At least the i915 and amd drivers enable a bunch more compiler warnings than the kernel defaults. Extend the W=1 warnings to the entire drm subsystem by default. Use the copy-pasted warnings from scripts/Makefile.extrawarn with s/KBUILD_CFLAGS/subdir-ccflags-y/ to make it easier to compare and keep up with them in the future. This is similar to the approach currently used in i915. Some of the -Wextra warnings do need to be disabled, just like in Makefile.extrawarn, but take care to not disable them for W=2 or W=3 builds, depending on the warning. Cc: David Airlie <airlied@xxxxxxxxx> Cc: Daniel Vetter <daniel@xxxxxxxx> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> Cc: Maxime Ripard <mripard@xxxxxxxxxx> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx> Cc: Alex Deucher <alexander.deucher@xxxxxxx> Cc: Christian König <christian.koenig@xxxxxxx> Cc: Pan, Xinhui <Xinhui.Pan@xxxxxxx> Cc: Karol Herbst <kherbst@xxxxxxxxxx> Cc: Lyude Paul <lyude@xxxxxxxxxx> Cc: Danilo Krummrich <dakr@xxxxxxxxxx> Cc: Rob Clark <robdclark@xxxxxxxxx> Cc: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> Cc: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> Cc: Sean Paul <sean@xxxxxxxxxx> Cc: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> --- With my admittedly limited and very much x86 focused kernel config, I get some -Wunused-but-set-variable and -Wformat-truncation= warnings, but nothing we can't handle. We could fix them up front, or disable the extra warnings on a per driver basis with a FIXME comment in their respective Makefiles. With the experience from i915, I think this would significantly reduce the constant loop of warnings added by people not using W=1 and subsequently fixed by people using W=1. Note: I've Cc'd the maintainers of drm, drm misc and some of the biggest drivers. --- drivers/gpu/drm/Makefile | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index b4cb0835620a..6939e4ea13d5 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -5,6 +5,33 @@ CFLAGS-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += -DDYNAMIC_DEBUG_MODULE +# Unconditionally enable W=1 warnings locally +# --- begin copy-paste W=1 warnings from scripts/Makefile.extrawarn +subdir-ccflags-y += -Wextra -Wunused -Wno-unused-parameter +subdir-ccflags-y += -Wmissing-declarations +subdir-ccflags-y += $(call cc-option, -Wrestrict) +subdir-ccflags-y += -Wmissing-format-attribute +subdir-ccflags-y += -Wmissing-prototypes +subdir-ccflags-y += -Wold-style-definition +subdir-ccflags-y += -Wmissing-include-dirs +subdir-ccflags-y += $(call cc-option, -Wunused-but-set-variable) +subdir-ccflags-y += $(call cc-option, -Wunused-const-variable) +subdir-ccflags-y += $(call cc-option, -Wpacked-not-aligned) +subdir-ccflags-y += $(call cc-option, -Wformat-overflow) +subdir-ccflags-y += $(call cc-option, -Wformat-truncation) +subdir-ccflags-y += $(call cc-option, -Wstringop-overflow) +subdir-ccflags-y += $(call cc-option, -Wstringop-truncation) +# The following turn off the warnings enabled by -Wextra +ifeq ($(findstring 2, $(KBUILD_EXTRA_WARN)),) +subdir-ccflags-y += -Wno-missing-field-initializers +subdir-ccflags-y += -Wno-type-limits +subdir-ccflags-y += -Wno-shift-negative-value +endif +ifeq ($(findstring 3, $(KBUILD_EXTRA_WARN)),) +subdir-ccflags-y += -Wno-sign-compare +endif +# --- end copy-paste + drm-y := \ drm_aperture.o \ drm_atomic.o \ -- 2.39.2
