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

[Julien Grall <julien.grall@xxxxxxxxxx>]

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.
--
Julien Grall


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