VT(4I) | Ioctl Requests | VT(4I) |
vt
— Solaris
virtual console interface
The virtual console device driver — also known as virtual terminal (VT) — is a layer of management functions that provides facilities to support and switch between multiple screen faces on a single physical device.
VT's are accessed in the same way as other devices. The open(2) system call is used to open the virtual console and read(2), write(2) and ioctl(2) are used in the normal way and support the functionality of the underlying device. In addition, some virtual console-specific ioctls are provided and described below.
The VT provides a link between different screen faces and the device. The active virtual console corresponds to the currently visible screen face. Device input is directed to the active console and any device-specific modes that change on a per virtual terminal basis are set to the characteristics associated with the active console.
You manage VT's by intercepting keyboard sequences (“hot key”). To maintain consistency with Xserver, the virtual console device driver supports the Ctrl, Alt, F# and arrow keys.
The sequence AltL + F# (where AltL represents the left Alt key and F# represents function keys 1 through 12) is used to select virtual console 1-12. The sequence AltGraph + F# (where AltGraph represents the right Alt key and F# represent function keys 1 through 12) is for virtual console 13-24. Alt + F1 chooses the system console (also known as virtual console 1). The sequence Alt + → (where "→" represents the right directional arrow) selects the next VT in a circular ring fashion and Alt + ← (where "←" represents the left directional arrow) changes to the previous console in a circular fashion. The sequence Alt + ↑ (where "↑" represents the up directional arrow) is for the last used console.
Virtual console switching can be done automatically
(VT_AUTO
) on receipt of a “hot-key” or
by the process owning the VT (VT_PROCESS
). When
performed automatically, the process associated with the virtual console is
unaware of the switch. Saving and restoring the device are handled by the
underlying device driver and the virtual console manager. Note that
automatic switching is the default mode.
When a “hot-key” is sent when in process-controlled
switch mode, the process owning the VT is sent a signal (relsig) it has
specified to the virtual console manager (see
signal(3C)) requesting the process to
release the physical device. At this point, the virtual console manager
awaits the VT_RELDISP
ioctl from the process. If the
process refuses to release the device (meaning the switch does not occur),
it performs a VT_RELDISP
ioctl with an argument of 0
(zero). If the process desires to release the device, it saves the device
state (keyboard, display, and I/O registers) and then performs a
VT_RELDISP
with an argument of 1 to complete the
switch.
A ring of VT's can contain intermixed auto mode and process
control mode consoles. When an auto mode process becomes active, the
underlying device driver and the virtual console manager handle the
restoring of the device. Process control mode processes are sent a specified
signal (acqsig) when they become the active console. The process then
restores the device state (keyboard, display, and I/O registers) and
performs VT_RELDISP
ioctl with an argument of
VT_ACKACQ
to complete the switching protocol.
The modify-operations ioctls (VT_SETMODE
,
VT_RELDISP
, VT_WAITACTIVE
,
KDSETMODE
) check if the VT is the controlling tty of
the calling process. If not, the sys_devices privilege is enforced.
VT_ACTIVATE
requires the sys_devices privilege. Note
that there is no controlling tty and privilege check for query/view
operations.
The following ioctls apply to devices that support virtual consoles:
VT_ENABLED
VT_OPENQRY
VT_GETMODE
VT_AUTO
or VT_PROCESS
. The argument is the address of the
following structure, as defined in
<sys/vt.h>
struct vt_mode { char mode; /* VT mode */ char waitv; /* not used */ short relsig; /* signal to use for release request */ short acqsig; /* signal to use for display acquired */ short frsig; /* not used */ } /* Virtual console Modes */ #define VT_AUTO 0 /* automatic VT switching */ #define VT_PROCESS 1 /* process controls switching */
The structure will be filled in with the current value for each field.
VT_SETMODE
SIGUSR1
(for
relsig and acqsig).VT_RELDISP
VT_ACKACQ
argument indicates if acquisition of the VT has been completed.VT_ACTIVATE
ENXIO
.VT_WAITACTIVE
VT_GETSTATE
struct vt_stat { unsigned short v_active, /* number of the active VT */ v_signal, /* not used */ /* * count of open VTs. For every 1 in this * field, there is an open VT */ v_state; }
With VT_GETSTATE
, the VT manager first
gets the number of the active VT, then determines the number of open VTs
in the system and sets a 1 for each open VT in v_state. Next, the VT
manager transfers the information in structure
vt_stat passed by the user process.
KDGETMODE
#define KD_TEXT 0 #define KD_GRAPHICS 1
KDSETMODE
KD_TEXT
KD_TEXT
is combined with
VT_AUTO
mode for text console terminals, so that
the console text display automatically is saved and restored on the hot
key screen switches.
KD_GRAPHICS
indicates that the
user/application (usually Xserver) has direct control of the display for
this VT in graphics mode. Normally KD_GRAPHICS
is combined with VT_PROCESS
mode for this VT
indicating direct control of the display in graphics mode. In this mode,
all writes to the VT using the write system call are ignored, and you
must save and restore the display on the hot key screen switches.
When the mode of the active VT is changed from
KD_TEXT
to KD_GRAPHICS
or a VT of KD_GRAPHICS
mode is made active from
a previous active VT of KD_TEXT
mode, the
virtual console manager initiates a KDSETMODE
ioctl with KD_GRAPHICS
as the argument to the
underlying console frame buffer device indicating that current display
is running into graphics mode.
When the mode of the active VT is changed from
KD_GRAPHICS
to KD_TEXT
or a VT of KD_TEXT
mode is activated from a
previous active VT of KD_GRAPHICS
mode, the
virtual console manager initiates a KDSETMODE
ioctl with KD_TEXT
as the argument to the
underlying console frame buffer device indicating that current display
is running into console text mode.
By default, there are only five virtual console instance login prompts running on /dev/vt/# (where "#" represents 2 to 6) in addition to the system console running on /dev/console. Normally Xorg uses the seventh virtual console (/dev/vt/7). To switch from consoles to Xserver (which normally picks up the first available virtual console), use [ Ctrl + ] Alt + F7 .
# svcs | grep login online 17:49:11 svc:/system/console-login:default online 17:49:11 svc:/system/console-login:vt2 online 17:49:11 svc:/system/console-login:vt3 online 17:49:11 svc:/system/console-login:vt4 online 17:49:11 svc:/system/console-login:vt5 online 17:49:11 svc:/system/console-login:vt6
console-login:default is for the system console, others for virtual consoles.
You can modify properties of, disable/enable, and remove/add virtual consoles using smf(7):
# svccfg -s console-login add vt8 # svccfg -s console-login:vt8 setprop \ ttymon/device=astring: "/dev/vt/8" # svcadm enable console-login:vt8
March 13, 2022 | OmniOS |