| 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. |
