Dual-booting OpenBSD 6.9 and 9front

First download and create installation medium for both

OpenBSD installation

Here we will do an unencrypted installation, if you want to make a full disk encryption install follow the following fqa :

https://www.openbsd.org/faq/faq14.html#softraidFDE

But instead of letting fdisk auto initialize partitions follow the partitioning disk step

boot

Press s to drop into a shell before installation

> Welcome to the OpenBSD/amd64 6.9 installation program.

> (I)nstall, (U)pgrade, (A)utoinstall or (S)hell? s

partitioning disk

we will use the following disk layout :

> bootloader (FAT32) : 200M

> OpenBSD : 50G

> 9front : 25G

Create the hard-drive device node

> # cd /dev && sh MAKEDEV sd0

enter the partition manager

> # fdisk -e sd0

Create a FAT32 partition

> sd0: 1> e 1

Choose 0B (FAT32) as your partition id

> Partition id : 0B

> Do you wish to edit in CHS mode? [n] n

> Partition offset [0 - xxxxxx]: [0] 1024

here I choose to make a 200MiB partition

> Partition size [1 - xxxxxx]: [1] 200M

take note of where you partition end so that they don't overlap

> sd0*: 1> p

Now let's do the same for our OpenBSD parition

> sd0*: 1> e 2

> Do you wish to edit in CHS mode? [n] n

> Partition id : A6

> Partition offset [0 - xxxxx]: 200M

> Partition size [1 - xxxxxx]: [1] 50G

Don't forget to set this partition as bootable

> sd0: 1> f 2

That's it for now, we will let 9front create its own partition

Write and quit :

> sd0*: 1> w

> sd0: 1> q

create the FAT file system

> # newfs_msdos sd0i

installing

Proceed with the installation until you encounter this prompt

> Use (W)hole disk MBR, whole disk (G)PT, (O)penBSD area or (E)dit? [OpenBSD] O

OpenBSD will auto-allocate a layout of virtual partitions for you, feel free to edit it if you want, here we won't

> Use (A)uto layout, (E)dit auto layout, or create (C)ustom layout? [a] a

Continue the installation as you would normally do.

And reboot

installing 9front

Boot your 9front install medium, and follow the installation step just has specified in the fqa

http://fqa.9front.org/fqa4.html

9front should automatically dedect the available free space

At the end of the installation process at this prompt :

> Task to do [bootsetup]:

drop into a shell by typing

> !rc

> term% dossrv -f /dev/sd0xxxx/dos

> term% mount -c /srv/sdos /n/dos

> term% 9fs 9fat

> term% dircp /n/9fat/ /n/dos/

> term% exit

Now proceed to the bootsetup by doing the following :

> Install the Plan 9 masterboot record (yes, no)[no default]: yes

> Mark the Plan 9 partition active (yes, no)[no default]: no

The system should reboot on OpenBSD

Installing syslinux

I haven't found a way to install a bootloader from OpenBSD itself, so instead I'm using an image of alpine

> # apk add syslinux

> # dd if=/usr/share/syslinux/mbr.bin of=/dev/sda

> # syslinux /dev/sda1

> # mount /dev/sda1 /mnt

> # cp /usr/share/syslinux/menu.c32 /mnt

> # cp /usr/share/syslinux/libutil.c32 /mnt

> # cp /usr/share/syslinux/libcom32.c32 /mnt

> # cp /usr/share/syslinux/chain.c32 /mnt

Activate MSDOS partition

> # fdisk /dev/sda

> a

> 1

> a

> 2

> w

> q

Then reboot and you should have a menu with both 9front and OpenBSD