On Oct 18,  3:08pm, thorpej@shagadelic.org (Jason Thorpe) wrote:
-- Subject: Re: delivering faulted-upon address in trap frame to userland

| 
| On Oct 17, 2006, at 3:22 PM, Christos Zoulas wrote:
| 
| > I don't see the benefit of changing the signal from SIGBUS to SIGILL
| > just because we don't have the faulting address available. I really
| > think that we should not send SIGILL back because you usually get
| > SIGILL when you start executing garbage, not when you are inside
| > your regular code.
| 
| I don't think that's necessarily true.  SIGILL could certainly be  
| interpreted also as the signal equivalent of EINVAL (invalid arguments  
| given to an instruction -- perhaps a value out of range).

Yes, such as referencing an invalid/non-existant register, but
usually something related to the internal functioning of the
cpu/co-processor and un-related to the memory/io subsystem.
SIGSEGV/SIGBUS are the signals used to indicate a problem outside
the cpu subsystem.

christos