Subject: Re: 32 bit dev_t, Revision 3
To: Jason Thorpe <>
From: Todd Vierling <tv@NetBSD.ORG>
List: tech-kern
Date: 01/14/1998 21:35:49
On Wed, 14 Jan 1998, Jason Thorpe wrote:

:  > Since we scan for sd, and attach them wherever we find them (even on
:  > ATAPI busses!), I'd say device,LUN -> unit and partition -> subunit.
: Can we _please please_ drop the idea of making a unit number out of
: a <target,lun>?  Autoconfiguration dynamically assigns the unit numbers
: based on locators configuration entries, does device cloning, etc.
: The suggestion of tying disk unit number to very specific-to-what-the-disk-
: sits-on locator information is contrary to how we've been assigning unit
: numbers for ... many years now.

Hear, hear.  It is far more efficient device node allocation to make the
allocations just start at 0 and go up, as they have been.

As part of the conversion code for 16->32 bit device numbers, I changed
DISKUNIT to use the 12 middle bits in a 12/12/8 split, and DISKPART to use
the bottom 4 bits.  That leaves four for slices or any other machine
dependent number for flags, as yet undefined and defaulting to zero.  This
can of course change at will later on....

===== Todd Vierling (Personal =====
== "There's a myth that there is a scarcity of justice to go around, so
== that if we extend justice to 'those people,' it will somehow erode the
== quality of justice everyone else receives."  -- Maria Price