Another try for dracut-ng

buildroot-external/configs/rpi4_64_defconfig

@@ -175,6 +175,7 @@ BR2_PACKAGE_ALSA_LIB_PYTHON=y
 BR2_PACKAGE_ALSA_PLUGINS=y
 BR2_PACKAGE_LIBSAMPLERATE=y
 BR2_PACKAGE_LIBSNDFILE=y
+BR2_PACKAGE_RNNOISE=y
 BR2_PACKAGE_LIBARCHIVE=y
 BR2_PACKAGE_LIBDEFLATE=y
 BR2_PACKAGE_LZO=y

buildroot-external/dracut/modules.d/99readonly-rootfs-overlay/init-readonly-rootfs-overlay-boot.sh

@@ -0,0 +1,256 @@
+#!/bin/bash
+
+PATH=/sbin:/bin:/usr/sbin:/usr/bin
+
+MOUNT="/bin/mount"
+
+PREINIT=""
+INIT="/sbin/init"
+ROOT_ROINIT="/sbin/init"
+
+ROOT_MOUNT="/mnt"
+ROOT_RODEVICE=""
+ROOT_RWDEVICE=""
+ROOT_ROMOUNT="/media/rfs/ro"
+ROOT_RWMOUNT="/media/rfs/rw"
+ROOT_RWRESET="no"
+
+ROOT_ROFSTYPE=""
+ROOT_ROMOUNTOPTIONS="bind"
+ROOT_ROMOUNTOPTIONS_DEVICE="noatime,nodiratime"
+
+ROOT_RWFSTYPE=""
+ROOT_RWMOUNTOPTIONS="rw,noatime,mode=755 tmpfs"
+ROOT_RWMOUNTOPTIONS_DEVICE="rw,noatime,mode=755"
+
+early_setup() {
+	mkdir -p /proc
+	mkdir -p /sys
+	$MOUNT -t proc proc /proc
+	grep -w "/sys" /proc/mounts >/dev/null || $MOUNT -t sysfs sysfs /sys
+	grep -w "/dev" /proc/mounts >/dev/null || $MOUNT -t devtmpfs none /dev
+}
+
+probe_fs() {
+    # Determine if we need to probe any modules to support the filesystem
+    if ! grep -w "$1" /proc/filesystems >/dev/null; then
+        modprobe "$optarg" 2> /dev/null || \
+            log "Could not load $optarg module"
+    fi
+}
+
+read_args() {
+	[ -z "${CMDLINE+x}" ] && CMDLINE=$(cat /proc/cmdline)
+	for arg in $CMDLINE; do
+		# Set optarg to option parameter, and '' if no parameter was
+		# given
+		optarg=$(expr "x$arg" : 'x[^=]*=\(.*\)' || echo '')
+		case $arg in
+			root=*)
+				ROOT_RODEVICE=$optarg ;;
+			rootfstype=*)
+				ROOT_ROFSTYPE="$optarg"
+				probe_fs "$optarg" ;;
+			rootinit=*)
+				ROOT_ROINIT=$optarg ;;
+			rootoptions=*)
+				ROOT_ROMOUNTOPTIONS_DEVICE="$optarg" ;;
+			rootrw=*)
+				ROOT_RWDEVICE=$optarg ;;
+			rootrwfstype=*)
+				ROOT_RWFSTYPE="$optarg"
+				probe_fs "$optarg" ;;
+			rootrwreset=*)
+				ROOT_RWRESET=$optarg ;;
+			rootrwoptions=*)
+				ROOT_RWMOUNTOPTIONS_DEVICE="$optarg" ;;
+			overlayfstype=*)
+				modprobe "$optarg" 2> /dev/null || \
+					log "Could not load $optarg module";;
+			preinit=*)
+				PREINIT=$optarg ;;
+			init=*)
+				INIT=$optarg ;;
+		esac
+	done
+}
+
+fatal() {
+	echo "rorootfs-overlay: $1" > "$CONSOLE"
+	echo > "$CONSOLE"
+	exec sh
+}
+
+log() {
+	echo "rorootfs-overlay: $1" > "$CONSOLE"
+}
+
+resolve_device() {
+	local dev=$1
+
+	if [ "$(echo $dev | cut -c1-5)" = "UUID=" ]; then
+		local uuid=$(echo $dev | cut -c6-)
+		new_dev="/dev/disk/by-uuid/$uuid"
+	elif [ "$(echo $dev | cut -c1-9)" = "PARTUUID=" ]; then
+		local partuuid=$(echo $dev | cut -c10-)
+		new_dev="/dev/disk/by-partuuid/$partuuid"
+	elif [ "$(echo $dev | cut -c1-10)" = "PARTLABEL=" ]; then
+		local partlabel=$(echo $dev | cut -c11-)
+		new_dev="/dev/disk/by-partlabel/$partlabel"
+	elif [ "$(echo $dev | cut -c1-6)" = "LABEL=" ]; then
+		local label=$(echo $dev | cut -c7-)
+		new_dev="/dev/disk/by-label/$label"
+	else
+		new_dev="$dev"
+	fi
+
+	if [ "$new_dev" != "$dev" ] && [ ! -d /dev/disk ]; then
+		fatal "$dev device naming is not supported without udev"
+	fi
+
+	echo "$new_dev"
+}
+
+wait_for_device() {
+	local dev=$1
+
+	# Skip for e.g. `rootrw=ubi0:overlay`
+	echo "$dev" | grep -q ":" && return
+
+	counter=0
+	while [ ! -b "$dev" ]; do
+		sleep .100
+		counter=$((counter + 1))
+		if [ $counter -ge 50 ]; then
+			fatal "$dev is not availble"
+			exit
+		fi
+	done
+}
+
+early_setup
+
+[ -z "${CONSOLE+x}" ] && CONSOLE="/dev/console"
+
+read_args
+
+mount_and_boot() {
+	mkdir -p $ROOT_MOUNT $ROOT_ROMOUNT $ROOT_RWMOUNT
+
+	# Build mount options for read only root file system.
