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[[Category:Installation]]
{{warning | 11 Feb 2021 - There is currently a known bug upstream <br />[https://github.com/raspberrypi/firmware/issues/1529 kernel/initramfs cannot be loaded from subdirectory with same name as volume label]. Since the kernel is installed to <code>boot/</code>, you must not use a label named <code>boot</code> for the fat32 partition. }}
This tutorial will help you install Alpine Linux on your Raspberry Pi.
 
{{TOC right}}
 
This tutorial explains how to install Alpine Linux on a Raspberry Pi. Alpine Linux will be installed in [[Installation#Diskless_Mode|diskless mode]], hence, [[Alpine local backup|Alpine Local Backup (lbu)]] is required to save modifications between reboots.
 
For scenarios where there is not expected to be significant changes to disk after setup (like running a static HTTP server), this is likely preferable, as running the entire system from memory will improve performance (by avoiding the slow SD card) and improve the SD card life (by reducing the writes to the card, as all logging will happen in RAM). Diskless installations still allow you to install packages, save local files, and tune the system to your needs.
 
If any of the following apply, then installation in [[Classic install or sys mode on Raspberry Pi|sys-mode installation]] is likely more appropriate.
 
* There will be constant changes to the disk after initial setup (for example, if you expect people to login and save files to their home directories)
* Logs should persists across reboots
* Plan to install packages which consume more space than can be loaded into RAM
* Plan to install kernel modules (such as ZFS)
 
== Compability list ==
As of Alpine 3.19:
* '''armhf''' (defconfig bcmrpi) - Raspberry Pi 1, Zero, ZeroW, cm1
* '''armv7''' (defconfig bcm2709) - Raspberry Pi 2, 3, 3+, Zero2W, cm3, cm3+
* '''aarch64''' (defconfig bcm2711) - Raspberry Pi 3, 3+, 4, 400, Zero2W, cm3, cm3+, cm4, 5


== Preparation ==
== Preparation ==


This section will help you format and partition your SD card:
# [https://alpinelinux.org/downloads/ Download] the Alpine for Raspberry Pi tarball. Use the compability list above when choosing image/file to download.
# [[Create_a_Bootable_Device#Manually_copying_Alpine_files|Create a bootable FAT32 partition on your SD card.]] The partitioning and formatting part of the instructions on the linked page could be done using a graphical partitioning tool such as [https://en.wikipedia.org/wiki/GNOME_Disks gnome-disks], just make sure the partition type is <code>W95 FAT32 (LBA)</code>. (The current type can be found in the "Type" column in the output of <code>fdisk -l</code>.)
# Extract the tarball to the root of the bootable FAT32 partition.
 
To setup a headless system, a bootstrapping configuration overlay file [https://github.com/macmpi/alpine-linux-headless-bootstrap  headless.apkovl.tar.gz] may be added to enable basic networking, so that following configuration steps can be performed under <code>ssh</code>. Pi Zero may be configured with simple USB ethernet-gadget networking with another computer sharing its internet connection.
 
It is recommended to create a '''usercfg.txt''' file on boot partition to configure low-level system settings, as '''config.txt''' may be replaced during bootloader/system upgrades: details can be found [https://www.raspberrypi.com/documentation/computers/config_txt.html here].<br>
However, note some [https://www.raspberrypi.com/documentation/computers/config_txt.html#include settings] can only be set in '''config.txt''', and will have no effect when specified in '''usercfg.txt''' (e.g. <code>gpu_mem</code>). Some interesting values include:
* To enable the UART console: <code>enable_uart=1</code>
* To enable audio: <code>dtparam=audio=on</code>
* By default system will use legacy video driver: some [https://www.raspberrypi.com/documentation/computers/legacy_config_txt.html#legacy-video-options options] may be used to adjust displays modes (e.g. if you see black edges around your screen after booting the Pi, you can add <code>disable_overscan=1</code>). Alternatively Linux DRM-KMS driver may be used (see below).
* If you plan to install on a Pi Compute Module 4 with I/O board, you may need to add: <code>otg_mode=1</code>


