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WSDISPLAY(4)              NetBSD Programmer's Manual              WSDISPLAY(4)


NAME

     wsdisplay - generic display device support in wscons


SYNOPSIS

     wsdisplay* at ega? console ?
     (EGA display on ISA)
     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)
     wsdisplay* at ... kbdmux N
     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 kbdmux locator in the configuration line refers to the wsmux(4) that
     will be used to get keyboard events.  If this locator is -1 no mux will
     be used.

     The logical unit of an independent 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 possesses the
     ``focus'', this means it is visible and its tty device will get the key-
     board 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 fo-
     cus can be switched by either special keyboard input (typically CTRL-ALT-
     Fn) or an ioctl command issued by a user program.  Screens are created
     and deleted through the /dev/ttyEcfg control device (preferably using the
     wsconscfg(8) utility). Alternatively, the compile-time option
     WSDISPLAY_DEFAULTSCREENS=n will also create (at autoconfiguration time) n
     initial screens of the display driver's default type with the system's
     default terminal emulator.


FILES

     /dev/ttyE* Terminal devices (per screen).

     /dev/ttyEcfg Control device.

     /usr/include/dev/wscons/wsconsio.h


SEE ALSO

     ega(4), pcdisplay(4), tty(4), vga(4), wscons(4), wsconscfg(8),
     wsconsctl(8), wsfontload(8)


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.

NetBSD 1.6.2                    March 20, 1999                               2