Virtual Terminal  [include/linux/vt.h]

VT_OPENQRY Retrieve the first available (non-opened) console. edx should point to 4 bytes long buffer which will receive the console number. See samples/ioctl/vtinfo.asm for an example.
VT_GETMODE Retrieve current VT settings. edx should point to a vt_mode structure which will receive the information:

struc vt_mode
{
.mode   rb 1
.waitv  rb 1
.relsig rw 1
.acqsig rw 1
.frsig  rw 1
}

vt_mode members:

mode
Mode which determines who switches the console:

VT_AUTO    - Automatic VT switching
VT_PROCESS - Process controlled switching.
VT_ACKACQ  - Acknowledge switching
waitv
*to be documented*
relsig
Signal to raise on release. (i.e. whenever user switches from the tty. e.g. Alt+F4). Set to 0 if no signal to be raised.
acqsig
Signal to raise on acquisition. Set to 0 if no signal to be raised.
frsig
Unused.
VT_SETMODE Set current VT settings. edx should point to a propely initialized vt_mode structure (see above).
VT_GETSTATE Retrieve global VT state. edx should point to a vt_stat structure which will receive the information:

struc vt_stat
{
.v_active rw 1
.v_signal rw 1
.v_state  rw 1
}

vt_stat members:

v_active
Currently active terminal number.
v_signal
*to be documented*
v_state
*to be documented*
VT_SENDSIG *to be documented*
VT_RELDISP *to be documented*
VT_ACTIVATE Switch focus to specific terminal. edx should contain terminal number (0 < edx <= MAX_NR_CONSOLES) to switch to.
VT_WAITACTIVE Suspend application execution until specific terminal becomes active. edx should contain terminal number (0 < edx <= MAX_NR_CONSOLES).
VT_DISALLOCATE Deallocate memory associated with the given VT. edx should contain terminal number different from the currently used (ebx). If edx is 0 than all tty devices which are not in use are freed.
VT_RESIZE Set kernel's idea of screensize. edx should point to a properly initialized vt_sizes structure:

struc vt_sizes
{
.v_rows       rw 1
.v_cols       rw 1
.v_scrollsize rw 1
}

vt_sizes members:

v_rows
Number of rows.
v_cols
Number of cols.
v_stcrollsize
Number of lines in scrollback.
VT_RESIZEX Set kernel's idea of various screen parameters. edx should point to a properly initialized vt_consize structure:

struc vt_consize
{
.v_rows rw 1
.v_cols rw 1
.v_vlin rw 1
.v_clin rw 1
.v_vcol rw 1
.v_ccol rw 1
}

vt_sizes members:

v_rows
Number of rows.
v_cols
Number of columns.
v_vlin
Number of pixel rows on screen.
v_clin
Number of pixel rows per character.
v_vcol
Number of pixel columns on screen.
v_ccol
Number of pixel columns per character.
VT_LOCKSWITCH Lock VT focus switching.
VT_UNLOCKSWITCH Unlock VT focus switching.
VT_GETHIFONTMASK
*to be documented*