Raspberry Pi: Difference between revisions

Revision as of 05:15, 2 April 2025

This page explains how to install and use Alpine Linux on Raspberry Pi.

For scenarios where there is not expected to be significant changes to disk after setup (like running a static HTTP server), diskless mode is 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). Use Alpine Local Backup (lbu) utility to install packages, save local files, and tune the system.

sys-mode installation is more appropriate for the following use cases:

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)

Compatibility list

Refer to the information regarding Raspberry Pi models in the below table when choosing image/file to download from Downloads page for your device. Verify the downloaded image before proceeding further.

Architecture	Port	Description	Since
Alpine Linux Hardware Support Matrix
x86	x86	32 bit i686 compatible (or later) CPUs with at least CMOV and SSE2	All
x86	x86_64	AMD64 compatible 64-bit x86 instruction set	All
ARM	armhf	32 bit ARM with hard-float ABI - for ARMv6 devices- Raspberry Pi 1, Zero, ZeroW, cm1 (defconfig bcmrpi)	v3.0
	armv7	32 bit ARM - for ARMv7 devices - Raspberry Pi 2, 3, 3+, Zero2W, cm3, cm3+ (defconfig bcm2709)	v3.9
	aarch64	64 bit ARM - for ARMv8+ devices - Raspberry Pi 3, 3+, 4, 400, Zero2W, cm3, cm3+, cm4, 5 (defconfig bcm2711)	v3.5
PowerPC	ppc64le	64 bit PowerPC (little-endian) mostly for POWER8 and POWER9	v3.6
IBM System Z	s390x	IBM Z mainframes, especially IBM Z and IBM LinuxONE (z196 minimum)	v3.6
RISC V	riscv64	64 bit RISC V	v3.20
LoongArch	loongarch64	64 bit LoongArch	v3.21

Preparing for the installation

Irrespective of the Install media size, the fat partition size created when using the disk image is around 100Mb. If you need a bigger partition (highly recommended for diskless), proceed to download the tarball and follow the Manual method.

Raspberry Pi Imager

Raspberry Pi Imager is an utility for writing a disk image file to a micro-SD card to be used as install media. When using the above utility, there is neither a need to download the image nor partition and format the media. This utility is available on Linux/macOS/Windows.

In Alpine linux, Install the rpi-imager package for the Raspberry Pi Imager utility. Follow the prompts and install media will be generated with few clicks. To launch the utility in graphical mode issue the command:

rpi-imager

--cli option is also available. For complete usage guide, check out the rpi-imager(1) manpages, which you can install with the rpi-imager-doc package.

Proceed to Installation, if no further customization is required.

Manual method

Alternatively, image or tarball may be downloaded, and SD card media formatted and prepared as per below:

Download the Alpine Linux image or tarball for Raspberry Pi . Use the compability list above when choosing image/tarball to download.
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.)
Warning: Do not use the volume label boot for the fat32 partition. Due to an upstream bug, kernel/initramfs cannot be loaded from subdirectory with same name as volume label. Since kernel is installed to boot/ folder in Alpine Linux, do not use the volume label boot for the fat32 partition.
Extract the tarball to the root of the bootable FAT32 partition.

Customize config.txt

Instead of the BIOS found on a conventional PC, Raspberry Pi devices use a configuration file called config.txt. The GPU reads config.txt before the Arm CPU and Linux initialise. 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, 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:

Contents of usercfg.txt

enable_uart=1 # To enable the UART console:
dtparam=audio=on # To enable audio 

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 Computer Module 4 with I/O board, you may need to add: otg_mode=1
Pi Zero may be configured as simple USB serial-gadget or ethernet-gadget networking with another computer sharing its internet connection.
To maximize available CPU memory if not requiring extra GPU features (i.e. headless/CLI use-cases), cut-down bootloader may be installed with raspberrypi-bootloader-cutdown package, and activated by adding gpu_mem=16 in config.txt.

