From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: [PATCH] drm/amd/display: add -msse2 to prevent Clang from emitting libcalls to undefined SW FP routines Date: Tue, 29 Jan 2019 10:56:01 -0800 Message-ID: <20190129185601.GA17525@roeck-us.net> References: <20190125005304.183322-1-ndesaulniers@google.com> <04bc6844-2a3b-2de8-60a7-a027149709fd@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: stable-owner@vger.kernel.org To: Alex Deucher Cc: "Wentland, Harry" , "ndesaulniers@google.com" , "airlied@linux.ie" , "daniel@ffwll.ch" , "S@google.com" , "Laktyushkin, Dmytro" , "Zhou, David(ChunMing)" , "Li, Sun peng (Leo)" , "dri-devel@lists.freedesktop.org" , "Daenzer, Michel" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , "S, Shirish" , Matthias Kaehlcke , Matthias Kaehlcke , "amd-gfx@lists.freedesktop.org" , James Y Knight List-Id: dri-devel@lists.freedesktop.org On Tue, Jan 29, 2019 at 10:30:31AM -0500, Alex Deucher wrote: > On Fri, Jan 25, 2019 at 10:29 AM Wentland, Harry wrote: > > > > On 2019-01-24 7:52 p.m., ndesaulniers@google.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@vger.kernel.org # 4.19 > > > Reported-by: S, Shirish > > > Reported-by: Matthias Kaehlcke > > > Suggested-by: James Y Knight > > > Suggested-by: Nathan Chancellor > > > Signed-off-by: Nick Desaulniers > > > Tested-by: Guenter Roeck > > > > Reviewed-by: Harry Wentland > > > > and applied. > > > > This patch causes a segfault: > https://bugs.freedesktop.org/show_bug.cgi?id=109487 > > Any ideas? > Set -msse2 only for clang ? I suspect, though, that this might only solve the compile problem. If I understand correctly, the first warning in the log is due to BREAK_TO_DEBUGGER(), suggesting that something is seriously wrong. Maybe enabling sse2 results in different results from floating point operations. Unfortunately I don't have a system with the affected GPU, so I can't run any tests on real hardware. Unless someone can test with real hardware, I think we have no choice but to revert the patch. Guenter > Alex > > > 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) > > > > > _______________________________________________ > > amd-gfx mailing list > > amd-gfx@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/amd-gfx