David Laight wrote:
> On Sun, Oct 29, 2006 at 09:13:38PM +0100, Christian Biere wrote:
> > John Nemeth wrote:
> > >      What does an i386-compatible MMU provide that the i386 MMU didn't?
> > 
> > It seems memory write-protection at cpl0 (ring0) doesn't work in an i386 MMU.
> 
> Define 'work'!
> 
> When the processor is executing at supervisor level, all pages are both
> readable and writable.

That's the difference. The WP-bit in cr0 is new in the i486. If it's set the
write-protection according to the page table entry is effective at the
supervisor level too.

-- 
Christian