Re: Going beyond 256 PCI buses

Jeff Garzik
2001-06-14T15:30:23Z

"David S. Miller" wrote:
> Jeff Garzik writes:
> > Why do you want to make the bus number larger than the PCI bus number
> > register?
>
> This isn't it. What I'm trying to provoke thought on is
> "is there a way to make mindless apps using these syscalls
> work transparently"
>
> I think the answer is no. Apps should really fetch info out
> of /proc/bus/pci and use the controller ioctl.
>
> But someone could surprise me :-)

yeah, those syscalls weren't built with much eye towards the future.
And I don't think they are present in other OS's either...

> > It seems like adding 'unsigned int domain_num' makes more sense, and is
> > more correct. Maybe that implies fixing up other code to use a
> > (domain,bus) pair, but that's IMHO a much better change than totally
> > changing the interpretation of pci_bus::bus_number...
>
> Correct, I agree. But I don't even believe we should be sticking
> the domain thing into struct pci_bus.
>
> It's a platform thing. Most platforms have a single domain, so why
> clutter up struct pci_bus with this value? By this reasoning we could
> say that since it's arch-specific, this stuff belongs in sysdata or
> wherever.

Pretty much any arch with a PCI slot can have multiple domains, now that
hotplug controllers are out and about. So it seems a generic enough
concept to me...

> And this is what is happening right now. So in essence, the work is
> done :-) The only "limiting factor" is that x86 doesn't support
> multiple domains as some other platforms do. So all these hot-plug
> patches just need to use domains properly, and perhaps add domain
> support to X86 when one of these hot-plug capable controllers are
> being used.

point.

Regards,

Jeff

--
Jeff Garzik | Andre the Giant has a posse.
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