From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1NHag4-00045K-78
	for qemu-devel@nongnu.org; Mon, 07 Dec 2009 05:18:48 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1NHafz-00044M-CR
	for qemu-devel@nongnu.org; Mon, 07 Dec 2009 05:18:47 -0500
Received: from [199.232.76.173] (port=54920 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1NHafy-00044F-Gk
	for qemu-devel@nongnu.org; Mon, 07 Dec 2009 05:18:43 -0500
Received: from mx1.redhat.com ([209.132.183.28]:61714)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <kwolf@redhat.com>) id 1NHafx-0004kZ-NI
	for qemu-devel@nongnu.org; Mon, 07 Dec 2009 05:18:42 -0500
Message-ID: <4B1CD624.5090404@redhat.com>
Date: Mon, 07 Dec 2009 11:17:08 +0100
From: Kevin Wolf <kwolf@redhat.com>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends
References: <m3skbwxgkp.fsf@crossbow.pond.sub.org>	<4B193DA5.6040507@codemonkey.ws>	<m3zl5x1q5x.fsf@crossbow.pond.sub.org>	<Pine.LNX.4.64.0912051957430.3457@linmac.oyster.ru>	<m31vj8zg8s.fsf@crossbow.pond.sub.org>	<Pine.LNX.4.64.0912061132190.8894@linmac.oyster.ru>	<m3bpicwk8r.fsf@crossbow.pond.sub.org>	<Pine.LNX.4.64.0912061302550.9087@linmac.oyster.ru>	<m3bpictl2j.fsf@crossbow.pond.sub.org>	<Pine.LNX.4.64.0912061454420.9249@linmac.oyster.ru>	<m3zl5vnmqo.fsf@crossbow.pond.sub.org>
	<Pine.LNX.4.64.0912071259110.2789@linmac.oyster.ru>
In-Reply-To: <Pine.LNX.4.64.0912071259110.2789@linmac.oyster.ru>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
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: malc <av1474@comtv.ru>
Cc: Paul Brook <paul@codesourcery.com>, Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org

Am 07.12.2009 11:00, schrieb malc:
>>>> Misunderstanding?  Such behavior is indeed permissible, and I can't see
>>>> where I restricted it away.  An implementation that behaves as you
>>>> describe returns "pointer to allocated space".  That the pointer has
>>>> some funny bit set doesn't matter.  That it can't be dereferenced is
>>>> just fine.
>>>>
> 
> Here you agree that it's permissible.

He's just differentiating between values that are generally permissible
in terms of the C standard...

>> You can't just pull pointers out of your ear and expect stuff to work.
> 
> And here you don't. Which renders whole discussion rather pointless.

...and values that can be used by a working implementation on Linux.
That's quite a difference. It is obvious that a libc implementation must
match the kernel, or nothing will work.

Kevin