         "%s,%s%i%s,netdev=hostnet0,x-txburst=4096",
> >  			         dev->name, dev->template, i, dev->template_post);
> >  		} else {
> >  			snprintf(dev_str, ARG_MAX,
> > -			         "{\"driver\":\"%s\",%s%x\"%s,\"netdev\":\"hostnet0\",\"x-txburst\":4096}",
> > +			         "{\"driver\":\"%s\",%s%i\"%s,\"netdev\":\"hostnet0\",\"x-txburst\":4096}",
> >  			         dev->name, dev->template_json, i, dev->template_json_post);
> >  		}
> 
> 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.

-- 
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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