Re: [RFC PATCH 1/1] PCI: skip release and reallocation of io port resources

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Fri, 9 Jul 2010 09:50:45 -0600
Bjorn Helgaas <bjorn.helgaas@hp.com> wrote:

> On Tuesday, July 06, 2010 06:49:32 pm Yinghai Lu wrote:
> > On 07/06/2010 04:58 PM, Linus Torvalds wrote:
> > > On Tue, Jul 6, 2010 at 4:13 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> > >>
> > >> So you want to use pci=override_bios to reallocate all bios assigned resource include
> > >> peer root buses resources and pci bridge resource and pci devices BAR?
> > > 
> > > In a perfect world, we'd never need this at all, but sicne that's not
> > > an option, the second-best alternative might be something like the
> > > following:
> > > 
> > >   pci=override=off # default
> > >   pci=override=conflict # override only on conflicts
> > >   pci=override=<device> # clear BIOS allocations for <device> (and any
> > > children, if it's a bus)
> > 
> > current:
> > if there is conflict, like pci bridge resources or pci devices resources is not in the scope of peer root bus resource range.
> > or pci devices is not in pci bridge resources range.
> > kernel would reject the resource and try to get new range in parent resource for the children.
> > 
> > so current default is overriding the conflicts already.
> 
> One conflict we don't handle correctly is when we find a device that
> doesn't fit inside the root bus resources.  We currently disable the
> device, but Windows just leaves it where BIOS put it.
> 
> This causes this bug: https://bugzilla.kernel.org/show_bug.cgi?id=16263
> It should be fairly simple to make Linux handle this conflict the same
> way, without requiring any special kernel arguments.

Sounds reasonable.  I'm open to suggestions on alternate approaches for
this issue as well.

Thanks,
-- 
Jesse Barnes, Intel Open Source Technology Center