L4virtio::Svr::Console::Port Struct Reference

Representation of a Virtio console port. More...

#include <virtio-console>

Inheritance diagram for L4virtio::Svr::Console::Port:

Collaboration diagram for L4virtio::Svr::Console::Port:

Data Structures
struct	Transition
	State transition from last report state to current state. More...

Public Types
enum	Port_status {   Port_disabled = 0 , Port_added , Port_ready , Port_open ,   Port_failed , Port_num_states }
	Possible states of a virtio console port. More...
enum
	Size of control queues, also used as default size.

Public Member Functions
bool	is_open () const
	Check that the port is open.
virtual void	reset ()
	Reset the port to the initial state and disable its virtqueues.
bool	queues_ready () const
	Check that both virtqueues are set up correctly.
bool	rx_ready () const
	Check that device implementation may write to receive queues.
bool	tx_ready () const
	Check that device implementation may read from transmit queues.

Data Fields
Virtqueue	tx
	Receiveq of the port.
Virtqueue	rx
	Transmitq of the port.
Port_status	status
	State the port is in.
Port_status	reported_status
	State the port was last reported.
unsigned	vq_max
	Maximum queue sizes for this port.

Static Public Attributes
static constexpr Transition	state_transitions [Port_num_states][Port_num_states]
	State transition table from last report state to current state.

Detailed Description

Representation of a Virtio console port.

Each port consists of a pair of queues for sending and receiving.

A port may be added and removed at runtime when the multi-port feature is enabled. The states are as follows:

+----------+      port_remove()
| DISABLED |<----------------------- [all]
+----------+
     |
     | port_add()
     v
+----------+   process_port_ready(0)
|  ADDED   + --------------+
+----------+               |             +--------+
     |                     +------------>|        |
     | process_port_ready(1)             |        |
     v                                   | FAILED |
+----------+   process_port_ready(0)     |        |
|          |---------------------------->|        |
|  READY   |   process_port_ready(1)     |        |
|          |<----------------------------|        |
+----------+<----------+                 +--------+
     |                 |                      ^
     | port_open(true) | port_open(false)     |
     v                 |                      | process_port_ready(0)
+----------+           |                      |
|   OPEN   |-----------+                      |
+----------+----------------------------------+

Definition at line 109 of file virtio-console.

Member Enumeration Documentation

Port_status

enum L4virtio::Svr::Console::Port::Port_status

Possible states of a virtio console port.

Enumerator
Port_disabled	Reset state, waiting for port to be added.
Port_added	Port has been added by device, waiting for ready message.
Port_ready	Port is ready but still closed.
Port_open	Port is in a working state.
Port_failed	Device failure, port unusable.
Port_num_states	Number of port states. Must be last.

Definition at line 114 of file virtio-console.

Field Documentation

state_transitions

constexpr Transition L4virtio::Svr::Console::Port::state_transitions[Port_num_states][Port_num_states]

staticconstexpr

State transition table from last report state to current state.

Not all transitions can be made directly. For example, if the last reported state was Port_disabled and the current state is Port_open, the device has to send two messages: Control_message::Device_add and Control_message::Port_open. This is expressed by going through an intermediate state (Port_ready) on the reporting side.

For the purpose of the driver there are only three coarse states:

1. The port does not exist (Port_disabled).
2. The port exists but is closed on the device side (Port_added, Port_ready, Port_failed).
3. The port exists and is open on the device side (Port_open).

The state transition table with Port_added, Port_ready and Port_failed as current state are thus identical.

Definition at line 195 of file virtio-console.

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The documentation for this struct was generated from the following file:

• l4/l4virtio/server/virtio-console