On Tue, Feb 08, 2022 at 01:23:32PM +0900, Masahiro Yamada wrote: > On Thu, Feb 3, 2022 at 8:12 AM Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote: > > > > On Wed, Feb 2, 2022 at 3:07 PM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > > > > > -Wunaligned-access is a new warning in clang that is default enabled for > > > arm and arm64 under certain circumstances within the clang frontend (see > > > LLVM commit below). On v5.17-rc2, an ARCH=arm allmodconfig build shows > > > 1284 total/70 unique instances of this warning (most of the instances > > > are in header files), which is quite noisy. > > > > > > To keep a normal build green through CONFIG_WERROR, only show this > > > warning with W=1, which will allow automated build systems to catch new > > > instances of the warning so that the total number can be driven down to > > > zero eventually since catching unaligned accesses at compile time would > > > be generally useful. > > > > > > Cc: stable@xxxxxxxxxxxxxxx > > > Link: https://github.com/llvm/llvm-project/commit/35737df4dcd28534bd3090157c224c19b501278a > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1569 > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1576 > > > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> > > > > Thanks to you and Arnd for working out whether this is important to > > pursue. Sounds like it is. > > Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > > > > --- > > > I assume this should be considered as a bug fix > to avoid the error for the combination of CONFIG_WERROR=y > and the latest Clang. > > Applied to linux-kbuild/fixes. > Thanks. Yes, this is what I was hoping for! Thank you, I'll try to make that more clear in the future. Cheers, Nathan > > > > > > v1 -> v2: https://lore.kernel.org/r/20220201232229.2992968-1-nathan@xxxxxxxxxx/ > > > > > > * Move to W=1 instead of W=2 so that new instances are caught (Arnd). > > > * Add links to the ClangBuiltLinux issue tracker. > > > > > > scripts/Makefile.extrawarn | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > > > index d53825503874..8be892887d71 100644 > > > --- a/scripts/Makefile.extrawarn > > > +++ b/scripts/Makefile.extrawarn > > > @@ -51,6 +51,7 @@ KBUILD_CFLAGS += -Wno-sign-compare > > > KBUILD_CFLAGS += -Wno-format-zero-length > > > KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast) > > > KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare > > > +KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access) > > > endif > > > > > > endif > > > > > > base-commit: 26291c54e111ff6ba87a164d85d4a4e134b7315c > > > -- > > > 2.35.1 > > > > > > > > > -- > > Thanks, > > ~Nick Desaulniers > > > > -- > Best Regards > Masahiro Yamada
