[ros-dev] (Free)DOS subsystem

[fd0man™—The Magical Floppy Man]

On Tue, 2006-08-29 at 20:10 -0600, ShadowFlare wrote:

> Heh, I still think that an actual NTVDM implementation might not
> necessarily be the best solution, though.  Well, if it could run on
> x64 editions of Windows then it would be fine, but if it couldn't,
> then that's why I was suggesting an alternative.  Of course, the
> alternative still wouldn't have to be just for DOS programs either, it
> could also be for 16-bit Windows applications as well. 
> 
> Hmm, if there could be an implementation with no kernel-mode code or
> at least something that could somehow work when running AMD64 CPUs in
> a 64-bit OS, then that would be a good thing to work toward.  Then if
> ReactOS was later made to support the API for Windows x64, then it
> could have 16-bit app support, while Microsoft's 64-bit OS
> doesn't. :) 
> 


Well, as I understand it, in long mode the v86 Mode functionality of
32-bit protected mode systems is no longer available, though that does
not, I do not think, preclude creating a new NTVDM type system that is
compatible with the 32-bit current NTVDM.  The only real difference is
that you would more likely than not have to have the v86 processes
running in an actual virtual machine with a monitor, though it should
(in theory) be possible to do that and retain compatibility, possibly at
a slight loss of speed.

Of course, there are a whole slew of choices that are available then;
should it be a virtual machine, or should it perhaps have some sort of
dynamic recompliation mechanism that would "turn" it into a native
executable, perhaps even ahead of time?  IANAP (at least, not a good
one, yet) and so I am not sure what would really be the more feasible
option, and other decisions would need to be made after that.  But, yes,
it would be nice to have a "one-up" of sorts on Microsoft.

    — Mike

--
The fd0man™—The Magical Floppy Man! (fd0man at gmail.com) 
"One world, one web, one program"  —Microsoft promotional ad 
"Ein Volk, ein Reich, ein Fuehrer"  —Adolf Hitler 
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