From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rusty Russell <rusty.russell@linaro.org>
Subject: Re: [PATCH] ARM: KVM: Check the cpuid we're being asked to emulate.
Date: Mon, 21 May 2012 10:43:56 +0930
Message-ID: <874nra49pn.fsf@rustcorp.com.au>
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Cc: Rusty Russell <rusty.russell@linaro.org>,
	android-virt@lists.cs.columbia.edu, kvm@vger.kernel.org,
	tech@virtualopensystems.com, Marc Zyngier <marc.zyngier@arm.com>,
	"Peter Maydell" <peter.maydell@linaro.org>
To: Christoffer Dall <c.dall@virtualopensystems.com>
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On Sun, 20 May 2012 14:34:48 -0400, Christoffer Dall <c.dall@virtualope=
nsystems.com> wrote:
> On Wed, May 16, 2012 at 7:58 PM, Rusty Russell <rusty@rustcorp.com.au=
> wrote:
> > On Mon, 14 May 2012 18:57:20 -0400, Christoffer Dall <c.dall@virtua=
lopensystems.com> wrote:
> >> On Thu, Mar 22, 2012 at 8:41 PM, Rusty Russell <rusty.russell@lina=
ro.org> wrote:
> >> > As our emulation gets more sophisticated, we need to know what C=
PU model
> >> > we're dealing with. =C2=A0Particularly for some of the nastier w=
orkarounds.
> >> >
> >> > Let's start with Cortex A-15. =C2=A0We can then test the MIDR el=
sewhere in the
> >> > code, knowing that it's one of a finite set of allowed values.
> >
> > (Revisiting this now)
> >
> > The intent is good, this patch is not the right way to do it though=
=2E =C2=A0I
> > think want an explicit ioctl to tell the kernel what CPU; since the
> > kernel initialized the regs, it needs to know.
> >
> not sure of your point exactly, but if I understand correctly, what
> you're saying is that since the kernel initializes all the regs (at
> least it's going to) we want an ioctl to say "this is the cpu for
> which you will initialize the regs"?
>=20
> that also makes for a more friendly user space interface than "you
> need to set this register to this cryptic value to emulate this
> cpu"...

Yes, exactly.  Esp. since it also effects some of the cp15 emulation
hacks.

Cheers,
Rusty.