> Finally, a good way to do SRMMU stack checking is to do no checking at
> all. 
> You dump the
> registed onto the stack (or read them from the stack) no matter what,
> only that you set the no_fault bit in the mmu control register prior
> to doing the loads/stores.  something like:
> 

Is this safe?  I don't know much about the Sparc, but what stops me from
pointing my %sp into what would be kernel address space then causing a
window trap, writing my registers into the kernel?  

Does the no-fault bit suppress faulted writes?