Re: [Qemu-devel] [PATCH] q35: fix mmconfig and PCI0._CRS

[Laszlo Ersek]

On 06/03/19 16:24, Gerd Hoffmann wrote:
>   Hi, 
> 
>> One question: are we sure all guest OSes we care about can deal with
>> discontiguous 32-bit PCI MMIO aperture(s)? Personally, I've got no clue.
>> Is a "naïve" OS imaginable that looks only at the first suitable range
>> in the _CRS?
> 
> Well, I know there is physical hardware doing the same thing,
> my work station for example:
> 
> [ ... ]
> c8000000-f7ffffff : PCI Bus 0000:00
>   c8000000-c81fffff : PCI Bus 0000:01
>   e0000000-efffffff : 0000:00:02.0
>     e0000000-e02fffff : BOOTFB
> [ ... ]
> f8000000-fbffffff : PCI MMCONFIG 0000 [bus 00-3f]
>   f8000000-fbffffff : Reserved
>     f8000000-fbffffff : pnp 00:06
> fd000000-fe7fffff : PCI Bus 0000:00
>   fd000000-fdabffff : pnp 00:07
> [ ... ]
> 
> Which of course is no guarantee that no naïve OS exists, but I think the
> chances that we'll run into trouble with this are rather small.

OK. Thank you.
Laszlo