On Wed, Aug 9, 2023 at 1:17 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > On Tue, Aug 08, 2023 at 09:01:38AM -0700, Nick Desaulniers wrote: > > On Tue, Aug 8, 2023 at 1:03 AM kernel test robot <lkp@xxxxxxxxx> wrote: > > > > > > Hi Nick, > > > > > > kernel test robot noticed the following build errors: > > > > > > [auto build test ERROR on 52a93d39b17dc7eb98b6aa3edb93943248e03b2f] > > > > > > url: https://github.com/intel-lab-lkp/linux/commits/Nick-Desaulniers/Makefile-extrawarn-enable-Wmissing-variable-declarations-for-W-1/20230808-005859 > > > base: 52a93d39b17dc7eb98b6aa3edb93943248e03b2f > > > patch link: https://lore.kernel.org/r/20230807-missing_proto-v2-1-3ae2e188bb0c%40google.com > > > patch subject: [PATCH v2] Makefile.extrawarn: enable -Wmissing-variable-declarations for W=1 > > > config: arm64-randconfig-r013-20230807 (https://download.01.org/0day-ci/archive/20230808/202308081508.EI3CRzQo-lkp@xxxxxxxxx/config) > > > compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a) > > > reproduce: (https://download.01.org/0day-ci/archive/20230808/202308081508.EI3CRzQo-lkp@xxxxxxxxx/reproduce) > > > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > > the same patch/commit), kindly add following tags > > > | Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > | Closes: https://lore.kernel.org/oe-kbuild-all/202308081508.EI3CRzQo-lkp@xxxxxxxxx/ > > > > > > All errors (new ones prefixed by >>): > > > > > > In file included from lib/test_bitops.c:9: > > > In file included from include/linux/module.h:13: > > > In file included from include/linux/stat.h:19: > > > In file included from include/linux/time.h:60: > > > In file included from include/linux/time32.h:13: > > > In file included from include/linux/timex.h:67: > > > In file included from arch/arm64/include/asm/timex.h:8: > > > In file included from arch/arm64/include/asm/arch_timer.h:18: > > > In file included from include/linux/smp.h:110: > > > In file included from include/linux/preempt.h:79: > > > In file included from arch/arm64/include/asm/preempt.h:6: > > > In file included from include/linux/thread_info.h:60: > > > In file included from arch/arm64/include/asm/thread_info.h:18: > > > >> arch/arm64/include/asm/stack_pointer.h:8:24: error: no previous extern declaration for non-static variable 'current_stack_pointer' [-Werror,-Wmissing-variable-declarations] > > > 8 | register unsigned long current_stack_pointer asm ("sp"); > > > | ^ > > > arch/arm64/include/asm/stack_pointer.h:8:10: note: declare 'static' if the variable is not intended to be used outside of this translation unit > > > 8 | register unsigned long current_stack_pointer asm ("sp"); > > > | ^ > > > > I actually don't think that either compiler should warn for variables > > with register storage. I spoke briefly with some GCC folks on IRC and > > the initial assesment was agreed. I've filed > > - https://github.com/llvm/llvm-project/issues/64509 > > - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110947 > > > > Also, I've received 3 emails from zero day; this is expected as the > > tree is not W=1 clean (actually, I think Arnd has been a lot of > > cleanup around these groups of warnings, so I take that back). What's > > more curious to me is that none are GCC builds. I wonder if 0day bot > > team is only testing W=1 with clang and not GCC? That would seem like > > perhaps the bar is higher for LLVM? > > As far as I am aware, the 0day bot tests both compilers with W=1. I > think the more likely explanation is that the robot is not testing with > prerelease versions of GCC, which is currently 14.x, which is the only > version of GCC that has this warning implemented. > > > Masahiro, Nathan, > > What are your thoughts on how to proceed here? Do we need the tree to > > be free of warnings before it can be added to W=1? Hopefully not; I > > No, otherwise we wouldn't be adding it to W=1 ;) > > > would think that's the criteria for promoting a warning from being > > hidden behind W=1 to being on by default in the top level Makefile. > > What are your thoughts? > > I think the register storage issue should be resolved in at least clang > before this patch is accepted, as that seems to be where the majority of > warnings are coming from so far. Like we talked about, I'll take a shot > at fixing that. Once that is fixed, I'll build mainline with > -Wmissing-variable-declarations to see how many instances there are and > if there are any other interesting edge cases that should be fixed in > the compiler. After that, I think this should be good to go in. Does > that sound reasonable? Sounds reasonable! Thank you. -- Best Regards Masahiro Yamada
