x86: EFI runtime service support: document for EFI runtime services

This patch adds document for EFI x86_64 runtime services support.

Signed-off-by: Chandramouli Narayanan <mouli@linux.intel.com>
Signed-off-by: Huang Ying <ying.huang@intel.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt
index d7a3332..638bf46 100644
--- a/Documentation/x86_64/boot-options.txt
+++ b/Documentation/x86_64/boot-options.txt
@@ -110,7 +110,7 @@
 
 Rebooting
 
-   reboot=b[ios] | t[riple] | k[bd] | a[cpi] [, [w]arm | [c]old]
+   reboot=b[ios] | t[riple] | k[bd] | a[cpi] | e[fi] [, [w]arm | [c]old]
    bios	  Use the CPU reboot vector for warm reset
    warm   Don't set the cold reboot flag
    cold   Set the cold reboot flag
@@ -119,6 +119,9 @@
    acpi   Use the ACPI RESET_REG in the FADT. If ACPI is not configured or the
           ACPI reset does not work, the reboot path attempts the reset using
           the keyboard controller.
+   efi    Use efi reset_system runtime service. If EFI is not configured or the
+          EFI reset does not work, the reboot path attempts the reset using
+          the keyboard controller.
 
    Using warm reset will be much faster especially on big memory
    systems because the BIOS will not go through the memory check.
@@ -303,4 +306,8 @@
 		newfallback: use new unwinder but fall back to old if it gets
 			stuck (default)
 
+EFI
+
+  noefi		Disable EFI support
+
 Miscellaneous