2 files changed, 34 insertions, 12 deletions

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 08c44b08bf5b..0c016f727695 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -36,7 +36,7 @@ EXPORT_SYMBOL(pm_power_off);
 
 static const struct desc_ptr no_idt = {};
 static int reboot_mode;
-enum reboot_type reboot_type = BOOT_KBD;
+enum reboot_type reboot_type = BOOT_ACPI;
 int reboot_force;
 
 #if defined(CONFIG_X86_32) && defined(CONFIG_SMP)
@@ -478,9 +478,24 @@ void __attribute__((weak)) mach_reboot_fixups(void)
 {
 }
 
+/*
+ * Windows compatible x86 hardware expects the following on reboot:
+ *
+ * 1) If the FADT has the ACPI reboot register flag set, try it
+ * 2) If still alive, write to the keyboard controller
+ * 3) If still alive, write to the ACPI reboot register again
+ * 4) If still alive, write to the keyboard controller again
+ *
+ * If the machine is still alive at this stage, it gives up. We default to
+ * following the same pattern, except that if we're still alive after (4) we'll
+ * try to force a triple fault and then cycle between hitting the keyboard
+ * controller and doing that
+ */
 static void native_machine_emergency_restart(void)
 {
         int i;
+        int attempt = 0;
+        int orig_reboot_type = reboot_type;
 
         if (reboot_emergency)
                 emergency_vmx_disable_all();
@@ -502,6 +517,13 @@ static void native_machine_emergency_restart(void)
                                 outb(0xfe, 0x64); /* pulse reset low */
                                 udelay(50);
                         }
+                        if (attempt == 0 && orig_reboot_type == BOOT_ACPI) {
+                                attempt = 1;
+                                reboot_type = BOOT_ACPI;
+                        } else {
+                                reboot_type = BOOT_TRIPLE;
+                        }
+                        break;
 
                 case BOOT_TRIPLE:
                         load_idt(&no_idt);
diff --git a/drivers/firmware/edd.c b/drivers/firmware/edd.c
index 96c25d93eed1..f1b7f659d3c9 100644
--- a/drivers/firmware/edd.c
+++ b/drivers/firmware/edd.c
@@ -531,8 +531,8 @@ static int
 edd_has_edd30(struct edd_device *edev)
 {
         struct edd_info *info;
-        int i, nonzero_path = 0;
-        char c;
+        int i;
+        u8 csum = 0;
 
         if (!edev)
                 return 0;
@@ -544,16 +544,16 @@ edd_has_edd30(struct edd_device *edev)
                 return 0;
         }
 
-        for (i = 30; i <= 73; i++) {
-                c = *(((uint8_t *) info) + i + 4);
-                if (c) {
-                        nonzero_path++;
-                        break;
-                }
-        }
-        if (!nonzero_path) {
+
+        /* We support only T13 spec */
+        if (info->params.device_path_info_length != 44)
+                return 0;
+
+        for (i = 30; i < info->params.device_path_info_length + 30; i++)
+                csum += *(((u8 *)&info->params) + i);
+
+        if (csum)
                 return 0;
-        }
 
         return 1;
 }