Re: RFC: Changes for PCI

From: Jeff Garzik (jgarzik@mandrakesoft.com)
Date: Thu Jun 28 2001 - 12:01:05 EST


Todd Inglett wrote:
>
> "David S. Miller" wrote:
> >
> > Tom Gall writes:
> > > The first part changes number, primary, and secondary to unsigned ints from
> > > chars. What we do is encode the PCI "domain" aka PCI Primary Host Bridge, aka
> > > pci controller in with the bus number. In our case we do it like this:
> > >
> > > pci_controller=dev->bus->number>>8) &0xFF0000
> > > bus_number= dev->bus->number&0x0000FF),
> > >
> > > Is this reasonable for everyone?
> >
> > This is totally unreasonable.
>
> Well, back in the "Going beyond 256 PCI buses" thread two weeks ago when
> you argued that Linux not supporting >256 busses was a fallacy...
>
> "David S. Miller" wrote:
> > There are only two real issues:
> >
> > 1) Extending the type bus numbers use inside the kernel.
> >
> > Basically how most multi-controller platforms work now
> > is they allocate bus numbers in the 256 bus space as
> > controllers are probed. If we change the internal type
> > used by the kernel to "u32" or whatever, we expand that
> > available space accordingly.
> >
> > For the lazy, basically go into include/linux/pci.h
> > and change the "unsigned char"s in struct pci_bus into
> > some larger type. This is mindless work.

> Yes it is mindless work and is in that patch. Should we attempt to go
> beyond 256 physical busses in 2.4? Maybe not. But it is a simple
> change and it does work and it works around the existing drivers which
> compare busid+devfn for uniqueness when they really should compare
> pci_dev pointers. Should it be redone the correct way (domains) in
> 2.5? Absolutely.

2.5 is right around the corner, and sysdata should handle PCI
domains/segments just fine in 2.4.

Why do we need to patch 2.4 at all right now? Since 2.5 is close I
don't think it's a big deal saying "use 2.5+ for >256 physical buses"

-- 
Jeff Garzik      | Andre the Giant has a posse.
Building 1024    |
MandrakeSoft     |
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This archive was generated by hypermail 2b29 : Sat Jun 30 2001 - 21:00:19 EST