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SYSMOUSE(4) Device Drivers Manual SYSMOUSE(4)


sysmousevirtualized mouse driver


#include <sys/mouse.h>
#include <sys/consio.h>


The console driver, in conjunction with the mouse daemon moused(8), supplies mouse data to the user process in the standardized way via the sysmouse driver. This arrangement makes it possible for the console and the user process (such as the X Window System) to share the mouse.

The user process which wants to utilize mouse operation simply opens /dev/sysmouse with a open(2) call and reads mouse data from the device via read(2). Make sure that moused(8) is running, otherwise the user process will not see any data coming from the mouse.

Operation Levels

The sysmouse driver has two levels of operation. The current operation level can be referred to and changed via ioctl calls.

The level zero, the basic level, is the lowest level at which the driver offers the basic service to user programs. The sysmouse driver provides horizontal and vertical movement of the mouse and state of up to three buttons in the MouseSystems format as follows.

Byte 1
bit 7
Always one.
bit 6..3
Always zero.
bit 2
Left button status; cleared if pressed, otherwise set.
bit 1
Middle button status; cleared if pressed, otherwise set. Always one, if the device does not have the middle button.
bit 0
Right button status; cleared if pressed, otherwise set.
Byte 2
The first half of horizontal movement count in two's complement; -128 through 127.
Byte 3
The first half of vertical movement count in two's complement; -128 through 127.
Byte 4
The second half of the horizontal movement count in two's complement; -128 through 127. To obtain the full horizontal movement count, add the byte 2 and 4.
Byte 5
The second half of the vertical movement count in two's complement; -128 through 127. To obtain the full vertical movement count, add the byte 3 and 5.

At the level one, the extended level, mouse data is encoded in the standard format MOUSE_PROTO_SYSMOUSE as defined in mouse(4).


This section describes two classes of ioctl(2) commands: commands for the sysmouse driver itself, and commands for the console and the console control drivers.

Sysmouse Ioctls

There are a few commands for mouse drivers. General description of the commands is given in mouse(4). Following are the features specific to the sysmouse driver.

int *level
int *level
These commands manipulate the operation level of the mouse driver.

mousehw_t *hw
Returns the hardware information of the attached device in the following structure. Only the iftype field is guaranteed to be filled with the correct value in the current version of the sysmouse driver.
typedef struct mousehw {
    int buttons;    /* number of buttons */
    int iftype;     /* I/F type */
    int type;       /* mouse/track ball/pad... */
    int model;      /* I/F dependent model ID */
    int hwid;       /* I/F dependent hardware ID */
} mousehw_t;

The buttons field holds the number of buttons detected by the driver.

The iftype is always MOUSE_IF_SYSMOUSE.


The model is always MOUSE_MODEL_GENERIC at the operation level 0. It may be MOUSE_MODEL_GENERIC or one of MOUSE_MODEL_XXX constants at higher operation levels.

The hwid is always zero.

mousemode_t *mode
The command gets the current operation parameters of the mouse driver.
typedef struct mousemode {
    int protocol;    /* MOUSE_PROTO_XXX */
    int rate;        /* report rate (per sec) */
    int resolution;  /* MOUSE_RES_XXX, -1 if unknown */
    int accelfactor; /* acceleration factor */
    int level;       /* driver operation level */
    int packetsize;  /* the length of the data packet */
    unsigned char syncmask[2]; /* sync. bits */
} mousemode_t;

The protocol field tells the format in which the device status is returned when the mouse data is read by the user program. It is MOUSE_PROTO_MSC at the operation level zero. MOUSE_PROTO_SYSMOUSE at the operation level one.

The rate is always set to -1.

The resolution is always set to -1.

The accelfactor is always 0.

The packetsize field specifies the length of the data packet. It depends on the operation level.

5 bytes
8 bytes

The array syncmask holds a bit mask and pattern to detect the first byte of the data packet. syncmask[0] is the bit mask to be ANDed with a byte. If the result is equal to syncmask[1], the byte is likely to be the first byte of the data packet. Note that this method of detecting the first byte is not 100% reliable; thus, it should be taken only as an advisory measure.

mousemode_t *mode
The command changes the current operation parameters of the mouse driver as specified in mode. Only level may be modifiable. Setting values in the other field does not generate error and has no effect.

mousedata_t *data
mousedata_t *state
These commands are not supported by the sysmouse driver.

mousestatus_t *status
The command returns the current state of buttons and movement counts in the structure as defined in mouse(4).

Console and Consolectl Ioctls

The user process issues console () calls to the current virtual console in order to control the mouse pointer. The console ioctl() also provides a method for the user process to receive a signal(3) when a button is pressed.

The mouse daemon moused(8) uses () calls to the console control device /dev/consolectl to inform the console of mouse actions including mouse movement and button status.

Both classes of () commands are defined as CONS_MOUSECTL which takes the following argument.

struct mouse_info {
    int operation;
    union {
        struct mouse_data data;
        struct mouse_mode mode;
        struct mouse_event event;
    } u;

This can be one of

Enables and displays mouse cursor.
Disables and hides mouse cursor.
Moves mouse cursor to position supplied in
Adds position supplied in to current position.
Returns current mouse position in the current virtual console and button status in
This sets the signal(3) to be delivered to the current process when a button is pressed. The signal to be delivered is set in u.mode.

The above operations are for virtual consoles. The operations defined below are for the console control device and are used by moused(8) to pass mouse data to the console driver.

These operations take the information in and act upon it. Mouse data will be sent to the sysmouse driver if it is open. MOUSE_ACTION also processes button press actions and sends signal to the process if requested or performs cut and paste operations if the current console is a text interface. specifies a button and its click count. The console driver will use this information for signal delivery if requested or for cut and paste operations if the console is in text mode.

MOUSE_MOTION_EVENT and MOUSE_BUTTON_EVENT are newer interface and are designed to be used together. They are intended to replace functions performed by MOUSE_ACTION alone.

This union is one of

struct mouse_data {
    int x;
    int y;
    int z;
    int buttons;

x, y and z represent movement of the mouse along respective directions. buttons tells the state of buttons. It encodes up to 31 buttons in the bit 0 though the bit 30. If a button is held down, the corresponding bit is set.

struct mouse_mode {
    int mode;
    int signal;

The signal field specifies the signal to be delivered to the process. It must be one of the values defined in <signal.h>. The mode field is currently unused.

struct mouse_event {
    int id;
    int value;

The id field specifies a button number as in Only one bit/button is set. The value field holds the click count: the number of times the user has clicked the button successively.


device to control the console
virtualized mouse driver
virtual consoles


vidcontrol(1), ioctl(2), signal(3), mouse(4), moused(8)


The sysmouse driver first appeared in FreeBSD 2.2.


This manual page was written by John-Mark Gurney <> and Kazutaka Yokota <>.

March 25, 2014 Debian