# git rev-parse -q --verify aa9581108f498991e309c4a90b1af0805d2e41b5^{commit}
aa9581108f498991e309c4a90b1af0805d2e41b5
already have revision, skipping fetch
# git checkout -q -f -B kisskb aa9581108f498991e309c4a90b1af0805d2e41b5
# git clean -qxdf
# < git log -1
# commit aa9581108f498991e309c4a90b1af0805d2e41b5
# Author: Masahiro Yamada <yamada.masahiro@socionext.com>
# Date:   Wed Nov 6 20:23:57 2019 +0900
# 
#     modpost: add an option to suppress 'exported twice' warnings
#     
#     Since commit "modpost: do not set ->preloaded for symbols from
#     Module.symvers", the modpost always warns about symbols exported
#     multiple times.
#     
#     Generally, I believe it is a good thing to show a warning when the
#     same symbol name is exported twice. This avoids the accidental symbol
#     conflict.
#     
#     However, in some cases, we build an external module to provide a
#     different version/variant of the in-kernel module, overriding the
#     same set of exported symbols.
#     
#     At least, there is one use-case in the upstream code;
#     tools/testing/nvdimm/libnvdimm.ko replaces drivers/nvdimm/libnvdimm.ko
#     in order to link it against mocked version of core kernel symbols.
#     
#     Now, this emits a lots of 'exported twice' warnings:
#     
#       https://lkml.org/lkml/2019/10/31/627
#     
#     To suppress those, add a new option KBUILD_MULTI_EXPORT_NO_WARN.
#     
#     If you intentionally override the existing symbols, you can pass it
#     from the command line:
#     
#       make M=tools/testing/nvdimm KBUILD_MULTI_EXPORT_NO_WARN=1
#     
#     Or, more conveniently, you can add it to the module Makefile, so
#     you can still do:
#     
#       make M=tools/testing/nvdimm
#     
#     without sprinkling the warnings.
#     
#     Reported-by: Jeff Moyer <jmoyer@redhat.com>
#     Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
#     Tested-by: Jeff Moyer <jmoyer@redhat.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 aa9581108f498991e309c4a90b1af0805d2e41b5
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_ppc64le-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
# yes \n | make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  oldconfig
yes: standard output: Broken pipe
# make -s -j 48 ARCH=powerpc O=/kisskb/build/kbuild_powernv_defconfig+NO_PERF_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
WARNING: vmlinux.o(.text+0x2fc8): Section mismatch in reference from the variable start_here_common to the function .init.text:start_kernel()
The function start_here_common() references
the function __init start_kernel().
This is often because start_here_common lacks a __init 
annotation or the annotation of start_kernel is wrong.

Completed OK
# rm -rf /kisskb/build/kbuild_powernv_defconfig+NO_PERF_ppc64le-gcc5
# Build took: 0:02:57.424564