Hello!
Both of these things are not required and normally not done by normal applications. Most time the application just go to supervisormode just to readout the cookie jar or to read some OS variables.and if during this phase does something dirty? or 'forget' to switch back? memory protection is here for dirty coded applications, isn't?
I just want to mention that's ist for most software enough to catch cookie jar and tos variable reading.
And MP don't help at all if applications still have access to exception vectors and such critical things.
Btw there's even more ellegant way to protect system ram in SV - use second (srp) mmu register, this fix everything and we don't need to play with cathing trap exceptions.
In supervisor mode an application can do anything it want. There is no protection in any way. The only possible protection is to disallow supervisor mode.
The ct60 driver software mark the MMU as in use (by setting the PMMU cookie). The kernel avoid then usage of the MMU. You can tryout if MP works on ct60, just remove the PMMU cookie before the kernel is loaded or disable the MMU cookie check in the kernel.thanks for the hint, but what is the reason?
This is historical so done. Sure you can change, but on the other side I'm curious that the ct60 driver mark the MMU as in use.
Ciao ...Frank -- ATARI FALCON 040 // MILAN 060 ----------------------------------------- http://www.cs.uni-magdeburg.de/~fnaumann/ e-Mail: fnaumann@freemint.de