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From: songer@orchestra.ecn.purdue.edu (Christopher M Songer)
Newsgroups: comp.sys.next
Subject: Re: NeXT equivalent of Shared Memory and Semaphores on SysV
Keywords: Shared Memory
Message-ID: <1991Mar12.170806.4691@noose.ecn.purdue.edu>
Date: 12 Mar 91 17:08:06 GMT
References: <1125@tokio.cs.utexas.edu> <michael.668476436@hapuna> <71219@microsoft.UUCP>
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     Being one of the people that started this thread, I'd just like
to comment that I have seen NO evidence to support the existence
of external pager support in Next OS of any version 1.0 or later.
An nm on the kernel shows the absence of several crucial calls.
Additionally, the nasty silence I have had out of ask_next doesn't
inspire hope. In reality, there seems to be only one call that will
even give you a memory object back, and this is certainly not an
allocation call, mearly an inquiry (vm_region).

     As a result, I've pretty much given up on doing a sysV shared
memory / IPC emulation library until a new OS version comes out. I 
suppose I'll look again at feasibility then. 

     I too have heard there were performance problems with Mach2.5's
external pager support, so maybe the absence is not a bad thing.
Still, sysV IPC compatibility would be nice from a user standpoint
(if not a purist standpoint) and I do hope support for some sort of
kernel service that would allow sysV shared memory emulation (maybe
non-copy on write files....) will come out in future releases.

-Chris