# [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.
Recent versions include Broadcom firmware files. If you're using an older Alpine version, see [[#Wireless_support_with_older_Alpine_images|section below]].
# 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 ==
== 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:
Follow these steps to install Alpine Linux in Diskless Mode:


# Insert the SD Card into the Raspberry Pi and turn it on
# Insert the SD card into the Raspberry Pi and power it on
# Login into the Alpine system as root.  Leave the password empty.
# Login into the Alpine system as root.  Leave the password empty.
# Check the current date and time by issuing <code>date</code>. Correct if necessary by issuing <code>date -s YYYYMMDDhhmm</code>.
# Type <code>setup-alpine</code>
# Type <code>setup-alpine</code>
# Once the installation is complete, commit the changes by typing <code>lbu commit</code>
# Once the installation is complete, commit the changes by typing <code>lbu commit -d</code>


Type <code>reboot</code> to verify that the installation was indeed successful.
Type <code>reboot</code> to verify that the installation was indeed successful.
Line 29: Line 53:
=== Update the System ===
=== Update the System ===


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


{{cmd|apk update
{{cmd|apk update
Line 36: Line 60:
Don't forget to save the changes:
Don't forget to save the changes:


{{cmd|lbu commit}}
{{cmd|lbu commit -d}}
 
Note: this does not upgrade the kernel. In order to upgrade the kernel, a full upgrade of the Alpine Linux version must be performed as described in [[Upgrading Alpine#Upgrading Alpine Linux on other removable media (such as CF/USB)|upgrading Alpine Linux for removable media]].
 
=== Linux Kernel Graphics Modes ===
By default system configuration will use legacy video driver: this driver has some limitations and is lacking support.<br>
It is recommended to enable Linux DRM-KMS driver by adding the following to '''usercfg.txt''':
# Enable DRM VC4 V3D driver
dtoverlay=vc4-kms-v3d
max_framebuffers=2
# Don't have the firmware create an initial video= setting in cmdline.txt.
# Use the kernel's default instead.
disable_fw_kms_setup=1
Note: This overlay disables legacy video [https://www.raspberrypi.com/documentation/computers/legacy_config_txt.html#legacy-video-options options].
 
Install the Mesa drivers (Pi4 and Pi5):
 
{{cmd|apk add {{pkg|mesa-dri-gallium|arch=a*}}}}
 
Then reboot:
 
{{cmd|lbu_commit -d; reboot}}
 
=== Wireless drivers ===
As of Alpine 3.17, Wifi and Bluetooth drivers are available within install image: they are part of <code>linux-firmware-brcm</code> (and linked dependencies).<br>
Since kernel 6.1.25 (i.e. Alpine 3.18), onboard bluetooth is enabled & autoprobed by default (it may be disabled by setting [https://github.com/raspberrypi/rpi-firmware/tree/master/overlays krnbt] off).
 
== Troubleshooting ==
<code>raspinfo</code> utility can be used as a first step to diagnose issues: it will make a log report of essential Pi system configuration, and is often used as a reference to submit questions or bug reports within Raspberry Pi community (Forums, Github, etc).<br>
It can be installed with <code>raspberrypi-utils-raspinfo</code> subpackage.
 
=== Long boot time when running headless ===
 
If no peripherals are connected, the system might hang for an exceptionally long period of time while it attempts to accumulate entropy.
 
If this is the case, simply plugging in any USB device should work around this issue, since it increases the amount of entropy available to the kernel via interrupts.
 
=== apk indicating 'No space left on device' ===
 
Note some models of the Raspberry Pi such as the 3A+ only have 512M of RAM, which on fresh Alpine deployment will only leave around 200M for tmpfs root. It's important to keep this limitation in mind when using these boards.


