lkml.org 
[lkml]   [2009]   [Apr]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
DateMon, 27 Apr 2009 12:53:42 -0700
FromJesse Barnes <>
SubjectRe: [PATCH] x86/pci: do assign root bus res if _CRS is used
On Mon, 27 Apr 2009 13:44:01 -0600
Bjorn Helgaas <bjorn.helgaas@hp.com> wrote:

> On Monday 20 April 2009 07:35:40 pm Yinghai Lu wrote:
> > it wil be overwriten later if _CRS is used, so don't bother to set
> > it.
> >
> > [ Impact: cleanup ]
> >
> > Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> >
> > ---
> > arch/x86/pci/amd_bus.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > Index: linux-2.6/arch/x86/pci/amd_bus.c
> > ===================================================================
> > --- linux-2.6.orig/arch/x86/pci/amd_bus.c
> > +++ linux-2.6/arch/x86/pci/amd_bus.c
> > @@ -100,6 +100,10 @@ void x86_pci_root_bus_res_quirks(struct
> > int j;
> > struct pci_root_info *info;
> >
> > + /* don't go for it if _CRS is used */
> > + if (pci_probe & PCI_USE__CRS)
> > + return;
> > +
> > /* if only one root bus, don't need to anything */
> > if (pci_root_num < 2)
> > return;
>
> This isn't a comment on this patch per se.
>
> I am concerned about the fact that "pci=use_crs" is not the default.
> From the changelog of 62f420f8282, it sounds like you have to boot an
> IBM x3850 with "pci=use_crs" to make hot-plug work, even though ACPI
> tells us everything we need to know. That's backwards.
>
> We shouldn't need an option to tell Linux that the firmware is
> trustworthy. We should have an option to *ignore* it for the times
> when we trip over something broken and haven't figured out a way to
> work around it yet.

Well, we could try using _CRS by default, but like many things ACPI we
can probably only trust firmwares after a certain date (i.e. the date
when Windows started relying on the data being correct in order to
boot). Do we have a good cutoff for that? Or should we try generally
enabling it early in 2.6.31 to see what happens?

--
Jesse Barnes, Intel Open Source Technology Center


\
 
 \ /
  Last update: 2009-04-27 21:57    [from the cache]
©2003-2010