Merge pull request #11 from bitinerant/master

add support for Ubuntu for ARM

Author: chesty

README.md

@@ -6,6 +6,10 @@ I use this for my Raspberry Pi, but it should work on any Debian or derivative.
 The root file system on the sd-card is mounted read-only on /overlay/lower, and / is a
 read-write copy on write overlay.
 
+There are two sets of instructions below: [Raspbian](#raspbian) and [Ubuntu for ARM](#ubuntu-for-arm).
+
+## Raspbian
+
 It uses initramfs. Stock Raspbian doesn't use one so step one would be to get initramfs working. 
 Something like:
 
@@ -39,6 +43,33 @@ then rerun
 ```bash
 sudo mkinitramfs -o /boot/init.gz
 ```
+Now skip down to [all distributions](#all-distributions) to finish the installation.
+
+## Ubuntu for ARM
+
+Add the following line to /etc/initramfs-tools/modules
+```
+overlay
+```
+
+Copy the following files
+- hooks-overlay to /etc/initramfs-tools/hooks/
+- init-bottom-overlay to /etc/initramfs-tools/scripts/init-bottom/
+
+install busybox-static
+```bash
+sudo apt-get install busybox-static
+```
+
+then run
+
+```bash
+sudo update-initramfs -k $(uname -r) -u
+```
+
+Now continue to [all distributions](#all-distributions) to finish the installation.
+
+## all distributions
 
 add to .bashrc
 
@@ -72,12 +103,18 @@ It's probably a good idea to reboot now for 2 reasons:
 - leaving /overlay/lower read-write could cause file corruption on power loss. 
 - to test it still boots ok after the changes you've just made.
 
-Whenever the kernel is updated you need to rerun 
+Whenever the kernel is updated, for Raspbian you need to rerun 
 
 ```bash
 sudo mkinitramfs -o /boot/init.gz
 ```
 
+and for Ubuntu for ARM
+
+```bash
+sudo update-initramfs -k $(uname -r) -u
+```
+
 TODO: see if there's a hook to automatically run `sudo mkinitramfs -o /boot/init.gz` 
 on kernel install
 

rootwork

@@ -56,11 +56,13 @@ test_mountpoints () {
 }
 
 mount -o remount,rw "$ROOT" || { echo "error remounting $ROOT rw"; exit 1; }
-if is_mounted /boot; then
-    mount -o remount,rw /boot || { echo "error remounting /boot rw"; exit 1; }
-fi
+for DIR in boot boot/firmware; do
+    if is_mounted "/$DIR"; then
+        mount -o remount,rw "/$DIR" || { echo "error remounting \"/$DIR\" rw"; exit 1; }
+    fi
+done
 
-for DIR in boot run; do
+for DIR in boot boot/firmware run; do
     if test_mountpoints "/$DIR" "$ROOT/$DIR"; then
         mount --rbind "/$DIR" "$ROOT/$DIR"
     fi
@@ -90,15 +92,17 @@ fi
 
 # with mount --rbind /run $ROOT/run, umounting $ROOT/run is problematic as it's busy and if you umount -lf it umounts directories in /run/.
 # I think because / is an overlay of $ROOT. So we don't unmount $ROOT/run
-for DIR in boot; do
+for DIR in boot/firmware boot; do
     if is_mounted "$ROOT/$DIR"; then
         umount -lf "$ROOT/$DIR"
     fi
 done
 
-if is_mounted /boot; then
-    mount -o remount,ro /boot
-fi
+for DIR in boot/firmware boot; do
+    if is_mounted "/$DIR"; then
+        mount -o remount,ro "/$DIR"
+    fi
+done
 
 mount -o remount,ro "$ROOT" || {
     echo "Failed to remount $ROOT read-only, possibly because of an open file."