From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1N5V5a-00055e-7C
	for qemu-devel@nongnu.org; Tue, 03 Nov 2009 20:55:10 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1N5V5V-000554-WF
	for qemu-devel@nongnu.org; Tue, 03 Nov 2009 20:55:09 -0500
Received: from [199.232.76.173] (port=60022 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1N5V5V-000551-Ph
	for qemu-devel@nongnu.org; Tue, 03 Nov 2009 20:55:05 -0500
Received: from mail-yw0-f176.google.com ([209.85.211.176]:64978)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <anthony@codemonkey.ws>) id 1N5V5V-0000yV-E8
	for qemu-devel@nongnu.org; Tue, 03 Nov 2009 20:55:05 -0500
Received: by ywh6 with SMTP id 6so5930478ywh.4
	for <qemu-devel@nongnu.org>; Tue, 03 Nov 2009 17:55:04 -0800 (PST)
Message-ID: <4AF0DEF5.6020805@codemonkey.ws>
Date: Tue, 03 Nov 2009 19:55:01 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] Re: PC machine types switched to SeaBIOS/gPXE
References: <4AEAFE39.1030302@us.ibm.com>
	<4AEB408F.9060205@web.de>	<4AEB426A.5080305@us.ibm.com>	<4AEC30A6.6020600@mail.berlios.de>
	<4AEC375E.50701@web.de>	<4AEF66BE.3070203@us.ibm.com>
	<4AEF6998.80103@codemonkey.ws>	<20091103041654.GB9856@morn.localdomain>
	<4AF03A1C.804@us.ibm.com> <20091104013804.GA24215@morn.localdomain>
In-Reply-To: <20091104013804.GA24215@morn.localdomain>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
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: Kevin O'Connor <kevin@koconnor.net>
Cc: Jan Kiszka <jan.kiszka@web.de>, Beth Kon <eak@us.ibm.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Gleb Natapov <gleb@redhat.com>, Avi Kivity <avi@redhat.com>

Kevin O'Connor wrote:
> I traced this down, and it looks like there is a series of subtle bugs
> that led to this situation.
>
> The bug causing the boot to fail is that gPXE didn't update its
> checksum.  This was supposed to be fixed in gPXE commit f16668d, but
> it looks like gPXE either regressed or the e1000 driver is special in
> some way.
>
> The reason SeaBIOS commit a5826b5a exposes this issue, is that commit
> a5826b5a broke SeaBIOS' PMM support - the gPXE bug only shows up when
> PMM is not available.
>
> So, why did commit a5826b5a break PMM?  This appears to be some weird
> interaction with gcc and its "-fwhole-program -combine" options.  One
> of the variables (ZoneTmpHigh) is incorrectly marked by gcc as being
> local instead of global after commit a5826b5a.  Unfortunately, instead
> of getting an error, the build proceeded and had a bogus reference to
> the ZoneTmpHigh variable - which caused PMM allocations to fail even
> when there was memory.
>
> I've reorganized the build slightly to work around this problem with
> "-combine".  I've also updated the SeaBIOS linker scripts so that they
> will cause a build failure if a similar issue arises in the future.
> The latest SeaBIOS git should have this all working again (even with
> the current e1000 gPXE).
>   

Thanks for tracking this down Kevin!

Regards,

Anthony Liguori