# git rev-parse -q --verify aef2599afe184cb32ea592185adf7065ece0743f^{commit}
aef2599afe184cb32ea592185adf7065ece0743f
already have revision, skipping fetch
# git checkout -q -f -B kisskb aef2599afe184cb32ea592185adf7065ece0743f
# git clean -qxdf
# < git log -1
# commit aef2599afe184cb32ea592185adf7065ece0743f
# Author: Michael Ellerman <mpe@ellerman.id.au>
# Date:   Wed Feb 22 00:03:31 2023 +1100
# 
#     powerpc: Avoid dead code/data elimination when using recordmcount
#     
#     Although powerpc now has objtool mcount support, it's not enabled in all
#     configurations due to dependencies.
#     
#     On those configurations, with some linkers (binutils 2.37 at least),
#     it's still possible to hit the dreaded "recordmcount bug", eg. errors
#     such as:
#     
#         CC      kernel/kexec_file.o
#       Cannot find symbol for section 10: .text.unlikely.
#       kernel/kexec_file.o: failed
#       make[1]: *** [scripts/Makefile.build:287 : kernel/kexec_file.o] Error 1
#     
#     Those errors are much more prevalent when building with
#     CONFIG_LD_DEAD_CODE_DATA_ELIMINATION, because it places every function
#     in a separate section.
#     
#     CONFIG_LD_DEAD_CODE_DATA_ELIMINATION is marked experimental and is not
#     enabled in any powerpc defconfigs or by major distros. Although it does
#     have at least some users on 32-bit where kernel size tends to be more
#     important.
#     
#     Avoid the build errors by blocking CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
#     when the build is using recordmcount, rather than objtool. In practice
#     that means for 64-bit big endian builds, or 64-bit clang builds - both
#     because they lack CONFIG_MPROFILE_KERNEL.
#     
#     On 32-bit objtool is always used, so
#     CONFIG_LD_DEAD_CODE_DATA_ELIMINATION is still available there.
#     
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/20230221130331.2714199-1-mpe@ellerman.id.au
# < /opt/cross/kisskb/korg/gcc-8.5.0-nolibc/x86_64-linux/bin/x86_64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.5.0-nolibc/x86_64-linux/bin/x86_64-linux-ld --version
# < git log --format=%s --max-count=1 aef2599afe184cb32ea592185adf7065ece0743f
# < make -s -j 160 ARCH=x86 O=/kisskb/build/powerpc-fixes_x86_64_defconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.5.0-nolibc/x86_64-linux/bin/x86_64-linux-  x86_64_defconfig
# < make -s -j 160 ARCH=x86 O=/kisskb/build/powerpc-fixes_x86_64_defconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.5.0-nolibc/x86_64-linux/bin/x86_64-linux-  help
# make -s -j 160 ARCH=x86 O=/kisskb/build/powerpc-fixes_x86_64_defconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.5.0-nolibc/x86_64-linux/bin/x86_64-linux-  olddefconfig
# make -s -j 160 ARCH=x86 O=/kisskb/build/powerpc-fixes_x86_64_defconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.5.0-nolibc/x86_64-linux/bin/x86_64-linux-  
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_x86_64_defconfig_x86_64-gcc8
# Build took: 0:03:43.407149