From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O3wDr-0002ho-VX for qemu-devel@nongnu.org; Mon, 19 Apr 2010 15:01:32 -0400 Received: from [140.186.70.92] (port=54666 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O3wDq-0002fd-BG for qemu-devel@nongnu.org; Mon, 19 Apr 2010 15:01:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O3wDo-0001iO-Il for qemu-devel@nongnu.org; Mon, 19 Apr 2010 15:01:30 -0400 Received: from chello084112167138.7.11.vie.surfer.at ([84.112.167.138]:46930 helo=wiesinger.com) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O3wDo-0001hm-5q for qemu-devel@nongnu.org; Mon, 19 Apr 2010 15:01:28 -0400 Date: Mon, 19 Apr 2010 21:00:13 +0200 (CEST) From: Gerhard Wiesinger Subject: Re: [Qemu-devel] Problem with DOS application and 286 DOS Extender application In-Reply-To: Message-ID: References: <20100413232056.GA21321@shareable.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, Roy Tam On Wed, 14 Apr 2010, Gerhard Wiesinger wrote: > On Wed, 14 Apr 2010, Jamie Lokier wrote: > >> 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? > > Yes, Bochs is very slow but works well. Any plans to improve the handling of > the above issues? > > BTW: 386 DOS Extender applications seem to work ok even on QEMU. > OK, 286 and 386 DOS Extender applications seem to work well with qemu-kvm: git://git.kernel.org/pub/scm/virt/kvm/qemu-kvm.git There is only a video performance problem left, see my next posts. Ciao, Gerhard -- http://www.wiesinger.com/