Re: [Xen-devel] [PATCH 01/10] xen: arm: map memory as inner shareable.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-07-01 at 16:39 +0100, Stefano Stabellini wrote:
> On Fri, 28 Jun 2013, Ian Campbell wrote:
> > The inner shareable domain contains all SMP processors, including different
> > clusters (e.g. big.LITTLE). Therefore this is the correct thing to use for 
> > Xen
> > memory mappings. The outer shareable domain is for devices on busses which 
> > are
> > barriers (e.g. AMBA4). While the system domain is for things behind bridges
> > which do not.
> > 
> > One wrinkle is that Normal memory with attributes Inner Non-cacheable, Outer
> > Non-cacheable (which we call BUFFERABLE) must be mapped Outer Shareable on 
> > ARM
> > v7. Therefore change the prototype of mfn_to_xen_entry to take the attribute
> > index so we can DTRT. On ARMv8 the sharability is ignored and considered to
> > always be Outer Shareable.
> > 
> > While I'm here change all the dmb/dsb with an implicit sy to an explicit sy,
> > to make future changes simpler. Other than that don't adjust the barriers,
> > flushes etc, those remain as they were (which is more than is now required).
> > I'll change those in a later patch.
> > 
> > Many thanks to Leif for explaining the difference between Inner- and
> > Outer-Shareable in words of two or less syllables, I hope I've replicated 
> > that
> > explanation properly above!
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Cc: Leif Lindholm <leif.lindholm@xxxxxxxxxx>
> 
> It looks OK.

Thanks.

>  I would have kept the dsb sy changes separate.

So would I if I'd have know then that it was going end up being so many
patches. I'll split them out when I resend.



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