Use netdev_rx_err() to report receive errors.

src/drivers/net/pnic.c

 			break;
 		iobuf = alloc_iob ( ETH_FRAME_LEN );
 		if ( ! iobuf ) {
-			printf ( "could not allocate buffer\n" );
+			DBG ( "could not allocate buffer\n" );
+			netdev_rx_err ( netdev, NULL, -ENOMEM );
 			break;
 		}
 		if ( pnic_command ( pnic, PNIC_CMD_RECV, NULL, 0,
 				    iobuf->data, ETH_FRAME_LEN, &length )
 		     != PNIC_STATUS_OK ) {
-			free_iob ( iobuf );
+			netdev_rx_err ( netdev, iobuf, -EIO );
 			break;
 		}
 		iob_put ( iobuf, length );

src/drivers/net/rtl8139.c

 
 			rx_iob = alloc_iob ( rx_len );
 			if ( ! rx_iob ) {
+				netdev_rx_err ( netdev, NULL, -ENOMEM );
 				/* Leave packet for next call to poll() */
 				break;
 			}
 		} else {
 			DBG ( "RX bad packet (status %#04x len %d)\n",
 			      rx_status, rx_len );
+			netdev_rx_err ( netdev, NULL, -EINVAL );
 		}
 		rtl->rx.offset = ( ( ( rtl->rx.offset + 4 + rx_len + 3 ) & ~3 )
 				   % RX_BUF_LEN );