[Qemu-devel] [PATCH v15.2 4/6] pvpanic: add document of pvpanic

[Hu Tao <hutao@cn.fujitsu.com>]

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
---
 docs/specs/pvpanic.txt | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 docs/specs/pvpanic.txt

diff --git a/docs/specs/pvpanic.txt b/docs/specs/pvpanic.txt
new file mode 100644
index 0000000..6fe8bb6
--- /dev/null
+++ b/docs/specs/pvpanic.txt
@@ -0,0 +1,37 @@
+PVPANIC DEVICE
+==============
+
+pvpanic device is a simulated ISA device, through which a guest panic
+event is sent to qemu, and a QMP event is generated. This allows
+management apps (e.g. libvirt) to be notified and respond to the event.
+
+The management app has the option of waiting for GUEST_PANICKED events,
+and/or polling for guest-panicked RunState, to learn when the pvpanic
+device has fired a panic event.
+
+ISA Interface
+-------------
+
+pvpanic uses port 0x505 to receive a panic event from the guest. On
+write, bit 0 is set to indicate guest panic has happened. On read, bit
+0 is set to indicate guest panic notification is supported. Remaining
+bits are reserved, and should be written as 0, and ignored on read.
+
+ACPI Interface
+--------------
+
+pvpanic device is defined with ACPI ID "QEMU0001". Custom methods:
+
+RDPT:       To determine whether guest panic notification is supported.
+Rrguments:  None
+Return:     Returns a byte, bit 0 set to indicate guest panic
+            notification is supported. Other bits are reserved and
+            should be ignored.
+
+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.
+Return:     None
+
+The ACPI device will automatically refer to the right port in case it
+is modified.
-- 
1.8.1.4