Quad-boot with three other operating systems (EFI)

[Zielonykid123]

Hi,
I would like to quad-boot OpenBSD with Manjaro Linux, Windows 10 and FreeBSD with EFI boot. I have some free disk space, however my main problem is the OpenBSD installer... It's terrible, i mean the partitioning tool... I'm scared of using it, im afraid of data removal, i think about installing it on a virtual machine, exporting to raw disk image and trying to duplicate the data onto a new partition on my disk. Any idea how to install it safely?

[Head_on_a_Stick]

If you have a UEFI system then use gdisk from Linux to create a partition for OpenBSD of type a600, the installer will recognise this and offer to place the system there. It will not over-write any of the other partitions.

The only caveat is that FreeBSD and OpenBSD both use the removable loader location for their UEFI bootloader (/EFI/BOOT/bootx64.efi on the EFI system partition) so you will have to move one of them before installing the other. I don't use Manjaro but if that employs systemd-boot or calls grub-install with the --removable flag then that will also use the same removable loader location. Should be fun

For a non-UEFI system use fdisk and create a partition of type a6. You will have to reinstall GRUB afterwards if you want to multi-boot with that.

If you don't want to use the suggested default layout for OpenBSD then experiment virtually to get the hang of the partitioning tool. FWIW I find the defaults to be mostly sane for smaller installations.

[Zielonykid123]

Originally Posted by Head_on_a_Stick

If you have a UEFI system then use gdisk from Linux to create a partition for OpenBSD of type a600, the installer will recognise this and offer to place the system there. It will not over-write any of the other partitions.

The only caveat is that FreeBSD and OpenBSD both use the removable loader location for their UEFI bootloader (/EFI/BOOT/bootx64.efi on the EFI system partition) so you will have to move one of them before installing the other. I don't use Manjaro but if that employs systemd-boot or calls grub-install with the --removable flag then that will also use the same removable loader location. Should be fun

For a non-UEFI system use fdisk and create a partition of type a6. You will have to reinstall GRUB afterwards if you want to multi-boot with that.

If you don't want to use the suggested default layout for OpenBSD then experiment virtually to get the hang of the partitioning tool. FWIW I find the defaults to be mostly sane for smaller installations.

FreeBSD installed its' bootloader to /EFI/freebsd/loader.efi, not to /EFI/BOOT/bootx64.efi as you said. Also, is a600 (OpenBSD disklabel) type for a partition that contains the OpenBSD partitions like root and swap? Or it is the root file system? It's so confusing for me as Linux user.

[jggimi]

Hello, and welcome! A question I can answer:

Originally Posted by Zielonykid123

... is a600 (OpenBSD disklabel) type for a partition that contains the OpenBSD partitions like root and swap? Or it is the root file system? It's so confusing for me as Linux user.

On architectures that use GPT or MBR partitions, the A600 or A6 GPT/MBR partition defines "the OpenBSD storage space on the drive." With one exception, OpenBSD's disklabel partitions fit within this single allocation. So the typical root partition "a", the typical swap partition "b", and any data partitions "d" through "p" all fit within the larger GPT/MBR partition.

The exception is disklabel partition "c", which maps to the entire physical drive from beginning to end, disregarding any and all partitioning schema.

---

(On architectures that don't have GPT or MBR, only the disklabel is used. Partition "c" is still the entire drive.)

[Zielonykid123]

Originally Posted by jggimi

Hello, and welcome! A question I can answer:On architectures that use GPT or MBR partitions, the A600 or A6 GPT/MBR partition defines "the OpenBSD storage space on the drive." With one exception, OpenBSD's disklabel partitions fit within this single allocation. So the typical root partition "a", the typical swap partition "b", and any data partitions "d" through "p" all fit within the larger GPT/MBR partition.

The exception is disklabel partition "c", which maps to the entire physical drive from beginning to end.

---

(On architectures that don't have GPT or MBR, only the disklabel is used.)

So.. that install way (the A600 partition) is for installing OpenBSD to a primary parition?

[jggimi]

I'll try to clarify.

OpenBSD's disklabel history predates the IBM PC/XT and its hard drive, which is where the MBR was born. And disklabels are still used on all architectures, whether or not the architecture has MBRs or GPTs.

An OpenBSD drive with an GPT or MBR partition table uses TWO LEVELS of partitioning: the GPT/MBR, and the disklabel. An OpenBSD disklabel has up to 15 user-defined partitions, "a", "b", and "d" through "p". Partition "c" references the entire hard disk, most often used when managing the drive itself: such as provisioning disklabels or MBRs and GPTs.

When a drive has a GPT or an MBR, the single "OpenBSD partition" provisioned within defines the entire contiguous space available to OpenBSD and all of its user-defined partitions. So if the OpenBSD GPT partition is defined to start at sector A and continue through sector B, OpenBSD disklabel partitions will all be assigned between sectors A and B.

The disklabel(8) program reads the GPT/MBR table and learns the location and length of the OpenBSD partition, and won't let the admin assign storage to disklabels outside this range unless intentionally overridden.

[Zielonykid123]

Originally Posted by jggimi

I'll try to clarify.

OpenBSD's disklabel history predates the IBM PC/XT and its hard drive, which is where the MBR was born. And disklabels are still used on all architectures, whether or not the architecture has MBRs or GPTs.

An OpenBSD drive with an GPT or MBR partition table uses TWO LEVELS of partitioning: the GPT/MBR, and the disklabel. An OpenBSD disklabel has up to 15 user-defined partitions, "a", "b", and "d" through "p". Partition "c" references the entire hard disk, most often used when managing the drive itself: such as provisioning disklabels or MBRs and GPTs.

When a drive has a GPT or an MBR, the single "OpenBSD partition" provisioned within defines the entire contiguous space available to OpenBSD and all of its user-defined partitions. So if the OpenBSD GPT partition is defined to start at sector A and continue through sector B, OpenBSD disklabel partitions will all be assigned between sectors A and B.

The disklabel(8) program reads the GPT/MBR table and learns the location and length of the OpenBSD partition, and won't let the admin assign storage to disklabels outside this range unless intentionally overridden.

So the A6 OpenBSD disklabel partition is not needed for GPT/MBR? As i can remember FreeBSD has the same, but named "BSD" and it's used on MBR..

[jggimi]

Originally Posted by Zielonykid123

So the A6 OpenBSD disklabel partition is not needed for GPT/MBR?

You're still confused. OpenBSD requires disklabel partitions. These are NOT -- are NOT -- MBR/GPT partitions. MBR/GPT partitions are only required on architectures that boot with them.

I hope this analogy helps:

Buy or bake an apple pie. Slice the pie into pieces, and put each slice of pie on its own plate.

Now, take ONE -- only ONE -- of those plates. Delicately chop it up into little bite-size, small pieces on the plate, and stick a toothpick into each little piece.

Your apple pie is a disk drive. Each piece of pie on its own plate is an MBR or GPT partition. Your little bite-size morsels of pie on one of those plates are disklabel partitions. OpenBSD needs toothpicks and bite-size morsels -- disklabel partitions -- even if the whole pie is dedicated to OpenBSD -- one large GPT partition.


This analogy disregards the EFI boot partition, but I hope it helps clarify further.

[Zielonykid123]

Originally Posted by jggimi

Your little bite-size morsels of pie on one of those plates are disklabel partitions.

These letters from a to p? I just need some time to get it...

[jggimi]

There are a maximum of 16 disklabel partitions on a drive. a = 1, b = 2, c = 3, ...

[Zielonykid123]

Originally Posted by jggimi

There are a maximum of 16 disklabel partitions on a drive. a = 1, b = 2, c = 3, ...

ok good