From: Shaohua Li <shaohua.li@intel.com>

ACPI defines a hardware signature. BIOS calculates the signature
according to hardware configure, if hardware changes, the signature
will change, in this case, S4 resume should fail.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
---
 drivers/acpi/sleep/main.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

Index: linux-2.6.25-rc5/drivers/acpi/sleep/main.c
===================================================================
--- linux-2.6.25-rc5.orig/drivers/acpi/sleep/main.c
+++ linux-2.6.25-rc5/drivers/acpi/sleep/main.c
@@ -283,6 +283,17 @@ static struct dmi_system_id __initdata a
 #endif /* CONFIG_SUSPEND */
 
 #ifdef CONFIG_HIBERNATION
+static unsigned long s4_hardware_signature;
+static struct acpi_table_facs *facs;
+static bool nosigcheck;
+
+static int __init acpi_s4_nosigcheck(char *str)
+{
+	nosigcheck = true;
+	return 1;
+}
+__setup("acpi_s4_nosigcheck", acpi_s4_nosigcheck);
+
 static int acpi_hibernation_begin(void)
 {
 	int error;
@@ -342,6 +353,12 @@ static void acpi_hibernation_leave(void)
 	acpi_enable();
 	/* Reprogram control registers and execute _BFS */
 	acpi_leave_sleep_state_prep(ACPI_STATE_S4);
+	/* Check the hardware signature */
+	if (facs && s4_hardware_signature != facs->hardware_signature) {
+		printk(KERN_EMERG "ACPI: Hardware changed while hibernated, "
+			"cannot resume!\n");
+		panic("ACPI S4 hardware signature mismatch");
+	}
 }
 
 static void acpi_hibernation_finish(void)
@@ -544,6 +561,13 @@ int __init acpi_sleep_init(void)
 		hibernation_set_ops(&acpi_hibernation_ops);
 		sleep_states[ACPI_STATE_S4] = 1;
 		printk(" S4");
+		if (!nosigcheck) {
+			acpi_get_table_by_index(ACPI_TABLE_INDEX_FACS,
+				(struct acpi_table_header **)&facs);
+			if (facs)
+				s4_hardware_signature =
+					facs->hardware_signature;
+		}
 	}
 #endif
 	status = acpi_get_sleep_type_data(ACPI_STATE_S5, &type_a, &type_b);