@@ -1,7 +1,7 @@
PVPANIC DEVICE
==============
-pvpanic device is a simulated ISA device, through which a guest panic
+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.
@@ -9,6 +9,9 @@ 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, since qemu 4.0, as a SYSBUS device (using MMIO).
+
ISA Interface
-------------
@@ -19,6 +22,13 @@ 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.
+SYSBUS Interface
+----------------
+
+The SYSBUS interface is similar to the ISA interface except that it uses
+MMIO. For example, the arm virt machine could put the pvpanic device at
+[0x9070000, 0x9070001], where currently only the first byte is used.
+
ACPI Interface
--------------