=== Clock-related error messages ===
=== Clock-related error messages ===


During the booting time, you might notice errors related to the hardware clock.  The Raspberry Pi does not have
During the booting time, you might notice errors related to the hardware clock.  Many Raspberry Pi do not have a hardware clock, or may have one without battery, in which case the behaviour depends on whether you physically cut power or not.
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
Also, <code>setup-alpine</code> will adapt the installation to the type of Raspberry Pi you use, which means for example that on a RPI5, you will see <code>hwclock></code> service, whereas on a RPI4 it will use <code>swclock</code>. In doubt, make sure to do the installation on the target hardware.
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
If you still experience clock errors, add the following line to '''/etc/chrony/chrony.conf''':
[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}}
<code>makestep 0.1 3</code>


Busybox NTP client might be the most lightweight solution. Save the changes and reboot, once the NTP software is
== Persistent storage ==
installed and running:
=== Traditional disk-based (sys) installation ===
{{Merge|Classic install or sys mode on Raspberry Pi|There's an existing page for sys-installations on RasPi.}}


{{cmd|lbu commit
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.
reboot}}


After reboot, make sure that the <code>date</code> command outputs the correct date and time.
Split your SD card into two partitions: the FAT32 boot partition described above (in this example it'll be <code>mmcblk0p1</code>) , and a second partition to hold the root filesystem (here it'll be <code>mmcblk0p2</code>). Boot and configure your diskless system as above, then create a root filesystem:


=== X11 Setup ===
{{cmd|apk add {{pkg|e2fsprogs|arch=a*}}
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
mkfs.ext4 /dev/mmcblk0p2}}
​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
Now do a disk install via a mountpoint. The <code>setup-disk</code> script will give some errors about syslinux/extlinux, but you can ignore them.
{{cmd|Section "Module"
The Raspberry Pi doesn't need them to boot.
    Load "fbdevhw"
    Load "fb"
    Load "shadow"
    Load "shadowfb"
    Load "dbe"
    Load "glx"
    Disable "dri"
EndSection}}


Commit your changes:
{{cmd|<nowiki>mkdir /stage
{{cmd|lbu_commit}}
mount /dev/mmcblk0p2 /stage
setup-disk -o /media/mmcblk0p1/MYHOSTNAME.apkovl.tar.gz /stage
# (ignore errors about syslinux/extlinux)</nowiki>}}


Now you should be able to run a browser or desktop. (Guides may follow)
Add a line to <code>/stage/etc/fstab</code> to mount the Pi's boot partition again:


If setup-xorg-base gives you an error regarding rc-update that fails to add mdev to sysinit just run:
{{cmd|/dev/mmcblk0p1 /media/mmcblk0p1 vfat defaults 0 0}}
{{cmd|rc-update mdev sysinit}}
to add it manually. If you skip this the next time you reboot your Raspberry Pi the screen maybe will not display anything on screen.


== Persistent storage ==
Now add a <code>root=/dev/mmcblk0p2</code> parameter to the Pi's boot command line, either <code>cmdline-rpi2.txt</code> or <code>cmdline-rpi.txt</code> depending on model:
 
{{cmd|<nowiki>mount -o remount,rw /media/mmcblk0p1
sed -i '$ s/$/ root=\/dev\/mmcblk0p2/' /media/mmcblk0p1/cmdline-rpi2.txt</nowiki>}}
 
You might also consider <code>overlaytmpfs=yes</code> 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 at shutdown.
 
N.B. <b>the contents of /boot will be ignored when the Pi boots</b>. 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 or you could use bind mount, in which case,
copying the files to boot partition manually, is not needed.
 
{{cmd|<nowiki>echo /media/mmcblk0p1/boot /boot none defaults,bind 0 0 >> /etc/fstab</nowiki>}}


=== Loopback image with overlayfs ===
=== 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.
When you install Alpine in diskless mode, the entire system is loaded into memory at boot. If you want additional storage (for example, if you need more space than offered by your RAM) we need to create loop-back storage onto the SD card mounted with overlayfs.


