From mboxrd@z Thu Jan 1 00:00:00 1970 From: phrostie Subject: Re: please explain to me why video/bios shadowing must be disabled to use graphics... Date: Mon, 30 Sep 2002 20:19:44 -0400 Sender: linux-msdos-owner@vger.kernel.org Message-ID: <103369195401@ispsnet.net> References: Mime-Version: 1.0 Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: List-Id: Content-Type: text/plain; charset="us-ascii" To: Bart Oldeman , linux-msdos@vger.kernel.org an update i did finally get dosemu working. i can run EZ cosmos, commander keen 1-3, and battle chess. commander keen 4 and above still lock up. i did notice that the startup windows are reporting no or low memory. On Monday 23 September 2002 17:14, Bart Oldeman wrote: > On Tue, 24 Sep 2002, Stas Sergeev wrote: > > This problem exists only on some (modern?) cards for VESA > > modes, but for VGA modes there must be no such problem at > > all (Bart, do you really have any examples when this is a > > problem even for VGA? Correct me then, please). > > Well VGA only uses standard ports so the only problem is to pass the > VBIOS initialization in the first place, that is executing the code at > c000:0003 (or c800:0003, whereever the VBIOS is). On some graphics cards > this init routine requires additional open ports and maybe even > accessible MMIO. > > Some people reported black screens, or even machines hanging which > happens when the VBIOS init routine is called. > > I'm not sure why this VBIOS init routine is always called if you set > $_graphics, but at least it gets the video card into a clean state. This > is esp. important if you use fbdev graphical textmodes on the console > instead of the standard VGA textmode (80x25). > > Maybe by just bypassing the VBIOS init you can avoid this problem; I > just have never looked into that possibility. > > The VBE 2.0 spec defines a protected mode interface - if DOSEMU would > use that it could ask which ports should be used and opened. However it > does not currently use that interface, I don't know how to do that and > am not able to test it anyway (being far away from my desktop where I > could take some risks). > > Bart > > - > To unsubscribe from this list: send the line "unsubscribe linux-msdos" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Oh, I have slipped the surly bonds of DOS, and danced the skies on Linux silvered wings. http://pfrostie.freeservers.com/cad-tastrafy/ http://www.freelists.org/list/cad-linux