# git rev-parse -q --verify 324332cb5445aa6470fe57ba6ddcfbc9504958e2^{commit}
324332cb5445aa6470fe57ba6ddcfbc9504958e2
already have revision, skipping fetch
# git checkout -q -f -B kisskb 324332cb5445aa6470fe57ba6ddcfbc9504958e2
# git clean -qxdf
# < git log -1
# commit 324332cb5445aa6470fe57ba6ddcfbc9504958e2
# Author: Nathan Chancellor <natechancellor@gmail.com>
# Date:   Mon Nov 18 21:57:12 2019 -0700
# 
#     powerpc/prom_init: Use -ffreestanding to avoid a reference to bcmp
#     
#     LLVM revision r374662 gives LLVM the ability to convert certain loops
#     into a reference to bcmp as an optimization; this breaks
#     prom_init_check.sh:
#     
#         CALL    arch/powerpc/kernel/prom_init_check.sh
#       Error: External symbol 'bcmp' referenced from prom_init.c
#       make[2]: *** [arch/powerpc/kernel/Makefile:196: prom_init_check] Error 1
#     
#     bcmp is defined in lib/string.c as a wrapper for memcmp so this could
#     be added to the whitelist. However, commit
#     450e7dd4001f ("powerpc/prom_init: don't use string functions from
#     lib/") copied memcmp as prom_memcmp to avoid KASAN instrumentation so
#     having bcmp be resolved to regular memcmp would break that assumption.
#     Furthermore, because the compiler is the one that inserted bcmp, we
#     cannot provide something like prom_bcmp.
#     
#     To prevent LLVM from being clever with optimizations like this, use
#     -ffreestanding to tell LLVM we are not hosted so it is not free to
#     make transformations like this.
#     
#     Reviewed-by: Nick Desaulneris <ndesaulniers@google.com>
#     Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/20191119045712.39633-4-natechancellor@gmail.com
# < /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 324332cb5445aa6470fe57ba6ddcfbc9504958e2
# < make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-next_mgcoge_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  mgcoge_defconfig
# make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-next_mgcoge_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
/kisskb/src/arch/powerpc/kernel/head_32.S: Assembler messages:
/kisskb/src/arch/powerpc/kernel/head_32.S:934: Warning: invalid register expression
Completed OK
# rm -rf /kisskb/build/powerpc-next_mgcoge_defconfig_powerpc-gcc5
# Build took: 0:00:44.963588