Re: [Qemu-ppc] [Qemu-devel] [PATCH 0/1] pci: allow 0 address for PCI IO/MEM regions

[Michael S. Tsirkin]

On Tue, Jan 13, 2015 at 06:01:53PM +0100, Alexander Graf wrote:
> On 01/13/15 17:17, Michael S. Tsirkin wrote:
> >On Tue, Jan 13, 2015 at 05:54:46PM +0200, Michael S. Tsirkin wrote:
> >>I think we already do this for PC:
> >>    commit 83d08f2673504a299194dcac1657a13754b5932a
> >>    Author: Michael S. Tsirkin <address@hidden>
> >>    Date:   Tue Oct 29 13:57:34 2013 +0100
> >>
> >>        pc: map PCI address space as catchall region for not mapped 
> >> addresses
> >>
> >>but we need to find and fix all other targets.
> >BTW this is very easy to test.
> >Add an unused device (like ivshmem) enable BAR, and set it to 0.
> >System should survive, as opposed to hanging.
> >
> >But the big question is whether this is the right
> >thing to do for each platform.
> >For PIIX whatever is not system memory, is PCI.
> >But other boxes might have a different view of the matter.
> 
> Only few platforms have PCI mapped at 0, no? So in most cases you get
> windows that simply don't have overlapping at all.
> 
> 
> Alex

What's missing is complete analysis of the problem.
Ideally testing on several targets.

-- 
MST