+	# If no read-only device was specified via kernel command line, use
+	# current root file system via bind mount.
+	ROOT_RODEVICE=$(resolve_device "$ROOT_RODEVICE")
+	wait_for_device "${ROOT_RODEVICE}"
+	ROOT_ROMOUNTPARAMS_BIND="-o ${ROOT_ROMOUNTOPTIONS} /"
+	if [ -n "${ROOT_RODEVICE}" ]; then
+		ROOT_ROMOUNTPARAMS="-o ${ROOT_ROMOUNTOPTIONS_DEVICE} $ROOT_RODEVICE"
+		if [ -n "${ROOT_ROFSTYPE}" ]; then
+			ROOT_ROMOUNTPARAMS="-t $ROOT_ROFSTYPE $ROOT_ROMOUNTPARAMS"
+		fi
+	else
+		ROOT_ROMOUNTPARAMS="$ROOT_ROMOUNTPARAMS_BIND"
+	fi
+
+	# Mount root file system to new mount-point, if unsuccessful, try bind
+	# mounting current root file system.
+	# shellcheck disable=SC2086
+	if ! $MOUNT $ROOT_ROMOUNTPARAMS "$ROOT_ROMOUNT" 2>/dev/null; then
+		log "Could not mount $ROOT_RODEVICE, bind mounting..."
+		if ! $MOUNT $ROOT_ROMOUNTPARAMS_BIND "$ROOT_ROMOUNT"; then
+			fatal "Could not mount read-only rootfs"
+		fi
+	fi
+
+	# Remounting root file system as read only.
+	if ! $MOUNT -o remount,ro "$ROOT_ROMOUNT"; then
+		fatal "Could not remount read-only rootfs as read only"
+	fi
+
+	# If future init is the same as current file, use $ROOT_ROINIT
+	# Tries to avoid loop to infinity if init is set to current file via
+	# kernel command line
+	if cmp -s "$0" "$INIT"; then
+		INIT="$ROOT_ROINIT"
+	fi
+
+	# Build mount options for read write root file system.
+	# If a read-write device was specified via kernel command line, use
+	# it, otherwise default to tmpfs.
+	if [ -n "${ROOT_RWDEVICE}" ]; then
+	        ROOT_RWDEVICE=$(resolve_device "$ROOT_RWDEVICE")
+		wait_for_device "${ROOT_RWDEVICE}"
+		ROOT_RWMOUNTPARAMS="-o $ROOT_RWMOUNTOPTIONS_DEVICE $ROOT_RWDEVICE"
+		if [ -n "${ROOT_RWFSTYPE}" ]; then
+			ROOT_RWMOUNTPARAMS="-t $ROOT_RWFSTYPE $ROOT_RWMOUNTPARAMS"
+		fi
+	else
+		ROOT_RWMOUNTPARAMS="-t tmpfs -o $ROOT_RWMOUNTOPTIONS"
+	fi
+
+	# Mount read-write file system into initram root file system
+	# shellcheck disable=SC2086
+	if ! $MOUNT $ROOT_RWMOUNTPARAMS $ROOT_RWMOUNT; then
+		fatal "Could not mount read-write rootfs"
+	fi
+
+	# Reset read-write file system if specified
+	if [ "yes" = "$ROOT_RWRESET" ] && [ -n "${ROOT_RWMOUNT}" ]; then
+		rm -rf ${ROOT_RWMOUNT:?}/*
+	fi
+
+	# Determine which unification file system to use
+	union_fs_type=""
+	if grep -w "overlay" /proc/filesystems >/dev/null; then
+		union_fs_type="overlay"
+	elif grep -w "aufs" /proc/filesystems >/dev/null; then
+		union_fs_type="aufs"
+	else
+		union_fs_type=""
+	fi
+
+	# Create/Mount overlay root file system
+	case $union_fs_type in
+		"overlay")
+			mkdir -p $ROOT_RWMOUNT/upperdir $ROOT_RWMOUNT/work
+			$MOUNT -t overlay overlay \
+				-o "$(printf "%s%s%s" \
+					"lowerdir=$ROOT_ROMOUNT," \
+					"upperdir=$ROOT_RWMOUNT/upperdir," \
+					"workdir=$ROOT_RWMOUNT/work")" \
+				$ROOT_MOUNT
+			;;
+		"aufs")
+			$MOUNT -t aufs i\
+				-o "dirs=$ROOT_RWMOUNT=rw:$ROOT_ROMOUNT=ro" \
+				aufs $ROOT_MOUNT
+			;;
+		"")
+			fatal "No overlay filesystem type available"
+			;;
+	esac
+
+    # Execute any preinit scripts
+	if [ -x "${PREINIT}" ]; then
+        ${PREINIT}
+	fi
+
+	# Move read-only and read-write root file system into the overlay
+	# file system
+	mkdir -p $ROOT_MOUNT/$ROOT_ROMOUNT $ROOT_MOUNT/$ROOT_RWMOUNT
+	$MOUNT -n --move $ROOT_ROMOUNT ${ROOT_MOUNT}/$ROOT_ROMOUNT
+	$MOUNT -n --move $ROOT_RWMOUNT ${ROOT_MOUNT}/$ROOT_RWMOUNT
+
+	$MOUNT -n --move /proc ${ROOT_MOUNT}/proc
+	$MOUNT -n --move /sys ${ROOT_MOUNT}/sys
+	$MOUNT -n --move /dev ${ROOT_MOUNT}/dev
+
+
+	cd $ROOT_MOUNT
+
+	# switch to actual init in the overlay root file system
+	exec switch_root $ROOT_MOUNT "$INIT" ||
+		fatal "Couldn't chroot, dropping to shell"
+}
+
+mount_and_boot

