Re: [PATCH 4/6] drm/amd/display: fix dcn21 Makefile for clang

[Alex Deucher]

On Wed, Oct 2, 2019 at 5:19 PM Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote:
>
> On Wed, Oct 2, 2019 at 5:03 AM Arnd Bergmann <arnd@xxxxxxxx> wrote:
> >
> > Just like all the other variants, this one passes invalid
> > compile-time options with clang after the new code got
> > merged:
> >
> > clang: error: unknown argument: '-mpreferred-stack-boundary=4'
> > scripts/Makefile.build:265: recipe for target 'drivers/gpu/drm/amd/amdgpu/../display/dc/dcn21/dcn21_resource.o' failed
> >
> > Use the same variant that we have for dcn20 to fix compilation.
> >
> > Fixes: eced51f9babb ("drm/amd/display: Add hubp block for Renoir (v2)")
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
>
> Thanks for the patch!
> Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> (Though I think it's already been merged)
>
> Alex, do you know why the AMDGPU driver uses a different stack
> alignment (16B) than the rest of the x86 kernel?  (see
> arch/x86/Makefile which uses 8B stack alignment).

Not sure.  Maybe Harry can comment.  I think it was added for the
floating point stuff.  Not sure if it's strictly required or not.

Alex

>
> > ---
> >  drivers/gpu/drm/amd/display/dc/dcn21/Makefile | 12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/dc/dcn21/Makefile b/drivers/gpu/drm/amd/display/dc/dcn21/Makefile
> > index 8cd9de8b1a7a..ef673bffc241 100644
> > --- a/drivers/gpu/drm/amd/display/dc/dcn21/Makefile
> > +++ b/drivers/gpu/drm/amd/display/dc/dcn21/Makefile
> > @@ -3,7 +3,17 @@
> >
> >  DCN21 = dcn21_hubp.o dcn21_hubbub.o dcn21_resource.o
> >
> > -CFLAGS_$(AMDDALPATH)/dc/dcn21/dcn21_resource.o := -mhard-float -msse -mpreferred-stack-boundary=4
> > +ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
> > +       cc_stack_align := -mpreferred-stack-boundary=4
> > +else ifneq ($(call cc-option, -mstack-alignment=16),)
> > +       cc_stack_align := -mstack-alignment=16
> > +endif
> > +
> > +CFLAGS_$(AMDDALPATH)/dc/dcn21/dcn21_resource.o := -mhard-float -msse $(cc_stack_align)
> > +
> > +ifdef CONFIG_CC_IS_CLANG
> > +CFLAGS_$(AMDDALPATH)/dc/dcn21/dcn21_resource.o += -msse2
> > +endif
> >
> >  AMD_DAL_DCN21 = $(addprefix $(AMDDALPATH)/dc/dcn21/,$(DCN21))
> >
> > --
> > 2.20.0
> >
> > --
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>
>
>
> --
> Thanks,
> ~Nick Desaulniers
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