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To: Greg Lehey <grog@lemis.com>
cc: Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de>,
        "hackers@freebsd.org" <hackers@FreeBSD.ORG>,
        Mike Burgett <mburgett@awen.com>
Subject: Re: special malloc needs... 
In-reply-to: Your message of "Tue, 26 Aug 1997 12:42:23 +0930."
             <19970826124223.62337@lemis.com> 
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Date: Tue, 26 Aug 1997 13:22:50 +0930
From: Mike Smith <mike@smith.net.au>
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> On Mon, Aug 25, 1997 at 10:20:08PM +0200, J Wunsch wrote:
> > As Mike Burgett wrote:
> >
> >> Is there any way to malloc memory (from userland code) that is at
> >> specific offsets from each other in physical memory (i.e. 2 chunks
> >> exactly XXM apart in physical RAM) or failing that, to allocate a
> >> very large (>32M) chunk of contig physical RAM? (again, from
> >> userland?)
> >
> > No, you can't do this.  You get virtual memory, nothing else.  It's
> > not even backed with physical memory at all when you've got it.
> 
> Well, you can't malloc() it, but you can try to mmap() it with
> MAP_FIXED.  man mmap(2).

This only gives you a fixed _virtual_ address.

> > What the h*ck would you need this in a userland program?
> 
> Good question.  It sounds like a bad practice to me.

It's almost guaranteed that either there is a hidden agenda (and I hate 
it when people don't explain their stupid questions), or the individual 
in question doesn't understand what they're asking.

So Mike, what is it?

mike