xenfb_refresh
xenfb_refresh(info, 0, miny, fb_info->var.xres, maxy - miny + 1);
xenfb_refresh(xenfb_info, 0, 0, xenfb_info->page->width, xenfb_info->page->height);
xenfb_refresh(xenfb_info, x, y, width, height);
xenfb_refresh(info, INT_MAX, INT_MAX, -INT_MAX, -INT_MAX);