From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Jm4Pm-0005gI-PD for qemu-devel@nongnu.org; Wed, 16 Apr 2008 05:58:54 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Jm4Pk-0005ft-Gl for qemu-devel@nongnu.org; Wed, 16 Apr 2008 05:58:53 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Jm4Pk-0005fp-5A for qemu-devel@nongnu.org; Wed, 16 Apr 2008 05:58:52 -0400 Received: from mx2.suse.de ([195.135.220.15]) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1Jm4Pj-0006sM-Te for qemu-devel@nongnu.org; Wed, 16 Apr 2008 05:58:52 -0400 Received: from Relay1.suse.de (relay-ext.suse.de [195.135.221.8]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id D4EF444E70 for ; Wed, 16 Apr 2008 11:58:49 +0200 (CEST) Message-ID: <4805CC9B.7050809@suse.de> Date: Wed, 16 Apr 2008 11:53:31 +0200 From: Kevin Wolf MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault References: <47EE86E0.4070703@reactos.org> <47F0B445.4030806@suse.de> <4804D254.5040301@siemens.com> <200804151757.05303.paul@codesourcery.com> <4805BAB0.1030707@suse.de> <20080416092340.GA27898@shareable.org> In-Reply-To: <20080416092340.GA27898@shareable.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Jamie Lokier schrieb: > Kevin Wolf wrote: >>> IMHO There's no reason to print a message to stderr. This is all >>> well defined behavior, and the accepted way of exiting from 286 >>> protected mode. >> How many users does qemu have who need triple faults to exit from 286 >> Protected Mode? > > Not many, only those users running old MS-DOS apps / OSes. MS-DOS is running in Real Mode, you'd additionally need an application which uses 286 PM. Apparently there aren't too many users relying on triple faults as in the past qemu aborted (or in earlier versions even hung) on triple faults and nobody complained. >> And how many users does it have who don't use triple >> faults (yes, it's called a fault, not a PM exiting feature) > > Faults don't mean errors. Think about page faults. Ok, you're right on my wording. But double faults (which always occur before a triple fault) are in fact despite their name not faults, but aborts. Just to reword it using the correct terminology. ;-) >> And honestly, a message on stderr really shouldn't hurt those 286 folks. > > For old MS-DOS apps / OSes, I have the impression this can happen > hundreds of times per second. It's part of task context switching and > BIOS calls. I have to admit that I'm all but an 286 PM expert. What exactly is a triple fault doing there? If it leads to a reset as implemented here, I can hardly imagine that it is of much use in regular context switching. Kevin