On Sun, Dec 2, 2012 at 3:43 PM, Peter Gavin <[email protected]> wrote: > On Sun, Dec 2, 2012 at 4:38 PM, Matthew Hicks <[email protected]> wrote: >> >> This is a bad idea. You want to make the processor fully >> virtualizable. This requires the ability for a hypervisor to >> interpose on an unmodified operating system. For this to work, the >> hypervisor changes the operating system privilege to 0 (user mode) and >> when the operating system accesses or modifies privileged state, an >> exception triggers and the hypervisor takes over. With your proposal, >> the hypervisor would never know and the system would collapse. > > > Shouldn't the hypervisor be implemented with another SR bit, or another SPR > altogether? Eg, a HM (hypervisor mode) bit? > > I don't see how pushing the OS into userspace would work. How can the OS > protect user processes from accessing each other's memory, for instance? > > -Pete
MMU and shadow pages tables. This is kind of virtual machines 101, which is beyond the scope of this thread. _______________________________________________ OpenRISC mailing list [email protected] http://lists.openrisc.net/listinfo/openrisc
