# git rev-parse -q --verify 0bc81767c5bd9d005fae1099fb39eb3688370cb1^{commit}
0bc81767c5bd9d005fae1099fb39eb3688370cb1
already have revision, skipping fetch
# git checkout -q -f -B kisskb 0bc81767c5bd9d005fae1099fb39eb3688370cb1
# git clean -qxdf
# < git log -1
# commit 0bc81767c5bd9d005fae1099fb39eb3688370cb1
# Author: Ard Biesheuvel <ardb@kernel.org>
# Date:   Fri Jan 17 17:43:18 2020 +0100
# 
#     crypto: arm/chacha - fix build failured when kernel mode NEON is disabled
#     
#     When the ARM accelerated ChaCha driver is built as part of a configuration
#     that has kernel mode NEON disabled, we expect the compiler to propagate
#     the build time constant expression IS_ENABLED(CONFIG_KERNEL_MODE_NEON) in
#     a way that eliminates all the cross-object references to the actual NEON
#     routines, which allows the chacha-neon-core.o object to be omitted from
#     the build entirely.
#     
#     Unfortunately, this fails to work as expected in some cases, and we may
#     end up with a build error such as
#     
#       chacha-glue.c:(.text+0xc0): undefined reference to `chacha_4block_xor_neon'
#     
#     caused by the fact that chacha_doneon() has not been eliminated from the
#     object code, even though it will never be called in practice.
#     
#     Let's fix this by adding some IS_ENABLED(CONFIG_KERNEL_MODE_NEON) tests
#     that are not strictly needed from a logical point of view, but should
#     help the compiler infer that the NEON code paths are unreachable in
#     those cases.
#     
#     Fixes: b36d8c09e710c71f ("crypto: arm/chacha - remove dependency on generic ...")
#     Reported-by: Russell King <linux@armlinux.org.uk>
#     Cc: Arnd Bergmann <arnd@arndb.de>
#     Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
#     Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
# < /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 0bc81767c5bd9d005fae1099fb39eb3688370cb1
# < make -s -j 32 ARCH=powerpc O=/kisskb/build/crypto_powernv_defconfig_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  powernv_defconfig
# make -s -j 32 ARCH=powerpc O=/kisskb/build/crypto_powernv_defconfig_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/crypto_powernv_defconfig_ppc64le-gcc5
# Build took: 0:03:20.123998