Hi Arnd, 2017-07-20 16:24 GMT+09:00 Arnd Bergmann <arnd@xxxxxxxx>: > On Wed, Jul 19, 2017 at 11:50 PM, <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: >> ------------------------------------------------------ >> From: Arnd Bergmann <arnd@xxxxxxxx> >> Subject: kbuild: disable -Wformat-truncation warnings by default >> >> With x86 allmodconfig, we currently get 233 -Wformat-truncation warnings, >> which makes the entire warnings rather useless. >> >> This turns off the warning by default, unless we specify W=1 or higher >> >> Link: http://lkml.kernel.org/r/20170714120720.906842-2-arnd@xxxxxxxx >> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> >> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >> --- >> >> scripts/Makefile.extrawarn | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff -puN scripts/Makefile.extrawarn~kbuild-disable-wformat-truncation-warnings-by-default scripts/Makefile.extrawarn >> --- a/scripts/Makefile.extrawarn~kbuild-disable-wformat-truncation-warnings-by-default >> +++ a/scripts/Makefile.extrawarn >> @@ -67,5 +67,8 @@ KBUILD_CFLAGS += $(call cc-disable-warni >> KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare) >> KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length) >> KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized) >> +else >> +# noisy gcc-7 warnings >> +KBUILD_CFLAGS += $(call cc-option,-Wformat-truncation=0) >> endif >> endif > > Hi Andrew, Linus, Greg, > > I noticed that Linus has made a similar patch in 4.13-rc1, commit bd664f6b3e37 > ("disable new gcc-7.1.1 warnings for now"), and it completely disables three > warnings (format-truncation, format-overflow and int-in-bool-context). > > Obviously there is no point in having both, so let's talk about what we > want for 4.13, stable-backports and for future kernels, I'll then send those > patches. Here is my first suggestion: > > - enable all three warnings with "make W=1" in 4.13, but leave them > disabled by default. > - backport Linus' patch, plus the follow-up for W=1 to stable kernels, > to allow stable kernels to build cleanly > - backport the patches that address any other gcc-7 warnings, as > well as those that are not obvious false-positives to stable kernels > - In 4.14+, use my version above and address all int-in-bool-context > and format-overflow warnings, but only use -Wformat-truncation > with make W=1. > Talking about 4.14+, shall we move -Wformat-truncation from the top Makefile (always disable) to Makefile.extrawarn (enable with W=1) ? -- Best Regards Masahiro Yamada -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
