XBP_MEDIA_REQ_SUP
if (xenbus_printf(XBT_NULL, xsname, XBP_MEDIA_REQ_SUP, "%d", 1) != 0)
vdp->xdf_media_req_supported = xenbus_exists(oename, XBP_MEDIA_REQ_SUP);
if (XD_IS_CD(vdp) && !xenbus_exists(oename, XBP_MEDIA_REQ_SUP)) {