diff --git a/docs/specs/pvpanic.txt b/docs/specs/pvpanic.txt
index c7bbacc778ac0caeab5eac5aa7fffd90e45c831a..bdea68a430c772cc48a189bae06bd6c48d73ad42 100644
--- a/docs/specs/pvpanic.txt
+++ b/docs/specs/pvpanic.txt
@@ -16,8 +16,12 @@ pvpanic exposes a single I/O port, by default 0x505. On read, the bits
 recognized by the device are set. Software should ignore bits it doesn't
 recognize. On write, the bits not recognized by the device are ignored.
 Software should set only bits both itself and the device recognize.
-Currently, only bit 0 is recognized, setting it indicates a guest panic
-has happened.
+
+Bit Definition
+--------------
+bit 0: setting it indicates a guest panic has happened.
+bit 1: named crashloaded. setting it indicates a guest panic and run
+       kexec to handle error by guest itself.
 
 ACPI Interface
 --------------