Re: [Fwd: Re: [PATCH 0/5]PCI: x86 MMCONFIG]

[Tony Camuso]

Matthew Wilcox wrote:

> Bad deduction.  What's happening is that the write to the BAR is causing
> it to overlap the decode for mmconfig space.  So the mmconfig write to
> set the BAR back never gets through.
>
> I have a different idea to fix this problem.  Instead of writing
> 0xffffffff, we could look for an unused bit of space in the E820 map and
> write, say, 0xdfffffff to the low 32-bits of a BAR.  Then it wouldn't
> overlap, and we could find its size using MMCONFIG.
The BAR claims to be a 64-bit BAR.

> Does anyone know how Windows handles these machines?  Obviously, if it's
> using MMCONFIG, it'd have the same problems.  Does it just use type 1
> for initial sizing?  Or does it use type 1 for all accesses below 256
> bytes?
As far as I know, Windows has a blacklist that limits systems with these
devices to legacy PCI config access.

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