OpenBSD On A Raspberry Pi 4

9 August 2025

Download the necessary files:

ftp ftp://ftp.nluug.nl/pub/OpenBSD/7.7/arm64/install77.img

ftp ftp://ftp.nluug.nl/pub/OpenBSD/7.7/arm64/miniroot77.img

ftp ftp://ftp.nluug.nl/pub/OpenBSD/7.7/arm64/SHA256.sig

ftp ftp://ftp.nluug.nl/pub/OpenBSD/7.7/arm64/SHA256

Notes to myself regarding download mirrors:

• install7x.img is around 800MB and takes about an hour to download from openbsd.org
• Most mirrors don't work with the openbsd command-line ftp client
• mirrors.sonic.net: works
• ftp.nluug.nl: works and is faster than openbsd.org

Verify openbsd downloads:

$ sha256 -C SHA256 install77.img

(SHA256) install76.img: OK

$ signify -Cp /etc/signify/openbsd-77-base.pub -x SHA256.sig install77.img

Signature Verified
install76.img: OK

Get the device name for the microSD card:

# hw.disknames
# dmesg
# disklabel sd1

Using OpenBSD, assuming the microSD card device was recognized as sd1: We can use install76.img or miniroot76.img. Although we CANNOT install the sets from the boot SD card because it will be re-partitioned during the first phase of the install, we can get the sets via http! Wait…what?! Why are we booting from the SD card and not from a USB drive??? Not sure…

Write the miniroot77.img to the microSD card:

# dd if=miniroot77.img of=/dev/rsd1c bs=1m

Note: rsd1c is the c partition of the raw sd1 device

Insert microSD card into the raspberry pi and power on

To get console on hdmi, at boot> prompt, type:

set tty fb0

Answer normal install questions

When asked which disk to use, choose sd0

Use Whole disk

For a 64GB microSD card, the auto-allocated layout is:

a:  1024.0M 65536   4.2BSD  2048    16384   1   #   /
b:  4189.8M 2162688 swap
c:  60350.0M    0   unused
d:  4023.0M 10743520    4.2BSD  2048    16384   1   #   /tmp
e:  6422.4M 18982656    4.2BSD  2048    16384   1   #   /var
f:  6378.8M 32135808    4.2BSD  2048    16384   1   #   /usr
g:  1024.0M 45199584    4.2BSD  2048    16384   1   #   /usr/X11R6
h:  8342.2M 47296736    4.2BSD  2048    16384   1   #   /usr/local
i:  16.0M   32768   MSDOS
j:  3023.8M 64381536    4.2BSD  2048    16384   1   #   /usr/src
k:  6144.0M 70574176    4.2BSD  2048    16384   1   #   /usr/obj
l:  19746.0M    83157088    4.2BSD  2048    16384   1   #   /home

Use Custom layout

a:  1024.0M 65536   4.2BSD  2048    16384   1   #   /
b:  4096.0M     2168768     swap
d:  20.0G   /usr
e:  12.0G   /usr/local
f:  *   /home

Let's install the sets!

Location of sets? http

HTTP server? cloudflare.cdn.openbsd.org

Reboot, login, and:

$ su root
# syspatch
# pkg_add -Uu

Some things that help when running off an SD card:

• Add noatime to root entry in /etc/fstab
• Disable library relinking with:

  # rcctl disable library_aslr

• To activate the console on HDMI, include "set tty fb0" in /etc/boot.conf

Configure doas:

# cp /etc/examples/doas.conf /etc/doas.conf

# vi /etc/doas.conf

Then while editing doas.conf in vi, add the following:

permit nopass keepenv :wheel

Then reload doas without rebooting with:

# doas -C /etc/doas.conf

Enjoy using OpenBSD on your Raspberry Pi 3 or 4!