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> > --- > > 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
