wsdisplay(4)
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WSDISPLAY(4) NetBSD Programmer's Manual WSDISPLAY(4)
NAME
wsdisplay - generic display device support in wscons
SYNOPSIS
wsdisplay* at vga? console ?
(VGA display on ISA or PCI)
wsdisplay* at pcdisplay? console ?
(generic PC (ISA) display)
wsdisplay* at tga? console ?
(DEC TGA display, alpha only)
wsdisplay* at pfb? console ?
(PCI framebuffer, bebox only)
wsdisplay0 at ofb? console ?
(Open Firmware framebuffer, macppc only)
wsdisplay* at nextdisplay? console ?
(NeXT display)
wsdisplay0 at smg0
(VAXstation small monochrome display)
options WSDISPLAY_DEFAULTSCREENS=N
DESCRIPTION
The wsdisplay driver is an abstraction layer for display devices within
the wscons(4) framework. It attaches to the hardware specific display de-
vice driver and and makes it available as text terminal or graphics in-
terface.
A display device can have the ability to display characters on it (with-
out help of an X server), either directly by hardware or through software
putting pixel data into the display memory. Such displays are called
``emulating'', the wsdisplay driver will connect a terminal emulation
module and provide a tty-like software interface. In contrary, non-emu-
lating displays can only be used by special programs like X servers.
The console locator in the configuration line refers to the device's use
as output part of the operating system console. A device specification
containing a positive value here will only match if the device is in use
as system console. (The console device selection in early system startup
is not influenced.) This way, the console device can be connected to a
known wsdisplay device instance. (Naturally, only ``emulating'' display
devices are usable as console.)
The logical unit of an independant contents displayed on a display (some-
times referred to as ``virtual terminal'' ) is called a ``screen'' here.
If the underlying device driver supports it, multiple screens can be used
on one display. (As of this writing, only the vga(4) and the VAX ``smg''
display drivers provide this ability.) Screens have different minor de-
vice numbers and separate tty instances. One screen posesses the
``focus'', this means it is displayed on the display and its tty device
will get the keyboard input. (In some cases - if no screen is set up or
if a screen was just deleted - it is possible that no focus is present at
all.) The focus can be switched by either special keyboard input (typi-
cally CTL-ALT-Fn) or an ioctl command issued by a user program. Screens
are set up or deleted through the /dev/ttyEcfg control decice (pre-
ferrably using the wsconscfg(8) utility). Alternatively, the compile-time
option
WSDISPLAY_DEFAULTSCREENS=N will set up N screens of the display driver's
default type and using the system's default terminal emulator at autocon-
figuration time.
FILES
/dev/ttyE* Terminal devices (per screen).
/dev/ttyEcfg Control device.
/usr/include/dev/wscons/wsconsio.h
BUGS
The wsdisplay code currently limits the number of screens on one display
to 8.
The terms ``wscons'' and ``wsdisplay'' are not cleanly distinguished in
the code and in manual pages.
``non-emulating'' display devices are not tested.
SEE ALSO
wscons(4), wsconscfg(8), wsconsctl(8), wsloadfont(8), vga(4),
pcdisplay(4), tty(4)
NetBSD 1.4 March 20, 1999 2
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