From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1MBATe-0002o6-St
	for qemu-devel@nongnu.org; Mon, 01 Jun 2009 12:35:10 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1MBATZ-0002di-Fp
	for qemu-devel@nongnu.org; Mon, 01 Jun 2009 12:35:09 -0400
Received: from [199.232.76.173] (port=56112 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1MBATZ-0002dA-8H
	for qemu-devel@nongnu.org; Mon, 01 Jun 2009 12:35:05 -0400
Received: from mx20.gnu.org ([199.232.41.8]:14930)
	by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32)
	(Exim 4.60) (envelope-from <paul@codesourcery.com>)
	id 1MBATY-0004AP-FW
	for qemu-devel@nongnu.org; Mon, 01 Jun 2009 12:35:04 -0400
Received: from mail.codesourcery.com ([65.74.133.4])
	by mx20.gnu.org with esmtp (Exim 4.60)
	(envelope-from <paul@codesourcery.com>) id 1MBATU-0007re-HY
	for qemu-devel@nongnu.org; Mon, 01 Jun 2009 12:35:00 -0400
From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] Add ARM920T to ARM emulation
Date: Mon, 1 Jun 2009 17:34:56 +0100
References: <1243603405-12989-1-git-send-email-vince@simtec.co.uk>
	<200906011313.49802.paul@codesourcery.com>
	<4A23D7B0.9050706@redhat.com>
In-Reply-To: <4A23D7B0.9050706@redhat.com>
MIME-Version: 1.0
Content-Type: Text/Plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200906011734.57129.paul@codesourcery.com>
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: Vincent Sanders <vince@simtec.co.uk>, Avi Kivity <avi@redhat.com>

On Monday 01 June 2009, Avi Kivity wrote:
> Paul Brook wrote:
> > B is a direct branch that never changes mode. BX is an indirect branch
> > that mode switches based on the low address bit.
> > BL and BLX(register) are exactly the same as B/BX except they also set
> > LR. BLX(immediate) is a direct mode switching call.
> > loads into the PC either ignore(v4t) or mode switch (v5) on the low
> > address bit.
> > ALU writes to the PC always ignore the low bit in Thumb mode. In ARM mode
> > the low bit is either ignored(v6) or used to mode switch (v7).
> >
> > BX was introduced in v4t, BLX was introduced in v5.
>
> Does no sane instruction set exist?

Thumb mode definitely has several "entertaining" aspects, but ARM mode is 
generally fairly sane.

Paul