Raspberry Pi

2016-01-25T13:22:47Z

SkAzZ: Added guides for Persistent Storage and X11 -Expecting criticisms and edits

[[Category:Installation]]
This tutorial will help you install Alpine Linux on your Raspberry Pi.

== Preparation ==

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

# [http://alpinelinux.org/downloads/ Download] Alpine for Raspberry Pi tarball which is named as <code>alpine-rpi-<version>-armhf.rpi.tar.gz</code>. You will need version 3.2.0 or greater if you have a Raspberry Pi 2.
# Mount your SD card to your workstation
# Use [https://en.wikipedia.org/wiki/GNOME_Disks gnome-disks] or [http://linux.die.net/man/8/fdisk 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.
# Mark the newly created partition as bootable and save
# Mount the previously created partition
# Extract the tarball contents to your FAT32 partition
# Unmount the SD Card.

== Installation ==

Alpine Linux will be installed as [[Installation#Installation_Handbook|diskless mode]], hence you need to use [[Alpine local backup|Alpine Local Backup (lbu)]] to save your modifications between reboots. Follow these steps to install Alpine Linux:

# Insert the SD Card into the Raspberry Pi and turn it on
# Login into the Alpine system as root. Leave the password empty.
# Type <code>setup-alpine</code>
# Once the installation is complete, commit the changes by typing <code>lbu commit</code>

Type <code>reboot</code> to verify that the installation was indeed successful.

== Post Installation ==

=== Update the System ===

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

{{cmd|apk update
apk upgrade}}

Don't forget to save the changes:

{{cmd|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:

{{cmd|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
[https://en.wikipedia.org/wiki/Network_Time_Protocol 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:

{{cmd|setup-ntp}}

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

{{cmd|lbu commit
reboot}}

After reboot, make sure that the <code>date</code> command outputs the correct date and time.

=== Persistent Storage ===
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:
{{cmd|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:

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

Install the ext utilities:

{{cmd|apk add e2fsprogs}}

Format the loop-back file:

{{cmd|mkfs.ext4 /media/mmcblk0p1/persist.img}}

Mount the storage:

{{cmd|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:

{{cmd|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:
{{Cmd|/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)
{{cmd|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.

=== 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: {{cmd|setup-xorg-base
apk add xf86-video-fbdev xf86-input-mouse xf86-input-keyboard dbus setxkbmap
rc-update add dbus}}

Also edit the default X11 module config: /etc/X11/xorg.conf.d/20-modules.conf
{{cmd|Section "Module"
Load "fbdevhw"
Load "fb"
Load "shadow"
Load "shadowfb"
Load "dbe"
Disable "glx"
Disable "dri"
EndSection}}

Commit your changes:
{{cmd|lbu_commit}}

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

== See Also ==

* [[Create a bootable SDHC from a Mac]]

Alpine Linux - User contributions [en]

Raspberry Pi