Re: [Qemu-devel] [PATCH rebased for-1.8] i386: pc: align gpa<->hpa on 1GB boundary (v6)

[Paolo Bonzini]

Il 10/12/2013 15:53, Gerd Hoffmann ha scritto:
>   Hi,
> 
>> If we could make a small guset visible change, it would be simpler to
>> always make the PCI hole 1GB in size; it is currently 256MB for i440FX
>> and 1.25GB for q35.
> 
> Easy for i440fx.
> 
> Tricky for q35 as the firmware knows qemu will not map ram above
> 0xb000000 and places the mmconfig bar @ 0xb0000000.  Making the window
> smaller (1.25GB -> 1GB) will create a conflict there.  Making it larger
> (2G) will work.  It's done this way to keep 0xc0000000+ free for pci
> bars, and we can map up to 512MB-sized bars there.

0xc0000000-0xfebfffff is almost 1GB, so there is room for 1 512MB-size
BAR.  mmconfig could move to 0xf0000000-0xf7ffffff; firmware is not a
problem because this would be only for new machine types.

Unless I'm missing something of course.

Paolo

>>   We can take a look as soon as the SeaBIOS patches
>> are in to use QEMU-built ACPI tables.
> 
> This is in master already.
> 
> cheers,
>   Gerd
> 
>