Re: [RFC] PCI extended conf space when MMCONFIG disabled because of e820

[Arjan van de Ven <arjan@linux.intel.com>]

Chuck Ebbert wrote:
> In-Reply-To: <p73ac8fqjix.fsf@verdi.suse.de>
> 
> On 15 Jun 2006 03:45:10 +0200, Andi Kleen wrote:
> 
>> Anyways I would say that if the BIOS can't get MCFG right then 
>> it's likely not been validated on that board and shouldn't be used.
> 
> According to Petr Vandrovec:
> 
>  ... "What is important (and checked) is address of MMCONFIG reported by MCFG
>  table...  Unfortunately code does not bother with printing that address :-(
>  
>  "Another problem is that code has hardcoded that MMCONFIG area is 256MB large. 
>  Unfortunately for the code PCI specification allows any power of two between 2MB 
>  and 256MB if vendor knows that such amount of busses (from 2 to 128) will be 
>  sufficient for system.  With notebook it is quite possible that not full 8 bits 
>  are implemented for MMCONFIG bus number."
> 
> 
> So here is a patch.  Unfortunately my system still fails the test because
> it doesn't reserve any part of the MMCONFIG area, but this may fix others.
> 
> Booted on x86_64, only compiled on i386.  x86_64 still remaps the max area
> (256MB) even though only 2MB is checked... but 2.6.16 had no check at all
> so it is still better.
> 
> 
> PCI: reduce size of x86 MMCONFIG reserved area check
> 
> 1.  Print the address of the MMCONFIG area when the test for that area
>     being reserved fails.
> 
> 2.  Only check if the first 2MB is reserved, as that is the minimum.
> 
> Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>

Acked-by: Arjan van de Ven <arjan@linux.intel.com>