fs/skeleton: allow rootfs not to be remounted read-write

[Peter: prefix option with TARGET_GENERIC_]
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

fs/skeleton/etc/inittab

@@ -15,7 +15,7 @@
 
 # Startup the system
 null::sysinit:/bin/mount -t proc proc /proc
-null::sysinit:/bin/mount -o remount,rw /
+null::sysinit:/bin/mount -o remount,rw / # REMOUNT_ROOTFS_RW
 null::sysinit:/bin/mkdir -p /dev/pts
 null::sysinit:/bin/mkdir -p /dev/shm
 null::sysinit:/bin/mount -a

package/sysvinit/inittab

@@ -5,7 +5,7 @@
 id:1:initdefault:
 
 proc::sysinit:/bin/mount -t proc proc /proc
-rwmo::sysinit:/bin/mount -o remount,rw /
+rwmo::sysinit:/bin/mount -o remount,rw / # REMOUNT_ROOTFS_RW
 dpts::sysinit:/bin/mkdir -p /dev/pts
 moun::sysinit:/bin/mount -a
 host::sysinit:/bin/hostname -F /etc/hostname

target/generic/Config.in

@@ -109,6 +109,17 @@ config BR2_TARGET_GENERIC_GETTY_BAUDRATE
 	default "57600"		if BR2_TARGET_GENERIC_GETTY_BAUDRATE_57600
 	default "115200"	if BR2_TARGET_GENERIC_GETTY_BAUDRATE_115200
 
+config BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW
+	bool "remount root filesystem read-write during boot"
+	default y
+	help
+	  The root filesystem is typically mounted read-only at boot.
+	  By default, buildroot remounts it in read-write mode early during the
+	  boot process.
+	  Say no here if you would rather like your root filesystem to remain
+	  read-only.
+	  If unsure, say Y.
+
 endif # BR2_ROOTFS_SKELETON_DEFAULT
 
 config BR2_ROOTFS_POST_BUILD_SCRIPT

target/generic/Makefile.in

@@ -23,6 +23,14 @@ target-generic-getty-sysvinit:
 	$(SED) '/# GENERIC_SERIAL$$/s~^.*#~$(shell echo $(TARGET_GENERIC_GETTY) | tail -c+4)::respawn:/sbin/getty -L $(TARGET_GENERIC_GETTY) $(TARGET_GENERIC_GETTY_BAUDRATE) vt100 #~' \
 		$(TARGET_DIR)/etc/inittab
 
+# Find commented line, if any, and remove leading '#'s
+target-generic-do-remount-rw:
+	$(SED) '/^#.*# REMOUNT_ROOTFS_RW$$/s~^#\+~~' $(TARGET_DIR)/etc/inittab
+
+# Find uncommented line, if any, and add a leading '#'
+target-generic-dont-remount-rw:
+	$(SED) '/^[^#].*# REMOUNT_ROOTFS_RW$$/s~^~#~' $(TARGET_DIR)/etc/inittab
+
 ifneq ($(TARGET_GENERIC_HOSTNAME),)
 TARGETS += target-generic-hostname
 endif
@@ -37,4 +45,9 @@ TARGETS += target-generic-getty-sysvinit
 else
 TARGETS += target-generic-getty-busybox
 endif
+ifeq ($(BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW),y)
+TARGETS += target-generic-do-remount-rw
+else
+TARGETS += target-generic-dont-remount-rw
+endif
 endif