- Remove some OBE comments regarding cpu_exit(). cpu_exit() is no longer

the last action of kern_exit().  Instead, it is a MD callout to cleanup
  per-process state during exit.
- Add notes of concern to Alpha and ia64 about the possible need to drop
  fp state in cpu_thread_exit() rather than in cpu_exit() since it is
  per-thread state rather than per-process.

sys/alpha/alpha/vm_machdep.c

@@ -224,17 +224,15 @@ cpu_set_fork_handler(td, func, arg)
 	td->td_pcb->pcb_context[2] = (u_long) arg;
 }
 
-/*
- * cpu_exit is called as the last action during exit.
- * We release the address space of the process, block interrupts,
- * and call switch_exit.  switch_exit switches to proc0's PCB and stack,
- * then jumps into the middle of cpu_switch, as if it were switching
- * from proc0.
- */
 void
 cpu_exit(struct thread *td)
 {
 
+	/*
+	 * XXX: Should this be in thread_exit instead?  If so,
+	 * alpha_fpstate_save() should be in cpu_set_upcall()
+	 * as well.
+	 */
 	alpha_fpstate_drop(td);
 }
 

sys/ia64/ia64/vm_machdep.c

@@ -297,6 +297,7 @@ void
 cpu_exit(struct thread *td)
 {
 
+	/* XXX: Should this be in cpu_thread_exit() instead? */
 	/* Throw away the high FP registers. */
 	ia64_highfp_drop(td);
 }

sys/powerpc/aim/vm_machdep.c

@@ -182,13 +182,6 @@ cpu_set_fork_handler(td, func, arg)
 	cf->cf_arg0 = (register_t)arg;
 }
 
-/*
- * cpu_exit is called as the last action during exit.
- * We release the address space of the process, block interrupts,
- * and call switch_exit.  switch_exit switches to proc0's PCB and stack,
- * then jumps into the middle of cpu_switch, as if it were switching
- * from proc0.
- */
 void
 cpu_exit(td)
 	register struct thread *td;

sys/powerpc/powerpc/vm_machdep.c

@@ -182,13 +182,6 @@ cpu_set_fork_handler(td, func, arg)
 	cf->cf_arg0 = (register_t)arg;
 }
 
-/*
- * cpu_exit is called as the last action during exit.
- * We release the address space of the process, block interrupts,
- * and call switch_exit.  switch_exit switches to proc0's PCB and stack,
- * then jumps into the middle of cpu_switch, as if it were switching
- * from proc0.
- */
 void
 cpu_exit(td)
 	register struct thread *td;