Xref: utzoo comp.unix.xenix:1653 comp.unix.microport:197 comp.sys.att:2731
Path: utzoo!mnetor!uunet!husc6!cmcl2!phri!manhat!mancol!marob!samperi
From: samperi@marob.MASA.COM (Dominick Samperi)
Newsgroups: comp.unix.xenix,comp.unix.microport,comp.sys.att
Subject: Re: IPC facilities (shared memory)
Message-ID: <150@marob.MASA.COM>
Date: 9 Mar 88 20:34:20 GMT
References: <335@mancol.UUCP> <9844@steinmetz.steinmetz.UUCP>
Reply-To: samperi@marob.UUCP (Dominick Samperi)
Organization: 18th Street Construction Co NY NY
Lines: 23
Keywords: IPC, shared memory, semaphores
Summary: The child must attach the segment

In article <9844@steinmetz.steinmetz.UUCP> davidsen@crdos1.UUCP (bill davidsen) writes:
>
>  SysV shared memory segments are inherited by the child, like any other
>open handle. If you open the segment and then do a fork, the child has
>access. If you fork and then open, the child will have to open, too.
>
>-- 
>	bill davidsen		(wedu@ge-crd.arpa)
>  {uunet | philabs | seismo}!steinmetz!crdos1!davidsen
>"Stupidity, like virtue, is its own reward" -me

Perhaps you are talking about the Xenix-style IPC facilities here (sgget, etc.)
which I no nothing about. When the SysV-style facilities are used a forked
child process must attach a shared memory segment (using the segment identifier
that the parent got when it created the segment) before it can use it. This
works fine on an AT&T 3b2 and under Microport's System V/AT, but the child gets
an "invalid argument" error under SCO Xenix (same source code used on each
system, compiled with -Mle in the Xenix environment).
-- 
Dominick Samperi, Manhattan College, NYC
    manhat!samperi@NYU.EDU           ihnp4!rutgers!nyu.edu!manhat!samperi
    philabs!cmcl2!manhat!samperi     ihnp4!rutgers!hombre!samperi
              (^ that's an ell)      uunet!swlabs!mancol!samperi