[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: memory protection
> > It can virtualise all memory but cannot run a true virtual
> > machine. However virtual memory is most of the time good enough.
> Why not?. It can virtualize memory, can relocate exception table and can
> retry bus errors?. Anything else?
That's virtual memory. A true virtual machine like the IBM VM architecture
is capable of running several machines in parallel (time slotted). It can
be viewed as a very advanced kernel.
If one stick to that definition the 030 is not a virtual machine although
it is pretty close.
That characteristic is a feature of the VM software, not the hardware.
(And yes, I have worked on IBM mainframe kernels.) All that's needed is
the proper software support, there is nothing in the 68030 CPU that
prevents you from writing this. The IBM 370 architecture and the 68000
architecture share a lot in common...