From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MLIF3-0003zq-A4 for qemu-devel@nongnu.org; Mon, 29 Jun 2009 10:53:57 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MLIEy-0003tP-9l for qemu-devel@nongnu.org; Mon, 29 Jun 2009 10:53:56 -0400 Received: from [199.232.76.173] (port=59889 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MLIEy-0003t7-1k for qemu-devel@nongnu.org; Mon, 29 Jun 2009 10:53:52 -0400 Received: from gecko.sbs.de ([194.138.37.40]:19566) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MLIEx-0006sT-BP for qemu-devel@nongnu.org; Mon, 29 Jun 2009 10:53:51 -0400 Message-ID: <4A48D579.8000305@siemens.com> Date: Mon, 29 Jun 2009 16:53:45 +0200 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [PATCH 4/4] gdbstub: x86: Switch 64/32 bit registers dynamically References: <20090627075350.13376.17936.stgit@mchn012c.ww002.siemens.net> <200906291507.05278.paul@codesourcery.com> <4A48CE13.6050800@siemens.com> <200906291543.34071.paul@codesourcery.com> In-Reply-To: <200906291543.34071.paul@codesourcery.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paul Brook Cc: Anthony Liguori , qemu-devel@nongnu.org Paul Brook wrote: >>> You've just deliberately broken the qemu gdbstub. After your patch it is >>> impossible to debug mixed 32/64-bit code. >> Please give it a try as it's the other way around: You can't properly >> debug mixed target code without my patch. > > Sure you can, you just need a gdb that doesn't suck. As soon as you encounter > actual mixed code (rather than just running the wrong qemu) your patch causes > things to die horribly. Just to recall the situation (again, please actually try it): if you have to debug code that switches between 16/32 bit and 64 bit, you _can't_ debug the 16 or 32 bit part as gdb will stumble and fall over qemu sending 64-bit register layout for 16/32 bit code. That is a gdb limitation, but this patch is about dealing with it until it's resolved in gdb. Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux