118 lines
3.4 KiB
Groff
118 lines
3.4 KiB
Groff
.\" $NetBSD: wsdisplay.4,v 1.9 2001/09/11 23:18:56 wiz Exp $
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.Dd March 20, 1999
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.Os
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.Dt WSDISPLAY 4
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.Sh NAME
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.Nm wsdisplay
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.Nd generic display device support in wscons
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.Sh SYNOPSIS
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.Cd wsdisplay* at ega? console ?
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(EGA display on ISA)
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.Cd wsdisplay* at vga? console ?
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(VGA display on ISA or PCI)
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.Cd wsdisplay* at pcdisplay? console ?
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(generic PC (ISA) display)
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.Cd wsdisplay* at tga? console ?
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(DEC TGA display, alpha only)
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.Cd wsdisplay* at pfb? console ?
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(PCI framebuffer, bebox only)
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.Cd wsdisplay0 at ofb? console ?
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(Open Firmware framebuffer, macppc only)
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.Cd wsdisplay* at nextdisplay? console ?
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(NeXT display)
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.Cd wsdisplay0 at smg0
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(VAXstation small monochrome display)
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.Cd options WSDISPLAY_DEFAULTSCREENS=N
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.Sh DESCRIPTION
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The
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.Nm
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driver is an abstraction layer for display devices within the
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.Xr wscons 4
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framework. It attaches to the hardware specific display device
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driver and and makes it available as text terminal or graphics
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interface.
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.Pp
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A display device can have the ability to display characters on it
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(without help of an X server), either directly by hardware or through
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software putting pixel data into the display memory.
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Such displays are called
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.Dq emulating ,
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the
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.Nm
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driver will connect a terminal emulation module and provide a
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tty-like software interface. In contrary, non-emulating displays can only
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be used by special programs like X servers.
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.Pp
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The
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.Em console
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locator in the configuration line refers to the device's use as output
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part of the operating system console. A device specification containing
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a positive value here will only match if the device is in use as system
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console. (The console device selection in early system startup is not
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influenced.) This way, the console device can be connected to a known
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wsdisplay device instance. (Naturally, only
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.Dq emulating
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display devices are usable as console.)
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.Pp
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The logical unit of an independent contents displayed on a display
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(sometimes referred to as
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.Dq virtual terminal
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) is called a
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.Dq screen
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here. If the underlying device driver supports it, multiple screens can
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be used on one display. (As of this writing, only the
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.Xr vga 4
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and the
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.Tn VAX
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.Dq smg
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display drivers provide this ability.)
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Screens have different minor device numbers and separate tty instances.
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One screen possesses the
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.Dq focus ,
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this means it is displayed on the display and its tty device will get
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the keyboard input. (In some cases - if no screen is set up or if a screen
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was just deleted - it is possible that no focus is present at all.)
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The focus can be switched by either special keyboard input (typically
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CTRL-ALT-Fn) or an ioctl command issued by a user program.
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Screens are set up or deleted through the
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.Pa /dev/ttyEcfg
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control device (preferably using the
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.Xr wsconscfg 8
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utility). Alternatively, the compile-time option
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.Cd WSDISPLAY_DEFAULTSCREENS=N
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will set up N screens of the display driver's default type and using
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the system's default terminal emulator at autoconfiguration time.
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.Sh FILES
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.Bl -item
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.It
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.Pa /dev/ttyE*
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Terminal devices (per screen).
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.It
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.Pa /dev/ttyEcfg
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Control device.
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.It
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.Pa /usr/include/dev/wscons/wsconsio.h
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.El
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.Sh SEE ALSO
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.Xr ega 4 ,
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.Xr pcdisplay 4 ,
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.Xr tty 4 ,
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.Xr vga 4 ,
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.Xr wscons 4 ,
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.Xr wsconscfg 8 ,
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.Xr wsconsctl 8 ,
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.Xr wsfontload 8
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.Sh BUGS
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The
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.Nm
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code currently limits the number of screens on one display to 8.
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.Pp
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The terms
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.Dq wscons
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and
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.Dq wsdisplay
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are not cleanly distinguished in the code and in manual pages.
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.Pp
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.Dq non-emulating
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display devices are not tested.
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