Re: [Xen-devel] [PATCH v2 04/15] xen: arm: add a quirk to handle platforms with unusual GIC layout

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-11-22 at 17:10 +0000, Julien Grall wrote:
> 
> On 11/22/2013 05:03 PM, Ian Campbell wrote:
> > On Fri, 2013-11-22 at 16:46 +0000, Julien Grall wrote:
> >>
> >> On 11/22/2013 04:24 PM, Ian Campbell wrote:
> >>> Use this quirk on the xgene platform.
> >>
> >> With this quirk you only fix xen GIC. What about dom0/guest GIC ? I know
> >> that Linux is not using the secondary page, but we expose 2 pages
> >> contiguous page. With this quirk the first page is valid ... but the
> >> second page could belong to another device.
> >
> > Damn, good point.
> >
> >> Can we remove the second page when the quirk is enabled?
> >
> > I think what I will do is make gicv_setup map the two discontiguous 4K
> > regions contiguously into the guest space. This is consistent with the
> > DTB we expose to the guest.
> >
> > The reason for the discontinuity at the h/w level is (AFAICT) to support
> > OSes using 64K pages and/or granules. I think we can live without these
> > for the time being.
> 
> I'm fine with this solution as long as we are sure there is no device 
> memory just after the first page.

The way the GIC memory map is defined that isn't possible and it's not
the case on this platform.

Ian.



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel