On Tuesday 19 January 2010 12:57:39 pm Yinghai Lu wrote: > On 01/19/2010 11:42 AM, Jeff Garrett wrote: > > On Fri, Jan 15, 2010 at 10:14:17AM -0800, Jesse Barnes wrote: > >> On Thu, 14 Jan 2010 16:39:13 -0800 > >> Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > >> > >>> On 01/14/2010 03:49 PM, Bjorn Helgaas wrote: > >>>> On Thursday 14 January 2010 04:38:08 pm Yinghai Lu wrote: > >>>>> On 01/14/2010 03:09 PM, Bjorn Helgaas wrote: > >>>>>> On Thursday 14 January 2010 03:46:35 pm Yinghai Lu wrote: > >>>>>>> > >>>>>>> Bjorn pointed out we need to remove mmconf range > >>>>>>> > >>>>>>> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx> > >>>>>>> > >>>>>>> --- > > ... > >>>>>> > >>>>>> This can't be right, can it? Let's say the kernel was built with > >>>>>> CONFIG_PCI_MMCONFIG turned off, or the user used "pci=nommconf", > >>>>>> or the kernel decides not to use MMCONFIG for some other reason. > >>>>>> > >>>>>> In that case, the hardware may still be configured to support > >>>>>> MMCONFIG, but the pci_mmcfg_list will be empty, so your code will > >>>>>> leave the window alone. We might assign some of that MMCONFIG > >>>>>> space to a device, but the hardware will route it to MMCONFIG, > >>>>>> not to the device. > >>>>> > >>>>> so if there is mmconf specified, we just skip the whole function? > >>>> > >>>> No, I'm saying that intel-bus.c must ALWAYS remove the MMCONFIG > >>>> region from the host bridge apertures, even if Linux isn't using > >>>> MMCONFIG. > >>>> > >>>> That means intel-bus.c has to be smart enough to figure out on its > >>>> own what the MMCONFIG area is. It can't depend on mmconfig-shared.c > >>>> to do it, because mmconfig-shared.c might not be there. > >>> > >>> that seems go too far away... > >>> > >>> Subject: [PATCH -v2] x86/pci: intel ioh need to subtrac mmconf range > >>> > >>> Bjorn pointed out we need to remove mmconf range > >>> > >>> -v2: if mmconf is not there, get out early. > >>> > >>> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx> > >>> > >>> --- > > ... > >> > >> This goes against the real intent of intel_bus.c doesn't it? When we > >> first added it, the thought was that it would be a purely native way of > >> getting at bridge window information and not rely on firmware. If > >> you're going to make it dependent on MMCONFIG now, why not trust other > >> firmware tables as well, like _CRS? > >> > >> The MMCONFIG ranges are pretty easy to get at, the public docs have > >> info about the registers that control the MMCONFIG decode ranges, so > >> you should be able to read them out and add them to this file, > >> preserving the original intent. > > > > I did attempt a bisection last week, but my pared down config kept > > hitting a sysfs_create_file panic. I didn't succeed. I don't think there's any need to bisect this; sorry I didn't mention this earlier. 2.6.32 didn't include intel-bus.c, so the kernel just assumed that all non-RAM addresses got routed to the PCI bus. This would have included the [mem 0xd0000000-0xdfffffff] used by your Radeon device, which explains why it would work there. After 2.6.32, we added intel-bus.c, which reads some of the host bridge aperture information from the chipset. This is apparently missing something, because intel-bus.c didn't find that region, so Linux thought the Radeon resource was wrong and disabled it, which broke it. > > Should I try the v2 patch above? What tree is it against? > > maybe later with -tip tree + pci/linux-next. Yinghai, did you figure out how to discover the [mem 0xd0000000-0xdfffffff] region in intel-bus.c? Jeff's video isn't going to work without that. I don't think we have anything that's worth testing yet. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
