diskimage-builder/diskimage_builder/elements/bootloader/finalise.d/50-bootloader

#!/bin/bash

# Configure grub. Note that the various conditionals here are to handle
# different distributions gracefully.

if [ ${DIB_DEBUG_TRACE:-1} -gt 0 ]; then
    set -x
fi
set -eu
set -o pipefail

if [ ${DIB_EXTLINUX:-0} != "0" ]; then
    echo "DIB_EXTLINUX no longer supported"
    exit 1
fi

# Some distros have pre-installed grub in some other way, and want to
# skip this.
if [[ -f "/tmp/grub/install" ]]; then
    exit 0
fi

BOOT_DEV=$IMAGE_BLOCK_DEVICE
# All available devices, handy for some bootloaders...
declare -A DEVICES
eval DEVICES=( $IMAGE_BLOCK_DEVICES )

# Right now we can't use pkg-map to branch by arch, so tag an
# architecture specific virtual package so we can install the
# rigth thing based on distribution.
if [[ "$ARCH" =~ "ppc" ]]; then
    install-packages -m bootloader grub-ppc64
elif [[ "${DIB_BLOCK_DEVICE}" == "mbr" ||
            "${DIB_BLOCK_DEVICE}" == "gpt" ]]; then
    install-packages -m bootloader grub-pc
elif [[ "${DIB_BLOCK_DEVICE}" == "efi" ]]; then
    install-packages -e -m bootloader grub-efi-$ARCH
    install-packages -m bootloader grub-efi grub-efi-$ARCH
else
    echo "Failure: I'm not sure what bootloader to install"
    echo "Ensure you have included a block-device-* element"
    exit 1
fi

GRUBNAME=$(type -p grub-install) || echo "trying grub2-install"
if [ -z "$GRUBNAME" ]; then
    GRUBNAME=$(type -p grub2-install)
fi

if type grub2-mkconfig >/dev/null; then
    GRUB_MKCONFIG="grub2-mkconfig"
else
    GRUB_MKCONFIG="grub-mkconfig"
fi

echo "Installing GRUB2..."

# When using EFI image-based builds, particularly rhel element
# based on RHEL>=8.2 .qcow2, we might have /boot/grub2/grubenv
# as a dangling symlink to /boot/efi because we have extracted
# it from the root fs, but we didn't populate the separate EFI
# boot partition from the image.  grub2-install calls rename()
# on this file, so if it's a dangling symlink it errors.  Just
# remove it if it exists.
if [[ -L /boot/grub2/grubenv ]]; then
    rm -f /boot/grub2/grubenv
fi

# We need --force so grub does not fail due to being installed on the
# root partition of a block device.
GRUB_OPTS=${GRUB_OPTS:-"--force"}
# XXX: This is buggy:
# - --target=i386-pc is invalid for non-i386/amd64 architectures
# - and for UEFI too.
#    GRUB_OPTS="$GRUB_OPTS --target=i386-pc"
if [[ ! $GRUB_OPTS == *--target* ]] && [[ $($GRUBNAME --version) =~ ' 2.' ]]; then
    # /sys/ comes from the host machine. If the host machine is using EFI
    # but the image being built doesn't have EFI boot-images installed we
    # should set the --target to use a BIOS-based boot-image.
    #
    # * --target tells grub what's the target platform
    # * the boot images are placed in /usr/lib/grub/<cpu>-<platform>
    # * i386-pc is used for BIOS-based machines
    # http://www.gnu.org/software/grub/manual/grub.html#Installation
    #
    if [ -d /sys/firmware/efi ]; then
        if [ ! -d /usr/lib/grub/*-efi ]; then
            case $ARCH in
                "x86_64"|"amd64")
                    GRUB_OPTS="$GRUB_OPTS --target=i386-pc"
                    ;;
                "i386")
                    target=i386-pc
                    if [ -e /proc/device-tree ]; then
                        for x in /proc/device-tree/*; do
                            if [ -e "$x" ]; then
                                target="i386-ieee1275"
                            fi
                        done
                    fi
                    GRUB_OPTS="$GRUB_OPTS --target=$target"
                    ;;
            esac
        fi
    fi
fi

if [[ "$ARCH" =~ "ppc" ]] ; then
    # For PPC (64-Bit regardless of Endian-ness), we use the "boot"
    # partition as the one to point grub-install to, not the loopback
    # device.  ppc has a dedicated PReP boot partition.
    # For grub2 < 2.02~beta3 this needs to be a /dev/mapper/... node after
    # that a dev/loopXpN node will work fine.
    $GRUBNAME --modules="part_msdos" $GRUB_OPTS ${DEVICES[boot]} --no-nvram
else
    # This set of modules is sufficient for all installs (mbr/gpt/efi)
    modules="part_msdos part_gpt lvm"
    if [[ ${DIB_BLOCK_DEVICE} == "mbr" || ${DIB_BLOCK_DEVICE} == "gpt" ]]; then
        $GRUBNAME --modules="$modules biosdisk" $GRUB_OPTS $BOOT_DEV
    elif [[ ${DIB_BLOCK_DEVICE} == "efi" ]]; then
        # We need to manually set the target if it's different to
        # the host.  Setup for EFI
        case $ARCH in
            "x86_64"|"amd64")
                # This call installs grub for BIOS compatability
                # which makes portable EFI/BIOS images.
                $GRUBNAME --modules="$modules" --target=i386-pc $BOOT_DEV
                # Set the x86_64 specific efi target for the generic
                # installation below.
                GRUB_OPTS="--target=x86_64-efi"
                ;;
            # At this point, we don't need to override the target
            # for any other architectures.
        esac
        # If we don't have a distro specific dir with presigned efi targets
        # we install a generic one.
        if [ ! -d /boot/efi/$EFI_BOOT_DIR ]; then
            echo "WARNING: /boot/efi/$EFI_BOOT_DIR does not exist, UEFI secure boot not supported"
            # This tells the EFI install to put the EFI binaries into
            # the generic /BOOT directory and avoids trying to update
            # nvram settings.
            extra_options="--removable"
            $GRUBNAME --modules="$modules" $extra_options $GRUB_OPTS $BOOT_DEV
        fi
    fi
fi