First make the sd-card writable again and change fstab to always do so:
First, make the SD card writable again and change fstab to always do so:
{{cmd|mount /media/mmcblk0p1 -o rw,remount
{{cmd|mount /media/mmcblk0p1 -o rw,remount
sed -i 's/vfat\ ro,/vfat\ rw,' /etc/fstab}}
sed -i 's/vfat\ ro,/vfat\ rw,/' /etc/fstab}}


Create the loop-back file, this example is 1 GB:
Create the loop-back file, this example is 1 GB:
Line 114: Line 173:
mount -a}}
mount -a}}


Make the overlay folders, we are doing /usr here, but you can do /home or anything else:
Make the overlay folders, we are using the /usr directory here, but you can use /home or anything else.
{{Warning|Overlay workdir needs to be an empty directory on the same filesystem mount as the upper directory. So each overlay must use its own workdir.}}
 


{{cmd|mkdir /media/persist/usr  
{{cmd|mkdir /media/persist/usr  
mkdir /media/persist/.work
mkdir /media/persist/.work_usr
echo "overlay /usr overlay lowerdir&#61;/usr,upperdir&#61;/media/persist/usr,workdir&#61;/media/persist/.work 0 0" >> /etc/fstab  
echo "overlay /usr overlay lowerdir&#61;/usr,upperdir&#61;/media/persist/usr,workdir&#61;/media/persist/.work_usr 0 0" >> /etc/fstab  
mount -a}}
mount -a}}


Line 126: Line 187:
/dev/mmcblk0p1 /media/mmcblk0p1 vfat rw,relatime,fmask&#61;0022,dmask&#61;0022,errors&#61;remount-ro 0 0
/dev/mmcblk0p1 /media/mmcblk0p1 vfat rw,relatime,fmask&#61;0022,dmask&#61;0022,errors&#61;remount-ro 0 0
/media/mmcblk0p1/persist.img /media/persist ext4 rw,relatime,errors&#61;remount-ro 0 0
/media/mmcblk0p1/persist.img /media/persist ext4 rw,relatime,errors&#61;remount-ro 0 0
overlay /usr overlay lowerdir&#61;/usr,upperdir&#61;/media/persist/usr,workdir&#61;/media/persist/.work 0 0}}
overlay /usr overlay lowerdir&#61;/usr,upperdir&#61;/media/persist/usr,workdir&#61;/media/persist/.work_usr 0 0}}


Now commit the changes: (optionally remove the e2fsprogs, but it does contain repair tools)
Now commit the changes: (optionally remove the e2fsprogs, but it does contain repair tools)
{{cmd|lbu_commit}}
{{cmd|lbu_commit -d}}
 
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, not to the persistent storage.
 
If you do want to install something small at boot, you can use <code>apk add</code> and <code>lbu commit -d</code>.
 
If it is something a bit bigger, then you can use <code>apk add</code> but then not commit it. It will be persistent (in <code>/user</code>), but be sure to check everything you need is in that directory and not in folders you have not made persistent.
 
== Netboot ==
 
=== Netbooting Raspberry Pi 4 ===
 
The Raspberry Pi 4 bootloader can be configured to boot from the network [https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#raspberry-pi-4-bootloader-configuration]. Configure the bootloader with at least


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.
{{cmd|<nowiki>BOOT_ORDER=0xf142
TFTP_PREFIX=1</nowiki>}}


If you do want to install something small at boot you can use `apk add` and `lbu commit`.
and optionally also {{cmd|<nowiki>TFTP_IP=x.x.x.x</nowiki>}} where <code>x.x.x.x</code> is the IP address of your TFTP server.


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.
If not configuring <code>TFTP_IP</code> in the bootloader, you'll need to configure your DHCP server to advertise the TFTP server IP address. This varies depending on your DHCP server; use the following details if applicable:


=== Traditional disk-based (sys) installation ===
# Vendor class: <code>PXEClient:Arch:00000:UNDI:002001</code>
# Filename: <code>/</code>
 
The minimal set of files that your TFTP server needs to host are:
 
