1 PVPANIC DEVICE 2 ============== 3 4 pvpanic device is a simulated device, through which a guest panic 5 event is sent to qemu, and a QMP event is generated. This allows 6 management apps (e.g. libvirt) to be notified and respond to the event. 7 8 The management app has the option of waiting for GUEST_PANICKED events, 9 and/or polling for guest-panicked RunState, to learn when the pvpanic 10 device has fired a panic event. 11 12 The pvpanic device can be implemented as an ISA device (using IOPORT) or as a 13 PCI device. 14 15 ISA Interface 16 ------------- 17 18 pvpanic exposes a single I/O port, by default 0x505. On read, the bits 19 recognized by the device are set. Software should ignore bits it doesn't 20 recognize. On write, the bits not recognized by the device are ignored. 21 Software should set only bits both itself and the device recognize. 22 23 Bit Definition 24 ~~~~~~~~~~~~~~ 25 26 bit 0 27 a guest panic has happened and should be processed by the host 28 bit 1 29 a guest panic has happened and will be handled by the guest; 30 the host should record it or report it, but should not affect 31 the execution of the guest. 32 bit 2 (to be implemented) 33 a regular guest shutdown has happened and should be processed by the host 34 35 PCI Interface 36 ------------- 37 38 The PCI interface is similar to the ISA interface except that it uses an MMIO 39 address space provided by its BAR0, 1 byte long. Any machine with a PCI bus 40 can enable a pvpanic device by adding ``-device pvpanic-pci`` to the command 41 line. 42 43 ACPI Interface 44 -------------- 45 46 pvpanic device is defined with ACPI ID "QEMU0001". Custom methods: 47 48 RDPT 49 ~~~~ 50 51 To determine whether guest panic notification is supported. 52 53 Arguments 54 None 55 Return 56 Returns a byte, with the same semantics as the I/O port interface. 57 58 WRPT 59 ~~~~ 60 61 To send a guest panic event. 62 63 Arguments 64 Arg0 is a byte to be written, with the same semantics as the I/O interface. 65 Return 66 None 67 68 The ACPI device will automatically refer to the right port in case it 69 is modified. 70