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Date:      23 Nov 1998 13:05:15 -0600
From:      Joel Ray Holveck <joelh@gnu.org>
To:        Terry Lambert <tlambert@primenet.com>
Cc:        DBECK@ludens.elte.hu (David Beck), freebsd-hackers@FreeBSD.ORG
Subject:   Re: SYSV Semaphores & mmap problems
Message-ID:  <86lnl2mdqs.fsf@detlev.UUCP>
In-Reply-To: Terry Lambert's message of "Mon, 23 Nov 1998 18:12:25 %2B0000 (GMT)"
References:  <199811231812.LAA18985@usr02.primenet.com>

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> You can actually get mmap'ed memory that is as fast as SYSV SHM
> by mmap'ing anonymous memory off of fd -1, or off of an fd that
> is attached to /dev/zero.  The problem with this is that there
> is no way to rendezvous this memory between processes, unless they
> are all descendents of the original process that did the mapping.
> BSD really needs to fix this deficiency, probably by adding a
> method, similar to that for passing fd's, to pass region mappings
> to other processes.

Have you tried passing an fd attached to /dev/zero around and see if
each process can mmap it separately and get shared memory?

Happy hacking,
joelh

-- 
Joel Ray Holveck - joelh@gnu.org
   Fourth law of programming:
   Anything that can go wrong wi
sendmail: segmentation violation - core dumped

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