Installation

Tip: To install Alpine Linux on a pi without keyboard, mouse & display, additional preparatory steps are available at headless Installation page.

Follow these steps to install Alpine Linux in Diskless Mode:

Insert the SD card into the Raspberry Pi and power it on
Login into the Alpine system as root. Leave the password empty.
Check the current date and time by issuing date. Correct if necessary by issuing date -s YYYYMMDDhhmm.
Type setup-alpine
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. This may be disabled by setting krnbt off).

Picam

Note: The below instructions to get picam to work with Pi Zero 2 W model has been tested in sys mode only.

Upgrade to edge version as rpicam-apps package is not yet supported in v3.21.
Setup eudev as device manager:
# setup-devd udev
Add camera_auto_detect=1 option to the user config file /boot/usercfg.txt
Install the package rpicam-apps available in the testing repository.
Due to bug #16911, change the permission after every reboot as follows:
$ doas chmod 666 /dev/dma_heap/*
Test the picam by the command
$ libcamera-hello --list-cameras

Custom installation instructions

To switch a Diskless installation to a fully disk-based installation refer Convert diskless to sys mode.
Mount root of sys mode installation as read only with Overlay filesystem to avoid constant writing to the sd card.
When using Diskless mode on memory constrained Raspberry Pi models(3A+,Pi0) with only 512M of RAM, consider using a loopback image with overlayfs.

Netboot

The Raspberry Pi 4 bootloader can be configured to boot from the network. 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:

Vendor class: PXEClient:Arch:00000:UNDI:002001
Filename: /

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

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

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

Troubleshooting

raspinfo utility from the raspberrypi-utils-raspinfo package 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).

After booting, you may find less system memory available than you expect, as default CPU/GPU RAM split depends on Pi models and activated settings (audio, camera, video drivers, etc). To find out how your system is actually split, use vcgencmd utility from the raspberrypi-utils-vcgencmd package as follows:

# vcgencmd get_mem gpu # vcgencmd get_mem arm

To modify the memory allocation refer to Customize config.txt section.

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'

While running Raspberry Pi models(3A+,Pi0) with only 512M of RAM, a fresh Alpine Linux installation in Diskless mode will only leave around 200M for tmpfs root. It's important to keep this limitation in mind or consider alternatives 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

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

Fileystem for boot partition

If you are trapped at the dreaded rainbow screen, with the green led blinking a few times in a row, repeatedly, check the boot partition type.

The rpi2 require fat32 for the boot partition, NOT fat16. Use linux fdisk to set the boot partition type as "c" (for fat32/lba) and set the lba and boot flags for the partition as suggested. Create the boot partition filesystem as fat32 with:

mkdosfs -F 32 /dev/sdX1

@@ Line 43: / Line 43: @@
 Instead of the BIOS found on a conventional PC, Raspberry Pi devices use a configuration file called '''config.txt'''. The GPU reads config.txt before the Arm CPU and Linux initialise.
 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]. However, 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:{{Cat|usercfg.txt|<nowiki>
+Some interesting values include:{{Cat|usercfg.txt|<nowiki>enable_uart=1 # To enable the UART console:
-enable_uart=1 # To enable the UART console:
 dtparam=audio=on # To enable audio </nowiki>}}
 * 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).
@@ Line 113: / Line 112: @@
 * To switch a Diskless installation to a fully disk-based installation refer [[Classic_install_or_sys_mode_on_Raspberry_Pi#Convert diskless to sys mode|Convert diskless to sys mode]].
-* Mount root of sys mode installation as [[OverlayFS#Overlay root filesystem|Overlay filesystem]] to avoid constant writing to the sd card.
+* Mount root of sys mode installation as read only with [[OverlayFS#Overlay root filesystem|Overlay filesystem]] to avoid constant writing to the sd card.
 * When using Diskless mode on memory constrained Raspberry Pi models(3A+,Pi0) with only 512M of RAM, consider using a [[OverlayFS#Loopback image with overlayfs|loopback image with overlayfs]].