On Fri, 17 Oct 1997 Havard.Eidnes@runit.sintef.no wrote:

> > You failed to create correct NetBSD/pmax diskimage because you
> > used /dev/sd1a.  As Bill Studenmund pointed out, use 'd' instead.
> >
> > NetBSD/i386 uses partition 'd' to refer to entire disk.  Not 'c',
> > nor 'a' no matter how you adjust the BSD disklabel parameter.
> 
> I think this is false.  On the i386 there is nothing special about
> partition 'd' except that it's permitted to use the partition even
> though it's marked as "unused".

There's one big difference. The "whole disk", or raw, partition can use
certain SCSI commands, for instance, which the kernel forbids on other
partitions.  Also, the raw partiton doesn't have any bounds checking. The
driver will happily let you try to write past where it thinks the disk
ends. And it will always start thr partition at sector 0. see
sys/dev/scsipi/sd.c:sdstrategy for details.

Take care,

Bill