Index: acpi_cpu.c
===================================================================
RCS file: /dragonfly/cvs/src/sys/dev/acpica5/acpi_cpu.c,v
retrieving revision 1.18
diff -u -p -r1.18 acpi_cpu.c
--- acpi_cpu.c	17 Jan 2007 17:31:19 -0000	1.18
+++ acpi_cpu.c	15 Feb 2007 09:01:51 -0000
@@ -237,7 +237,10 @@ acpi_cpu_probe(device_t dev)
     cx_count = 0;
     buf.Pointer = NULL;
     buf.Length = ACPI_ALLOCATE_BUFFER;
-    status = AcpiEvaluateObject(handle, "_CST", NULL, &buf);
+    if (ktestenv("debug.acpi.cpu.nocst"))
+	status = AE_ERROR;
+    else
+	status = AcpiEvaluateObject(handle, "_CST", NULL, &buf);
     if (ACPI_SUCCESS(status)) {
 	obj = (ACPI_OBJECT *)buf.Pointer;
 	if (ACPI_PKG_VALID(obj, 2))
@@ -584,7 +587,8 @@ acpi_cpu_cx_cst(struct acpi_cpu_softc *s
 
     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
 
-    buf.Pointer = NULL;
+    if (ktestenv("debug.acpi.cpu.nocst"))
+    	return (ENXIO);
     buf.Length = ACPI_ALLOCATE_BUFFER;
     status = AcpiEvaluateObject(sc->cpu_handle, "_CST", NULL, &buf);
     if (ACPI_FAILURE(status))