build.sh

#!/bin/bash

# From https://stackoverflow.com/q/59895
SCRIPT_DIR="$( cd -- "$( dirname -- "${BASH_SOURCE[0]:-$0}"; )" &> /dev/null && pwd 2> /dev/null; )";

# Source our utils
# shellcheck source=../utils/functions.sh
. "${SCRIPT_DIR}/../utils/functions.sh"

sudo apt update -y
sudo apt install -y netpbm imagemagick git build-essential ncurses-dev xz-utils libssl-dev bc flex libelf-dev bison cgpt vboot-kernel-utils

# Exit on errors
set -e

if [[ $# -eq 0 ]]; then
    
    printq "What kernel version would you like? (choose a number 1-3)"
    printq "This can be any ChromeOS kernel branch, but the recommended versions are:"
    printf "1: chromeos-5.10:\n  (Kernel version that is up-to-date and has good audio support with SOF)\n"
    printf "2: alt-chromeos-5.10:\n  (Kernel version that is up-to-date but is pinned to a commit that supports KBL/SKL devices which do not support SOF)\n"
    printf "3: chromeos-5.4:\n  (Often causes more issues despite being a commonly-used kernel in ChromeOS)\n"
    printq "Older kernels that may provide better support for specific boards:"
    printf "4: chromeos-4.19:\n  (For testing purposes)\n"
    printf "5: chromeos-4.14:\n  (For testing purposes)\n"
    printf "6: chromeos-4.4:\n  (For testing purposes; too old for Mesa3D and some other Linux userspace software)\n"
    printq "Newer kernels that are not widely used within ChromeOS devices:"
    printf "7: chromeos-5.15:\n  (Similar version to those used in Linux distributions, not used in any ChromeOS devices currently)\n"

    read KERNEL_VERSION

else

    export KERNEL_VERSION=$1

fi

case $KERNEL_VERSION in
	# latest working 5.10 commit: 38577b2007cb6cbe54b2dfb4b4f38db77471426f
    "1"|"chromeos-5.10")     KERNEL_VERSION="release-R101-14588.B-chromeos-5.10"                          ;;
    "2"|"alt-chromeos-5.10") KERNEL_VERSION="release-R86-13421.B-chromeos-5.4"       ;;
    "3"|"chromeos-5.4")      KERNEL_VERSION="release-R101-14588.B-chromeos-5.4"      ;;
    "4"|"chromeos-4.19")     KERNEL_VERSION="release-R101-14588.B-chromeos-4.19"     ;;
    "5"|"chromeos-4.14")     KERNEL_VERSION="release-R101-14588.B-chromeos-4.14"     ;;
    "6"|"chromeos-4.4")      KERNEL_VERSION="release-R101-14588.B-chromeos-4.4"      ;;
    "7"|"chromeos-5.15")     KERNEL_VERSION="chromeos-5.15"                          ;;
    *) printerr "Please supply a valid kernel version"; exit ;;
esac

printq "Cloning kernel $KERNEL_VERSION"

if [[ ! -d $KERNEL_VERSION ]]; then

    if [[ $KERNEL_VERSION == "alt-chromeos-5.10" ]]; then
        git clone --branch chromeos-5.10 --single-branch https://chromium.googlesource.com/chromiumos/third_party/kernel.git $KERNEL_VERSION
        cd $KERNEL_VERSION
        git checkout $(git rev-list -n 1 --first-parent --before="2021-08-1 23:59" chromeos-5.10)
        cd ..
    else
        git clone --branch $KERNEL_VERSION --single-branch --depth 1 https://chromium.googlesource.com/chromiumos/third_party/kernel.git $KERNEL_VERSION
    fi

fi

(
    # Bootlogo not working for now
    printq "Setting up the bootlogo"
    cd logo
    mogrify -format ppm "logo.png"
    ppmquant 224 logo.ppm > logo_224.ppm
    pnmnoraw logo_224.ppm > logo_final.ppm
)

cd $KERNEL_VERSION

printq "Patching the kernel"
cp ../logo/logo_final.ppm drivers/video/logo/logo_linux_clut224.ppm

# A somewhat commonly-used device, lesser priority than JSL i915
git apply ../patches/bloog-audio.patch || {
    git apply ../patches/bloog-audio.patch -R --check && printq "Bloog Audio Patch already applied"
}

