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@xxxxxxxxxxxx> 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)
