From: joel@wam.umd.edu (Joel M. Hoffman) Subject: Re: VM86 Date: Thu, 3 Sep 1992 12:15:37 GMT
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.
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)