Re: [Qemu-devel] [PATCH] hw/arm/virt: Allow zero address for PCI IO space

[Michael S. Tsirkin]

On Tue, Oct 13, 2015 at 02:12:34PM +0100, Peter Maydell wrote:
> On 13 October 2015 at 14:04, Michael S. Tsirkin <address@hidden> wrote:
> > On Tue, Oct 13, 2015 at 02:47:33PM +0200, Laurent Vivier wrote:
> >> MST asked for a global flag:
> >>
> >> https://lists.gnu.org/archive/html/qemu-ppc/2015-07/msg00364.html
> >>
> >> But perhaps the machine is not the good place for this global flag ?
> >>
> >> CC: Michael for that.
> >
> > Whether controllers treat zero specially should be expressed
> > using priorities in memory APIs.
> 
> Mmm, I guess it's a bug in how the machine model
> wires up the controller rather than in the controller
> model itself.
> 
> > This is just about buggy machine types that do
> > not specify priority for overlapping regions correctly.
> >
> > As a temporary hacky work-around, a global seems sufficient.
> 
> Well, if we're going to go around and fix the machines which
> don't get things right, I guess. It's a shame the default for
> the global is "this machine is broken", because now every
> new machine will default unnecessarily to broken, and there's
> no way to grep the source tree for machines which need fixing.
> 
> -- PMM

It'd be easy enough to revert the logic if someone's willing to start on
this.  I'm reluctant to make this patchset depend on changing all
machines, but if you think I'm wrong, pls let me know.

-- 
MST