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Date: Mon, 13 Jan 2003 17:54:24 -0800 (PST)
From: Matthew Dillon <dillon@apollo.backplane.com>
Message-Id: <200301140154.h0E1sOe6015613@apollo.backplane.com>
To: Peter Wemm <peter@wemm.org>
Cc: "Alan L. Cox" <alc@imimic.com>, arch@FreeBSD.ORG
Subject: Re: Virtual memory question 
References:  <20030114002831.1C8C12A89E@canning.wemm.org>
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:> > 
:> >         getmemfd().
:> > 
:> 
:> Roughly speaking, this is shm_open(3), which we currently implement
:> using files.
:
:.. which is expressly what I wanted to avoid.
:
:Cheers,
:-Peter

    I can work up basic operation (i.e. getmemfd() and mmap()) in an hour
    or two.  I'll have a patch set tonight.  It looks utterly trivial.

    I think I'll generalize the system call, though, with two parameters:

    getsysfd(int type, off_t size)

    fd = getsysfd(SYSFD_MEMORY, 1024*1024);	/* get 1MB memory object */

    fd = getsysfd(SYSFD_MEMORY, -1);	/* get infinite-sized memory object */
    mmap(...)

    This way we can use it to implement and obtain other special purpose
    descriptors.  For example, like the controlling terminal, or a timer,
    or a kqueue, etc etc etc.   Since we seeem to be implementing special
    purpose FDs more and more these days.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>

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