--- linux-2.4.22.org/drivers/isdn/hisax/avm_pci.c       2002-11-29 00:53:13.000000000 +0100
+++ linux-2.4.22/drivers/isdn/hisax/avm_pci.c   2003-11-10 10:37:18.000000000 +0100
@@ -448,6 +448,7 @@
                /* Here we lost an TX interrupt, so
                 * restart transmitting the whole frame.
                 */
+               printk(KERN_WARNING "avm fritz XDU %p %lx\n", bcs->tx_skb, bcs->Flag);
                if (bcs->tx_skb) {
                        skb_push(bcs->tx_skb, bcs->hw.hdlc.count);
                        bcs->tx_cnt += bcs->hw.hdlc.count;