# <code>bcm2711-rpi-4-b.dtb</code> (from [https://raw.githubusercontent.com/raspberrypi/firmware/master/boot/bcm2711-rpi-4-b.dtb raspberrypi/firmware/master/boot/bcm2711-rpi-4-b.dtb])
# <code>cmdline.txt</code> (see below)
# <code>config.txt</code> (see below)
# <code>fixup4.dat</code> (from [https://raw.githubusercontent.com/raspberrypi/firmware/master/boot/fixup4.dat raspberrypi/firmware/master/boot/fixup4.dat], alternatively <code>fixup4cd.dat</code> for the cut down version)
# <code>initramfs-rpi4</code> (from [https://dl-cdn.alpinelinux.org/alpine/edge/releases/aarch64/netboot/initramfs-rpi4 alpine/edge/releases/aarch64/netboot/initramfs-rpi4])
# <code>start4.elf</code> (from [https://raw.githubusercontent.com/raspberrypi/firmware/master/boot/start4.elf raspberrypi/firmware/master/boot/start4.elf], alternatively <code>start4cd.elf</code> for the cut down version)
# <code>vmlinuz-rpi4</code> (from [https://dl-cdn.alpinelinux.org/alpine/edge/releases/aarch64/netboot/vmlinuz-rpi4 alpine/edge/releases/aarch64/netboot/vmlinuz-rpi4])


{{Warning|This isn't yet supported by the Alpine setup scripts for Raspberry Pi. It requires manual intervention, and might break.}}
<code>config.txt</code>:
{{cmd|<nowiki>[pi4]
kernel=vmlinuz-rpi4
initramfs initramfs-rpi4
arm_64bit=1
</nowiki>}}


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.
<code>cmdline.txt</code>:
{{cmd|<nowiki>modules=loop,squashfs console=ttyAMA0,115200 ip=dhcp alpine_repo=http://dl-cdn.alpinelinux.org/alpine/edge/main modloop=http://dl-cdn.alpinelinux.org/alpine/edge/releases/aarch64/netboot/modloop-rpi4</nowiki>}}


Split your SD card into two partitions: the FAT32 boot partition described above (in this example it'll be <code>mmcblk0p1</code>) , and a second partition to hold the root filesystem (here it'll be <code>mmcblk0p2</code>). Boot and configure your diskless system as above, then create a root filesystem:
Instead of using the <nowiki>http://dl-cdn.alpinelinux.org/alpine/edge/releases/aarch64/netboot/</nowiki> base URL above, pinning to a specific point in time is preferred. Raspberry Pi 4 netboot files are available from https://dl-cdn.alpinelinux.org/alpine/edge/releases/aarch64/netboot-20230329/ onward.


{{cmd|apk add e2fsprogs
With the above configured the Raspberry Pi 4 should be able to boot from the network without an SD card.
mkfs.ext4 /dev/mmcblk0p2}}


Now do a disk install via a mountpoint. The <code>setup-disk</code> script will give some errors about syslinux/extlinux, but you can ignore these: the Raspberry Pi doesn't need this to boot anyway.
=== Wireless support with older Alpine images ===


{{cmd|<nowiki>mkdir /stage
In Alpine 3.14, the WiFi drivers for the Raspberry Pi were moved from <code>linux-firmware-brcm</code> to the <code>linux-firmware-cypress</code> package (source?). Since the images seem to be an outdated version of the former, Wi-Fi will work during installation, but after the first update it will break.
mount /dev/mmcblk0p2 /stage
Use the ethernet interface to download the required packages:
setup-disk -o /media/mmcblk0p1/MYHOSTNAME.apkovl.tar.gz /stage
# (ignore errors about syslinux/extlinux)</nowiki>}}


Add a line to <code>/stage/etc/fstab</code> to mount the Pi's boot partition again:
{{cmd|apk add {{pkg|linux-firmware-cypress|arch=a*}}}}


{{cmd|/dev/mmcblk0p1 /media/mmcblk0p1 vfat defaults 0 0}}
And reboot.


Now add a <code>root=/dev/mmcblk0p2</code> parameter to the Pi's boot command line, either <code>cmdline-rpi2.txt</code> or <code>cmdline-rpi.txt</code> depending on model:
If you need Wi-Fi, you'll need to [https://github.com/RPi-Distro/firmware-nonfree/tree/master/brcm download] the latest Broadcom drivers to your SD card.
(Replace /mnt/sdcard with the correct mount point.)


