Hello,
2015-01-03 19:00 GMT+01:00 Mercury Thirteen <mercury0x0...@gmail.com>:
> As far as I have seen, DOS allocates one Program Segment Prefix and runs
> an app in that segment. When you exit the program, it clears that app out
> then loads the next one you run in the same segment. I don't think it would
> be that hard to make it allocate an additional PSP every time a new app is
> launched. Of course you have the whole hardware sharing issue, also, but
> there should be some way to mitigate this issue too. Maybe an internal flag
> which signifies that a certain program is using a specific resource, so
> FreeDOS knows to make the other app wait until the first is finished before
> allowing the request? That may cut down on the majority of conflicts.
>
Under 32-bit protected mode and VMM32, I/O Access and interrupts can be
controled and hooked. This is exactly that the VxD does: it catches all
these calls, and cares that there are no conflicts (for example, the VCOMD
presumably controlls the COM port calls and interrupts among the different
VM's, VKD for the keyboard, and so on).
The DOS running in each VM runs without caring or noticing that is living
inside a VM, so needs not even to be touched.
>
> Memory protection should be fairly easy to implement also, as all the
> kernel would have to do is make a note of which process ID requested which
> block of RAM and disallow writing into blocks owned by other processes.
> This should be switchable, also, in case the user is depending on software
> which *must* write into the far reaches of RAM.
>
Same as above.
Aitor
------------------------------------------------------------------------------
Dive into the World of Parallel Programming! The Go Parallel Website,
sponsored by Intel and developed in partnership with Slashdot Media, is your
hub for all things parallel software development, from weekly thought
leadership blogs to news, videos, case studies, tutorials and more. Take a
look and join the conversation now. http://goparallel.sourceforge.net
_______________________________________________
Freedos-devel mailing list
Freedos-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/freedos-devel
