Re: [plex86] Performance enhancement: elminiating mode and context

[Ulrich Weigand]

Ramon van Handel wrote:

> On Fri, 15 Dec 2000, Kevin Lawton wrote:
> > Running guest ring0 code at ring0 open memory access to PTE.P==1 pages,
> > which includes the monitor interrupt handlers, and monitor data
> > structures.  Thus, all memory access instructions would be dangerous.
> > We'd have to move to the concept of 'shortening' guest kernel segments,
> > so we leave our selves a safe hole to put the monitor in.
> 
> You need to prescan memory accesses anyway in order to catch MMIO.  

Eh?  Whether a memory access is MMIO or not depends not on the
instruction stream, but on the *address* that is used.  You cannot
know from just looking at the instructions (which is what prescanning
does), what values the registers used for address generation will have 
when the code is executed ...

The only way to catch memory accesses without hardware assistance
is full emulation, which I don't think you want to advocate ;-)

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  [EMAIL PROTECTED]