Messages in this thread Patch in this message | | | Date | Thu, 14 Jul 2022 13:24:23 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH] drm/amd/display: Add missing hard-float compile flags for PPC64 builds |
| |
On 7/14/22 11:49, Melissa Wen wrote: > O 07/13, Alex Deucher wrote: >> On Wed, Jul 13, 2022 at 7:09 PM Guenter Roeck <linux@roeck-us.net> wrote: >>> >>> On Wed, Jul 13, 2022 at 05:20:40PM -0400, Alex Deucher wrote: >>>>> >>>>> The problem is not the FPU operations, but the fact that soft-float >>>>> and hard-float compiled code is linked together. The soft-float and >>>>> hard-float ABIs on powerpc are not compatible, so one ends up with >>>>> an object file which is partially soft-float and partially hard-float >>>>> compiled and thus uses different ABIs. That can only create chaos, >>>>> so the linker complains about it. >>>> >>>> I get that, I just don't see why only DCN 3.1.x files have this >>>> problem. The DCN 2.x files should as well. >>>> >>> >>> Seen in drivers/gpu/drm/amd/display/dc/clk_mgr/Makefile: >>> >>> # prevent build errors regarding soft-float vs hard-float FP ABI tags >>> # this code is currently unused on ppc64, as it applies to Renoir APUs only >>> ifdef CONFIG_PPC64 >>> CFLAGS_$(AMDDALPATH)/dc/clk_mgr/dcn21/rn_clk_mgr.o := $(call cc-option,-mno-gnu-attribute) >>> endif >>> >>> Does that explain it ? >> >> I would expect to see it in dcn20_resource.c and dcn30_clk_mgr.c for >> example. They follow the same pattern as the dcn 3.1.x files. They >> call functions that use FP, but maybe there is some FP code still in >> those functions that we missed somehow. > > Hi, > > I'm a little late here, but I'm not able to reproduce the issue yet. > I have this setup: > - gcc 11.3.0 > - binutils 2.38.50 > - mainline kernel (torvalds) version: 5.19.0-rc6 (cross-compiling) > -> make ARCH=powerpc CROSS_COMPILE=powerpc64-linux-gnu- allmodconfig > => DRM_AMD_DC [=y] && HAS_IOMEM [=y] && DRM [=m] && DRM_AMDGPU [=m] && (X86 || PPC64 [=y]) && (!KCOV_INSTRUMENT_ALL [=n] || !KCOV_ENABLE_COMPARISONS [=n]) > -> make -j16 ARCH=powerpc CROSS_COMPILE=powerpc64-linux-gnu- > > Am I missing something? > > So, as Alex mentioned the possibility of some non-isolated FPU code in > 3.1, I reviewed dcn31 code and my best bet so far is that the issue > is here: > > https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c#L1721 > > Although dcn31_update_soc_for_wm_a() is only called inside > dml/dcn31/dcn31_fpu: > - dc->res_pool->funcs->update_soc_for_wm_a(dc, context); > > it's declared in dcn31_resource and has FPU code. So, we should move it > to dml/dcn31/dcn31_fpu. > > However, as I can't reproduce the issue, I don't know if it addresses > the problem reported here and also if everything will be clean after > moving it. >
I don't think that would solve anything. As I have tried to point out, the problem is that code compiled with hard-float is linked together with code compiled with soft-float. An alternate fix might be something like the one attached below, but I don't know if that would be correct and/or complete.
> Guenter, > > Can you provide more info about your setup: cross-compile or not, any > flags, branch, etc? >
Nothing special. Same compile options as the ones you use, and it is a cross-compile environment. I tried gcc 11.2.0 with binutils 2.36.1 and gcc 11.3.0 with binutils 2.38.
Guenter
--- diff --git a/drivers/gpu/drm/amd/display/dc/dcn31/Makefile b/drivers/gpu/drm/amd/display/dc/dcn31/Makefile index ec041e3cda30..44ff6f196860 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn31/Makefile +++ b/drivers/gpu/drm/amd/display/dc/dcn31/Makefile @@ -10,6 +10,8 @@ # # Makefile for dcn31.
+CFLAGS_$(AMDDALPATH)/dc/dcn31/dcn31_resource.o := $(call cc-option,-mno-gnu-attribute) + DCN31 = dcn31_resource.o dcn31_hubbub.o dcn31_hwseq.o dcn31_init.o dcn31_hubp.o \ dcn31_dccg.o dcn31_optc.o dcn31_dio_link_encoder.o dcn31_panel_cntl.o \ dcn31_apg.o dcn31_hpo_dp_stream_encoder.o dcn31_hpo_dp_link_encoder.o \ diff --git a/drivers/gpu/drm/amd/display/dc/dcn315/Makefile b/drivers/gpu/drm/amd/display/dc/dcn315/Makefile index 59381d24800b..55fcae2d2aae 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn315/Makefile +++ b/drivers/gpu/drm/amd/display/dc/dcn315/Makefile @@ -25,6 +25,8 @@
DCN315 = dcn315_resource.o
+CFLAGS_$(AMDDALPATH)/dc/dcn315/$(DCN315) := $(call cc-option,-mno-gnu-attribute) + AMD_DAL_DCN315 = $(addprefix $(AMDDALPATH)/dc/dcn315/,$(DCN315))
AMD_DISPLAY_FILES += $(AMD_DAL_DCN315) diff --git a/drivers/gpu/drm/amd/display/dc/dcn316/Makefile b/drivers/gpu/drm/amd/display/dc/dcn316/Makefile index 819d44a9439b..7251ef9c1afb 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn316/Makefile +++ b/drivers/gpu/drm/amd/display/dc/dcn316/Makefile @@ -25,6 +25,8 @@
DCN316 = dcn316_resource.o
+CFLAGS_$(AMDDALPATH)/dc/dcn316/$(DCN316) := $(call cc-option,-mno-gnu-attribute) + AMD_DAL_DCN316 = $(addprefix $(AMDDALPATH)/dc/dcn316/,$(DCN316))
AMD_DISPLAY_FILES += $(AMD_DAL_DCN316)
| |