From: cummings@tiger1.prime.com (Kevin J. Cummings) Subject: Re: VM86 Date: Thu, 3 Sep 1992 17:56:07 GMT
In article <1992Sep3.121537.13126@wam.umd.edu>, joel@wam.umd.edu (Joel M. Hoffman) writes:
> In article <richard.715353503@stat.tamu.edu> richard@stat.tamu.edu (richard henderson) writes:
> >peterd@pjd.dev.cdx.mot.com (Peter Desnoyers) writes:
> >
> >>davidsen@ariel.crd.GE.COM (william E Davidsen) writes:
> >
> >>>In article <1992Aug29.091200.16019@klaava.Helsinki.FI>, torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) writes:
> >
> >>>| SIGALRM_handler()
> >>>| {
> >>>| check the screen memory in the vm86 box, and update the real
> >>>| screen every now and then. Do any other regular house-keeping
> >>>| fn's.
> >>>| }
> >
> >
> >Unfortunately, if this is intended to be a DOS emulator, you are going to
> >have to trap the VGA registers that bank the video ram into and out of
> >the memory map. This could be made easier if sysv shared memory blocks
> >were in place. Create (1M/64K) shared memory blocks, and when the VGA
> >registers are twiddled, change the mapping of the memory blocks.
>
> I think what we really need (for the DOS emulator but on other grounds
> as well) is fully indepent VC's that utilize all of the features of
> the video card installed. This means that one VC can be in graphics
> mode, another in 25x80 mode, another in 43x123 (or whatever), etc.
> The code for storing and restoring the entire state of a VGA (SVGA?)
> card is available from CMU.
If the video card is VESA compliant, there should be VESA BIOS code that is
capable of doing the same. But now we are back to the age old question of
how well will we be able to use (run) VBIOS code in a VM86 process? How
about from a protected mode process (like the kernel)?
> Surely this is the way to do. Then the DOS emulator could do what it
> liked with the display (as DOS programs do), another VC could be
> running X, and root could still be logged in on a text terminal.
>
> I haven't seen 0.97 yet. Is this by chance implemented? Also, are my
> codepage modifications included?
>
> -Joel
> (joel@wam.umd.edu)
>
>
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Kevin J. Cummings PrimeService
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