# git rev-parse -q --verify df85055f4421b6d147cca0ac6df8535392128775^{commit}
# git fetch -q -n -f git://gitlab.ozlabs.ibm.com/linuxppc/linux.git next-test
# git rev-parse -q --verify df85055f4421b6d147cca0ac6df8535392128775^{commit}
df85055f4421b6d147cca0ac6df8535392128775
# git checkout -q -f -B kisskb df85055f4421b6d147cca0ac6df8535392128775
# git clean -qxdf
# < git log -1
# commit df85055f4421b6d147cca0ac6df8535392128775
# Author: Nathan Chancellor <nathan@kernel.org>
# Date:   Fri May 28 11:27:52 2021 -0700
# 
#     powerpc/barrier: Avoid collision with clang's __lwsync macro
#     
#     A change in clang 13 results in the __lwsync macro being defined as
#     __builtin_ppc_lwsync, which emits 'lwsync' or 'msync' depending on what
#     the target supports. This breaks the build because of -Werror in
#     arch/powerpc, along with thousands of warnings:
#     
#      In file included from arch/powerpc/kernel/pmc.c:12:
#      In file included from include/linux/bug.h:5:
#      In file included from arch/powerpc/include/asm/bug.h:109:
#      In file included from include/asm-generic/bug.h:20:
#      In file included from include/linux/kernel.h:12:
#      In file included from include/linux/bitops.h:32:
#      In file included from arch/powerpc/include/asm/bitops.h:62:
#      arch/powerpc/include/asm/barrier.h:49:9: error: '__lwsync' macro redefined [-Werror,-Wmacro-redefined]
#      #define __lwsync()      __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory")
#             ^
#      <built-in>:308:9: note: previous definition is here
#      #define __lwsync __builtin_ppc_lwsync
#             ^
#      1 error generated.
#     
#     Undefine this macro so that the runtime patching introduced by
#     commit 2d1b2027626d ("powerpc: Fixup lwsync at runtime") continues to
#     work properly with clang and the build no longer breaks.
#     
#     Cc: stable@vger.kernel.org
#     Signed-off-by: Nathan Chancellor <nathan@kernel.org>
#     Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://github.com/ClangBuiltLinux/linux/issues/1386
#     Link: https://github.com/llvm/llvm-project/commit/62b5df7fe2b3fda1772befeda15598fbef96a614
#     Link: https://lore.kernel.org/r/20210528182752.1852002-1-nathan@kernel.org
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version
# < git log --format=%s --max-count=1 df85055f4421b6d147cca0ac6df8535392128775
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_pseries_defconfig+FA_DUMP_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  pseries_defconfig
# Added to kconfig CONFIG_CRASH_DUMP=y
# Added to kconfig CONFIG_FA_DUMP=y
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_pseries_defconfig+FA_DUMP_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  help
# make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_pseries_defconfig+FA_DUMP_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  olddefconfig
.config:4117:warning: override: reassigning to symbol CRASH_DUMP
.config:4118:warning: override: reassigning to symbol FA_DUMP
# make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_pseries_defconfig+FA_DUMP_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
Completed OK
# rm -rf /kisskb/build/powerpc-next_pseries_defconfig+FA_DUMP_powerpc-gcc5
# Build took: 0:03:18.709147