Re: [PATCH] kbuild: add $(CLANG_CFLAGS) to KBUILD_CPPFLAGS

[Nathan Chancellor <nathan@kernel.org>]

On Mon, Apr 10, 2023 at 04:09:37AM +0800, kernel test robot wrote:
> Hi Masahiro,
> 
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on masahiroy-kbuild/for-next]
> [also build test WARNING on masahiroy-kbuild/fixes linus/master v6.3-rc6 next-20230406]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Masahiro-Yamada/kbuild-add-CLANG_CFLAGS-to-KBUILD_CPPFLAGS/20230409-225441
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
> patch link:    https://lore.kernel.org/r/20230409145358.2538266-1-masahiroy%40kernel.org
> patch subject: [PATCH] kbuild: add $(CLANG_CFLAGS) to KBUILD_CPPFLAGS
> config: mips-ip22_defconfig (https://download.01.org/0day-ci/archive/20230410/202304100319.Wfcfuyqz-lkp@intel.com/config)
> compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project 2c57868e2e877f73c339796c3374ae660bb77f0d)
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # install mips cross compiling tool for clang build
>         # apt-get install binutils-mips-linux-gnu
>         # https://github.com/intel-lab-lkp/linux/commit/4a97e93c7f8c2aaf7bcca67a061264a1126d0e25
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review Masahiro-Yamada/kbuild-add-CLANG_CFLAGS-to-KBUILD_CPPFLAGS/20230409-225441
>         git checkout 4a97e93c7f8c2aaf7bcca67a061264a1126d0e25
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=mips olddefconfig
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=mips prepare
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Link: https://lore.kernel.org/oe-kbuild-all/202304100319.Wfcfuyqz-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> clang: warning: argument unused during compilation: '-mno-check-zero-division' [-Wunused-command-line-argument]
>    clang: warning: argument unused during compilation: '-mabi=32' [-Wunused-command-line-argument]
> >> clang: warning: argument unused during compilation: '-G 0' [-Wunused-command-line-argument]
> >> clang: warning: argument unused during compilation: '-mno-abicalls' [-Wunused-command-line-argument]
>    error: unknown target CPU 'r5000'
>    note: valid target CPU values are: nocona, core2, penryn, bonnell, atom, silvermont, slm, goldmont, goldmont-plus, tremont, nehalem, corei7, westmere, sandybridge, corei7-avx, ivybridge, core-avx-i, haswell, core-avx2, broadwell, skylake, skylake-avx512, skx, cascadelake, cooperlake, cannonlake, icelake-client, rocketlake, icelake-server, tigerlake, sapphirerapids, alderlake, raptorlake, meteorlake, sierraforest, grandridge, graniterapids, emeraldrapids, knl, knm, k8, athlon64, athlon-fx, opteron, k8-sse3, athlon64-sse3, opteron-sse3, amdfam10, barcelona, btver1, btver2, bdver1, bdver2, bdver3, bdver4, znver1, znver2, znver3, znver4, x86-64, x86-64-v2, x86-64-v3, x86-64-v4

While r5000 is not a valid MIPS CPU for LLVM (as you can see from the
values below), the note here seems to imply that there is a place where
KBUILD_{A,C}FLAGS is used without KBUILD_CPPFLAGS because we are
dropping '--target'. V=1 does not make it obvious where that is
happening though, as I see the error right after syncing the
configuration (is it coming from Kconfig internally?). I can see the
same issue with 32r2_defconfig, which uses an LLVM supported CPU value.

>    scripts/genksyms/parse.y: warning: 9 shift/reduce conflicts [-Wconflicts-sr]
>    scripts/genksyms/parse.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
>    scripts/genksyms/parse.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
>    error: unknown target CPU 'r5000'
>    note: valid target CPU values are: mips1, mips2, mips3, mips4, mips5, mips32, mips32r2, mips32r3, mips32r5, mips32r6, mips64, mips64r2, mips64r3, mips64r5, mips64r6, octeon, octeon+, p5600
>    make[2]: *** [scripts/Makefile.build:252: scripts/mod/empty.o] Error 1
>    error: unknown target CPU 'r5000'
>    note: valid target CPU values are: mips1, mips2, mips3, mips4, mips5, mips32, mips32r2, mips32r3, mips32r5, mips32r6, mips64, mips64r2, mips64r3, mips64r5, mips64r6, octeon, octeon+, p5600
>    make[2]: *** [scripts/Makefile.build:114: scripts/mod/devicetable-offsets.s] Error 1
>    make[2]: Target 'scripts/mod/' not remade because of errors.
>    make[1]: *** [Makefile:1285: prepare0] Error 2
>    make[1]: Target 'prepare' not remade because of errors.
>    make: *** [Makefile:226: __sub-make] Error 2
>    make: Target 'prepare' not remade because of errors.
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests