[PATCH -mm] 0/2: PCI MMCONFIG-related updates

[PATCH -mm] 0/2: PCI MMCONFIG-related updates

[Robert Hancock]

These two patches implement some changes in behavior related to PCI
MMCONFIG configuration space access. One changes the way in which we
validate the MCFG table provided by the BIOS by checking it against
ACPI motherboard resources instead of the E820 table. The BIOS is not
required to reserve this area in the E820 table, so checking that
results in MMCONFIG being unnecessarily disabled on some machines.

Some Intel chipsets where MMCONFIG was being disabled previously
(but won't be with the first patch) had problems, not due to the
MCFG table being broken, but because the access was hosed by the way
in which we do PCI BAR sizing. The second patch fixes this problem.

This is requested for inclusion in the -mm tree for testing.

Re: [PATCH -mm] 0/2: PCI MMCONFIG-related updates

[Jesse Barnes]

On Tuesday, May 29, 2007 9:01:22 Robert Hancock wrote:
> These two patches implement some changes in behavior related to PCI
> MMCONFIG configuration space access. One changes the way in which we
> validate the MCFG table provided by the BIOS by checking it against
> ACPI motherboard resources instead of the E820 table. The BIOS is not
> required to reserve this area in the E820 table, so checking that
> results in MMCONFIG being unnecessarily disabled on some machines.
>
> Some Intel chipsets where MMCONFIG was being disabled previously
> (but won't be with the first patch) had problems, not due to the
> MCFG table being broken, but because the access was hosed by the way
> in which we do PCI BAR sizing. The second patch fixes this problem.
>
> This is requested for inclusion in the -mm tree for testing.

Robert, should we also pull in the 915 and 965 chipset specific register 
poking code?  It might be a good sanity check against ACPI (i.e. if ACPI and 
the actual register window disagree, we can assume the BIOS is broken and 
MCFG is not safe to use).  If so, I'll update and repost them against your 
patchset.

Thanks,
Jesse

Re: [PATCH -mm] 0/2: PCI MMCONFIG-related updates

[Robert Hancock]

Jesse Barnes wrote:
> On Tuesday, May 29, 2007 9:01:22 Robert Hancock wrote:
>> These two patches implement some changes in behavior related to PCI
>> MMCONFIG configuration space access. One changes the way in which we
>> validate the MCFG table provided by the BIOS by checking it against
>> ACPI motherboard resources instead of the E820 table. The BIOS is not
>> required to reserve this area in the E820 table, so checking that
>> results in MMCONFIG being unnecessarily disabled on some machines.
>>
>> Some Intel chipsets where MMCONFIG was being disabled previously
>> (but won't be with the first patch) had problems, not due to the
>> MCFG table being broken, but because the access was hosed by the way
>> in which we do PCI BAR sizing. The second patch fixes this problem.
>>
>> This is requested for inclusion in the -mm tree for testing.
> 
> Robert, should we also pull in the 915 and 965 chipset specific register 
> poking code?  It might be a good sanity check against ACPI (i.e. if ACPI and 
> the actual register window disagree, we can assume the BIOS is broken and 
> MCFG is not safe to use).  If so, I'll update and repost them against your 
> patchset.

Probably not a bad idea..

-- 
Robert Hancock      Saskatoon, SK, Canada
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Home Page: http://www.roberthancock.com/