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-rw-r--r--docs/specs/pvpanic.txt18
1 files changed, 11 insertions, 7 deletions
diff --git a/docs/specs/pvpanic.txt b/docs/specs/pvpanic.txt
index c7bbacc778..a90fbca72b 100644
--- a/docs/specs/pvpanic.txt
+++ b/docs/specs/pvpanic.txt
@@ -16,8 +16,13 @@ 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: a guest panic has happened and should be processed by the host
+bit 1: a guest panic has happened and will be handled by the guest;
+ the host should record it or report it, but should not affect
+ the execution of the guest.
ACPI Interface
--------------
@@ -26,13 +31,12 @@ pvpanic device is defined with ACPI ID "QEMU0001". Custom methods:
RDPT: To determine whether guest panic notification is supported.
Arguments: None
-Return: Returns a byte, bit 0 set to indicate guest panic
- notification is supported. Other bits are reserved and
- should be ignored.
+Return: Returns a byte, with the same semantics as the I/O port
+ interface.
WRPT: To send a guest panic event
-Arguments: Arg0 is a byte, with bit 0 set to indicate guest panic has
- happened. Other bits are reserved and should be cleared.
+Arguments: Arg0 is a byte to be written, with the same semantics as
+ the I/O interface.
Return: None
The ACPI device will automatically refer to the right port in case it