Messages in this thread |  | | | Date | Mon, 27 Apr 2009 12:53:42 -0700 | | From | Jesse Barnes <> | | Subject | Re: [PATCH] x86/pci: do assign root bus res if _CRS is used |
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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
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