From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269018AbUHMHn3 (ORCPT ); Fri, 13 Aug 2004 03:43:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269019AbUHMHn2 (ORCPT ); Fri, 13 Aug 2004 03:43:28 -0400 Received: from twilight.ucw.cz ([81.30.235.3]:17025 "EHLO midnight.ucw.cz") by vger.kernel.org with ESMTP id S269018AbUHMHn1 (ORCPT ); Fri, 13 Aug 2004 03:43:27 -0400 Date: Fri, 13 Aug 2004 09:44:57 +0200 From: Vojtech Pavlik To: Jakub Vana Cc: alan@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org Subject: Re: x86 - Realmode BIOS and Code calling module Message-ID: <20040813074457.GA503@ucw.cz> References: <20040812133854Z2097966-29039+40063@mail.centrum.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040812133854Z2097966-29039+40063@mail.centrum.cz> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 12, 2004 at 03:38:45PM +0200, Jakub Vana wrote: > > Why is this better than LRMI in user mode. > > I was now looking on LRMI. It must be a nice code, but It is still > only V86 emulation. I have listen that some BIOSes use something > called Unreal mode, that is realmode with segment registers used like > in protected mode. There is only one way, how to set this segregs - > switch to prot. mode, but if the BIOS try to switch when is running in > V86 CPU generates #GP (Global Protection fault). Not if it is running > in real Real Mode. Well, if it's running an emulated CPU (x86emu), there are no problems with that. Even the unreal mode could be emulated, although I have yet to see a BIOS which uses that to handle an INT call. -- Vojtech Pavlik SuSE Labs, SuSE CR