Super-rough script to generate a UEFI-ready LEDE disk image and boot QEMU with it

init_lede.sh

#!/bin/bash

LEDE_KERNEL="${HOME}/Downloads/lede-17.01.0-r3205-59508e3-x86-64-vmlinuz"
LEDE_KERNEL_URL="https://downloads.lede-project.org/releases/17.01.0/targets/x86/64/lede-17.01.0-r3205-59508e3-x86-64-vmlinuz"
LEDE_ROOT_IMG_GZ="${HOME}/Downloads/lede-17.01.0-r3205-59508e3-x86-64-combined-ext4.img.gz"
LEDE_ROOT_IMG=""
LEDE_ROOT_IMG_URL="https://downloads.lede-project.org/releases/17.01.0/targets/x86/64/lede-17.01.0-r3205-59508e3-x86-64-generic-rootfs.tar.gz"

QEMU_RAM_MEG="1024"
QEMU_DISK_IMG="${HOME}/sda.img"
QEMU_DISK_SIZE_MiB="1024"
QEMU_UEFI_IMG="/usr/share/ovmf/OVMF.fd"
QEMU_EXTRA_FLAGS="-net none -snapshot"

MOUNT_ROOT="/mnt"

LOOP=""

function get_stack () {
	STACK=""
	local i message="${1:-""}"
	local stack_size=${#FUNCNAME[@]}
	# to avoid noise we start with 1 to skip the get_stack function
	for (( i=1; i<$stack_size; i++ )); do
		local func="${FUNCNAME[$i]}"
		[ x$func = x ] && func=MAIN
		local linen="${BASH_LINENO[$(( i - 1 ))]}"
		local src="${BASH_SOURCE[$i]}"
		[ x"$src" = x ] && src=non_file_source

		STACK+=$'\n'"   at: "$func" "$src" "$linen
	done
	STACK="${message}${STACK}"
}


function cleanup_before_exit () {
	local rv=$?
	if [ ${rv} -ne 0 ]; then
		get_stack "Failed executing"
		error "${STACK}"
		info "Check ${LOG_FILE} for details."
	fi

	deinit
	info "Clean up completed"
}

trap cleanup_before_exit EXIT

function prompt() {
	local msg="$1"
	local var="$2"
	local default="${3:-${!var}}"

	while true; do
		# prompt user for input
		if [ -n "${default}" ]; then
			read -p "${msg} [${default}] " ${var}
		else
			read -p "${msg} " ${var}
		fi

		# verify input, fall back on default if available
		if [ -z "${!var}" ] && [ -n "${default}" ]; then
			eval "${var}=${default}"
		fi
		if [ -n "${var}" ]; then
			break
		fi
	done
}


function configure() {
	prompt "Path to kernel:" LEDE_KERNEL
	if [ ! -f "${LEDE_KERNEL}" ]; then
		echo "Specified kernel does not exist."
		prompt "Kernel download url:" LEDE_KERNEL_URL
		wget "${LEDE_KERNEL_URL}" --output-document "${LEDE_KERNEL}"
	fi
	if [ ! -f "${LEDE_KERNEL}" ]; then
		echo "Requested kernel doesn't exist."
		exit 1
	fi

	prompt "Path to compressed rootfs:" LEDE_ROOT_IMG_GZ
	if [ ! -f "${LEDE_ROOT_IMG_GZ}" ]; then
		echo "Specified kernel does not exist."
		prompt "LEDE rootfs download url:" LEDE_ROOT_IMG_URL
		wget "${LEDE_ROOT_IMG_URL}" --output-document "${LEDE_ROOT_IMG_GZ}"
	fi
	if [ ! -f "${LEDE_ROOT_IMG_GZ}" ]; then
		echo "Requested rootfs doesn't exist."
		exit 1
	fi

	prompt "QEMU RAM size:" QEMU_RAM_MEG
	prompt "QEMU disk size:" QEMU_DISK_SIZE_MiB

	if [ ! -f "${QEMU_UEFI_IMG}" ]; then
		echo "UEFI image file doesn't exist (${QEMU_UEFI_IMG}).  Install 'ovmf' and retry."
		exit 1
	fi

	prompt "Local mount point:" MOUNT_ROOT
}

function init() {
	echo "Creating QEMU disk image..."
	dd if=/dev/zero of="${QEMU_DISK_IMG}" bs=1MiB count=${QEMU_DISK_SIZE_MiB}

