Il 14/03/2013 10:19, Gleb Natapov ha scritto: > On Thu, Mar 14, 2013 at 10:14:12AM +0100, Paolo Bonzini wrote: >> Il 14/03/2013 09:15, Hu Tao ha scritto: >>> pvevent device is used to send guest panic event from guest to qemu. >>> >>> When guest panic happens, pvevent device driver will write a event >>> number to IO port 0x505(which is the IO port occupied by pvevent device, >>> by default). On receiving the event, pvevent device will pause guest >>> cpu(s), and send a qmp event QEVENT_GUEST_PANICKED. >>> >>> TODO: make the IO port configurable >> >> The port is already configurable as far as the device is concerned; when >> you add the port to the PC boards you will have to wind up fw-cfg. > > Why not add fw-cfg when device is created (with -device for instance)?
It depends on what we decide is the supported interface for the device: * it can be an ISA device; the interface is the I/O port and ACPI support is provided just for convenience of the OSPM. In this case, "-device pvevent" should just add handlers for the port. The ACPI support is similar to what we do for other on-board ISA devices, for example serial ports (the serial ports use PIIX PCI configuration instead of fw-cfg, but that's a minor detail). It only needs to work for port 0x505, so the fw-cfg data can be a single yes/no value and only the _STA method needs patching. See piix4_pm_machine_ready in hw/acpi_piix4.c. * ACPI support is a first-class part of the device. Each instance of the device should be there in the ACPI tables. In this case the fw-cfg data needs to be a list of ports, and it is probably simpler to combine all the definitions in an SSDT that is dynamically-built (similar to what we do for PCI hotplug slots). Or even provide a separate SSDT for each instance of the device. I prefer the first, the second seems to be over-engineered. >> So these patches can go in already, with the sole change that the HID >> must be in the QEMU namespace rather than MSFT. >> > We should request one for QEMU. Yes. BTW, the QEMU patches can go in only in the first of the two cases above. Paolo
