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From: thomas@mipsbx.nac.dec.com (Matt Thomas)
Newsgroups: comp.unix.ultrix
Subject: Re: struct cdevsw in ULTRIX-32 (RISC)
Keywords: cdevsw
Message-ID: <13131@shlump.nac.dec.com>
Date: 6 Jul 90 03:02:21 GMT
References: <20851@versatc.versatec.COM>
Sender: news@shlump.nac.dec.com
Reply-To: thomas@wrl.dec.com
Organization: Digital Equipment Corporation
Lines: 30

> 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?

struct cdevsw
{
        int     (*d_open)();
        int     (*d_close)();
        int     (*d_read)();
        int     (*d_write)();
        int     (*d_ioctl)();
        int     (*d_stop)();
        int     (*d_reset)();
        struct tty *d_ttys;
        int     (*d_select)();
        int     (*d_mmap)();
        int     (*d_strat)();	/* Not in BSD 4.3 */
        int     d_affinity;	/* New for ULTRIX V4.0 (SMP support) */
};

And from /sys/machine/common/conf.c (V4.0):
 * 11-Mar-86 -- lp
 *      Add strat to entire cdevsw for n-buffered I/O.

-- 
Matt Thomas                     Internet:   thomas@wrl.dec.com
DECnet-ULTRIX Development       UUCP:       ...!decwrl!thomas
Digital Equipment Corporation   Disclaimer: This message reflects my own
Littleton, MA                               warped views, etc.