On Tue, 10 Oct 2023, Jani Nikula <jani.nikula@xxxxxxxxx> wrote: > On Mon, 09 Oct 2023, Nathan Chancellor <nathan@xxxxxxxxxx> wrote: >> On Sun, Oct 08, 2023 at 12:28:46AM +0900, Masahiro Yamada wrote: >>> On Fri, Oct 6, 2023 at 9:35 PM Jani Nikula <jani.nikula@xxxxxxxxx> wrote: >>> > >>> > The kernel top level Makefile, and recently scripts/Makefile.extrawarn, >>> > have included -Wall, and the disables -Wno-format-security and >>> > $(call cc-disable-warning,frame-address,) for a very long time. They're >>> > redundant in our local subdir-ccflags-y and can be dropped. >>> > >>> > Cc: Arnd Bergmann <arnd@xxxxxxxx> >>> > Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> >>> > Cc: Nathan Chancellor <nathan@xxxxxxxxxx> >>> > Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx> >>> > Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> >>> >>> >>> I made a similar suggestion in the past >>> https://lore.kernel.org/dri-devel/20190515043753.9853-1-yamada.masahiro@xxxxxxxxxxxxx/ >>> >>> So, I am glad that Intel has decided to de-duplicate the flags. >>> >>> >>> >>> I think you can drop more flags. >>> >>> For example, >>> >>> subdir-ccflags-y += -Wno-sign-compare >>> >>> >>> It is set by scripts/Makefile.extrawarn >>> unless W=3 is passed. >>> >>> >>> If W=3 is set by a user, -Wsign-compare should be warned >>> as it is the user's request. >>> >>> >>> drivers/gpu/drm/i915/Makefile negates W=3. >>> There is no good reason to do so. >>> >>> >>> Same applied to >>> >>> >>> subdir-ccflags-y += -Wno-shift-negative-value >> >> As I point out in my review of the second patch [1], I am not sure these >> should be dropped because -Wextra turns these warnings back on, at least >> for clang according to this build report [2] and my own testing, so they >> need to be disabled again. > > Yeah. The focus is on enabling W=1 warnings by default for i915. I get > that the disables we have to add to achieve that also disable some W=2 > and W=3 warnings. But taking all of that into account requires > duplicating even more of Makefile.extrawarn (checking for warning > levels, maintaining parity with the different levels, etc.). > > I guess we could check if KBUILD_EXTRA_WARN does not have any of 1, 2, > or 3, but very few places outside of the build system look at > KBUILD_EXTRA_WARN, so feels wrong. This is the simplest I could think of: # The following turn off the warnings enabled by -Wextra ifeq ($(findstring 2, $(KBUILD_EXTRA_WARN)),) KBUILD_CFLAGS += -Wno-missing-field-initializers KBUILD_CFLAGS += -Wno-type-limits KBUILD_CFLAGS += -Wno-shift-negative-value endif ifeq ($(findstring 3, $(KBUILD_EXTRA_WARN)),) KBUILD_CFLAGS += -Wno-sign-compare endif Masahiro, I'd like to get your feedback on which to choose, unconditionally silencing the W=2/W=3 warnings for i915, or looking at KBUILD_EXTRA_WARN. Not silencing them is not an option, because we also use -Werror locally. BR, Jani. > > BR, > Jani. > > >> >> [1]: https://lore.kernel.org/20231006174550.GC3359308@dev-arch.thelio-3990X/ >> [2]: https://lore.kernel.org/202310070011.Fji48IBk-lkp@xxxxxxxxx/ >> >> Cheers, >> Nathan. -- Jani Nikula, Intel
