Subject: Re: 32 bit dev_t, Revision 3
To: Jason Thorpe <firstname.lastname@example.org>
From: Todd Vierling <tv@NetBSD.ORG>
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 email@example.com) =====
== "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