Build the macOS High Sierra (10.13.3) xnu kernel.

build_xnu.sh

#!/bin/bash
#
# This is more or less just a bash script for this tutorial: https://0xcc.re/building-xnu-kernel-macosx-sierrra-10-12-x/
# So, huge thanks to Mikal Villa! I updated the tarballs for macOS 10.13 and added line 29.

#
function checkError {
    if [ $? -ne 0 ] ; then
        echo "Script failed"
        exit
    fi
}

bold=$(tput bold)
normal=$(tput sgr0)

echo "${bold}Downloading sources${normal}"
curl -O https://opensource.apple.com/tarballs/dtrace/dtrace-262.tar.gz && \
checkError
curl -O https://opensource.apple.com/tarballs/AvailabilityVersions/AvailabilityVersions-32.30.1.tar.gz && \
checkError
curl -O https://opensource.apple.com/tarballs/libdispatch/libdispatch-913.30.4.tar.gz && \
checkError
curl -O https://opensource.apple.com/tarballs/libplatform/libplatform-161.20.1.tar.gz
checkError
curl -O https://opensource.apple.com/tarballs/xnu/xnu-4570.41.2.tar.gz
checkError

export XNUPATH=$(pwd)/xnu-4570.41.2

for file in *.tar.gz; do tar -zxf $file; done && rm -f *.tar.gz

echo "${bold}Building dtrace${normal}"
cd dtrace-262
mkdir -p obj sym dst
xcodebuild install -target ctfconvert -target ctfdump -target ctfmerge ARCHS="x86_64" SRCROOT=$PWD OBJROOT=$PWD/obj SYMROOT=$PWD/sym DSTROOT=$PWD/dst
checkError
sudo ditto $PWD/dst/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain
checkError

echo "${bold}Building AvailabilityVersions${normal}"
cd ../AvailabilityVersions-32.30.1/
mkdir -p dst
make install SRCROOT=$PWD DSTROOT=$PWD/dst
checkError
sudo ditto $PWD/dst/usr/local `xcrun -sdk macosx -show-sdk-path`/usr/local
checkError

echo "${bold}Building libplatform${normal}"
cd ../libplatform-161.20.1
sudo ditto $PWD/include `xcrun -sdk macosx -show-sdk-path`/usr/local/include
checkError
sudo ditto $PWD/private/os/internal `xcrun -sdk macosx -show-sdk-path`/usr/local/include/os/internal
checkError

echo "${bold}Installing Headers${normal}"
cd $XNUPATH
mkdir -p BUILD.hdrs/obj BUILD.hdrs/sym BUILD.hdrs/dst
make installhdrs SDKROOT=macosx ARCH_CONFIGS=X86_64 SRCROOT=$PWD OBJROOT=$PWD/BUILD.hdrs/obj SYMROOT=$PWD/BUILD.hdrs/sym DSTROOT=$PWD/BUILD.hdrs/dst
checkError
# HACK: The subsequent build command fails with a missing file error. We create
# that file so that the build continues.
touch libsyscall/os/thread_self_restrict.h
sudo xcodebuild installhdrs -project libsyscall/Libsyscall.xcodeproj -sdk macosx ARCHS='x86_64 i386' SRCROOT=$PWD/libsyscall OBJROOT=$PWD/BUILD.hdrs/obj SYMROOT=$PWD/BUILD.hdrs/sym DSTROOT=$PWD/BUILD.hdrs/dst
checkError
# Set permissions correctly before dittoing over MacOSX10.13.sdk.
sudo chown -R root:wheel BUILD.hdrs/dst/
checkError
sudo ditto BUILD.hdrs/dst `xcrun -sdk macosx -show-sdk-path`
checkError

echo "${bold}Building libdispatch${normal}"
cd ../libdispatch-913.30.4
mkdir -p BUILD.hdrs/obj BUILD.hdrs/sym BUILD.hdrs/dst
sudo xcodebuild install -project libdispatch.xcodeproj -target libfirehose_kernel -sdk macosx ARCHS='x86_64 i386' SRCROOT=$PWD OBJROOT=$PWD/obj SYMROOT=$PWD/sym DSTROOT=$PWD/dst
checkError
sudo ditto $PWD/dst/usr/local `xcrun -sdk macosx -show-sdk-path`/usr/local
checkError

echo "${bold}Building xnu${normal}"
cd $XNUPATH

# You can choose between RELEASE, DEVELOPMENT or DEBUG, or all.
make SDKROOT=macosx ARCH_CONFIGS=X86_64 KERNEL_CONFIGS="RELEASE" BUILD_WERROR=0 LOGCOLORS=y