--- sys/dev/acpica/acpi_acad.c.orig	2007-03-23 02:16:40.000000000 +0800
+++ sys/dev/acpica/acpi_acad.c	2008-05-16 19:49:03.000000000 +0800
@@ -33,6 +33,7 @@
 #include <sys/bus.h>
 
 #include <machine/bus.h>
+#include <machine/md_var.h>
 #include <sys/rman.h>
 #include <sys/ioccom.h>
 #include <sys/malloc.h>
@@ -127,6 +128,28 @@
     case ACPI_NOTIFY_BUS_CHECK:
     case ACPI_NOTIFY_DEVICE_CHECK:
     case ACPI_POWERSOURCE_STAT_CHANGE:
+	if (strcmp(cpu_vendor, "AuthenticAMD") == 0) {
+		/*
+		 * Detect the presence of C1E capability mostly on latest
+		 * dual-cores (or future) k8 family.  This feature renders
+		 * the local APIC timer dead, so we disable it by reading
+		 * the Interrupt Pending Message register and clearing both
+		 * C1eOnCmpHalt (bit 28) and SmiOnCmpHalt (bit 27).
+		 * 
+		 * Reference:
+		 *   "BIOS and Kernel Developer's Guide for AMD NPT
+		 *    Family 0Fh Processors"
+		 *   #32559 revision 3.00
+		 */
+		if ((cpu_id & 0x00000f00) == 0x00000f00 &&
+		    (cpu_id & 0x0fff0000) >=  0x00040000) {
+			uint64_t msr;
+
+			msr = rdmsr(0xc0010055);
+			if (msr & 0x18000000)
+				wrmsr(0xc0010055, msr & ~0x18000000ULL);
+		}
+	}
 	/* Temporarily.  It is better to notify policy manager */
 	AcpiOsExecute(OSL_NOTIFY_HANDLER, acpi_acad_get_status, context);
 	break;