# Super important patch, adds support for Jasperlake i915 (many DEDEDE devices)
# This is why we have a check to make sure again
git apply ../patches/jsl-i915.patch || {
    git apply ../patches/jsl-i915.patch -R --check && printq "Jasperlake iGPU Patch already applied"
}
grep -C3 "BIT(RCS0) | BIT(BCS0) | BIT(VCS0) | BIT(VECS0)" drivers/gpu/drm/i915/i915_pci.c | grep "jsl_info" -A5 | grep ".require_force_probe = 1" && { printerr "JSL Patch failed, exiting!"; exit; }

# Important Jack Detection patch that fixes headphone jacks
git apply ../patches/jack-detection.patch || {
    git apply ../patches/jack-detection.patch -R --check && printq "Jack Detection Patch already applied"
}

# Utility functions not in the ChromeOS Kernel that are needed for the above patch to work
git apply ../patches/jack-detection-utils.patch || {
    git apply ../patches/jack-detection-utils.patch -R --check && printq "Jack Detection Utils Patch already applied"
}

printq "$(ls ../patches) applied"

# Prevents a dirty kernel
echo "mod" >> .gitignore
touch .scmversion

printq "Copying and updating kernel config"

if [[ $KERNEL_VERSION == "alt-chromeos-5.10" ]]; then
    MODULES="modules.alt.tar.xz"
    VMLINUZ="bzImage.alt"
    SYSTEM_MAP="System.map-breath-alt"
    CONFIG="config-breath-alt"
    [[ -f .config ]] || cp ../../kernel.alt.conf .config || exit
else
    MODULES="modules.tar.xz"
    VMLINUZ="bzImage"
    SYSTEM_MAP="System.map-breath"
    CONFIG="config-breath"
    [[ -f .config ]] || cp ../../kernel.conf .config || exit
fi

make olddefconfig

# If the terminal is interactive and not running in docker
if [[ -t 0 ]] && [[ ! -f /.dockerenv ]]; then

    read -p "Would you like to make edits to the kernel config? (y/n) " -n 1 -r
    echo
    if [[ $REPLY =~ ^[Yy]$ ]]; then
        make menuconfig
    fi

    read -p "Would you like to write the new config to github? (y/n) " -n 1 -r
    echo
    if [[ $REPLY =~ ^[Yy]$ ]]; then
        if [[ $KERNEL_VERSION == "alt-chromeos-5.10" ]]; then
            cp .config ../../kernel.alt.conf
        else
            cp .config ../../kernel.conf
        fi
    fi

    printq "Building kernel"
    read -p "Would you like a full rebuild? (y/n) " -n 1 -r
    echo
    if [[ $REPLY =~ ^[Yy]$ ]]; then
        make clean; make -j$(nproc) || exit
    else
        make -j$(nproc) || exit
    fi
    
else

    make -j$(nproc)

fi

cp arch/x86/boot/bzImage ../$VMLINUZ
printq "bzImage and modules built"

# Sign the kernel
futility --debug vbutil_kernel \
    --arch x86_64 --version 1 \
    --keyblock /usr/share/vboot/devkeys/kernel.keyblock \
    --signprivate /usr/share/vboot/devkeys/kernel_data_key.vbprivk \
    --bootloader ../kernel.flags \
    --config ../kernel.flags \
    --vmlinuz ../$VMLINUZ \
    --pack ../${VMLINUZ}.signed
printq "Signed bzImage created\!" # Shell expansion weirdness

rm -rf mod || true
mkdir mod
make -j$(nproc) modules_install INSTALL_MOD_PATH=mod

# Creates an archive containing /lib/modules/...
cd mod
# Speedy multicore compression
# Some version of tar don't support arguments after the command in the -I option,
# so we're putting the arguments and the command in a script
echo "xz -9 -T0" > fastxz
chmod +x fastxz
tar -cvI './fastxz' -f ../../$MODULES lib/
printq "modules.tar.xz created!"

# Copy the vmlinuz, system.map, and kernel config to the kernel directory
cd ..
cp System.map ../$SYSTEM_MAP
cp .config ../$CONFIG

cd ..
printq "Command to extract modules to USB:"
printq "sudo rm -rf /mnt/lib/modules/* && sudo cp -Rv kernel/mod/lib/modules/* /mnt/lib/modules && sync"