Re: [Xen-devel] [PATCH 08/45] xen: arm64: spinlocks

[Tim Deegan <tim@xxxxxxx>]

At 15:51 +0000 on 07 Feb (1360252296), Ian Campbell wrote:
> On Thu, 2013-02-07 at 15:34 +0000, Tim Deegan wrote:
> > At 14:42 +0000 on 07 Feb (1360248122), Tim Deegan wrote:
> > > The 32-bit ones have a scattering of DSBs and SEVs that aren't there in
> > > 64-bit.  The DSBs at least seem useful.  Not sure about SEV - presumably
> > > that's useful if the slow path has a WFE in it?
> > 
> > OK, I see the arm64 versions are using the new load-acquire/store-release
> > instructions so no DSBs or DMBs should be necessary.  Still puzzled by
> > the SEV.
> 
> The ldar/strl generate the sev's as appropriate too.

OK.

We talked aout working the WFE into the loop for spinlocks, which would
be non-trivial since today that loop happens in common code.  I'm OK
with taking this much in to unblock other dev work, as long as a WFE is
going to happen eventually.

Acked-by: Tim Deegan <tim@xxxxxxx>


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