Processes and Communication (2)

[Dr. Hayden]

Hello all!

Three days ago I just got over a 2 week long case of the flu, and I
have been _swamped_ with makeup work.  Sorry I haven't been
participating much.  I promised a workup of a memory management scheme
I've been working on.  I'll get it out very soon ;-)

"Gary D. Duzan" <duzan@udel.edu> writes:

>   I'm mainly thinking about something like the system described in the
>paper "A Micro Kernel Architecture for Next Generation Processors",
>presented in Proceedings of the USENIX Workshop on Micro-Kernels and
>Other Kernel Architectures, and "Coordination Languages and their
>Significance", presented in Communications of the ACM, February 1992
>(Volume 35, Number 2.) In case you haven't read these articles (which
>is likely, I suppose, given the audience (no offense intended -- I'm
>just an OS research weenie)) I'll ramble a bit again.

Gary,

Do you know where I can get a hold of that USENIX paper?  That sounds
very interesting.

>   Imagine a system that automatically changes the protection level
>when the code enters a particular code area. Each protected block of
>code would provide a special block of memory containing jump
>operations. This block would allow other code to execute it, and
>executing it causes a protection switch, so when the CPU hits the jump
>target, the processor will be executing with a new set of rights.
>Hence, communication would be via normal function calls. Even if this
>communication mechanism isn't used, any secure communication method
>between entities with different protection levels would suffice for a
>complete system. One entity could have memory allocation rights, while
>another might have access to a particular device, while others may
>provide high-level services. Accessing these resources is simply a
>matter of communicating with the entities that provide them.

This can easily be implemented on the 386, if we decide to use that
feature.  Does anyone know if the Motorola chips can do this as well?
I have a very good book, published by Intel, called "80386 System
Software Writer's Guide," that explains this concept.  Perhaps it's
time to give ol Motorola lit a call.

>   Please keep the flames down to simmer; this is all hypothetical/
>theoretical stuff, and won't necessarily apply to MOOSE. However,
>there may be some ideas we can use in there somewhere.
>
>                                        Gary Duzan
>                                        Time  Lord
>                                    Third Regeneration
>                         Humble Practitioner of the Computer Arts
>

AS soon as I get past all these makeup assignments (and spring break!)
I plan to start participating much more.

Thanks,
Ross