On Wed, 7 Feb 2001, Brian Hechinger wrote:

: > That depends! If you say ra*, then it's so, but you can just as well say
: >
: > ra0 at mscpbus0 drive0

: but why is the default behaivor to be dynamic?  i wasn't able to build a new
: kernel on my NetBSD/sparc machine until i got new disks in it. and standard
: old sun SCSI sets ID3 to be the first disk and ID1 to be the second disk

Note that we do provide a hardwired kernel (GENERIC_SCSI3) for just this
purpose on sparc (hardwiring IDs 0-3 to /dev/sd[3-0], respectively).

However, NetBSD has to be dynamic by default in allocating device numbers --
on any given platform, you could have M*N different places where a "sd"
could be found, for instance.  To continue with sparc, If you have a SCSI
card in SBus slot 3 with a drive on unit 6, should it show up as /dev/sd30?
In systems with more expansive busses, that unit number could easily reach
into the *millions*.  Now, if we had controller-based device nodes (a la
SVR4/Solaris, /dev/dsk/cNtNdNsN), that may be easier to your way of
thinking, but even Solaris does our kind of dynamic mapping when it comes to
the SunOS compatibility /dev/sdN* nodes.

However, once your system is set up, you can hardwire your kernel by
reconfiguring it, and once done, your existing disks won't budge if new ones
are added.

So what did I miss?

-- 
-- Todd Vierling <tv@wasabisystems.com>  *  Wasabi NetBSD:  Run with it.
-- NetBSD 1.5 now available on CD-ROM  --  http://www.wasabisystems.com/