Subject: Re: [PATCH 3/3] powerpc: Load Monitor Register Tests

From: Michael Neuling <[email-masked]>
Date: Wed, 04 May 2016 21:41:16 +1000

On Wed, 2016-05-04 at 21:31 +1000, Michael Ellerman wrote:
> On Wed, 2016-05-04 at 20:43 +1000, Michael Neuling wrote:
> > 
> > On Mon, 2016-04-18 at 16:08 -0500, Jack Miller wrote:
> > 
> > > 
> > > +int ebb_lmr(void)
> > > +{
> > > +	int i;
> > > +
> > > +	SKIP_IF(!ebb_is_supported());
> > We skip this test currently as EBB is not enabled on POWER9.
> > 
> > On POWER8 we enable EBB in the PMU code. Should we do this elsewhere for
> > POWER9 since EBB doesn't directly require the PMU?
> Probably. But we will need to check that if the PMU code is *not* enabled we
> still do the context switching of EBB regs correctly. We probably do, but I
> don't now for sure.

I think we're fine.  The code to switch BESCR, EBBHR & EBBRR is in
save/restore_sprs() and just depends on cpu_has_feature(CPU_FTR_ARCH_207S).

Actually, do we really need be using PPC_FEATURE2_EBB for this test? Should
we really be using PPC_FEATURE2_ARCH_3_00?

Should the existing PPC_FEATURE2_EBB really signify PPC_FEATURE2_EBB_PMU?

Mikey