{{cmd|<nowiki>mount -o remount,rw /media/mmcblk0p1
  git clone --depth 1 https://github.com/RPi-Distro/firmware-nonfree.git
sed -i '$ s/$/ root=\/dev\/mmcblk0p2/' /media/mmcblk0p1/cmdline-rpi2.txt</nowiki>}}
  cp firmware-nonfree/brcm/* /mnt/sdcard/firmware/brcm


You might also consider <code>overlaytmpfs=yes</code> 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.
== Enable the Serial Console ==
Besides having <code>enable_uart=1</code> in ''usercfg.txt'', the kernel command-line option <var>console</var> needs to be changed to <code>console=serial0,115200</code> in ''cmdline.txt''.


Beware, though, that <b>the contents of /boot will be ignored when the Pi boots</b>: 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.
From a Linux desktop, connect to it with something like this:


{{cmd|cu -l /dev/ttyUSB0 -s 115200}}


== See Also ==
== See Also ==


* [[Classic install or sys mode on Raspberry Pi]] - a variant.
* [[Raspberry Pi 3 - Setting Up Bluetooth]]
* [[Raspberry Pi 3 - Configuring it as wireless access point -AP Mode]]
* [[Raspberry Pi 3 - Browser Client]]
* [[Linux Router with VPN on a Raspberry Pi]]
* [[Create a bootable SDHC from a Mac]]
* [[Create a bootable SDHC from a Mac]]
* Build custom Raspberry Pi images based on Alpine via [https://github.com/tolstoyevsky/pieman Pieman]
* [[Tutorials and Howtos#Raspberry Pi]]
[[Category:Installation]]
[[Category: Raspberry]]

Latest revision as of 16:02, 31 October 2024

Warning: 11 Feb 2021 - There is currently a known bug upstream
kernel/initramfs cannot be loaded from subdirectory with same name as volume label. Since the kernel is installed to boot/, you must not use a label named boot for the fat32 partition.


This tutorial explains how to install Alpine Linux on a Raspberry Pi. Alpine Linux will be installed in diskless mode, hence, Alpine Local Backup (lbu) is required to save modifications between reboots.

For scenarios where there is not expected to be significant changes to disk after setup (like running a static HTTP server), this is likely preferable, as running the entire system from memory will improve performance (by avoiding the slow SD card) and improve the SD card life (by reducing the writes to the card, as all logging will happen in RAM). Diskless installations still allow you to install packages, save local files, and tune the system to your needs.

If any of the following apply, then installation in sys-mode installation is likely more appropriate.

  • There will be constant changes to the disk after initial setup (for example, if you expect people to login and save files to their home directories)
  • Logs should persists across reboots
  • Plan to install packages which consume more space than can be loaded into RAM
  • Plan to install kernel modules (such as ZFS)

Compability list

As of Alpine 3.19:

  • armhf (defconfig bcmrpi) - Raspberry Pi 1, Zero, ZeroW, cm1
  • armv7 (defconfig bcm2709) - Raspberry Pi 2, 3, 3+, Zero2W, cm3, cm3+
  • aarch64 (defconfig bcm2711) - Raspberry Pi 3, 3+, 4, 400, Zero2W, cm3, cm3+, cm4, 5

Preparation

  1. Download the Alpine for Raspberry Pi tarball. Use the compability list above when choosing image/file to download.
  2. Create a bootable FAT32 partition on your SD card. The partitioning and formatting part of the instructions on the linked page could be done using a graphical partitioning tool such as gnome-disks, just make sure the partition type is W95 FAT32 (LBA). (The current type can be found in the "Type" column in the output of fdisk -l.)
  3. Extract the tarball to the root of the bootable FAT32 partition.

To setup a headless system, a bootstrapping configuration overlay file headless.apkovl.tar.gz may be added to enable basic networking, so that following configuration steps can be performed under ssh. Pi Zero may be configured with simple USB ethernet-gadget networking with another computer sharing its internet connection.

