Thomas Mueller writes:

>from Matthias Buelow <mkb@mukappabeta.de>:
>
>> you don't need any mbr-partitions ("slices") at all, the NetBSD
>> mbr will set up a fake mbr nevertheless, I think, in case some
>> sick BIOSes assume they're going to boot some incarnation from
>> Redmond.  Yet you don't need that dance on non-boot disks of
>> course.  I don't have any PCish structures on the beginning of
>> disks that do not have a boot record -- they just have the disklabel
>> at sector 0 how it's supposed to be and that was it.
>
>Now I'm curious, could you make a Linux subpartition in there, and an msdos
>subpartition, and install DOS and Linux, booting with NetBSD boot selector?
>I can't really figure how that would be done for DOS, maybe Linux could see the
>Linux subpartition?

Where? In a DOS mbr, sure. That's how Gnu/Linux manages it's partitioning.
It uses a slot in the mbr's partition table for each filesystem, just
like DOS. This obviously stems from Linux' history as an x86-only system,
where it was perhaps easier to go with the existing conventions than to
setup an extra, more flexible layer (like BSD does on x86 when cooperating
with other systems via an mbr.)
I don't know if other x86 Unix(-like) systems like Xenix or Minix also use
DOS partitioning, I think in the case of Xenix that might be true, dunno
about Minix.

In a BSD disklabel, you could probably specify a partition entry as
type ext2fs or similar and perhaps even format it (don't know about the
ext2fs on-disk layout and bsd commands for ext2 support) but I very much
doubt that a typical Gnu/Linux system could do anything with that.
It would need a valid DOS partition table in the mbr where the respective
ext2fs slice occupies a slot, in addition to the BSD label somewhere
else on the disk.

--mkb