virtualkm - Virtual keyboard and mouse




#include <sys/types.h>

#include <sys/kbio.h>

int ioctl(int fildes, int command, ... /*arg*/);


A virtual keyboard or mouse is an abstraction of one or more physical
keyboards or mice (USB or PS2) connected to a system. Input streams for
these physical devices are coalesced into a single input stream and
appear as a single device to the upper layers.

/dev/kbd is the virtual keyboard device file. Inputs from multiple
keyboards are coalesced into a single input stream, meaning that all
keyboards appear as a single keyboard to a console or window system and
accordingly, are treated as a single device. The virtual keyboard layout
is consistent with the layout of the first keyboard plugged into the
system. Note that on x86 platforms, the virtual keyboard layout can be
overloaded by eeprom(8).

/dev/mouse is the virtual mouse device file. Inputs from multiple mice
are coalesced into a single input stream, meaning that all mice appear as
single mouse to the window system.

Commands from applications are dispatched by the virtual keyboard/mouse
facility to the underlying physical devices and will succeed provided
that one of the underlying devices responds with success. For example, a
single command issued to turn on LED's will turn on corresponding LED's
for all underlying physical keyboards.

Although physical keyboards/mice are linked to the virtual keyboard/mouse
facility, each may be opened separately by accessing its associated
device file. (For example, /dev/usb/hid0 for a usb mouse). Directly
accessing a device file can be useful for multi-seat or similar purposes.

When a single physical device is opened via its associated device file,
it is automatically removed from the single virtual input stream. When
closed, it is automatically re- coalesced into the single virtual input

Under the virtualkm facility, the PS/2 mouse is coalesced into a virtual
mouse single input stream and can be accessed using the /dev/mouse file.
(Note that in previous releases, the PS/2 mouse was accessed via the
/dev/kdmouse physical device file). In the current release, you use the
/dev/kdmouse file to directly access the physical PS/2 mouse.


The virtual mouse provides the following event ID's for mouse capability

This event is reported when the total
number of mouse buttons changes. The
Firm_event.value is set to the new button
total, which is the maximum number of all
mice buttons. Other fields are ignored.

This event is reported when the total
number of mouse wheels changes. The
Firm_event.value is set to the new wheel
total. Other fields are ignored. The event
value (Firm_event.value) can be 0 (no
wheel), 1 (vertical wheel), or 2 (vertical
and horizontal wheel).

The Firm_event structure is described in <sys/vuid_event.h>. As with
other events, firm events are received using read(2).

Event ID's are used by applications (including certain mouse demo
applications) that are programmed to graphically represent the actual
number of buttons and wheels on a mouse. When an application of this type
receives a Firm_event with a ID MOUSE_CAP_CHANGE_NUM_BUT or
MOUSE_CAP_CHANGE_NUM_WHEEL event, it is instructed to update its state
information using the new value. Consider, for example, a mouse demo
application whose sole function is to display a mouse with buttons that
graphically correspond to the actual number of buttons on the mouse. If,
for example, the system has a single two-button USB mouse attached, the
application, by default, will graphically display the mouse with a left
and a right button. However, if a another three-button USB mouse is hot-
plugged into the system, a MOUSE_CAP_CHANGE_NUM_BUT Firm event with
Firm_event.value of three instructs the demo application to update the
mouse display to indicate three buttons.


Sets the frequency for either keyboard beeper or console
beeper. To set the corresponding beeper frequency, arg
must point to a freq_request structure:

struct freq_request {
enum fr_beep_type type; /* beep type */
int16_t freq; /* frequency */

Where type is the corresponding beeper type defined as:

enum fr_beep_type { CONSOLE_BEEP =1, KBD_BEEP =2 };

and freq is the frequency value to be set as the beeper
frequency indicated by type. This value should be between
0 and 32767 with border inclusive.


Virtual Keyboard device file.

Virtual Mouse device file.

Physical PS/2 mouse device file.

Physical USB keyboard/mouse device file.

Device auto-configuration file.


See attributes(7) for descriptions of the following attributes:

|Architecture SPARC, x86 |
|Interface Stability Evolving |


kbd(1), read(2), hid(4D), usba(4D), kb(4M), usbkbm(4M), usbms(4M),
vuidmice(4M), attributes(7), eeprom(8)


The messages described below may appear on the system console as well as
being logged. All messages are formatted in the following manner:

WARNING: Error message...

conskbd: keyboard is not available for system debugging: device_path.

Errors were encountered while entering kmdb during initialization for
debugger mode. As a result, the keyboard is not available.

conskbd: keyboard is not available: <device_path>

Errors were encountered while exiting kmdb during un-initialization
for debugger mode. As a result, the keyboard is not available.

Failed to relink the mouse <device_path> underneath virtual mouse

An error was encountered and the mouse is unavailable. (When a mouse
is physically opened via a physical device file such as
/dev/usb/hid0, it is removed from the single virtual input stream
(/dev/mouse). When closed, it is re-coalesced into a single virtual
input stream beneath /dev/mouse. If an error is encountered, (for
example, the mouse has been physically removed), it is unavailable
beneath /dev/mouse.


Currently, the virtualkm device supports only USB and PS2 keyboards and

The virtualkm device maintains complete compatibility on select legacy
systems, (including Ultra 10's), that are equipped with serial

May 13, 2017 VIRTUALKM(4D)