From owner-freebsd-hackers@FreeBSD.ORG  Mon Mar 12 10:33:14 2007
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
X-Original-To: freebsd-hackers@freebsd.org
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 76D0E16A402
	for <freebsd-hackers@freebsd.org>; Mon, 12 Mar 2007 10:33:14 +0000 (UTC)
	(envelope-from citrin@citrin.ru)
Received: from mail.classis.ru (classis.ru [213.248.60.120])
	by mx1.freebsd.org (Postfix) with ESMTP id 3A9E713C457
	for <freebsd-hackers@freebsd.org>; Mon, 12 Mar 2007 10:33:14 +0000 (UTC)
	(envelope-from citrin@citrin.ru)
Received: from citrin (unknown [81.19.65.95])
	(using TLSv1 with cipher AES256-SHA (256/256 bits))
	(No client certificate requested)
	(Authenticated sender: citrin.citrin.ru)
	by mail.classis.ru (Postfix) with ESMTP id 9FBA41227A80
	for <freebsd-hackers@freebsd.org>; Mon, 12 Mar 2007 13:11:26 +0300 (MSK)
Date: Mon, 12 Mar 2007 13:10:34 +0300
From: Anton Yuzhaninov <citrin@citrin.ru>
X-Mailer: The Bat! (v3.62.14) Professional
Organization: Rambler
X-Priority: 3 (Normal)
Message-ID: <782951585.20070312131034@citrin.ru>
To: freebsd-hackers@freebsd.org
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Subject: Why max mmap size limited to half of virtual address space?
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: Mon, 12 Mar 2007 10:33:14 -0000

Hello,

Why  max mmap size limited to half virtual address space?
On i386 it limited to 2 Gb:

/sys/vm/vm_mmap.c

      /* make sure mapping fits into numeric range etc */
        if ((ssize_t) uap->len < 0 ||
            ((flags & MAP_ANON) && uap->fd != -1))
                return (EINVAL);


(ssize_t) uap->len < 0
limit maximum value for uap->len to SIZE_T_MAX/2

May be this check can be removed?

It test it on FreeBSD 6.2 i386 - without this check a can map 2400 Mb
file.

Also mmap man page say, that 2 Gb limit was a documentation bug, but this
limit still exist on i386.

-- 
 Anton Yuzhaninov.