XENFB_DEPTH
var->xres <= info->fix.line_length / (XENFB_DEPTH / 8) &&
if (video[KPARAM_WIDTH] * video[KPARAM_HEIGHT] * XENFB_DEPTH / 8
fb_info->var.bits_per_pixel = XENFB_DEPTH;
fb_info->fix.line_length = fb_info->var.xres * XENFB_DEPTH / 8;
#define XENFB_DEFAULT_FB_LEN (XENFB_WIDTH * XENFB_HEIGHT * XENFB_DEPTH / 8)