# git rev-parse -q --verify a0d1c951ef08ed24f35129267e3595d86f57f5d3^{commit}
a0d1c951ef08ed24f35129267e3595d86f57f5d3
already have revision, skipping fetch
# git checkout -q -f -B kisskb a0d1c951ef08ed24f35129267e3595d86f57f5d3
# git clean -qxdf
# < git log -1
# commit a0d1c951ef08ed24f35129267e3595d86f57f5d3
# Author: Masahiro Yamada <masahiroy@kernel.org>
# Date:   Wed Apr 8 10:36:23 2020 +0900
# 
#     kbuild: support LLVM=1 to switch the default tools to Clang/LLVM
#     
#     As Documentation/kbuild/llvm.rst implies, building the kernel with a
#     full set of LLVM tools gets very verbose and unwieldy.
#     
#     Provide a single switch LLVM=1 to use Clang and LLVM tools instead
#     of GCC and Binutils. You can pass it from the command line or as an
#     environment variable.
#     
#     Please note LLVM=1 does not turn on the integrated assembler. You need
#     to pass LLVM_IAS=1 to use it. When the upstream kernel is ready for the
#     integrated assembler, I think we can make it default.
#     
#     We discussed what we need, and we agreed to go with a simple boolean
#     flag that switches both target and host tools:
#     
#       https://lkml.org/lkml/2020/3/28/494
#       https://lkml.org/lkml/2020/4/3/43
#     
#     Some items discussed, but not adopted:
#     
#     - LLVM_DIR
#     
#       When multiple versions of LLVM are installed, I just thought supporting
#       LLVM_DIR=/path/to/my/llvm/bin/ might be useful.
#     
#       CC      = $(LLVM_DIR)clang
#       LD      = $(LLVM_DIR)ld.lld
#         ...
#     
#       However, we can handle this by modifying PATH. So, we decided to not do
#       this.
#     
#     - LLVM_SUFFIX
#     
#       Some distributions (e.g. Debian) package specific versions of LLVM with
#       naming conventions that use the version as a suffix.
#     
#       CC      = clang$(LLVM_SUFFIX)
#       LD      = ld.lld(LLVM_SUFFIX)
#         ...
#     
#       will allow a user to pass LLVM_SUFFIX=-11 to use clang-11 etc.,
#       but the suffixed versions in /usr/bin/ are symlinks to binaries in
#       /usr/lib/llvm-#/bin/, so this can also be handled by PATH.
#     
#     Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
#     Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
#     Tested-by: Nathan Chancellor <natechancellor@gmail.com> # build
#     Tested-by: Nick Desaulniers <ndesaulniers@google.com>
#     Reviewed-by: Nick Desaulniers <ndesaulniers@google.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 a0d1c951ef08ed24f35129267e3595d86f57f5d3
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  powernv_defconfig
# Added to kconfig CONFIG_PERF_EVENTS=n
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_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/kbuild_powernv_defconfig+NO_PERF_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  olddefconfig
# make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
/kisskb/src/kernel/trace/ftrace.c: In function 'pid_open':
/kisskb/src/kernel/trace/ftrace.c:7166:6: warning: 'seq_ops' may be used uninitialized in this function [-Wmaybe-uninitialized]
  ret = seq_open(file, seq_ops);
      ^
/kisskb/src/kernel/trace/ftrace.c: In function 'pid_write':
/kisskb/src/kernel/trace/ftrace.c:7244:8: warning: 'filtered_pids' may be used uninitialized in this function [-Wmaybe-uninitialized]
  ret = trace_pid_write(filtered_pids, &pid_list, ubuf, cnt);
        ^
/kisskb/src/kernel/trace/ftrace.c:7261:22: warning: 'other_pids' may be used uninitialized in this function [-Wmaybe-uninitialized]
  } else if (pid_list && !other_pids) {
                      ^
WARNING: modpost: vmlinux.o(.text.unlikely+0x1a0): Section mismatch in reference from the function early_init_mmu() to the function .init.text:radix__early_init_mmu()
The function early_init_mmu() references
the function __init radix__early_init_mmu().
This is often because early_init_mmu lacks a __init 
annotation or the annotation of radix__early_init_mmu is wrong.

WARNING: modpost: vmlinux.o(.text.unlikely+0x1ac): Section mismatch in reference from the function early_init_mmu() to the function .init.text:hash__early_init_mmu()
The function early_init_mmu() references
the function __init hash__early_init_mmu().
This is often because early_init_mmu lacks a __init 
annotation or the annotation of hash__early_init_mmu is wrong.

Completed OK
# rm -rf /kisskb/build/kbuild_powernv_defconfig+NO_PERF_powerpc-gcc5
# Build took: 0:03:10.211574