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Date: Mon, 19 Sep 2011 16:00:23 +1000
From: David Gibson <david@gibson.dropbear.id.au>
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Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 47/58] Implement POWER7's CFAR
	in TCG
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To: Blue Swirl <blauwirbel@gmail.com>
Cc: qemu-ppc@nongnu.org, Alexander Graf <agraf@suse.de>, qemu-devel Developers <qemu-devel@nongnu.org>

On Sat, Sep 17, 2011 at 05:08:29PM +0000, Blue Swirl wrote:
> On Wed, Sep 14, 2011 at 8:43 AM, Alexander Graf <agraf@suse.de> wrote:
> > From: David Gibson <david@gibson.dropbear.id.au>
> >
> > This patch implements support for the CFAR SPR on POWER7 (Come From
> > Address Register), which snapshots the PC value at the time of a bran=
ch or
> > an rfid. =A0The latest powerpc-next kernel also catches it and can sh=
ow it in
> > xmon or in the signal frames.
> >
> > This works well enough to let recent kernels boot (which otherwise oo=
ps
> > on the CFAR access). =A0It hasn't been tested enough to be confident =
that the
> > CFAR values are actually accurate, but one thing at a time.
>=20
> This looks accurate at least for the cases covered.
>=20
> A higher performance implementation could be to only update the
> register lazily when the SPR is read, in most other times CFAR would
> be only stored to DisasContext.

Uh, yeah.  I think I'll leave that to someone who actually understands
TCG, rather than just bluffing it.

--=20
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other=
_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson