Re: Accessing BIOS Partition from NetBSD

[Martin Husemann <martin%duskware.de@localhost>]

On Wed, Nov 10, 2021 at 08:27:15PM +0000, evil cRaftKnife wrote:
> I created the two partitions at install time in my practice run but
> couldn't find any comprehensive instructions on how to access the second
> BIOS partition or even what it's device name is under /dev.

Well, you need to give us more information here. For starters there is no
such thing as a BIOS partition, I guess you mean an MBR partition. From
this I would also guess that you are using an amd64 notebook.

Now the most important part is: how did you create those partitions (and
how are they stored)?

The most common ways are GPT and MBR. If you are dealing with a real BIOS
(instead of UEFI) you probably have used the latter.

Then we need to guess the name of your disk, which is probably wd0.

You can check by booting into the installed system and doing:

	mount

that should show you something like

	/dev/wd0a on / type ffs (log, local)

(and a few more lines, we are looking for the "/" one).

The wd0a tells us that there is a NetBSD disklabel involved (a GPT partition
would show up as dk0 or some other number).

You can check (as root) with:

	disklabel wd0

and show us the output please. This will also show any other partitions
in the disklabel (typically wd0b = swap, wd0c = all of the NetBSD part
of the disk, wd0d = all of the disk, also called raw partition). Maybe
your supposed-to-be-ZFS partitions is already there.

Then also show the output of

	fdisk wd0

which will show the MBR partitions. You said you created a BIOS partition
outside of the NetBSD area - that is something you don't really need
for you planned setup, but it would show up here.

How big is your disk? you could quote all lines from /var/run/dmesg
that start with wd0 (still assuming that is your disk name).

Next steps depend on this details. If all guesses above are true and
your disk is <= 2TB you can keep your existing configuration and either
have the answer already (disklabel shows your ZFS partition, but maybe
you need to fix the partition type), or just need to import the ZFS
part from MBR into the disklabel (mbrlabel will do that).

The topic is quite complex (and it gets worth when you throw other
architectures into the mix).

My recomendation if you would start from scratch: use GPT for
partitioning (the 9.2 and -current installer offer that option) and do
all partitions directly  in the first setup (there is a GPT partition
type for ZFS). Make sure to give all partitions proper names, then the
installer will use those names and your partitions will show up as dk0
... dkN, and dmesg will list the name at boot time (or you can query it
later with "dkctl wd0 listwedges"). This way avoids duplicate data (MBR
vs. disklabel) and all size limits.

Martin