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+PVPANIC DEVICE
+==============
+
+pvpanic device is a simulated 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.
+
+The pvpanic device can be implemented as an ISA device (using IOPORT) or as a
+PCI device.
+
+ISA Interface
+-------------
+
+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.
+
+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.
+
+PCI Interface
+-------------
+
+The PCI interface is similar to the ISA interface except that it uses an MMIO
+address space provided by its BAR0, 1 byte long. Any machine with a PCI bus
+can enable a pvpanic device by adding ``-device pvpanic-pci`` to the command
+line.
+
+ACPI Interface
+--------------
+
+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, with the same semantics as the I/O port interface.
+
+WRPT
+~~~~
+
+To send a guest panic event.
+
+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
+is modified.