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Preparation of microSD card for Turris MOX⚓︎

Using rescue modes⚓︎

If your Turris MOX A is connected to the Internet, you can insert the microSD card into it and choose rescue mode number 6 when starting the router. Turris MOX will download the latest image from the Internet, create a partition if there is none, format your microSD card to the Btrfs filesystem to be able to use snapshots. Those can be useful when you plan to make major changes to the system. See schnapps – a tool for managing snapshots.

If you don’t like the previous option – flashing from the cloud, you can download the image and save it to your microSD card or any USB drive. Don’t extract it. We recommend to use Ext4 or Btrfs formatted drive although Fat32 should work as well. Then use rescue mode number 4 to reformat your MicroSD card.

Manual setup⚓︎

You can also prepare your micro SD card manually. To do that you would most likely need a Linux machine.


You can use the manual setup to prepare any other media as well and MOX will boot out of it. For example USB flash drive.

FS layout⚓︎

You should have at least one partition on your micro SD card and the first one should be used by Turris OS.

First, we need to format it to Btrfs. Let’s assume, that your micro SD is /dev/mmcbkl0. If your card reader exposes itself as something else, you have to figure the device yourself, usually dmesg output is quite helpful.

To format your MicroSD, use the following command:

mkfs.btrfs -f -L turris /dev/mmcblk0p1


Now we need to get the actual content on the micro SD card. Turris routers by default boot from @ snaphot. So we need to create it and populate it. For that we need mounted filesystem, so let’s assume, that you have /mnt/turris directory empty to be used as mounting point of your microSD card. Also as you need to create files owned by various users and various devices, you should run the following as root.

mount /dev/mmcblk0p1 /mnt/turris
btrfs subvol create /mnt/turris/@
wget -O - | tar -C /mnt/turris/@ -xzvf -

If everything goes well, we are almost done. What is left is to create a factory snapshot to be used during recovery and to create a symlink for boot script so U-Boot can find it easily.

btrfs subvol snapshot /mnt/turris/@ /mnt/turris/@factory
ln -s @/boot/boot.scr /mnt/turris/boot.scr
umount /mnt/turris

Now you have a micro SD card with the latest medkit.

2021-09-20 2019-05-07