Raspberry Pi

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This tutorial will help you install Alpine Linux on your Raspberry Pi.

Preparation

This section will help you format and partition your SD card:

  1. Download Alpine for Raspberry Pi tarball which is named as alpine-rpi-<version>-armhf.rpi.tar.gz. You will need version 3.2.0 or greater if you have a Raspberry Pi 2.
  2. Mount your SD card to your workstation
  3. Use gnome-disks or fdisk to create a FAT32 partition. If you are using fdisk, the FAT32 partition type is called W95 FAT32 (LBA) and its ID is 0xC.
  4. Mark the newly created partition as bootable and save
  5. Mount the previously created partition
  6. Extract the tarball contents to your FAT32 partition
  7. Unmount the SD Card.

Installation

Alpine Linux will be installed as diskless mode, hence you need to use Alpine Local Backup (lbu) to save your modifications between reboots. Follow these steps to install Alpine Linux:

  1. Insert the SD Card into the Raspberry Pi and turn it on
  2. Login into the Alpine system as root. Leave the password empty.
  3. Type setup-alpine
  4. Once the installation is complete, commit the changes by typing lbu commit

Type reboot to verify that the installation was indeed successful.

Post Installation

Update the System

Upon installation, make sure that your system is up-to-date:

apk update apk upgrade

Don't forget to save the changes:

lbu commit

Clock-related error messages

During the booting time, you might notice errors related to the hardware clock. The Raspberry Pi does not have a hardware clock and therefore you need to disable the hwclock daemon and enable swclock:

rc-update add swclock boot # enable the software clock rc-update del hwclock boot # disable the hardware clock

Since Raspberry Pi does not have a clock, the Alpine Linux needs to know what the time is by using a Network Time Protocol (NTP) daemon. Make sure that you a NTP daemon installed and running. If you are not sure, then you can install NTP client by running the following command:

setup-ntp

Busybox NTP client might be the most lightweight solution. Save the changes and reboot, once the NTP software is installed and running:

lbu commit reboot

After reboot, make sure that the date command outputs the correct date and time.

X11 Setup

Here are what you need if you want to try and run a single X11 application like a browser kiosk or maybe even a desktop: ​

setup-xorg-base ​apk add xf86-video-fbdev xf86-input-mouse xf86-input-keyboard dbus ​set​xkbmap rc-update ​​add dbus

Also edit the default X11 module config: /etc/X11/xorg.conf.d/20-modules.conf

Section "Module" Load "fbdevhw" Load "fb" Load "shadow" Load "shadowfb" Load "dbe" Load "glx" Disable "dri" EndSection

Commit your changes:

lbu_commit

Now you should be able to run a browser or desktop. (Guides may follow)

Persistent storage

Loopback image with overlayfs

The install is in disk-less mode and forces everything into memory, if you want additional storage we need to create loop-back storage onto the SD mounted with overlayfs.

First make the sd-card writable again and change fstab to always do so:

mount /media/mmcblk0p1 -o rw,remount sed -i 's/vfat\ ro,/vfat\ rw,' /etc/fstab

Create the loop-back file, this example is 1 GB:

dd if=/dev/zero of=/media/mmcblk0p1/persist.img bs=1024 count=0 seek=1048576

Install the ext utilities:

apk add e2fsprogs

Format the loop-back file:

mkfs.ext4 /media/mmcblk0p1/persist.img

Mount the storage:

echo "/media/mmcblk0p1/persist.img /media/persist ext4 rw,relatime,errors=remount-ro 0 0" >> /etc/fstab mkdir /media/persist mount -a

Make the overlay folders, we are doing /usr here, but you can do /home or anything else:

mkdir /media/persist/usr mkdir /media/persist/.work echo "overlay /usr overlay lowerdir=/usr,upperdir=/media/persist/usr,workdir=/media/persist/.work 0 0" >> /etc/fstab mount -a

Your /etc/fstab should look something like this:

/dev/cdrom /media/cdrom iso9660 noauto,ro 0 0 /dev/usbdisk /media/usb vfat noauto,ro 0 0 /dev/mmcblk0p1 /media/mmcblk0p1 vfat rw,relatime,fmask=0022,dmask=0022,errors=remount-ro 0 0 /media/mmcblk0p1/persist.img /media/persist ext4 rw,relatime,errors=remount-ro 0 0 overlay /usr overlay lowerdir=/usr,upperdir=/media/persist/usr,workdir=/media/persist/.work 0 0

Now commit the changes: (optionally remove the e2fsprogs, but it does contain repair tools)

lbu_commit

Remember with this setup, if you install things and you have done this overlay for /usr, you must not commit the 'apk add', otherwise while it boots it will try and install it to memory and not to the persist storage.

If you do want to install something small at boot you can use `apk add` and `lbu commit`.

If it is something a bit bigger then you can use `apk add` but then not commit it, it will be persistent (in /user), but do check everything you need is in that directory and not in folders you have not made persistent.

Traditional disk-based (sys) installation

Tango-dialog-warning.png
Warning: This isn't yet supported by the Alpine setup scripts for Raspberry Pi. It requires manual intervention, and might break.

It is also possible to switch to a fully disk-based installation: this is not yet formally supported, but can be done somewhat manually. This frees all the memory otherwise needed for the root filesystem, allowing more installed packages.

Split your SD card into two partitions: the FAT32 boot partition described above (in this example it'll be mmcblk0p1) , and a second partition to hold the root filesystem (here it'll be mmcblk0p2). Boot and configure your diskless system as above, then create a root filesystem:

apk add e2fsprogs mkfs.ext4 /dev/mmcblk0p2

Now do a disk install via a mountpoint. The setup-disk script will give some errors about syslinux/extlinux, but you can ignore these: the Raspberry Pi doesn't need this to boot anyway.

mkdir /stage mount /dev/mmcblk0p2 /stage setup-disk -o /media/mmcblk0p1/MYHOSTNAME.apkovl.tar.gz /stage # (ignore errors about syslinux/extlinux)

Add a line to /stage/etc/fstab to mount the Pi's boot partition again:

/dev/mmcblk0p1 /media/mmcblk0p1 vfat defaults 0 0

Now add a root=/dev/mmcblk0p2 parameter to the Pi's boot command line, either cmdline-rpi2.txt or cmdline-rpi.txt depending on model:

mount -o remount,rw /media/mmcblk0p1 sed -i '$ s/$/ root=\/dev\/mmcblk0p2/' /media/mmcblk0p1/cmdline-rpi2.txt

You might also consider overlaytmpfs=yes here, which will cause the underlying SD card root filesystem to be mounted read-only, with an overlayed tmpfs for modifications which will be discarded on shutdown.

Beware, though, that the contents of /boot will be ignored when the Pi boots: it will use the kernel, initramfs, and modloop images from the FAT32 boot partition. To update the kernel, initfs or modules, you will need to manually (generate and) copy these to the boot partition, too.


See Also