[PATCH] powerpc: add denormalisation exception handling for POWER6/7

[Michael Neuling]

In message <5E6FBB75-BE97-4D97-AEA2-EC8EAF1E0ECF at kernel.crashing.org> you wrote
:
> 
> On Jul 11, 2011, at 12:52 AM, Michael Neuling wrote:
> 
> > On POWER6 and POWER7 if the input operand to an instruction is a
> > denormalised single precision binary floating we can take a
> > denormalisation exception where it's expected that the hypervisor =
> (HV=3D1)
> > will fix up the inputs before the instruction is run.
> >=20
> > This adds code to handle this denormalisation exception for POWER6 and
> > POWER7.
> >=20
> > It also add a CONFIG_PPC_DENORMALISATION option and sets it in
> > pseries/ppc64_defconfig.=20
> >=20
> > This is useful on bare metal systems only.  Based on patch from Milton
> > Miller.
> >=20
> > Signed-off-by: Michael Neuling <mikey at neuling.org>
> >=20
> > ---
> > arch/powerpc/Kconfig                   |    7 +
> > arch/powerpc/configs/ppc64_defconfig   |    1=20
> > arch/powerpc/configs/pseries_defconfig |    1=20
> > arch/powerpc/include/asm/ppc-opcode.h  |    2=20
> > arch/powerpc/include/asm/reg.h         |    1=20
> > arch/powerpc/kernel/exceptions-64s.S   |  125 =
> +++++++++++++++++++++++++++++++++
> > 6 files changed, 137 insertions(+)
> >=20
> > Index: linux-ozlabs/arch/powerpc/Kconfig
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > --- linux-ozlabs.orig/arch/powerpc/Kconfig
> > +++ linux-ozlabs/arch/powerpc/Kconfig
> > @@ -556,6 +556,13 @@ config SCHED_SMT
> > 	  when dealing with POWER5 cpus at a cost of slightly increased
> > 	  overhead in some places. If unsure say N here.
> >=20
> > +config PPC_DENORMALISATION
> > +	bool "PowerPC denormalisation exception handling"
> 
> Should this at least depend on PPC_BOOK3S_64 ?

Yep, thanks!

Mikey