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VCONS(9)                   Kernel Developer's Manual                  VCONS(9)

     vcons - generic virtual console framework

     #include <wscons/wsdisplay_vconsvar.h>

     vcons_init(struct vcons_data *vd, void *cookie,
         struct wsscreen_descr *desc, struct wsdisplay_accessops *accops);

     vcons_init_screen(struct vcons_data *vd, struct vcons_screen *scr,
         int exists, long *defattr);

     vcons_redraw_screen(struct vcons_screen *scr);

     These functions are used to setup and control the generic virtual console

     The vcons_init() function initializes the framework, it needs to be
     called for each driver that's going to use vcons.

     vcons_init_screen() adds a virtual screen to a display.

     vcons_redraw_screen() redraws a screen.  A driver should call it when
     returning to terminal emulation mode, for instance when X exits.

     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.

     struct vcons_screen describes a virtual screen.

     To use vcons with a driver it needs to be initialized by calling
     vcons_init(), usually in the driver's attach function.

     vd        should be a pointer to the driver's struct vcons_data.

     cookie    should be a pointer to the driver's softc.

     desc      should point to a struct wsscreen_descr describing the default
               screen type for this display.

     accops    points to the driver's struct wsdisplay_accessops so
               vcons_init() can fill it in with its own implementations of
               alloc_screen(), free_screen(), and show_screen().

     A driver should however provide its own ioctl() and mmap()
     implementations.  Both will receive a pointer to the driver's struct
     vcons_data as first parameter.

     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
     struct rasops_info describing the screen.  After that the drawing methods
     in 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 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 struct rasops_info,
     and add the screen to a list kept in struct vcons_data.

     The callback needs to have this form:

     void init_screen(void *cookie, struct vcons_screen *scr, int existing,
     long *defattr)

     and should be stored in the init_screen member found in struct
     vcons_data.  The arguments are:

     cookie    is the cookie passed to vcons_init()

     scr       points to the struct vcons_screen being added, its scr_ri
               member, a struct rasops_info, needs to be filled in.

     existing  is non-zero if the screen already exists and is only added to
               the list.

     defattr   points to the screen's default text attribute.  It's filled in
               by vcons_init_screen() by calling the alloc_attr() method found
               in struct rasops_info.

     When attaching a wsdisplay(9) the accesscookie member of the struct
     wsemuldisplaydev_attach_args passed to config_found() needs to be a
     pointer to the driver's struct vcons_data.

     The following members of struct vcons_screen may be of interest to

     scr_ri        contains the struct rasops_info describing the screen's
                   geometry, access methods and so on.

     scr_cookie    the value passed as cookie to vcons_init().  Usually the
                   driver's softc.

     scr_vd        the driver's struct vcons_data.

     scr_flags     can be zero or any combination of:
                   VCONS_NO_REDRAW         don't call vcons_redraw_screen()
                                           when this screen becomes visible.
                   VCONS_SCREEN_IS_STATIC  don't free(9) this screen's struct
                                           vcons_screen in free_screen() -
                                           useful if the screen has been
                                           statically allocated.

     scr_status    currently contains only one flag, VCONS_IS_VISIBLE, which
                   is set when the screen is visible.

     wscons(4), wsdisplay(4)

NetBSD 9.99                    February 12, 2006                   NetBSD 9.99