From: spierce@wam.umd.edu (Stephen Pierce) Subject: Re: How to switch back to VGA-text from SVGA-text mode??? Date: Sat, 27 Mar 1993 10:45:11 GMT
In article <23830@venera.isi.edu> rogers@blips.isi.edu (Craig Milo Rogers) writes:
>In article <csaba.4.733195427@vuse.vanderbilt.edu> csaba@vuse.vanderbilt.edu (Csaba A. Biegl) writes:
>>>Because nobody has bothered to write to interrupt handlers in protected-mode
>>>to run real-mode code. It certainly CAN be done, only those who want it don't
>>>have enough knowledge about 386 programming, whilst those who know have a
>>>religious thing about not supporting the BIOS :-)
>>
>>There is on more thing to consider: most SVGA cards come with some clock
>>tweaking, image centering TSR-s that you have to install in your
>...
>>order to be compatible with any monitor. It is the TSR which augments and/or
>>takes over the mode set INT 10H BIOS call to provide higher refresh rates
>>and non-interlaced modes.
>...
>>For the majority of the cards the BIOS interface would be useful only if
>>Linux booted from DOS AFTER you had a chance to install your video TSR.
>>Furthermore, the Linux kernel would have to keep a copy of the low memory
>>where the video TSR was installed. It's getting more complicated, doesn't it?
>
> Um, would it be possible to startup a dosemu-controlled
>process, map the video BIOS (and any video memory), enable privileged
>I/O to the video ports, then run the video TSRs and setup programs? I
>haven't yet acquired Linux (I'm still using an 8088!), so I can't
>answer this question directly. I suppose that dosemu might need a
>change or two to support this. Any comments?
Something else: Why not use VM8086 mode? Then the bios runs under
a 8086 in real mode (essentially) and it can do it's work. Then Linux
can determine (?) what the BIOS did, or somehow allow the changes to
stick. Please foregive my simple language, I am not a VM p[rogrammer
but I do know about the different modes of the 386...
Comments?
Steve