.\" $NetBSD: vcons.9,v 1.2 2006/02/13 19:57:58 wiz Exp $
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.\" Copyright (c) 2006 Michael Lorenz
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.Dd February 12, 2006
.Dt VCONS 9
.Os
.Sh NAME
.Nm vcons
.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"
.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
These functions are used to setup and control the generic virtual
console framework.
.Pp
.\"
The
.Fn vcons_init
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
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
.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
.Vt struct vcons_data .
.It Fa cookie
should be a pointer to the driver's softc.
.It Fa desc
should point to a
.Vt struct wsscreen_descr
describing the default screen type for this display.
.It Fa accops
points to the driver's
.Vt struct wsdisplay_accessops
so
.Fn vcons_init
can fill it in with its own implementations of
.Fn alloc_screen ,
.Fn free_screen ,
and
.Fn show_screen .
.El
.Pp
A driver should however provide its own
.Fn ioctl
and
.Fn mmap
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
will be called whenever a screen is added.
Its purpose is to set up the
.Vt struct rasops_info
describing the screen.
After that the drawing methods in
.Vt struct rasops_info
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.
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
.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
and should be stored in the
.Va init_screen
member found in
.Vt struct vcons_data .
The arguments are:
.Bl -tag -width cookieXX
.It Fa cookie
is the cookie passed to
.Fn vcons_init
.It Fa scr
points to the
.Vt struct vcons_screen
being added, its
.Va scr_ri
member, a
.Vt struct rasops_info ,
needs to be filled in.
.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
by calling the
.Fn alloc_attr
method found in
.Vt struct rasops_info .
.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
.Vt struct vcons_screen
may be of interest to drivers:
.Bl -tag -width scr_cookieXX
.It Va scr_ri
contains the
.Vt struct rasops_info
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.
.It Va scr_vd
the driver's
.Vt struct vcons_data .
.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
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
.It Va scr_status
currently contains only one flag,
.Dv VCONS_IS_VISIBLE ,
which is set when the screen is visible.
.El
.Sh SEE ALSO
.Xr wscons 4 ,
.Xr wsdisplay 4