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 device driver and and makes it available as text terminal or graphics interface.

A display device can have the ability to display characters on it (without 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-emulating 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 (sometimes 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 device 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 (typically CTL-ALT-Fn) or an ioctl command issued by a user program. Screens are set up or deleted through the /dev/ttyEcfg control decice (preferrably 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 autoconfiguration 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)