buildroot-external/dracut/modules.d/99readonly-rootfs-overlay/module-setup.sh

@@ -0,0 +1,66 @@
+#!/bin/bash
+# -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*-
+# ex: ts=8 sw=4 sts=4 et filetype=sh
+
+check() {
+	require_binaries busybox || return 1
+	require_binaries cat || return 1
+	require_binaries switch_root || return 1
+	require_binaries cmp || return 1
+	require_binaries expr || return 1
+	require_binaries grep || return 1
+	require_binaries mkdir || return 1
+	require_binaries mount || return 1
+	require_binaries modprobe || return 1
+	require_binaries log || return 1
+	return 0
+}
+
+depends() {
+    return 0
+}
+
+installkernel() {
+    return 0
+}
+
+install_busybox_links() {
+	dir="${1}"
+	linkname="${2}"
+
+	(cd "${dracutsysrootdir?}${dir}" &&
+	for x in *; do
+		if [ "$(readlink "${x}")" = "${linkname}" ]; then
+			ln -sf "${linkname}" "${initdir?}/${dir}/${x}"
+		fi
+	done
+	)
+}
+
+install() {
+
+        inst_multiple mount umount cat cmp grep mkdir expr chroot
+
+        # Install busybox binary
+        inst_multiple /bin/busybox
+        if [ -e "${dracutsysrootdir?}/lib64" ]; then
+                ln -sf lib "${initdir?}/lib64"
+                ln -sf lib "${initdir?}/usr/lib64"
+        fi
+
+        if [ -e "${dracutsysrootdir?}/lib32" ]; then
+                ln -sf lib "${initdir?}/lib32"
+                ln -sf lib "${initdir?}/usr/lib32"
+        fi
+
+        install_busybox_links "/bin" "busybox"
+        install_busybox_links "/sbin" "../bin/busybox"
+        if [ ! -L "${dracutsysrootdir?}/bin" ]; then
+                install_busybox_links "/usr/bin" "../../bin/busybox"
+                install_busybox_links "/usr/sbin" "../../bin/busybox"
+        fi
+
+    # inst does not work for some reason. Use cp(1) instead.
+    #inst "$moddir/init-readonly-rootfs-overlay-boot.sh" "/init"
+    cp $moddir/init-readonly-rootfs-overlay-boot.sh $initdir/init
+}