It is recommended to create a usercfg.txt file on boot partition to configure low-level system settings, as config.txt may be replaced during bootloader/system upgrades: details can be found here.
However, note some settings can only be set in config.txt, and will have no effect when specified in usercfg.txt (e.g. gpu_mem). Some interesting values include:

  • To enable the UART console: enable_uart=1
  • To enable audio: dtparam=audio=on
  • By default system will use legacy video driver: some options may be used to adjust displays modes (e.g. if you see black edges around your screen after booting the Pi, you can add disable_overscan=1). Alternatively Linux DRM-KMS driver may be used (see below).
  • If you plan to install on a Pi Compute Module 4 with I/O board, you may need to add: otg_mode=1

Recent versions include Broadcom firmware files. If you're using an older Alpine version, see section below.

Installation

Follow these steps to install Alpine Linux in Diskless Mode:

  1. Insert the SD card into the Raspberry Pi and power it on
  2. Login into the Alpine system as root. Leave the password empty.
  3. Check the current date and time by issuing date. Correct if necessary by issuing date -s YYYYMMDDhhmm.
  4. Type setup-alpine
  5. Once the installation is complete, commit the changes by typing lbu commit -d

Type reboot to verify that the installation was indeed successful.

Post Installation

Update the System

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

apk update apk upgrade

Don't forget to save the changes:

lbu commit -d

Note: this does not upgrade the kernel. In order to upgrade the kernel, a full upgrade of the Alpine Linux version must be performed as described in upgrading Alpine Linux for removable media.

Linux Kernel Graphics Modes

By default system configuration will use legacy video driver: this driver has some limitations and is lacking support.
It is recommended to enable Linux DRM-KMS driver by adding the following to usercfg.txt:

# Enable DRM VC4 V3D driver
dtoverlay=vc4-kms-v3d
max_framebuffers=2

# Don't have the firmware create an initial video= setting in cmdline.txt.
# Use the kernel's default instead.
disable_fw_kms_setup=1

Note: This overlay disables legacy video options.

Install the Mesa drivers (Pi4 and Pi5):

apk add mesa-dri-gallium

Then reboot:

lbu_commit -d; reboot

Wireless drivers

As of Alpine 3.17, Wifi and Bluetooth drivers are available within install image: they are part of linux-firmware-brcm (and linked dependencies).
Since kernel 6.1.25 (i.e. Alpine 3.18), onboard bluetooth is enabled & autoprobed by default (it may be disabled by setting krnbt off).

Troubleshooting

raspinfo utility can be used as a first step to diagnose issues: it will make a log report of essential Pi system configuration, and is often used as a reference to submit questions or bug reports within Raspberry Pi community (Forums, Github, etc).
It can be installed with raspberrypi-utils-raspinfo subpackage.

Long boot time when running headless

If no peripherals are connected, the system might hang for an exceptionally long period of time while it attempts to accumulate entropy.

If this is the case, simply plugging in any USB device should work around this issue, since it increases the amount of entropy available to the kernel via interrupts.

apk indicating 'No space left on device'

Note some models of the Raspberry Pi such as the 3A+ only have 512M of RAM, which on fresh Alpine deployment will only leave around 200M for tmpfs root. It's important to keep this limitation in mind when using these boards.

Clock-related error messages

During the booting time, you might notice errors related to the hardware clock. Many Raspberry Pi do not have a hardware clock, or may have one without battery, in which case the behaviour depends on whether you physically cut power or not.

Also, setup-alpine will adapt the installation to the type of Raspberry Pi you use, which means for example that on a RPI5, you will see hwclock> service, whereas on a RPI4 it will use swclock. In doubt, make sure to do the installation on the target hardware.

If you still experience clock errors, add the following line to /etc/chrony/chrony.conf:

makestep 0.1 3

Persistent storage

Traditional disk-based (sys) installation

This material is proposed for merging ...

It should be merged with Classic install or sys mode on Raspberry Pi. There's an existing page for sys-installations on RasPi. (Discuss)

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 them. The Raspberry Pi doesn't need them to boot.

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 at shutdown.