	echo "Mounting disk image..."
	LOOP=$(sudo losetup --find --show "${QEMU_DISK_IMG}")
	if [ $? -ne 0 ] || [ -z "${LOOP}" ]; then
		echo "Unable to set up loopback device."
		exit 1
	fi

	echo "Partitioning QEMU disk image..."
  echo "Currently, the next bits are broken,"
  echo "and we don't want to mess up your system"
  exit 1
	sudo parted "${LOOP}" mkpart ESP fat32 1MiB 257MiB
	sudo parted "${LOOP}" set 1 boot on
	sudo parted "${LOOP}" mkpart primary ext4 257MiB 100%
	sudo kpartx -v -a "${QEMU_DISK_IMG}"
	if [ $? -ne 0 ]; then
		echo "Unable to mount partitioned disk image."
		exit 1
	fi

	echo "Formatting QEMU disk image..."
	sudo mkfs.vfat -F 32 -n BOOT /dev/mapper/${LOOP}p1
	sudo mkfs.ext4 -L ROOT /dev/mapper/${LOOP}p2

	echo "Mounting QEMU BOOT partition..."
	sudo mkdir "${MOUNT_ROOT}/qemuboot"
	sudo mount /dev/mapper/${LOOP}p1 "${MOUNT_ROOT}/qemuboot"

	echo "Populating QEMU BOOT partition..."
	sudo mkdir -p "${MOUNT_ROOT}/qemuboot/EFI/BOOT"
	sudo cp "${LEDE_KERNEL}" "${MOUNT_ROOT}/qemuboot/EFI/BOOT/bootx64.efi"
	echo -n "fs0:\\EFI\\BOOT\\bootx64.efi root=sda2 rootfstype=ext4 rootwait console=tty0 console=ttyS0,115200n8 earlyprintk=serial,ttyS0,115200,keep noinitrd verbose" | sudo tee --append "${MOUNT_ROOT}/qemuboot/startup.nsh"

	echo "Mounting QEMU ROOT partition..."
	sudo mkdir "${MOUNT_ROOT}/qemuroot"
	sudo mount /dev/mapper/${LOOP}p2 "${MOUNT_ROOT}/qemuroot"

	echo "Decompressing LEDE root image..."
	gunzip "${LEDE_ROOT_IMG_GZ}"
	LEDE_ROOT_IMG="${LEDE_ROOT_IMG_GZ%%.*}"

	echo "Mounting LEDE root image..."
	sudo mkdir "${MOUNT_ROOT}/lederoot"
	sudo mount -o loop "${LEDE_ROOT_IMG}" "${MOUNT_ROOT}/lederoot"

	echo "Copying files from LEDE root to QEMU disk image..."
	sudo rsync -avxHAWX --numeric-ids --info=progress2 "${MOUNT_ROOT}/lederoot/" "${MOUNT_ROOT}/qemuroot/"
}

function deinit() {
	if [ -d "${MOUNT_ROOT}/qemuboot" ]; then
		echo "Unmounting QEMU boot image..."
		sudo umount "${MOUNT_ROOT}/qemuboot"
		sudo rmdir "${MOUNT_ROOT}/qemuboot"
	fi

	if [ -d "${MOUNT_ROOT}/qemuroot" ]; then
		echo "Unmounting QEMU root image..."
		sudo umount "${MOUNT_ROOT}/qemuroot"
		sudo rmdir "${MOUNT_ROOT}/qemuroot"
	fi

	if [ -d "${MOUNT_ROOT}/lederoot" ]; then
		echo "Unmounting lede root image..."
		sudo umount "${MOUNT_ROOT}/lederoot"
		sudo rmdir "${MOUNT_ROOT}/lederoot"
	fi

	if [ -n "${LOOP}" ]; then
		echo "Cleaning up loopback device ${LOOP}..."
		sudo kpartx -v -d "${QEMU_DISK_IMG}"
		sudo losetup --detach "${LOOP}"
	fi
}

function start() {
	echo qemu-system-x86_64 -m ${QEMU_RAM_MEG} -hda "${QEMU_DISK_IMG}" --bios "${QEMU_UEFI_IMG}" ${EXTRA_FLAGS}
}

configure

init

start

deini