Linux kernel compilation by clang as Debian .deb package

clang-kbuild.sh

#!/bin/sh

if ! which clang ld.lld llvm-ar >/dev/null; then
  echo "Please install clang, lld, and llvm packages."
  exit 1
fi

if ! [ -d /usr/src/linux-config-5.15 ]; then
  echo "Please install linux-config-5.15 package."
  exit 1
fi

cd /var/tmp

arch=`dpkg --print-architecture`
if [ $arch = amd64 ]; then
    variant=amd64_none_amd64
    march='-march=native'
elif [ $arch = arm64 ]; then
    variant=arm64_none_arm64
    march='-mcpu=native'
elif [ $arch = armhf ]; then
    variant=armhf_none_armmp-lpae
    march='-mtune=native'
else
    echo "Please find a suitable config of $arch."
    exit 1
fi

KVER=5.15.4
exec </dev/null >build-log-${KVER}.txt 2>&1
set -xe
wget -T 10 -c https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-${KVER}.tar.xz
tar Jxf linux-${KVER}.tar.xz
cd linux-${KVER}
# install linux-config-5.15 from sid or experimental
xzcat /usr/src/linux-config-5.15/config.${variant}.xz >.config
cat >>.config <<EOF
CONFIG_MCORE2=y
CONFIG_DEBUG_STACK_USAGE=y
CONFIG_DEBUG_INFO=n
CONFIG_LTO_CLANG_FULL=y
CONFIG_TRIM_UNUSED_KSYMS=y
CONFIG_CFI_CLANG=y
CONFIG_CFI_CLANG_SHADOW=y
CONFIG_SHADOW_CALL_STACK=y
CONFIG_INIT_STACK_ALL_ZERO=y
CONFIG_VGA_SWITCHEROO=n
CONFIG_VGA_ARB=n
CONFIG_DEVPORT=n
CONFIG_DEVMEM=n
CONFIG_DEVKMEM=n
CONFIG_SND_OSSEMUL=n
CONFIG_ZONE_DEVICE=y
CONFIG_DEVICE_PRIVATE=y
CONFIG_PREEMPT=y
CONFIG_DEBUG_PREEMPT=n
CONFIG_HZ_100=y
CONFIG_HYPERVISOR_GUEST=n
CONFIG_KVM_GUEST=n
CONFIG_HYPERV=n
CONFIG_VBOXGUEST=n
CONFIG_XEN=n
CONFIG_PARAVIRT=n
CONFIG_IRQ_TIME_ACCOUNTING=y
CONFIG_CLEAN_CACHE=y
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y
CONFIG_STACK_VALIDATION=y
CONFIG_WQ_WATCHDOG=y

CONFIG_XFS_FS=n
EOF

if [ $arch = armhf ]; then
    cat >>.config <<EOF
CONFIG_LTO_CLANG_FULL=n
CONFIG_LTO_CLANG_THIN=y
CONFIG_PCIE_BRCMSTB=m
CONFIG_VIDEO_VIVID=n
EOF
fi

sed -i 's/-O2/-O3/g' Makefile
sed -i 's/-Os/-Oz/g' Makefile

set +e
if [ $arch = armhf ]; then
  yes '' |
    chrt --batch 0 nice -19 /usr/bin/time -v make -j `nproc` ARCH=arm LLVM=1 LLVM_IAS=1 \
         KCFLAGS="-pipe ${march} -fintegrated-cc1 -mllvm -polly -mllvm -polly-ast-use-context -mllvm -polly-invariant-load-hoisting -mllvm -polly-opt-fusion=max -mllvm -polly-run-inliner -mllvm -polly-vectorizer=stripmine -mllvm -polly-run-dce" \
         LOCALVERSION=-clang \
         bindeb-pkg
else
  yes '' |
    chrt --batch 0 nice -19 /usr/bin/time -v make -j `nproc` LLVM=1 LLVM_IAS=1 \
         KCFLAGS="-pipe ${march} -fintegrated-cc1 -mllvm -polly -mllvm -polly-ast-use-context -mllvm -polly-invariant-load-hoisting -mllvm -polly-opt-fusion=max -mllvm -polly-run-inliner -mllvm -polly-vectorizer=stripmine -mllvm -polly-run-dce" \
         LOCALVERSION=-clang \
         bindeb-pkg
fi
echo 'If compilation failed, please do "sudo apt-get build-dep linux/sid"'
echo "This script was verified by clang, lld, llvm in Debian/experimental and linux-5.15.2."
echo "CONFIG_XFS_FS=m causes runtime error in clang."