On Mon, Oct 26, 2020 at 11:03:13PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@xxxxxxxx> > > This warning behaves differently depending on the architecture > and compiler. Using x86 gcc, we get no output at all because > gcc knows the architecture can handle unaligned accesses. > > Using x86 clang, or gcc on an architecture that needs to > manually deal with unaligned accesses, the build log is > completely flooded with these warnings, as they are commonly > invoked by inline functions of networking headers, e.g. > > include/linux/skbuff.h:1426:26: warning: cast increases required alignment of target type [-Wcast-align] > > The compiler is correct to point this out, as we are dealing > with undefined behavior that does cause problems in practice, > but there is also no good way to rewrite the code in commonly > included headers to a safer method. > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Always sad to see a warning move further down the list but noisy headers are rough to deal with. This seems okay. Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > --- > scripts/Makefile.extrawarn | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > index 95e4cdb94fe9..6baee1200615 100644 > --- a/scripts/Makefile.extrawarn > +++ b/scripts/Makefile.extrawarn > @@ -60,7 +60,6 @@ endif > # > ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),) > > -KBUILD_CFLAGS += -Wcast-align > KBUILD_CFLAGS += -Wdisabled-optimization > KBUILD_CFLAGS += -Wnested-externs > KBUILD_CFLAGS += -Wshadow > @@ -80,6 +79,7 @@ endif > ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),) > > KBUILD_CFLAGS += -Wbad-function-cast > +KBUILD_CFLAGS += -Wcast-align > KBUILD_CFLAGS += -Wcast-qual > KBUILD_CFLAGS += -Wconversion > KBUILD_CFLAGS += -Wpacked > -- > 2.27.0 >
