Data of a KGI display are:

• KGI display revision

kgi_u_t		revision;

• Vendor and Model strings

kgi_ascii_t	vendor[KGI_MAX_VENDOR_STRING];
kgi_ascii_t	model[KGI_MAX_VENDOR_STRING];

• Flags about special capabilities

kgi_u32_t	flags;

• Size of the private mode data

kgi_u_t		mode_size;

• Current mode

kgi_mode_t	*mode;

• The display id

kgi_u_t	id;

• non-console device attached

kgi_u_t	graphic;

• Previous display in linked list

struct kgi_display_s *prev;

• Device currently focused to the display

struct kgi_device_s		*focus;

The methods of a KGI display are:

kgi_display_refcount_fn		*IncRefcount;

kgi_display_refcount_fn		*DecRefcount;

kgi_display_check_mode_fn	*CheckMode;

kgi_display_set_mode_fn		*SetMode;

kgi_display_set_mode_fn		*UnsetMode;

kgi_display_command_fn		*Command;

A display must register itself to offer its services to the KgiDevice.

kgi_s_t kgi_register_display(

 /* Comment: the preinitialized display to register */
 kgi_display_t *dpy,

 /* Comment: the suggested id for the display */
 kgi_u_t id
);

A registration typically occur when loading a display module. The display must be initialized before registration: at least one KgiImage must be defined and the display resources must be described.

For example, for the FreeBSD native VESA display:

       dpy->revision = KGI_DISPLAY_REVISION;
snprintf(dpy->vendor, KGI_MAX_VENDOR_STRING, "KGI FreeBSD");
snprintf(dpy->model, KGI_MAX_VENDOR_STRING, "dpysw");

No specific flag and the display mode specific area is sizeof(vidsw_mode_t) long.

dpy->flags = 0;
dpy->mode_size = sizeof(vidsw_mode_t);

with (dpm is mandatory here IIRC):

typedef struct vidsw_mode_s {

	kgi_dot_port_mode_t dpm;

	video_info_t mode_info;
	video_info_t oldmode_info;

} vidsw_mode_t;

The display methods are then initialized with yet not device focused:

mode = &sc->mode;

dpy->mode = mode;
dpy->id = -1;
dpy->graphic = 0;
dpy->IncRefcount = dpysw_inc_refcount;
dpy->DecRefcount = dpysw_dec_refcount;

dpy->CheckMode = dpysw_check_mode;
dpy->SetMode = dpysw_set_mode;
dpy->UnsetMode = dpysw_unset_mode;
dpy->Command = dpysw_display_command;

dpy->focus = NULL;

mode->revision 		= KGI_MODE_REVISION;
mode->dev_mode 		= NULL;
mode->images 		= 1;
mode->img[0].out 	= NULL;
mode->img[0].flags 	= KGI_IF_TEXT16;
mode->img[0].virt.x 	= adp->va_info.vi_width;
mode->img[0].virt.y 	= adp->va_info.vi_height;
mode->img[0].size.x 	= adp->va_info.vi_width;
mode->img[0].size.y 	= adp->va_info.vi_height;
mode->img[0].frames 	= 1;
mode->img[0].tluts 	= 0;
mode->img[0].aluts 	= 0;
mode->img[0].ilutm 	= 0;
mode->img[0].alutm 	= 0;
mode->img[0].fam 	= 0;
mode->img[0].cam 	= 0;

The framebuffer resource is described that way:

fb->meta 		= dpy;
fb->type 		= KGI_RT_MMIO_FRAME_BUFFER;
fb->prot 		= KGI_PF_APP_RWS | KGI_PF_LIB_RWS | KGI_PF_DRV_RWS;
fb->name 		= "Frame buffer";
fb->access 		= 8 + 16 + 32 + 64;
fb->align 		= 8 + 16;
fb->win.size 		= (kgi_size_t)adp->va_window_size;
fb->win.virt 		= (kgi_virt_addr_t)adp->va_window;
fb->win.bus 		= (kgi_bus_addr_t)0;
fb->win.phys 		= (kgi_phys_addr_t)adp->va_mem_base;
fb->size 		= (kgi_size_t)adp->va_mem_size;
fb->offset 		= 0;
fb->SetOffset 		= dpysw_set_offset;

void    kgi_unregister_display(

 /* Comment: the display to unregister */
 kgi_display_t *dpy
);

kgi_display_registered shall be used to know if a display id is already bound to a registered display.

kgi_s_t kgi_display_registered(

 /* Comment: the display id */
 kgi_u_t id
);

Returns KGI_EOK if bound, KGI_ENODEV otherwise.