From owner-freebsd-hackers@FreeBSD.ORG  Fri Mar  4 14:36:43 2011
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 55F37106566B
	for <freebsd-hackers@freebsd.org>; Fri,  4 Mar 2011 14:36:43 +0000 (UTC)
	(envelope-from krivenok.dmitry@gmail.com)
Received: from mail-iw0-f182.google.com (mail-iw0-f182.google.com
	[209.85.214.182])
	by mx1.freebsd.org (Postfix) with ESMTP id 23A6A8FC15
	for <freebsd-hackers@freebsd.org>; Fri,  4 Mar 2011 14:36:42 +0000 (UTC)
Received: by iwn33 with SMTP id 33so2265128iwn.13
	for <freebsd-hackers@freebsd.org>; Fri, 04 Mar 2011 06:36:42 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma;
	h=domainkey-signature:mime-version:date:message-id:subject:from:to
	:content-type; bh=H4rqihW7a+WK3sXtrdviNwZkGRSTPVhwOqrh56elEvs=;
	b=bRL/9CNA/kymGVx1p07J68UDiDIEqe+hVgY6lDwShU2t9rbDrGBrJAKvS7K18sn56m
	VLmsq5Z+naIg7ZCOPV83pkK2HyGHchKJEmHLroLQP3uFRk1+FBk3hkKF4Q2NBquofz1g
	YkuWWYGlDXsFdVsoq5OGBUgXSt1W63Ogvht40=
DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma;
	h=mime-version:date:message-id:subject:from:to:content-type;
	b=vIxLt9A85BOUSDIk9JbK+yxQ53Y30Q9zDUFoNWtdm/lkwcISx690m2al8rBBasXNLJ
	Zvyv2+IbynsUA10HtkhcucAhkkKHtNJIP47CiwW5ekAKksYBdunf7lhM+S1EhY5zSFO7
	nVS3bzw3m5npFPSWlNnBhHDy8go775lcJqkO0=
MIME-Version: 1.0
Received: by 10.42.159.6 with SMTP id j6mr689256icx.260.1299249402394; Fri, 04
	Mar 2011 06:36:42 -0800 (PST)
Received: by 10.231.144.140 with HTTP; Fri, 4 Mar 2011 06:36:42 -0800 (PST)
Date: Fri, 4 Mar 2011 17:36:42 +0300
Message-ID: <AANLkTi=QDBjw26fhZSRg6wrTB=E0-yEsWZuRK+Z7L03J@mail.gmail.com>
From: Dmitry Krivenok <krivenok.dmitry@gmail.com>
To: freebsd-hackers@freebsd.org
Content-Type: text/plain; charset=ISO-8859-1
Subject: hw.physmem (loader.conf and sysctl)
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 04 Mar 2011 14:36:43 -0000

Hello Hackers,
I've limited the amount of physical memory visible for my FreeBSD-8.2 by adding
the following in loader.conf:

$ cat /boot/loader.conf | grep hw.physmem
hw.physmem="500M"
$

However, according to sysctl, the system sees

$ sysctl hw.physmem
hw.physmem: 507445248
$

The difference is (500 * 2**20 - 507445248) / 2**20 == 16.0625 Mb.
How does the system use this "hidden" memory?

Thanks!

-- 
Sincerely yours, Dmitry V. Krivenok
e-mail: krivenok.dmitry@gmail.com
skype: krivenok_dmitry
jabber: krivenok_dmitry@jabber.ru
icq: 242-526-443