From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Nlkdj-0006Sr-EL for qemu-devel@nongnu.org; Sun, 28 Feb 2010 10:01:03 -0500 Received: from [199.232.76.173] (port=35260 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Nlkdj-0006Sd-1m for qemu-devel@nongnu.org; Sun, 28 Feb 2010 10:01:03 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1Nlkdh-0007JI-JJ for qemu-devel@nongnu.org; Sun, 28 Feb 2010 10:01:02 -0500 Received: from hall.aurel32.net ([88.191.82.174]:53436) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1Nlkdh-0007JB-8j for qemu-devel@nongnu.org; Sun, 28 Feb 2010 10:01:01 -0500 Date: Sun, 28 Feb 2010 16:00:58 +0100 From: Aurelien Jarno Subject: Re: [Qemu-devel] [Bug] qemu-system-ppc: "invalid/unsupported opcode" during debug session Message-ID: <20100228150058.GA8952@hall.aurel32.net> References: <4B3A1B9D.7010004@mail.berlios.de> <20100228131830.GJ10291@volta.aurel32.net> <201002281402.34086.paul@codesourcery.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <201002281402.34086.paul@codesourcery.com> Sender: Aurelien Jarno List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paul Brook Cc: qemu-devel@nongnu.org On Sun, Feb 28, 2010 at 02:02:33PM +0000, Paul Brook wrote: > > > invalid/unsupported opcode: 00 - 00 - 00 (00000000) 4800fa44 1 > > > > I have fixed that in HEAD by stopping the translation just after a trap, > > as the instructions might never be executed. > > > > It is not a full fix, as the OS can actually use any instruction that > > always generate a trap (even a memory access) as an instruction barrier > > to make sure the following instructions are never executed. This > > actually affects all targets, but is unlikely to happen. > > > > One solution for that would be to only generate an exception for an > > unsupported instruction when it is the first instruction of a TB, and > > otherwise just end the translation before this instruction. > > By my reading the code is correct. We end up calling gen_invalid which output > code to raise an invalid instruction exception. If earlier code faults at > runtime then that code is never executed, and everything is happy. You are correct, I have read the code too quickly. So ignore what I said above. > The real bug is that we have debugging printfs enabled by default. Agreed, I'll fix that. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurelien@aurel32.net http://www.aurel32.net