2021-09-30 16:04:19

by Nathan Chancellor

Subject: [PATCH] drm/amd: Guard IS_OLD_GCC assignment with CONFIG_CC_IS_GCC

cc-ifversion only works for GCC, as clang pretends to be GCC 4.2.1 for
glibc compatibility, which means IS_OLD_GCC will get set and unsupported
flags will be passed to clang when building certain code within the DCN
files:

clang-14: error: unknown argument: '-mpreferred-stack-boundary=4'
make[5]: *** [scripts/Makefile.build:277: drivers/gpu/drm/amd/amdgpu/../display/dc/dcn201/dcn201_resource.o] Error 1

Guard the call to cc-ifversion with CONFIG_CC_IS_GCC so that everything
continues to work properly. See commit 00db297106e8 ("drm/amdgpu: fix stack
alignment ABI mismatch for GCC 7.1+") for more context.

Fixes: ff7e396f822f ("drm/amd/display: add cyan_skillfish display support")
Link: https://github.com/ClangBuiltLinux/linux/issues/1468
Signed-off-by: Nathan Chancellor <[email protected]>
---
drivers/gpu/drm/amd/display/dc/dcn201/Makefile | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn201/Makefile b/drivers/gpu/drm/amd/display/dc/dcn201/Makefile
index d98d69705117..96cbd4ccd344 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn201/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/dcn201/Makefile
@@ -14,9 +14,11 @@ ifdef CONFIG_PPC64
CFLAGS_$(AMDDALPATH)/dc/dcn201/dcn201_resource.o := -mhard-float -maltivec
endif

+ifdef CONFIG_CC_IS_GCC
ifeq ($(call cc-ifversion, -lt, 0701, y), y)
IS_OLD_GCC = 1
endif
+endif

ifdef CONFIG_X86
ifdef IS_OLD_GCC

base-commit: b47b99e30cca8906753c83205e8c6179045dd725
--
2.33.0.591.gddb1055343

2021-09-30 17:32:08

by Nick Desaulniers

Subject: Re: [PATCH] drm/amd: Guard IS_OLD_GCC assignment with CONFIG_CC_IS_GCC

On Thu, Sep 30, 2021 at 9:02 AM Nathan Chancellor <[email protected]> wrote:
>
> cc-ifversion only works for GCC, as clang pretends to be GCC 4.2.1 for
> glibc compatibility, which means IS_OLD_GCC will get set and unsupported
> flags will be passed to clang when building certain code within the DCN
> files:
>
> clang-14: error: unknown argument: '-mpreferred-stack-boundary=4'
> make[5]: *** [scripts/Makefile.build:277: drivers/gpu/drm/amd/amdgpu/../display/dc/dcn201/dcn201_resource.o] Error 1
>
> Guard the call to cc-ifversion with CONFIG_CC_IS_GCC so that everything
> continues to work properly. See commit 00db297106e8 ("drm/amdgpu: fix stack
> alignment ABI mismatch for GCC 7.1+") for more context.
>
> Fixes: ff7e396f822f ("drm/amd/display: add cyan_skillfish display support")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1468
> Signed-off-by: Nathan Chancellor <[email protected]>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <[email protected]>

$ grep -rn "ifdef IS_OLD_GCC" drivers/gpu/drm/amd/display/dc/ | wc -l
11

It's probably time to put this pattern in a Makefile under scripts/
and include it in all of these Makefiles. Anything to minimize the
amount of code that has to be carried forward to new subdirs.

> ---
> drivers/gpu/drm/amd/display/dc/dcn201/Makefile | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn201/Makefile b/drivers/gpu/drm/amd/display/dc/dcn201/Makefile
> index d98d69705117..96cbd4ccd344 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn201/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/dcn201/Makefile
> @@ -14,9 +14,11 @@ ifdef CONFIG_PPC64
> CFLAGS_$(AMDDALPATH)/dc/dcn201/dcn201_resource.o := -mhard-float -maltivec
> endif
>
> +ifdef CONFIG_CC_IS_GCC
> ifeq ($(call cc-ifversion, -lt, 0701, y), y)
> IS_OLD_GCC = 1
> endif
> +endif
>
> ifdef CONFIG_X86
> ifdef IS_OLD_GCC
>
> base-commit: b47b99e30cca8906753c83205e8c6179045dd725
> --
> 2.33.0.591.gddb1055343
>


--
Thanks,
~Nick Desaulniers

2021-09-30 21:54:07

by Alex Deucher

Subject: Re: [PATCH] drm/amd: Guard IS_OLD_GCC assignment with CONFIG_CC_IS_GCC

On Thu, Sep 30, 2021 at 12:02 PM Nathan Chancellor <[email protected]> wrote:
>
> cc-ifversion only works for GCC, as clang pretends to be GCC 4.2.1 for
> glibc compatibility, which means IS_OLD_GCC will get set and unsupported
> flags will be passed to clang when building certain code within the DCN
> files:
>
> clang-14: error: unknown argument: '-mpreferred-stack-boundary=4'
> make[5]: *** [scripts/Makefile.build:277: drivers/gpu/drm/amd/amdgpu/../display/dc/dcn201/dcn201_resource.o] Error 1
>
> Guard the call to cc-ifversion with CONFIG_CC_IS_GCC so that everything
> continues to work properly. See commit 00db297106e8 ("drm/amdgpu: fix stack
> alignment ABI mismatch for GCC 7.1+") for more context.
>
> Fixes: ff7e396f822f ("drm/amd/display: add cyan_skillfish display support")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1468
> Signed-off-by: Nathan Chancellor <[email protected]>

Harry beat you to the punch by a little bit.

Thanks!

Alex

> ---
> drivers/gpu/drm/amd/display/dc/dcn201/Makefile | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn201/Makefile b/drivers/gpu/drm/amd/display/dc/dcn201/Makefile
> index d98d69705117..96cbd4ccd344 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn201/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/dcn201/Makefile
> @@ -14,9 +14,11 @@ ifdef CONFIG_PPC64
> CFLAGS_$(AMDDALPATH)/dc/dcn201/dcn201_resource.o := -mhard-float -maltivec
> endif
>
> +ifdef CONFIG_CC_IS_GCC
> ifeq ($(call cc-ifversion, -lt, 0701, y), y)
> IS_OLD_GCC = 1
> endif
> +endif
>
> ifdef CONFIG_X86
> ifdef IS_OLD_GCC
>
> base-commit: b47b99e30cca8906753c83205e8c6179045dd725
> --
> 2.33.0.591.gddb1055343
>