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From: Terry Lambert <terry@lambert.org>
Message-Id: <199511171848.LAA05946@phaeton.artisoft.com>
Subject: Re: elm problem - "solved"
To: grog@lemis.de
Date: Fri, 17 Nov 1995 11:48:19 -0700 (MST)
Cc: hackers@FreeBSD.ORG
In-Reply-To: <199511171732.SAA26447@allegro.lemis.de> from "Greg Lehey" at Nov 17, 95 06:32:43 pm
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> Well, we found the problem.  lock_info is of type struct flock.  In
> BSD systems derived from Net/2, and also in Linux, SunOS 4, System
> V.3, struct flock is defined as
> 
> /*
>  * Advisory file segment locking data type -
>  * information passed to system by user
>  */
> struct flock {
> 	short	l_type;		/* lock type: read/write, etc. */
> 	short	l_whence;	/* type of l_start */
> 	off_t	l_start;	/* starting offset */
> 	off_t	l_len;		/* len = 0 means until end of file */
> 	pid_t	l_pid;		/* lock owner */
> };

BZZZT.  SunOS4 has the syspid as well.  It's necessary for NFS locking,
which is why my NFS locking kernel support patches had it as well.

> I really have great difficulty understanding why this change was made.
> It means that old FreeBSD and BSD/386 binaries won't work correctly
> under FreeBSD or BSD/OS Versions 2.  I can't see any advantage at all
> in this change.  Grrrr.

Think packing on RISC systems.  You put the largest followed by the
smallest to reduce the copyin overhead.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.