linux-kernel - Re: [PATCH] drm/amd/display: add -msse2 to prevent Clang from emitting libcalls to undefined SW FP routines

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Message-ID: <04bc6844-2a3b-2de8-60a7-a027149709fd@amd.com>
Date:   Fri, 25 Jan 2019 15:29:37 +0000
From:   "Wentland, Harry" <Harry.Wentland@....com>
To:     "ndesaulniers@...gle.com" <ndesaulniers@...gle.com>,
        "airlied@...ux.ie" <airlied@...ux.ie>,
        "daniel@...ll.ch" <daniel@...ll.ch>
CC:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "S@...gle.com" <S@...gle.com>, "S, Shirish" <Shirish.S@....com>,
        Matthias Kaehlcke <mka@...gle.com>,
        James Y Knight <jyknight@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Guenter Roeck <linux@...ck-us.net>,
        "Li, Sun peng (Leo)" <Sunpeng.Li@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        "Zhou, David(ChunMing)" <David1.Zhou@....com>,
        Matthias Kaehlcke <mka@...omium.org>,
        "Daenzer, Michel" <Michel.Daenzer@....com>,
        "Cheng, Tony" <Tony.Cheng@....com>,
        "Laktyushkin, Dmytro" <Dmytro.Laktyushkin@....com>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/amd/display: add -msse2 to prevent Clang from
 emitting libcalls to undefined SW FP routines

On 2019-01-24 7:52 p.m., ndesaulniers@...gle.com wrote:
> arch/x86/Makefile disables SSE and SSE2 for the whole kernel.  The
> AMDGPU drivers modified in this patch re-enable SSE but not SSE2.  Turn
> on SSE2 to support emitting double precision floating point instructions
> rather than calls to non-existent (usually available from gcc_s or
> compiler_rt) floating point helper routines.
> 
> Link: https://gcc.gnu.org/onlinedocs/gccint/Soft-float-library-routines.html
> Link: https://github.com/ClangBuiltLinux/linux/issues/327
> Cc: stable@...r.kernel.org # 4.19
> Reported-by: S, Shirish <Shirish.S@....com>
> Reported-by: Matthias Kaehlcke <mka@...gle.com>
> Suggested-by: James Y Knight <jyknight@...gle.com>
> Suggested-by: Nathan Chancellor <natechancellor@...il.com>
> Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
> Tested-by: Guenter Roeck <linux@...ck-us.net>

Reviewed-by: Harry Wentland <harry.wentland@....com>

and applied.

Harry

> ---
>  drivers/gpu/drm/amd/display/dc/calcs/Makefile | 2 +-
>  drivers/gpu/drm/amd/display/dc/dml/Makefile   | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/calcs/Makefile b/drivers/gpu/drm/amd/display/dc/calcs/Makefile
> index 95f332ee3e7e..dc85a3c088af 100644
> --- a/drivers/gpu/drm/amd/display/dc/calcs/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/calcs/Makefile
> @@ -30,7 +30,7 @@ else ifneq ($(call cc-option, -mstack-alignment=16),)
>  	cc_stack_align := -mstack-alignment=16
>  endif
>  
> -calcs_ccflags := -mhard-float -msse $(cc_stack_align)
> +calcs_ccflags := -mhard-float -msse -msse2 $(cc_stack_align)
>  
>  CFLAGS_dcn_calcs.o := $(calcs_ccflags)
>  CFLAGS_dcn_calc_auto.o := $(calcs_ccflags)
> diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> index d97ca6528f9d..33c7d7588712 100644
> --- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> @@ -30,7 +30,7 @@ else ifneq ($(call cc-option, -mstack-alignment=16),)
>  	cc_stack_align := -mstack-alignment=16
>  endif
>  
> -dml_ccflags := -mhard-float -msse $(cc_stack_align)
> +dml_ccflags := -mhard-float -msse -msse2 $(cc_stack_align)
>  
>  CFLAGS_display_mode_lib.o := $(dml_ccflags)
>  CFLAGS_display_pipe_clocks.o := $(dml_ccflags)
>