On Wed, 3 Mar 1999 11:41:15 -0500 
 Andrew Brown <atatat@atatdot.net> wrote:

 > >For this reason, we trap the unaligned access fault, and do one of 4
 > >things, depending on sysctl variables:
 > >
 > >	(1) Silently fixup the unaligned access.
 > >
 > >	(2) Print out a message and fixup the unaligned access.
 > >
 > >	(3) Silently send the process a SIGBUS.
 > >
 > >	(4) Print out a message and send the process a SIGBUS.
 > 
 > hmm.  sigbus or not and message or not.  so processes on alphas don't
 > get sigbus'ed at all (modulo the sysctl setting)?  would it
 > "theoretically" be possible to do the same thing for other
 > architectures?  i'm just curious...

Well, a NetBSD/alpha process will get SIGBUS'd if it does other SIGBUS'able
access :-)  i.e. accessing a nonexistent (vs. unmapped) memory location.

 > >Also note that the NetBSD kernel will panic if unaligned access is
 > >performed by the kernel, rather than by a user process.
 > 
 > certainly.  to where would it trap?

Same unaligned access fault handler, but if the processor is in kernel
mode when the fault occurs, the fault handler decides to panic, instead.

        -- Jason R. Thorpe <thorpej@nas.nasa.gov>