Scenario: You want to have OpenBSD as your main desktop but you have 2x4TB external HDDs that are formatted as ext4. Oops!

Problem: OpenBSD does not support ext4 and for accessing your files, you have to either run a GNU/Linux on a USB stick or dual-boot your laptop.

Solution: Installing Void Linux on 1st partition, having your swap as the 2nd one, having a “shared” partition(FAT32) as 3rd one and finally having the OpenBSD partition as the last primary partition.(e.g, /dev/sda4)

The fun part: OpenBSD’s disklabel is a totally unknown world for those who are coming from GNU/Linux but no worries, it will be all clear for ya.

Step 0: Preparing the installation media

I used a 2GB USB stick as the installation media for Void and for doing so, you need to run only one command:

# dd if=/path/to/void.iso /dev/sdb

And that’s it! No need for unetbootin or any extra stuff.

My OpenBSD 6.1 was already on CD but of course you can have it on a USB stick as well. Check their website for more information.

Step 1: Partitioning the disk

Since OpenBSD’s fdisk is pretty “unique” in some ways, I’d like to suggest you to use the cfdisk that’s coming with your Void install disk.

My laptop had a ~92GB HDD and I decided to use ~35GB for GNU/Linux, 3.2 for its swap, a 20GB “shared” partition(that FAT32 dude) and ~35GB for OpenBSD. (No wonder if the numbers are not matching, I’m not really good at math!)

All I did was running cfdisk as root and after creating the partitions, I marked the 1st one(/dev/sda1) as bootable. The types are 83, 82, 0B and A6. (Linux, Linux swap, FAT32, OpenBSD)

When you’re done, choose write, then quit and then # reboot your machine and make it get into the OpenBSD installer. (ESC, TAB, F2, F8, F10, etc.)

Step 2: OpenBSD disk encryption

Choose (S)hell and run the following command:

# disklabel -E wd0

Now it’s time to add a new label(slice, partition, whatever you prefer) inside that “OpenBSD area”(/dev/sda4) and for doing so, we use a a and choose the RAID as its FS type:

> a a
..
..
RAID

> w
> q

Now it’s time to enable the crypto device(aka encrypted partition) and for doing so, we use:

# bioctl -c C -l /dev/wd0a softraid0

Now it’s ready and during the installation, instead of choosing wd0, you can choose sd0 or sd1, depends on your internal HDD type and SATA implementation of your BIOS and so on.

Step 3: Installing Void

Believe me or not, it was the easiest GNU/Linux installation that I’ve ever done. Pretty straightforward and human-friendly.

Step 4: Adding OpenBSD to GRUB

Now when you’re done installing the Void, you should be able to boot into that and after doing so, we need to add the OpenBSD to our GRUB menu:

# vi /etc/grub.d/40_custom

So we append the following lines AFTER all those comments:

menuentry "OpenBSD"{
  set root=(hd0,4)
  chainloader +1
}

Then we run:

# update-grub

That’s it! I’m writing this post from a machine that’s configured the same way that I’ve explained in this post.