See also

🏗️ This part deals with maintenance burden. Not the funniest part but always needed to ensure a healthy system. I've divided the sections as if they were 'flight rules', they aren't meant to be read sequentially.

Remounting as a read/write FS

When updates are needed or simply updating the configuration is needed, one could need to temporarily deactivate the read only filesystem.

Although overlayroot package gives an overlayroot-chroot command, don’t use it for two reasons:

  1. The /media/root-ro directory is remounted as ro and changes wouldn’t persist
  2. Packages updates / installation might break because some operations are forbidden in chrooted environment. You might experience some Running in chroot, ignoring request. errors.
sudo mount -o remount,defaults,noatime,rw -t ext4 /dev/mmcblk0p2 /media/root-ro

sudo vim /media/root-ro/etc/overlayroot.local.conf
# → Add '#' before `overlayroot="tmpfs:swap=1,recurse=0"` line

sudo reboot

Updating Nextcloud

  1. Remount the filesystem as read/write (see above) and reboot
  2. Upgrade Nextcloud from the command line: 
      sudo -u www-data php /var/www/nextcloud/updater/updater.phar  --no-interaction

    See Offical Doc

  3. Remount the system in readonly mode 
     sudo vim /etc/overlayroot.local.conf # uncomment the line
 sudo reboot

Updating the Kernel

If you recompiled your kernel in Part 2, you’ll have to recompile it regularly to keep it up to date.

  1. Compile kernel sources

    # On the HOST machine

# Assuming you still have a linux git clone from part 2
git branch # Will tell you on which branch you currently are
git pull origin linux-5.4.y

# Restart incremental compilation
make zImage ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j16
make modules ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j16

# Compile the DTS (should not be necessary)
make ARCH=arm rk3288-tinker.dtb CROSS_COMPILE=arm-linux-gnueabihf- -j8

# Transfer to SDCard
# Installing drivers on SD Card
sudo make ARCH=arm INSTALL_MOD_PATH=/media/$USER/324cd421-b656-4326-9882-de35a3ad335a/ modules_install

# Installing on the target's /boot partition
cp arch/arm/boot/zImage /media/$USER/4C89-2DED/
cp arch/arm/boot/dts/rk3288-miniarm.dtb /media/$USER/4C89-2DED/

  2. When rebooting, recreate an initframfs:

    En bootant, refaire un initrd:
su root
export PATH="/usr/sbin:$PATH"
update-initramfs -c -k "$(uname -r)"
# This will create an initrd in /boot (ex: "initrd.img-5.4.94+")

  3. You’ll have to update the /boot/extlinux/extlinux.conf file with the two new files.

Backing up your SD Card

  1. Put your SD Card in your host pc
  2. Umount it manually
  3. Launch a terminal and type: 
      sudo dd if=/dev/mmcblk0 conv=sync,noerror bs=64K | gzip -c  > /PATH/TO/DRIVE/backup_image.img.gz

    (adapt mmcblk0 with your SD Card actual dev name)

Restoring a backup

Same procedure but goes the other way round:

  gunzip  backup_image.img.gz
  sudo sh -c 'cat backup_image.img > /dev/mmcblk0'

(again, adapt mmcblk0 with your SD Card actual dev name)