Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!rutgers!cbmvax!grr
From: grr@cbmvax.commodore.com (George Robbins)
Newsgroups: comp.unix.ultrix
Subject: Re: struct cdevsw in ULTRIX-32 (RISC)
Keywords: cdevsw
Message-ID: <13069@cbmvax.commodore.com>
Date: 6 Jul 90 06:06:45 GMT
References: <20851@versatc.versatec.COM>
Reply-To: grr@cbmvax (George Robbins)
Organization: Commodore, West Chester, PA
Lines: 22

In article <20851@versatc.versatec.COM> tamura@versatc.versatec.COM (Mark Tamura) writes:
> question: why does the ULTRIX-32 (VAX) V3.1 cdevsw struct have eleven entries
> per device while the generic Berkeley 4.3 have only ten?  and when did this
> extra entry appear and what is its purpose?

From /sys/h/conf.h:

 *	11-Mar-86	Larry Palmer -- lp
 * 	Added strategy routine to cdevsw for n-buffered I/O. If
 *	the strategy routine is non-null this implies device can do
 *	multiple bufferring.

It is moderatly important to keep in mind that Ultrix is *not* 4.3BSD, rather
it 4.2BSD with a lot of Ultrixism's, many of which bear passing resemblance to
those in 4.3BSD or SunOS (NFS et.al.).  Some other sets of changes you may
notice in the driver area are ioctls for returning "generic device info" and
various tag/label fields for use in system error reporting.

-- 
George Robbins - now working for,     uucp:   {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing:   domain: grr@cbmvax.commodore.com
Commodore, Engineering Department     phone:  215-431-9349 (only by moonlite)