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    SubjectRe: 2.6.33-rc3: pci host bridge windows ignored (works with pci=use_crs)
    On Thursday 14 January 2010 12:46:22 am Yinghai Lu wrote:
    > On 01/13/2010 05:24 AM, Jeff Garrett wrote:
    > > On Wed, Jan 13, 2010 at 12:45:17AM -0800, Yinghai Lu wrote:
    > >> On Wed, Jan 13, 2010 at 12:44 AM, Yinghai Lu <> wrote:
    > >>> On Tue, Jan 12, 2010 at 9:37 PM, Jeff Garrett <> wrote:
    > >>>> Took a stab at getting the right emails. If I missed anyone, sorry...
    > >>>>
    > >>>> I have a desktop machine with a radeon HD 4850, and on recent kernels
    > >>>> the radeon driver has failed with the message "No valid linear
    > >>>> framebuffer address". lspci on the broken configuration showed the
    > >>>> first memory region at d0000000 of the radeon card to be ignored. dmesg
    > >>>> showed there to be a host bridge window at that address which was also
    > >>>> ignored.

    > >>> it seems HW IOH only can use [e000000 - fdffffff] under that bridge...
    > >>>
    > >>> and _CRS said the peer root bus could use [c000000 - dfffffff]
    > >>>
    > >>> could be that we need to check other register to decide if we can use
    > >>> reading from ioh reg directly.

    > not sure why [0xc000000 - 0xcffffff] should work with 00:07.0
    > checked with intel doc, that is out of scope to LMMIOL register...
    > really don't know how it works with your platform.

    I wonder about that [mem 0xc0000000-0xcfffffff] range, too. But as
    far as I can tell, we don't actually try to use that anywhere yet.
    (We assign part of that range to the 00:1c.0 bridge to bus 03, but
    I don't see any devices actually using it.)

    One problem I see is that _CRS includes the [mem 0xd0000000-0xdfffffff]
    range, but intel_bus.c didn't find it. We DO need this range for the
    Radeon, and the Radeon works with "pci=use_crs", so the host bridge must
    be routing it.

    I think this must be a detail of the Intel host bridge, not something
    specific to Jeff's Dell system. This problem should affect all systems
    using that host bridge.

    PCI: MMCONFIG for domain 0000 [bus 00-ff] at [mem 0xe0000000-0xefffffff] (base 0xe0000000)

    ACPI: PCI Root Bridge [PCI0] (0000:00)
    pci_root PNP0A08:00: host bridge window [mem 0xc0000000-0xdfffffff]
    pci_root PNP0A08:00: host bridge window [mem 0xf0000000-0xfed8ffff]

    IOH bus: [00, fb]
    IOH bus: 00 index 1 mmio: [e0000000, fdffffff]

    pci 0000:00:07.0: PCI bridge to [bus 04-04]
    pci 0000:00:07.0: bridge window [mem 0xd0000000-0xdfffffff 64bit pref]
    pci 0000:04:00.0: reg 10: [mem 0xd0000000-0xdfffffff 64bit pref]

    Another problem is that intel_bus.c didn't remove the MMCONFIG region
    [mem 0xe0000000-0xefffffff] from the window. I think there's code there
    to do that, but there must be something wrong with it.


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