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Date:      Mon, 25 Aug 1997 22:20:08 +0200
From:      j@uriah.heep.sax.de (J Wunsch)
To:        hackers@FreeBSD.ORG (hackers@freebsd.org)
Cc:        mburgett@awen.com (Mike Burgett)
Subject:   Re: special malloc needs...
Message-ID:  <19970825222008.PD53308@uriah.heep.sax.de>
In-Reply-To: <199708251630.JAA18241@dragon.awen.com>; from Mike Burgett on Aug 25, 1997 09:30:51 -0700
References:  <199708251630.JAA18241@dragon.awen.com>

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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.

What the h*ck would you need this in a userland program?

> Browsing the kernel/dd sources, I found contigmalloc, but it doesn't
> appear to be available in any of the libs... (kernel only?)

Kernel only, and only likely to succeed when being called at kernel
init time.  This is natural, if you think about it.  Once the physical
memory is fragmented, you cannot get a guarantee for contiguous memory
at all.

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)



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