From owner-freebsd-stable@freebsd.org  Sun Jan 28 16:32:46 2018
Return-Path: <owner-freebsd-stable@freebsd.org>
Delivered-To: freebsd-stable@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 5053FED155D
 for <freebsd-stable@mailman.ysv.freebsd.org>;
 Sun, 28 Jan 2018 16:32:46 +0000 (UTC) (envelope-from mike@karels.net)
Received: from mail.karels.net (mail.karels.net [216.160.39.52])
 by mx1.freebsd.org (Postfix) with ESMTP id CFF0E84CA0;
 Sun, 28 Jan 2018 16:32:45 +0000 (UTC) (envelope-from mike@karels.net)
Received: from mail.karels.net (localhost [127.0.0.1])
 by mail.karels.net (8.15.2/8.15.2) with ESMTP id w0SGWiui055204;
 Sun, 28 Jan 2018 10:32:44 -0600 (CST) (envelope-from mike@karels.net)
Message-Id: <201801281632.w0SGWiui055204@mail.karels.net>
To: Dimitry Andric <dim@FreeBSD.org>
cc: Andre Albsmeier <Andre.Albsmeier@siemens.com>, freebsd-stable@freebsd.org
From: Mike Karels <mike@karels.net>
Reply-to: mike@karels.net
Subject: Re: i386 with 4GB RAM: less than 2GB available on A2SAV (Intel Atom
 E3940)
In-reply-to: Your message of Sun, 28 Jan 2018 17:05:54 +0100.
 <FF56490E-BD56-4BF1-B1D7-866ACEB32DC4@FreeBSD.org>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <55202.1517157164.1@mail.karels.net>
Date: Sun, 28 Jan 2018 10:32:44 -0600
X-BeenThere: freebsd-stable@freebsd.org
X-Mailman-Version: 2.1.25
Precedence: list
List-Id: Production branch of FreeBSD source code <freebsd-stable.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-stable>, 
 <mailto:freebsd-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-stable/>
List-Post: <mailto:freebsd-stable@freebsd.org>
List-Help: <mailto:freebsd-stable-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
 <mailto:freebsd-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 28 Jan 2018 16:32:46 -0000

> On 28 Jan 2018, at 15:57, Andre Albsmeier <Andre.Albsmeier@siemens.com> =
> wrote:
> > I have a lot of machines running with 4 GB physical RAM and, for
> > some reasons, I still have to use a 32 bits OS.
> >=20
> > All of them show something between 3 and 3.5 GB of RAM available
> > in dmesg but the brand new Supermicro A2SAV really shocked me:
> >=20
> > FreeBSD 11.1-STABLE #0: Mon Jan 15 06:57:10 CET 2018
> > ...
> > real memory  =3D 4294967296 (4096 MB)
> > avail memory =3D 1939558400 (1849 MB)
> > ...
> >=20
> > So do people have any ideas how I might get a bit closer to at least
> > 3 GB? I assume there are no FreeBSD knobs which might help but hope
> > dies last...

> This is a common problem on i386.  Most likely some ranges are reserved
> for I/O mappings, such as video cards.  If you boot with -v, I think the
> kernel prints an overview of the physical ram chunks available?  I don't
> know of any other way to get such an overview.

> Another option is to try PAE, but I have no idea how stable that is...

> -Dimitry

I suspect that the unavailable RAM has been mapped above 4 GB by the BIOS.

About PAE: at $JOB, we have a FreeBSD 8.2 system that has been running
PAE reliably since 8.2 was new.  Also, we ship amd64 systems that run
mostly 32-bit binaries, which works well.

		Mike