# This might be better factored out into a per-distro 'install-bootblock'
# helper.
if [ -d /boot/grub2 ]; then
    GRUB_CFG=/boot/grub2/grub.cfg
elif [ -d /boot/grub ]; then
    GRUB_CFG=/boot/grub/grub.cfg
fi

# Override the root device to the default label, and disable uuid
# lookup.
echo "GRUB_DEVICE=LABEL=${DIB_ROOT_LABEL}" >> /etc/default/grub
echo 'GRUB_DISABLE_LINUX_UUID=true' >> /etc/default/grub
echo "GRUB_TIMEOUT=${DIB_GRUB_TIMEOUT:-5}" >>/etc/default/grub
echo 'GRUB_TERMINAL="serial console"' >>/etc/default/grub
echo 'GRUB_GFXPAYLOAD_LINUX=auto' >>/etc/default/grub

# NOTE(ianw) : 2021-05-11
# On Fedora there has been a switch to BLS
#  https://fedoraproject.org/wiki/Changes/BootLoaderSpecByDefault
# which means that kernel-install will have created entries in
#  /boot/loader/entries/...
# and, as the wiki page says
#
#   The main issue appears to be that a number of places document
#   a way to pass kernel options that is no longer working with
#   BLS, i.e. edit /etc/default/grub before running
#   grub2-mkconfig.
#
# i.e. exactly what we're doing above to override the root device
# in particular.  Override grub2 to use it's old config format and
# remove any BLS entries the kernel install made.
#
# I imagine at some point we will reworking things in a more
# general sense to support BLS if that's what everything is
# switching to.
#
if [[ ${DISTRO_NAME} = fedora ]]; then
    echo 'GRUB_ENABLE_BLSCFG=false' >> /etc/default/grub
    rm -rf /boot/loader/
fi

if [[ -n "${DIB_BOOTLOADER_SERIAL_CONSOLE}" ]]; then
    SERIAL_CONSOLE="${DIB_BOOTLOADER_SERIAL_CONSOLE}"
elif [[ "powerpc ppc64 ppc64le" =~ "$ARCH" ]]; then
    # Serial console on Power is hvc0
    SERIAL_CONSOLE="hvc0"
elif [[ "arm64" =~ "$ARCH" ]]; then
    SERIAL_CONSOLE="ttyAMA0,115200"
else
    SERIAL_CONSOLE="ttyS0,115200"
fi

GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=${SERIAL_CONSOLE} no_timer_check"

echo "GRUB_CMDLINE_LINUX_DEFAULT=\"${GRUB_CMDLINE_LINUX_DEFAULT} ${DIB_BOOTLOADER_DEFAULT_CMDLINE}\"" >>/etc/default/grub
echo 'GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"' >>/etc/default/grub

# os-prober leaks /dev/sda into config file in dual-boot host
# Disable grub-os-prober to avoid the issue  while running
# grub-mkconfig
# Setting a flag to track whether the entry is already there in grub config
PROBER_DISABLED=
if ! grep -qe "^\s*GRUB_DISABLE_OS_PROBER=true" /etc/default/grub; then
    PROBER_DISABLED=true
    echo 'GRUB_DISABLE_OS_PROBER=true' >> /etc/default/grub
fi

# GRUB_MKCONFIG call needs to happen after we configure
# /etc/default/grub above. Without this we can set inappropriate
# root device labels and then images don't boot.
#
# This produces a legacy config which both bios and uefi can boot
# Later we copy the final config to an efi specific location to
# support uefi specific functionality like secure boot.
$GRUB_MKCONFIG -o $GRUB_CFG

# Remove the fix to disable os_prober
if [ -n "$PROBER_DISABLED" ]; then
    sed -i '$d' /etc/default/grub
fi

# Fix efi specific instructions in grub config file
if [ -d /sys/firmware/efi ]; then
    sed -i 's%\(initrd\|linux\)efi /boot%\1 /boot%g' $GRUB_CFG
fi

# when using efi, and having linux16/initrd16, it needs to be replaced
# by linuxefi/initrdefi. When building images on a non-efi system,
# the 16 suffix is added to linux/initrd entries, but we need it to be
# linuxefi/initrdefi for the image to boot under efi
if [[ ${DIB_BLOCK_DEVICE} == "efi" ]]; then
    sed -i 's%\(linux\|initrd\)16 /boot%\1efi /boot%g' $GRUB_CFG

    # Finally copy the grub.cfg to the EFI specific dir to support
    # functionality like secure boot. We make a copy because
    # /boot and /boot/efi may be different partitions and uefi looks
    # for a specific partition UUID preventing symlinks from working.
    if [ -d /boot/efi/$EFI_BOOT_DIR ] ; then
        cp $GRUB_CFG /boot/efi/$EFI_BOOT_DIR/grub.cfg
    fi
fi