2021-03-12 22:41:44 +01:00
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Virtual System Controller
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=========================
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2023-09-27 17:12:03 +02:00
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The ``virt-ctrl`` device is a simple interface defined for the pure
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virtual machine with no hardware reference implementation to allow the
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guest kernel to send command to the host hypervisor.
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2021-03-12 22:41:44 +01:00
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The specification can evolve, the current state is defined as below.
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This is a MMIO mapped device using 256 bytes.
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Two 32bit registers are defined:
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2023-09-27 17:12:03 +02:00
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the features register (read-only, address 0x00)
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2021-03-12 22:41:44 +01:00
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This register allows the device to report features supported by the
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controller.
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The only feature supported for the moment is power control (0x01).
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2023-09-27 17:12:03 +02:00
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the command register (write-only, address 0x04)
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2021-03-12 22:41:44 +01:00
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This register allows the kernel to send the commands to the hypervisor.
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The implemented commands are part of the power control feature and
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are reset (1), halt (2) and panic (3).
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A basic command, no-op (0), is always present and can be used to test the
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register access. This command has no effect.
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