From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O1pPq-0004rI-Do for qemu-devel@nongnu.org; Tue, 13 Apr 2010 19:21:10 -0400 Received: from [140.186.70.92] (port=60338 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O1pPo-0004rA-0K for qemu-devel@nongnu.org; Tue, 13 Apr 2010 19:21:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O1pPm-0004Do-Gd for qemu-devel@nongnu.org; Tue, 13 Apr 2010 19:21:07 -0400 Received: from mail2.shareable.org ([80.68.89.115]:55716) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O1pPm-0004DN-CM for qemu-devel@nongnu.org; Tue, 13 Apr 2010 19:21:06 -0400 Date: Wed, 14 Apr 2010 00:20:56 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] Problem with DOS application and 286 DOS Extender application Message-ID: <20100413232056.GA21321@shareable.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerhard Wiesinger Cc: qemu-devel@nongnu.org, Roy Tam Gerhard Wiesinger wrote: > It is a non public, proprietary application which uses the Ergo Computing > 286 DOS Extender. I guess some other application which use the same DOS > extender have the same problem. So best thing is to find another > application which uses the Ergo Computing 286 DOS Extender, too. The 286 was obsolete 20 years ago, although code depending on it persisted for some years after. I'm fairly sure the number of people using (or trying to use) Qemu with 286-specific code is very small indeed, so unfortunately for a 286 problem, you will need to help reproduce it as much as you can for it to be fixed. Note that Qemu doesn't emulate segments properly even for 32-bit x86 code, and 16-bit (286) code depends on that all the more. That may be the problem. Or it may be the "reset using keyboard controller and BIOS" method used to switch from protected mode to real mode on a 286 is not implemented properly, or is not supported by the BIOS properly. Or it may simply be a bug in 16-bit task segment switching or something like that, which is quite complex and so rarely used that it might never have been properly tested. Did you try running the application under Bochs, which has a more accurate emulation of very old x86 CPUs? -- Jamie