[PATCH 1/2] powerpc/boot: Disable vector instructions

[Joel Stanley]

On Wed, 10 Oct 2018 at 22:41, Michael Ellerman <mpe at ellerman.id.au> wrote:
>
> Joel Stanley <joel at jms.id.au> writes:
>
> > This will avoid auto-vectorisation when building with higher
> > optimisation levels.
> >
> > We don't know if the machine can support VSX and even if it's present
> > it's probably not going to be enabled at this point in boot.
> >
> > Signed-off-by: Joel Stanley <joel at jms.id.au>
> > ---
> >  arch/powerpc/boot/Makefile | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
> > index 0fb96c26136f..739ef8d43b91 100644
> > --- a/arch/powerpc/boot/Makefile
> > +++ b/arch/powerpc/boot/Makefile
> > @@ -32,8 +32,8 @@ else
> >  endif
> >
> >  BOOTCFLAGS    := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
> > -              -fno-strict-aliasing -Os -msoft-float -pipe \
> > -              -fomit-frame-pointer -fno-builtin -fPIC -nostdinc \
> > +              -fno-strict-aliasing -Os -msoft-float -mno-altivec -mno-vsx \
>
> That's going to break if the compiler doesn't understand -mno-vsx isn't it?
>
> I'm not sure if "support" a compiler that old though.

Segher, the kernel mandates 4.6 as the minimum. Do we need to worry
about the compiler not supporting  -mno-altivec -mno-vsx?