Improve cpu_idle():

o   cpu_idle_hook is expected to be called with interrupts
    disabled and re-enables interrupts on return.
o   sync with x86: don't idle when the CPU has runnable tasks
o   have callers of ia64_call_pal_static() disable interrupts
    and re-enable interrupts.
o   add, but compile-out, support for idle mode. This will be
    enabled at some later time, after proper testing.

sys/ia64/acpica/acpi_machdep.c

@@ -56,7 +56,14 @@ acpi_machdep_quirks(int *quirks)
 void
 acpi_cpu_c1()
 {
+#ifdef INVARIANTS
+	register_t ie;
+
+	ie = intr_disable();
+	KASSERT(ie == 0, ("%s called with interrupts enabled\n", __func__));
+#endif
 	ia64_call_pal_static(PAL_HALT_LIGHT, 0, 0, 0);
+	ia64_enable_intr();
 }
 
 void *

sys/ia64/ia64/machdep.c

@@ -411,12 +411,34 @@ cpu_halt()
 void
 cpu_idle(int busy)
 {
-	struct ia64_pal_result res;
+	register_t ie;
 
-	if (cpu_idle_hook != NULL)
+#if 0
+	if (!busy) {
+		critical_enter();
+		cpu_idleclock();
+	}
+#endif
+
+	ie = intr_disable();
+	KASSERT(ie != 0, ("%s called with interrupts disabled\n", __func__));
+
+	if (sched_runnable())
+		ia64_enable_intr();
+	else if (cpu_idle_hook != NULL) {
 		(*cpu_idle_hook)();
-	else
-		res = ia64_call_pal_static(PAL_HALT_LIGHT, 0, 0, 0);
+		/* The hook must enable interrupts! */
+	} else {
+		ia64_call_pal_static(PAL_HALT_LIGHT, 0, 0, 0);
+		ia64_enable_intr();
+	}
+
+#if 0
+	if (!busy) {
+		cpu_activeclock();
+		critical_exit();
+	}
+#endif
 }
 
 int
@@ -644,9 +666,12 @@ calculate_frequencies(void)
 {
 	struct ia64_sal_result sal;
 	struct ia64_pal_result pal;
+	register_t ie;
 
+	ie = intr_disable();
 	sal = ia64_sal_entry(SAL_FREQ_BASE, 0, 0, 0, 0, 0, 0, 0);
 	pal = ia64_call_pal_static(PAL_FREQ_RATIOS, 0, 0, 0);
+	intr_restore(ie);
 
 	if (sal.sal_status == 0 && pal.pal_status == 0) {
 		if (bootverbose) {

sys/ia64/ia64/pal.S

@@ -38,43 +38,40 @@ ia64_pal_entry:	.quad 0
  *	u_int64_t arg1, u_int64_t arg2, u_int64_t arg3)
  */
 ENTRY(ia64_call_pal_static, 4)
-	
-	.regstk	4,5,0,0
+
+	.regstk	4,4,0,0
 palret	=	loc0
 entry	=	loc1
 rpsave	=	loc2
 pfssave =	loc3
-psrsave	=	loc4
 
-	alloc	pfssave=ar.pfs,4,5,0,0
+	alloc	pfssave=ar.pfs,4,4,0,0
 	;; 
 	mov	rpsave=rp
-
 	movl	entry=@gprel(ia64_pal_entry)
+
 1:	mov	palret=ip		// for return address
 	;;
 	add	entry=entry,gp
-	mov	psrsave=psr
+	add	palret=2f-1b,palret	// calculate return address
 	mov	r28=in0			// procedure number
-	;;
-	ld8	entry=[entry]		// read entry point
 	mov	r29=in1			// copy arguments
 	mov	r30=in2
 	mov	r31=in3
 	;;
-	mov	b6=entry
-	add	palret=2f-1b,palret	// calculate return address
-	;;
+	ld8	entry=[entry]		// read entry point
 	mov	b0=palret
-	rsm	psr.i			// disable interrupts
+	;;
+	mov	b6=entry
 	;;
 	br.cond.sptk b6			// call into firmware
-2:	mov	psr.l=psrsave
+	;;
+2:
 	mov	rp=rpsave
 	mov	ar.pfs=pfssave
 	;;
-	srlz.d
 	br.ret.sptk rp
+	;;
 END(ia64_call_pal_static)
 
 /*