--- /usr/src/linux/drivers/acpi/processor.c	2004-08-07 18:25:15.064497551 +0200
+++ processor.c	2004-08-07 18:31:24.013809421 +0200
@@ -30,6 +30,14 @@
  *	4. Need C1 timing -- must modify kernel (IRQ handler) to get this.
  */
 
+/*
+ * 07/08/04; Jos Delbar <jos.delbar-Cru1EgDzd7c@public.gmane.org>:
+ * Recognize power state limit as a boot parameter.
+ *
+ * 31/07/04; Jos Delbar <jos.delbar-Cru1EgDzd7c@public.gmane.org>:
+ * Add user-definable processor power state limit.
+ */
+
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -80,6 +88,16 @@
 MODULE_DESCRIPTION(ACPI_PROCESSOR_DRIVER_NAME);
 MODULE_LICENSE("GPL");
 
+/*
+ * The acpi_cstate_limit module parameter represents the maximum processor power state or
+ * C state to promote to. Values of 1, 2 and 3 are equivalent to the C1, C2 and C3 sleep
+ * states, respectively. A value of 0 disables processor power management altogether.
+ */
+
+static int acpi_cstate_limit = ACPI_C_STATES_MAX;
+
+module_param(acpi_cstate_limit, int, S_IRUSR | S_IRGRP | S_IROTH);
+MODULE_PARM_DESC(acpi_cstate_limit, "Limit the processor power state (0 = disable power management)");
 
 static int acpi_processor_add (struct acpi_device *device);
 static int acpi_processor_remove (struct acpi_device *device, int type);
@@ -449,6 +467,7 @@
 		sleep_ticks = ticks_elapsed(t1, t2) - cx->latency_ticks - C3_OVERHEAD;
 		break;
 
+	case ACPI_STATE_C0:
 	default:
 		local_irq_enable();
 		return;
@@ -535,7 +554,7 @@
 	 * C0/C1
 	 * -----
 	 */
-	pr->power.state = ACPI_STATE_C1;
+	pr->power.state = (acpi_cstate_limit != ACPI_STATE_C0 ? ACPI_STATE_C1 : ACPI_STATE_C0);
 	pr->power.default_state = ACPI_STATE_C1;
 
 	/*
@@ -554,7 +573,7 @@
 	 * TBD: Demote to default C-State after long periods of activity.
 	 * TBD: Investigate policy's use of CPU utilization -vs- sleep duration.
 	 */
-	if (pr->power.states[ACPI_STATE_C2].valid) {
+	if (pr->power.states[ACPI_STATE_C2].valid && (acpi_cstate_limit >= ACPI_STATE_C2)) {
 		pr->power.states[ACPI_STATE_C1].promotion.threshold.count = 10;
 		pr->power.states[ACPI_STATE_C1].promotion.threshold.ticks =
 			pr->power.states[ACPI_STATE_C2].latency_ticks;
@@ -575,7 +594,7 @@
 	 * short or whenever bus mastering activity occurs.
 	 */
 	if ((pr->power.states[ACPI_STATE_C2].valid) &&
-		(pr->power.states[ACPI_STATE_C3].valid)) {
+		(pr->power.states[ACPI_STATE_C3].valid) && (acpi_cstate_limit >= ACPI_STATE_C3)) {
 		pr->power.states[ACPI_STATE_C2].promotion.threshold.count = 4;
 		pr->power.states[ACPI_STATE_C2].promotion.threshold.ticks =
 			pr->power.states[ACPI_STATE_C3].latency_ticks;
@@ -1859,10 +1878,15 @@
 		goto end;
 
 	seq_printf(seq, "active state:            C%d\n"
-			"default state:           C%d\n"
-			"bus master activity:     %08x\n",
+			"default state:           C%d\n",
 			pr->power.state,
-			pr->power.default_state,
+			pr->power.default_state);
+
+	if (acpi_cstate_limit < ACPI_C_STATES_MAX) seq_printf(seq,
+			"user limit:              C%d\n",
+			acpi_cstate_limit);
+
+	seq_printf(seq, "bus master activity:     %08x\n",
 			pr->power.bm_activity);
 
 	seq_puts(seq, "states:\n");
@@ -1876,6 +1900,11 @@
 			continue;
 		}
 
+		if (i > acpi_cstate_limit) {
+			seq_puts(seq, "<disabled>\n");
+			continue;
+		}
+
 		if (pr->power.states[i].promotion.state)
 			seq_printf(seq, "promotion[C%d] ",
 				pr->power.states[i].promotion.state);
@@ -2384,7 +2413,7 @@
 	
 	printk(KERN_INFO PREFIX "%s [%s] (supports",
 		acpi_device_name(device), acpi_device_bid(device));
-	for (i=1; i<ACPI_C_STATE_COUNT; i++)
+	for (i=0; i<=acpi_cstate_limit; i++)
 		if (pr->power.states[i].valid)
 			printk(" C%d", i);
 	if (pr->flags.throttling)
@@ -2417,7 +2446,7 @@
 	pr = (struct acpi_processor *) acpi_driver_data(device);
 
 	/* Unregister the idle handler when processor #0 is removed. */
-	if (pr->id == 0)
+	if ((pr->id == 0) && (pr->flags.power))
 		pm_idle = pm_idle_save;
 
 	status = acpi_remove_notify_handler(pr->handle, ACPI_DEVICE_NOTIFY, 
@@ -2447,6 +2476,10 @@
 	memset(&processors, 0, sizeof(processors));
 	memset(&errata, 0, sizeof(errata));
 
+	/* Check for illegal user limits. */
+	if(acpi_cstate_limit < ACPI_STATE_C0 || acpi_cstate_limit > ACPI_C_STATES_MAX)
+		return_VALUE(-EINVAL);
+
 	acpi_processor_dir = proc_mkdir(ACPI_PROCESSOR_CLASS, acpi_root_dir);
 	if (!acpi_processor_dir)
 		return_VALUE(-ENODEV);