NetBSD/share/man/man9/vcons.9

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.\" $NetBSD: vcons.9,v 1.2 2006/02/13 19:57:58 wiz Exp $
.\"
.\" Copyright (c) 2006 Michael Lorenz
.\" All rights reserved.
.\"
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.Dd February 12, 2006
.Dt VCONS 9
.Os
.Sh NAME
.Nm vcons
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.Nd generic virtual console framework
.Sh SYNOPSIS
.In wscons/wsdisplay_vconsvar.h
.Ft int
.Fn vcons_init "struct vcons_data *vd" "void *cookie" \
"struct wsscreen_descr *desc" "struct wsdisplay_accessops *accops"
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.Ft int
.Fn vcons_init_screen "struct vcons_data *vd" "struct vcons_screen *scr" \
"int exists" "long *defattr"
.Ft void
.Fn vcons_redraw_screen "struct vcons_screen *scr"
.Sh DESCRIPTION
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These functions are used to setup and control the generic virtual
console framework.
.Pp
.\"
The
.Fn vcons_init
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function initializes the framework, it needs to be called for each
driver that's going to use
.Nm .
.Pp
.Fn vcons_init_screen
adds a virtual screen to a display.
.Pp
.Fn vcons_redraw_screen
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redraws a screen.
A driver should call it when returning to terminal emulation mode,
for instance when X exits.
.Pp
.\"
.Vt struct vcons_data
contains all information needed to manage virtual consoles on a display,
usually it will be a member of the driver's softc.
.Pp
.Vt struct vcons_screen
describes a virtual screen.
.Sh USAGE
.\"
To use vcons with a driver it needs to be initialized by calling
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.Fn vcons_init ,
usually in the driver's attach function.
.Bl -tag -width cookieXX
.It Fa vd
should be a pointer to the driver's
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.Vt struct vcons_data .
.It Fa cookie
should be a pointer to the driver's softc.
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.It Fa desc
should point to a
.Vt struct wsscreen_descr
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describing the default screen type for this display.
.It Fa accops
points to the driver's
.Vt struct wsdisplay_accessops
so
.Fn vcons_init
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can fill it in with its own implementations of
.Fn alloc_screen ,
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.Fn free_screen ,
and
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.Fn show_screen .
.El
.Pp
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A driver should however provide its own
.Fn ioctl
and
.Fn mmap
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implementations.
Both will receive a pointer to the driver's
.Vt struct vcons_data
as first parameter.
.Pp
After initialization the driver needs to provide a callback function that
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will be called whenever a screen is added.
Its purpose is to set up the
.Vt struct rasops_info
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describing the screen.
After that the drawing methods in
.Vt struct rasops_info
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will be replaced with wrappers which call the original drawing functions
(which may or may not be provided by the driver) only when the respective
screen is visible.
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To add a virtual screen the driver one should call
.Fn vcons_init_screen
which will call the callback function described above, allocate storage for
characters and attributes based on whatever the callback set up in
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.Vt struct rasops_info ,
and add the screen to a list kept in
.Vt struct vcons_data .
.Pp
The callback needs to have this form:
.Pp
.Ft void
.Fn init_screen "void *cookie" "struct vcons_screen *scr" "int existing" \
"long *defattr"
.Pp
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and should be stored in the
.Va init_screen
member found in
.Vt struct vcons_data .
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The arguments are:
.Bl -tag -width cookieXX
.It Fa cookie
is the cookie passed to
.Fn vcons_init
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.It Fa scr
points to the
.Vt struct vcons_screen
being added, its
.Va scr_ri
member, a
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.Vt struct rasops_info ,
needs to be filled in.
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.It Fa existing
is non-zero if the screen already exists and is only added to the list.
.It Fa defattr
points to the screen's default text attribute.
It's filled in by
.Fn vcons_init_screen
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by calling the
.Fn alloc_attr
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method found in
.Vt struct rasops_info .
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.El
.Pp
When attaching a
.Xr wsdisplay 9
the
.Va accesscookie
member of the
.Vt struct wsemuldisplaydev_attach_args
passed to
.Fn config_found
needs to be a pointer to the driver's
.Vt struct vcons_data .
.Pp
The following members of
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.Vt struct vcons_screen
may be of interest to drivers:
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.Bl -tag -width scr_cookieXX
.It Va scr_ri
contains the
.Vt struct rasops_info
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describing the screen's geometry, access methods and so on.
.It Va scr_cookie
the value passed as cookie to
.Fn vcons_init .
Usually the driver's softc.
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.It Va scr_vd
the driver's
.Vt struct vcons_data .
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.It Va scr_flags
can be zero or any combination of:
.Bl -tag -width XXXXXXXXXXXXXXXXXXXXXX -compact
.It Dv VCONS_NO_REDRAW
don't call
.Fn vcons_redraw_screen
when this screen becomes visible.
.It Dv VCONS_SCREEN_IS_STATIC
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don't
.Xr free 9
this screen's
.Vt struct vcons_screen
in
.Fn free_screen
- useful if the screen has been statically allocated.
.El
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.It Va scr_status
currently contains only one flag,
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.Dv VCONS_IS_VISIBLE ,
which is set when the screen is visible.
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.El
.Sh SEE ALSO
.Xr wscons 4 ,
.Xr wsdisplay 4