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-rw-r--r--docs/specs/pvpanic.txt13
1 files changed, 12 insertions, 1 deletions
diff --git a/docs/specs/pvpanic.txt b/docs/specs/pvpanic.txt
index a90fbca72b..8afcde11cc 100644
--- a/docs/specs/pvpanic.txt
+++ b/docs/specs/pvpanic.txt
@@ -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 as a
+PCI device.
+
ISA Interface
-------------
@@ -24,6 +27,14 @@ 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
--------------