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Add pvpanic PCI device support details in docs/specs/pvpanic.txt. Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
55 lines
1.8 KiB
Plaintext
55 lines
1.8 KiB
Plaintext
PVPANIC DEVICE
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==============
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pvpanic device is a simulated device, through which a guest panic
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event is sent to qemu, and a QMP event is generated. This allows
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management apps (e.g. libvirt) to be notified and respond to the event.
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The management app has the option of waiting for GUEST_PANICKED events,
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and/or polling for guest-panicked RunState, to learn when the pvpanic
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device has fired a panic event.
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The pvpanic device can be implemented as an ISA device (using IOPORT) or as a
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PCI device.
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ISA Interface
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-------------
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pvpanic exposes a single I/O port, by default 0x505. On read, the bits
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recognized by the device are set. Software should ignore bits it doesn't
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recognize. On write, the bits not recognized by the device are ignored.
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Software should set only bits both itself and the device recognize.
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Bit Definition
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--------------
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bit 0: a guest panic has happened and should be processed by the host
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bit 1: a guest panic has happened and will be handled by the guest;
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the host should record it or report it, but should not affect
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the execution of the guest.
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PCI Interface
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-------------
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The PCI interface is similar to the ISA interface except that it uses an MMIO
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address space provided by its BAR0, 1 byte long. Any machine with a PCI bus
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can enable a pvpanic device by adding '-device pvpanic-pci' to the command
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line.
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ACPI Interface
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--------------
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pvpanic device is defined with ACPI ID "QEMU0001". Custom methods:
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RDPT: To determine whether guest panic notification is supported.
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Arguments: None
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Return: Returns a byte, with the same semantics as the I/O port
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interface.
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WRPT: To send a guest panic event
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Arguments: Arg0 is a byte to be written, with the same semantics as
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the I/O interface.
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Return: None
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The ACPI device will automatically refer to the right port in case it
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is modified.
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