From owner-freebsd-arch@FreeBSD.ORG  Wed Aug 27 09:10:56 2008
Return-Path: <owner-freebsd-arch@FreeBSD.ORG>
Delivered-To: freebsd-arch@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 100AD106566C;
	Wed, 27 Aug 2008 09:10:56 +0000 (UTC)
	(envelope-from rwatson@FreeBSD.org)
Received: from cyrus.watson.org (cyrus.watson.org [209.31.154.42])
	by mx1.freebsd.org (Postfix) with ESMTP id A8D5A8FC20;
	Wed, 27 Aug 2008 09:10:55 +0000 (UTC)
	(envelope-from rwatson@FreeBSD.org)
Received: from fledge.watson.org (fledge.watson.org [209.31.154.41])
	by cyrus.watson.org (Postfix) with ESMTP id 26BBB46C99;
	Wed, 27 Aug 2008 05:10:55 -0400 (EDT)
Date: Wed, 27 Aug 2008 10:10:55 +0100 (BST)
From: Robert Watson <rwatson@FreeBSD.org>
X-X-Sender: robert@fledge.watson.org
To: Andrew Reilly <andrew-freebsd@areilly.bpc-users.org>
In-Reply-To: <20080827011949.GA98242@duncan.reilly.home>
Message-ID: <alpine.BSF.1.10.0808271009340.60038@fledge.watson.org>
References: <g8q8i5$s9g$2@ger.gmane.org>
	<3c1674c90808231713x47e42de5oa9fc2f2f244d2e74@mail.gmail.com>
	<20080826074943.GB85357@duncan.reilly.home>
	<20080826162807.GF16977@elvis.mu.org>
	<20080827011949.GA98242@duncan.reilly.home>
User-Agent: Alpine 1.10 (BSF 962 2008-03-14)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
Cc: Matthew Macy <mat.macy@gmail.com>, Alfred Perlstein <alfred@freebsd.org>,
	Ivan Voras <ivoras@freebsd.org>, freebsd-arch@freebsd.org
Subject: Re: FreeBSD and DEP aka "NX bit"?
X-BeenThere: freebsd-arch@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussion related to FreeBSD architecture <freebsd-arch.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-arch>
List-Post: <mailto:freebsd-arch@freebsd.org>
List-Help: <mailto:freebsd-arch-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 27 Aug 2008 09:10:56 -0000

On Wed, 27 Aug 2008, Andrew Reilly wrote:

> On Tue, Aug 26, 2008 at 09:28:07AM -0700, Alfred Perlstein wrote:
>> * Andrew Reilly <andrew-freebsd@areilly.bpc-users.org> [080826 00:51] 
>> wrote:
>>> I've been using 7-STABLE on amd64 for a long time, and haven't noticed any 
>>> problems with Java or SBCL lisp or PLT-scheme, all of which use JIT code 
>>> generation (but probably neither use jemalloc?)
>>
>> mprotect(2)?
>
> Fair enough.  Good to know that it's actually tweaking the NX permissions, I 
> guess.  The man page seems a little vague about when it might succeed, and 
> what effect it might have...

We're behind on the not-mapping-writable stuff, so for better (and worse) 
quite a few such things in application have been faulted in by other operating 
systems already.  That doesn't mean there won't be issues, but does have the 
redeeming aspect that things should be less bumpy for us going forward. 
Hopefully we can start making that progress a bit more quickly...

Robert N M Watson
Computer Laboratory
University of Cambridge