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Diffstat (limited to 'docs/specs/virt-ctlr.rst')
| -rw-r--r-- | docs/specs/virt-ctlr.rst | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/docs/specs/virt-ctlr.rst b/docs/specs/virt-ctlr.rst new file mode 100644 index 0000000000..ad3edde82d --- /dev/null +++ b/docs/specs/virt-ctlr.rst @@ -0,0 +1,24 @@ +Virtual System Controller +========================= + +The ``virt-ctrl`` device is a simple interface defined for the pure +virtual machine with no hardware reference implementation to allow the +guest kernel to send command to the host hypervisor. + +The specification can evolve, the current state is defined as below. + +This is a MMIO mapped device using 256 bytes. + +Two 32bit registers are defined: + +the features register (read-only, address 0x00) + This register allows the device to report features supported by the + controller. + The only feature supported for the moment is power control (0x01). + +the command register (write-only, address 0x04) + This register allows the kernel to send the commands to the hypervisor. + The implemented commands are part of the power control feature and + are reset (1), halt (2) and panic (3). + A basic command, no-op (0), is always present and can be used to test the + register access. This command has no effect. |