Date: Sun, 10 Aug 1997 04:30:00 -0700 From: Jonathan Mini <j_mini@efn.org> To: "Helmut F. Wirth" <hfwirth@ping.at> Cc: emulation@freebsd.org Subject: Re: Fun with DOSCMD (was Re: modifying boot mgrs FROM FREEBSD) Message-ID: <19970810043000.13645@micron.efn.org> In-Reply-To: <33ED7E33.167EB0E7@ping.at>; from Helmut F. Wirth on Sun, Aug 10, 1997 at 10:39:15AM %2B0200 References: <199708090129.PAA08057@pegasus.com> <33EC7977.167EB0E7@ping.at> <19970809235411.04335@micron.efn.org> <33ED7E33.167EB0E7@ping.at>
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Helmut F. Wirth stands accused of saying : > Jonathan Mini wrote: > > > > Um. Have you looked at the VGA specification? Two things : > > > > 1) 640x480x256 isn't a VGA video mode. > > True. I was sloppy to call it that. But todays VGAs are nearly all > SVGAs. Well. THe thing is is that VGA emulation and something like VESA VBE implementation are completely different, since you need to actually emulate the VGA chipset for VGA implementation, whereas VESA VBE just some extension to the BIOS code. > Yes. IMHO we would need to support only a few modes for starters. Mmm. Are you talking VGA emulation here or something else? (pretending to be a Cirrus Logic 54xx? Being VESA VBE 1.2?) > > > Using the XFree86 DGA extension and the ability to switch modes > > > via software maybe it would be possible to act like the DOS box > > > under MSWindows. This woulde be faster, but it would not be inside > > > a window. The application would takeover the XServer and the entire > > > screen, until ASCII mode is restored. > > > > IMO, while this is possible, it is not the best alternative. > > > > > Any better ideas ? > > > > What you're describing sounds more like VESA VBE emulation than VGA > > emulation, but I would like to see both. :) > > I was thinking of a sort of VESA emulation. But a full VGA emulation > including a VESA BIOS emulation is much work. We would need to monitor > in/out commands to many VGA registers. This is true, that is the reason I was asking. I'd like to see a VGA emulation in the future, but wouldn't be surprised if that was a ways down the road :) > I thought a little about doscmd in console mode too, that is when no > Xserver is running. Here it should be possible to do real hardware > access for hardware not sensitive for the kernel and security. For > doscmd in non X11 environments I think we could simply map the VGA/VESA > original BIOS of the card and use it under VM86. We would need an > advisory call (ioctl) to the screen drivers (syscons, ...) to save > and restore the environment and for screen switching. Not for anything but a few video modes. (i.e. text modes and like 320x200x256) Also, I am leery of letting my DOS app change the state of my system console's hardware. -- Jonathan Mini (j_mini@efn.org) ... bleakness ... desolation ... plastic forks ...
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