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Date:      Mon, 13 Jan 2003 21:20:24 -0600
From:      "Alan L. Cox" <alc@imimic.com>
To:        Peter Wemm <peter@wemm.org>
Cc:        Matthew Dillon <dillon@apollo.backplane.com>, arch@FreeBSD.ORG
Subject:   Re: Virtual memory question
Message-ID:  <3E2381F8.85BB90A0@imimic.com>
References:  <20030114002831.1C8C12A89E@canning.wemm.org>

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Peter Wemm wrote:
> 
> "Alan L. Cox" wrote:
> > Matthew Dillon wrote:
> > > ...
> > >     How about something like:
> > >
> > >         getmemfd().
> > >
> >
> > Roughly speaking, this is shm_open(3), which we currently implement
> > using files.
> 
> .. which is expressly what I wanted to avoid.
> 

Your response is ambiguous.  :-)  It doesn't say whether you want to
avoid shm_open(3) the interface or rather FreeBSD's implementation of
it.  Personally, I'm all for changing the implementation in the way Matt
describes, but I haven't yet heard a rationale for a new interface. 
Specifically, the interface proposed thus far could be emulated by

	fd = shm_open("unique name", ...);
	shm_unlink("unique name");

The spec also seems to makes the creation of unique names easy: "If name
does not begin with the slash character, the effect is
implementation-dependent."  So, a per-process name space is allowed for
names not beginning with slash.

Furthermore, the only operations that I know of on a "path" are
shm_open() and shm_unlink(), and my reading of those was that a hash
table keyed on the "path" was a legal implementation.  

In summary, a new implementation would be good, but I haven't seen the
rationale for a new interface, especially given that shm_open(3) is an
existing standard.

Regards,
Alan

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