From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1JAxWA-0002e9-LQ
	for qemu-devel@nongnu.org; Fri, 04 Jan 2008 20:08:06 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1JAxW9-0002df-47
	for qemu-devel@nongnu.org; Fri, 04 Jan 2008 20:08:06 -0500
Received: from [199.232.76.173] (helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1JAxW9-0002dc-0P
	for qemu-devel@nongnu.org; Fri, 04 Jan 2008 20:08:05 -0500
Received: from mail.codesourcery.com ([65.74.133.4])
	by monty-python.gnu.org with esmtps
	(TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60)
	(envelope-from <paul@codesourcery.com>) id 1JAxW8-0002qW-Go
	for qemu-devel@nongnu.org; Fri, 04 Jan 2008 20:08:04 -0500
From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [PATCH] fix possible NULL pointer use in hw/ptimer.c
Date: Sat, 5 Jan 2008 01:07:58 +0000
References: <477C489C.1000208@earthlink.net>
	<99DF1970-75E9-4D9D-A6D3-C0F71B2CC6C5@jump-ing.de>
	<200801041844.43789.rob@landley.net>
In-Reply-To: <200801041844.43789.rob@landley.net>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
Message-Id: <200801050107.59131.paul@codesourcery.com>
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org
Cc: Markus Hitter <mah@jump-ing.de>, Robert Reif <reif@earthlink.net>

> On modern operating systems, allocations only return zero when you exhaust
> virtual memory. =A0Returning nonzero doesn't mean you have enough memory,
> because it's given you a redundant copy on write mapping of the zero page
> and will fault in physical pages when you write to 'em, which has _no_
> return value. =A0Instead, the out of memory killer will shoot your progra=
m in
> the head in the middle of it's run

Decent operating systems allow the system administrator gets to choose how=
=20
optimistic memory allocation is. You're describing wildly-optimistic mode,=
=20
which is often but not always the default.

Paul