On Mon, Aug 16, 2021 at 1:06 PM Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote: > > On Fri, Aug 13, 2021 at 6:43 PM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote: > > > > On Wed, Aug 11, 2021 at 5:42 AM Nick Desaulniers > > <ndesaulniers@xxxxxxxxxx> wrote: > > > > > > diff --git a/Makefile b/Makefile > > > index 027fdf2a14fe..3e3fb4affba1 100644 > > > --- a/Makefile > > > +++ b/Makefile > > > @@ -798,7 +801,7 @@ include/config/auto.conf: > > > endif # may-sync-config > > > endif # need-config > > > > > > -KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,) > > > +KBUILD_CFLAGS += -fno-delete-null-pointer-checks > > > KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) > > > KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation) > > > KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow) > > > @@ -844,17 +847,17 @@ KBUILD_RUSTFLAGS += -Copt-level=z > > > endif > > > > > > # Tell gcc to never replace conditional load with a non-conditional one > > > -KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0) > > > +ifdef CONFIG_CC_IS_GCC > > > > > > Can you insert a comment here? > > > > # GCC 10 renamed --param=allow-store-data-races=0 to --allow-store-data-races > > > > > > It will remind us of dropping this conditional > > in the (long long distant) future. > > > > > > > > > > > +KBUILD_CFLAGS += $(call cc-option,--allow-store-data-races,--param=allow-store-data-races=0) > > > KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races) > > > +endif > > So it looks like `-fallow-store-data-races` was also supported. Reading through > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97309 > https://gcc.gnu.org/wiki/Atomic/GCCMM/ExecutiveSummary > it seems that the default is not to allow "store data races." So I > should not be adding `--allow-store-data-races` or > `-fallow-store-data-races`; so this just should be the existing test, > with a comment that it can be removed once gcc-10+ is the minimum. > Will update that in v2. Ah, perhaps I should combine the following line: KBUILD_CFLAGS += $(call cc-option,-fallow-store-data-races,--param=allow-store-data-races=0) Though I don't understand the csky failure. cc-option appends to a running list of flags; if an unsupported flag gets added to CFLAGS, it can cause cc-option to failure subsequent checks in spooky ways. I usually debug those by adding print statements to cc-option to see what the full command it's testing; then invoke the compiler manually with those to see what went wrong. (bookmarked and referenced often: https://stackoverflow.com/questions/16467718/how-to-print-out-a-variable-in-makefile) Though my distro doesn't package csky-linux-gnu-gcc... -- Thanks, ~Nick Desaulniers
