diff -Nru a/arch/i386/kernel/apm.c b/arch/i386/kernel/apm.c
--- a/arch/i386/kernel/apm.c	Fri Jul 26 16:48:55 2002
+++ b/arch/i386/kernel/apm.c	Fri Jul 26 16:48:55 2002
@@ -1313,6 +1313,34 @@
 			break;
 		}
 	}
+
+	/*
+	 * The Sony Vaio doesn't seem to want to send us a notify
+	 * about AC line power status changes.  So, we have to keep track
+	 * of it by hand and emulate it here.
+	 *   -- Cort <cort@fsmlabs.com>
+	 */
+	if ( apm_bios_power_change_bug ) {
+		static int last_status = 0;
+		u_short status, bat, life;
+
+		/* get the current power state */
+		if ( apm_get_power_status(&status, &bat, &life) !=
+		     APM_SUCCESS ) {
+			printk("%s:%s error checking power status\n",
+			       __FILE__,__FUNCTION__);
+		}
+		
+		/* has the status changed since we were last here? */
+		if (((status >> 8) & 0xff) != last_status) {
+			last_status = (status >> 8) & 0xff;
+			
+			/* fake a APM_POWER_STATUS_CHANGE event */
+			send_event(APM_POWER_STATUS_CHANGE);
+			queue_event(APM_POWER_STATUS_CHANGE, NULL);
+		}
+		
+	}
 }
 
 static void apm_event_handler(void)
diff -Nru a/arch/i386/kernel/dmi_scan.c b/arch/i386/kernel/dmi_scan.c
--- a/arch/i386/kernel/dmi_scan.c	Fri Jul 26 16:48:55 2002
+++ b/arch/i386/kernel/dmi_scan.c	Fri Jul 26 16:48:55 2002
@@ -12,6 +12,7 @@
 
 unsigned long dmi_broken;
 int is_sony_vaio_laptop;
+int apm_bios_power_change_bug = 0;
 
 struct dmi_header
 {
@@ -346,6 +347,27 @@
 	return 0;
 }
 
+
+/*
+ * Some Vaio laptops don't notify the kernel of a power status change
+ * such as on-AC/on-battery.  This detects some of the faulty machines
+ * and sets a variable that lets arch/i386/kernel/apm.c deal with it.
+ *
+ * I've seen this with the Vaio z505js PCG-5201 and PCG-SR33:
+ 
+ * model PCG-Z505JS(UC), bios Phoenix Technologies LTD version R0121Z1
+ * model PCG-SR33(UC), bios Phoenix Technologies LTD version R0211D1
+ *   -- Cort <cort@fsmlabs.com>
+ */ 
+static __init int sony_vaio_apm_change(struct dmi_blacklist *d)
+{
+	apm_bios_power_change_bug = 1;
+	printk(KERN_WARNING "%s detected: APM power status change workaround enabled\n",
+	       d->ident);
+	return 0;
+}
+
+
 /*
  * The Intel 440GX hall of shame. 
  *
@@ -611,6 +633,12 @@
 	{ set_apm_ints, "IBM", {	/* Allow interrupts during suspend on IBM laptops */
 			MATCH(DMI_SYS_VENDOR, "IBM"),
 			NO_MATCH, NO_MATCH, NO_MATCH
+			} },
+
+	{ sony_vaio_apm_change, "Sony Vaio", {	/* APM won't send power change events */
+			MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
+			MATCH(DMI_BIOS_VENDOR, "Phoenix Technologies LTD"),
+			NO_MATCH, NO_MATCH
 			} },
 
 	{ NULL, }
diff -Nru a/include/asm-i386/system.h b/include/asm-i386/system.h
--- a/include/asm-i386/system.h	Fri Jul 26 16:48:55 2002
+++ b/include/asm-i386/system.h	Fri Jul 26 16:48:55 2002
@@ -356,6 +356,7 @@
 
 extern unsigned long dmi_broken;
 extern int is_sony_vaio_laptop;
+extern int apm_bios_power_change_bug;
 
 #define BROKEN_ACPI_Sx		0x0001
 #define BROKEN_INIT_AFTER_S1	0x0002