N.B. 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 or you could use bind mount, in which case, copying the files to boot partition manually, is not needed.

echo /media/mmcblk0p1/boot /boot none defaults,bind 0 0 >> /etc/fstab

Loopback image with overlayfs

When you install Alpine in diskless mode, the entire system is loaded into memory at boot. If you want additional storage (for example, if you need more space than offered by your RAM) we need to create loop-back storage onto the SD card 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 using the /usr directory here, but you can use /home or anything else.

Warning: Overlay workdir needs to be an empty directory on the same filesystem mount as the upper directory. So each overlay must use its own workdir.



mkdir /media/persist/usr mkdir /media/persist/.work_usr echo "overlay /usr overlay lowerdir=/usr,upperdir=/media/persist/usr,workdir=/media/persist/.work_usr 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_usr 0 0

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

lbu_commit -d

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, not to the persistent storage.

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

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 be sure to check everything you need is in that directory and not in folders you have not made persistent.

Netboot

Netbooting Raspberry Pi 4

The Raspberry Pi 4 bootloader can be configured to boot from the network [1]. Configure the bootloader with at least

BOOT_ORDER=0xf142 TFTP_PREFIX=1

and optionally also

TFTP_IP=x.x.x.x

where x.x.x.x is the IP address of your TFTP server.

If not configuring TFTP_IP in the bootloader, you'll need to configure your DHCP server to advertise the TFTP server IP address. This varies depending on your DHCP server; use the following details if applicable:

  1. Vendor class: PXEClient:Arch:00000:UNDI:002001
  2. Filename: /

The minimal set of files that your TFTP server needs to host are:

  1. bcm2711-rpi-4-b.dtb (from raspberrypi/firmware/master/boot/bcm2711-rpi-4-b.dtb)
  2. cmdline.txt (see below)
  3. config.txt (see below)
  4. fixup4.dat (from raspberrypi/firmware/master/boot/fixup4.dat, alternatively fixup4cd.dat for the cut down version)
  5. initramfs-rpi4 (from alpine/edge/releases/aarch64/netboot/initramfs-rpi4)
  6. start4.elf (from raspberrypi/firmware/master/boot/start4.elf, alternatively start4cd.elf for the cut down version)
  7. vmlinuz-rpi4 (from alpine/edge/releases/aarch64/netboot/vmlinuz-rpi4)

config.txt:

[pi4] kernel=vmlinuz-rpi4 initramfs initramfs-rpi4 arm_64bit=1

cmdline.txt:

modules=loop,squashfs console=ttyAMA0,115200 ip=dhcp alpine_repo=http://dl-cdn.alpinelinux.org/alpine/edge/main modloop=http://dl-cdn.alpinelinux.org/alpine/edge/releases/aarch64/netboot/modloop-rpi4

Instead of using the http://dl-cdn.alpinelinux.org/alpine/edge/releases/aarch64/netboot/ base URL above, pinning to a specific point in time is preferred. Raspberry Pi 4 netboot files are available from https://dl-cdn.alpinelinux.org/alpine/edge/releases/aarch64/netboot-20230329/ onward.

With the above configured the Raspberry Pi 4 should be able to boot from the network without an SD card.

Wireless support with older Alpine images

In Alpine 3.14, the WiFi drivers for the Raspberry Pi were moved from linux-firmware-brcm to the linux-firmware-cypress package (source?). Since the images seem to be an outdated version of the former, Wi-Fi will work during installation, but after the first update it will break. Use the ethernet interface to download the required packages:

apk add linux-firmware-cypress

And reboot.

If you need Wi-Fi, you'll need to download the latest Broadcom drivers to your SD card. (Replace /mnt/sdcard with the correct mount point.)

 git clone --depth 1 https://github.com/RPi-Distro/firmware-nonfree.git
 cp firmware-nonfree/brcm/* /mnt/sdcard/firmware/brcm

Enable the Serial Console

Besides having enable_uart=1 in usercfg.txt, the kernel command-line option console needs to be changed to console=serial0,115200 in cmdline.txt.

From a Linux desktop, connect to it with something like this:

cu -l /dev/ttyUSB0 -s 115200

See Also