From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1NSFVs-0003Fr-DM
	for qemu-devel@nongnu.org; Tue, 05 Jan 2010 14:56:20 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1NSFVd-00032s-De
	for qemu-devel@nongnu.org; Tue, 05 Jan 2010 14:56:12 -0500
Received: from [199.232.76.173] (port=43137 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1NSFVb-00031B-FI
	for qemu-devel@nongnu.org; Tue, 05 Jan 2010 14:56:03 -0500
Received: from mx20.gnu.org ([199.232.41.8]:36470)
	by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32)
	(Exim 4.60) (envelope-from <benh@kernel.crashing.org>)
	id 1NSFVX-0005H3-HL
	for qemu-devel@nongnu.org; Tue, 05 Jan 2010 14:55:59 -0500
Received: from gate.crashing.org ([63.228.1.57])
	by mx20.gnu.org with esmtp (Exim 4.60)
	(envelope-from <benh@kernel.crashing.org>) id 1NRwSg-0001aP-Us
	for qemu-devel@nongnu.org; Mon, 04 Jan 2010 18:35:47 -0500
Subject: Re: [Qemu-devel] Re: [PATCH 1/6] Make config space accessor host
	bus trapable
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
In-Reply-To: <20100104225938.GC21659@redhat.com>
References: <19BFDDD5-85E0-42EC-9D71-391CECC023F5@suse.de>
	<20100104104516.GD4672@valinux.co.jp>
	<20100104110758.GE8522@redhat.com>
	<1262635858.2173.371.camel@pasglop> <20100104211208.GA21488@redhat.com>
	<1262640330.2173.386.camel@pasglop> <20100104213021.GC21488@redhat.com>
	<1262642032.2173.388.camel@pasglop> <20100104222535.GA21659@redhat.com>
	<1262645508.2173.394.camel@pasglop> <20100104225938.GC21659@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Date: Tue, 05 Jan 2010 10:33:19 +1100
Message-ID: <1262647999.2173.416.camel@pasglop>
Mime-Version: 1.0
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: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Blue Swirl <blauwirbel@gmail.com>, Isaku Yamahata <yamahata@valinux.co.jp>, Alexander Graf <agraf@suse.de>, Aurelien Jarno <aurelien@aurel32.net>, QEMU Developers <qemu-devel@nongnu.org>


> So, it appears that this is not the case for many platforms: bridge
> itself does a byteswap to make devices behind it work according to spec,
> but this does not apply to programming bridge itself.
> 
> This seems common on BE platforms, this is why qemu has
> ifdef TARGET_WORDS_BIGENDIAN there IIUC.

Sadly, it is quite often that misleaded HW designers thing they are
doing SW a service by making something BE instead of LE on a BE
platform, but in the end just forcing everybody to special case :-)

It's hard to say what is the most common. All powerpc chrp have it LE
afaik, FSL tried to be smart (FAIL) and got their SoC config space
access reg BE instead. Apple stuff is just "special", etc...

In any case, it doesn't matter much as long as qemu gets normal MMIO
emulation right. Host bridge config space is chipset specific and as
such platform specific.

Cheers,
Ben.