Index: local_apic.c
===================================================================
RCS file: /usr/cvs/src/sys/i386/i386/local_apic.c,v
retrieving revision 1.38
diff -u -r1.38 local_apic.c
--- local_apic.c	6 Mar 2007 17:16:47 -0000	1.38
+++ local_apic.c	12 Mar 2007 19:27:59 -0000
@@ -813,6 +813,7 @@
 	    ("No ISR handler for vector %u", vector));
 	setidt(vector, ioint_handlers[vector / 32], SDT_SYS386IGT, SEL_KPL,
 	    GSEL(GCODE_SEL, SEL_KPL));
+	smp_rendezvous(NULL, NULL, NULL, NULL);
 }
 
 /* Release an APIC vector when it's no longer in use. */
Index: mp_machdep.c
===================================================================
RCS file: /usr/cvs/src/sys/i386/i386/mp_machdep.c,v
retrieving revision 1.276
diff -u -r1.276 mp_machdep.c
--- mp_machdep.c	6 Mar 2007 17:16:47 -0000	1.276
+++ mp_machdep.c	20 Mar 2007 16:52:46 -0000
@@ -916,13 +916,20 @@
 	/* wait for pending status end */
 	lapic_ipi_wait(-1);
 
-	/* do an INIT IPI: deassert RESET */
-	lapic_ipi_raw(APIC_DEST_ALLESELF | APIC_TRIGMOD_LEVEL |
-	    APIC_LEVEL_DEASSERT | APIC_DESTMODE_PHY | APIC_DELMODE_INIT, 0);
-
-	/* wait for pending status end */
-	DELAY(10000);		/* wait ~10mS */
-	lapic_ipi_wait(-1);
+	/*
+	 * do an INIT IPI: deassert RESET on older systems to reset APIC ID
+	 * arbitration.  XXX: Should we only do this once?
+	 */
+	if (strcmp(cpu_vendor, "GenuineIntel") != 0 ||
+	    (cpu_id & 0xf00) != 0xf00) {
+		lapic_ipi_raw(APIC_DEST_ALLESELF | APIC_TRIGMOD_LEVEL |
+		    APIC_LEVEL_DEASSERT | APIC_DESTMODE_PHY | APIC_DELMODE_INIT,
+		    0);
+
+		/* wait for pending status end */
+		DELAY(10000);		/* wait ~10mS */
+		lapic_ipi_wait(-1);
+	}
 
 	/*
 	 * next we do a STARTUP IPI: the previous INIT IPI might still be