>>It doesn't. The swap can be outside the NetBSD-type partition too (I share
>>my swap partition between NetBSD and Linux).

I do this too, but at least for Linux 2.0.x, you have to re-initialize
the swap area for Linux on each Linux boot, since nonvolatile info on
swap blocksize is kept inside the swap partition.  And if you want
more than 128Mbyte of swap space, it needs to be chopped into separate
DOS partitions of no more than 128M.  The Linux mkswap(8) manpage has
the ghastly details. ``Linux software engineering is an oxymoron.'' (anon)


>How does the system identify those partitions outside the main NetBSD
>partition?  (I'm thinking /dev/wdxx type stuff here, but if there's other
>info I need to know too, please include it.)

Via the BSD disklabel, which lives inside the first 8k of the
MBR-labeleld partition, right above the bootblock loaded by the MBR.
see /usr/src/sbin/disklabel/disklabel.c.