X300: Dual channel TX performance improvements

6 files changed, 157 insertions, 118 deletions

diff --git a/host/lib/rfnoc/legacy_compat.cpp b/host/lib/rfnoc/legacy_compat.cpp
index 7acaa898c..bf653a89a 100644
--- a/host/lib/rfnoc/legacy_compat.cpp
+++ b/host/lib/rfnoc/legacy_compat.cpp
@@ -45,6 +45,7 @@ using uhd::stream_cmd_t;
  ***********************************************************************/
 static const std::string RADIO_BLOCK_NAME = "Radio";
 static const std::string DFIFO_BLOCK_NAME = "DmaFIFO";
+static const std::string SFIFO_BLOCK_NAME = "FIFO";
 static const std::string DDC_BLOCK_NAME = "DDC";
 static const std::string DUC_BLOCK_NAME = "DUC";
 static const size_t MAX_BYTES_PER_HEADER =
@@ -131,6 +132,7 @@ public:
         _has_ducs(not args.has_key("skip_duc") and not device->find_blocks(DUC_BLOCK_NAME).empty()),
         _has_ddcs(not args.has_key("skip_ddc") and not device->find_blocks(DDC_BLOCK_NAME).empty()),
         _has_dmafifo(not args.has_key("skip_dram") and not device->find_blocks(DFIFO_BLOCK_NAME).empty()),
+        _has_sramfifo(not args.has_key("skip_sram") and not device->find_blocks(SFIFO_BLOCK_NAME).empty()),
         _num_mboards(_tree->list("/mboards").size()),
         _num_radios_per_board(device->find_blocks<radio_ctrl>("0/Radio").size()), // These might throw, maybe we catch that and provide a nicer error message.
         _num_tx_chans_per_radio(
@@ -165,8 +167,12 @@ public:
         }
         if (args.has_key("skip_dram")) {
             UHD_LEGACY_LOG() << "[legacy_compat] Skipping DRAM by user request." << std::endl;
-        } else if (not _has_dmafifo) {
-            UHD_MSG(warning) << "[legacy_compat] No DMA FIFO detected. You will only be able to transmit at slow rates." << std::endl;
+        }
+        if (args.has_key("skip_sram")) {
+            UHD_LEGACY_LOG() << "[legacy_compat] Skipping SRAM by user request." << std::endl;
+        }
+        if (not _has_dmafifo and not _has_sramfifo) {
+            UHD_MSG(warning) << "[legacy_compat] No FIFO detected. Higher transmit rates may encounter errors." << std::endl;
         }
 
         for (size_t mboard = 0; mboard < _num_mboards; mboard++) {
@@ -522,7 +528,9 @@ private: // methods
             size_t &port_index
     ) {
         if (dir == uhd::TX_DIRECTION) {
-            if (_has_dmafifo) {
+            if (_has_sramfifo) {
+                return block_id_t(mboard_idx, SFIFO_BLOCK_NAME, radio_index).to_string();
+            } else if (_has_dmafifo) {
                 port_index = radio_index;
                 return block_id_t(mboard_idx, DFIFO_BLOCK_NAME, 0).to_string();
             } else {
@@ -736,7 +744,15 @@ private: // methods
                             block_id_t(mboard, RADIO_BLOCK_NAME, radio), chan,
                             tx_bpp
                         );
-                        if (_has_dmafifo) {
+                        // Prioritize SRAM over DRAM for performance
+                        if (_has_sramfifo) {
+                            // We have SRAM FIFO *and* DUCs
+                            _graph->connect(
+                                block_id_t(mboard, SFIFO_BLOCK_NAME, radio), chan,
+                                block_id_t(mboard, DUC_BLOCK_NAME, radio), chan,
+                                tx_bpp
+                            );
+                        } else if (_has_dmafifo) {
                             // We have DMA FIFO *and* DUCs
                             _graph->connect(
                                 block_id_t(mboard, DFIFO_BLOCK_NAME, 0), radio,
@@ -744,6 +760,13 @@ private: // methods
                                 tx_bpp
                             );
                         }
+                    } else if (_has_sramfifo) {
+                            // We have SRAM FIFO, *no* DUCs
+                            _graph->connect(
+                                block_id_t(mboard, SFIFO_BLOCK_NAME, radio), radio,
+                                block_id_t(mboard, RADIO_BLOCK_NAME, radio), chan,
+                                tx_bpp
+                            );
                     } else if (_has_dmafifo) {
                             // We have DMA FIFO, *no* DUCs
                             _graph->connect(
@@ -843,6 +866,7 @@ private: // attributes
     const bool _has_ducs;
     const bool _has_ddcs;
     const bool _has_dmafifo;
+    const bool _has_sramfifo;
     const size_t _num_mboards;
     const size_t _num_radios_per_board;
     const size_t _num_tx_chans_per_radio;
diff --git a/host/lib/usrp/common/async_packet_handler.hpp b/host/lib/usrp/common/async_packet_handler.hpp
index 20409c77a..4b162677b 100644
--- a/host/lib/usrp/common/async_packet_handler.hpp
+++ b/host/lib/usrp/common/async_packet_handler.hpp
@@ -40,7 +40,11 @@ namespace uhd{ namespace usrp{
         //load into metadata
         metadata.channel = channel;
         metadata.has_time_spec = if_packet_info.has_tsf;
-        metadata.time_spec = time_spec_t::from_ticks(if_packet_info.tsf, tick_rate);
+        if (tick_rate == 0.0) {
+            metadata.time_spec = 0.0;
+        } else {
+            metadata.time_spec = time_spec_t::from_ticks(if_packet_info.tsf, tick_rate);
+        }
         metadata.event_code = async_metadata_t::event_code_t(to_host(payload[0]) & 0xff);
 
         //load user payload
diff --git a/host/lib/usrp/device3/device3_impl.hpp b/host/lib/usrp/device3/device3_impl.hpp
index 117e4af1c..22c93f25f 100644
--- a/host/lib/usrp/device3/device3_impl.hpp
+++ b/host/lib/usrp/device3/device3_impl.hpp
@@ -57,7 +57,8 @@ public:
     enum xport_type_t {
         CTRL = 0,
         TX_DATA,
-        RX_DATA
+        RX_DATA,
+        ASYNC_TX_MSG
     };
 
     enum xport_t {AXI, ETH, PCIE};
diff --git a/host/lib/usrp/device3/device3_io_impl.cpp b/host/lib/usrp/device3/device3_io_impl.cpp
index 199cb2786..dc4aacff8 100644
--- a/host/lib/usrp/device3/device3_io_impl.cpp
+++ b/host/lib/usrp/device3/device3_io_impl.cpp
@@ -298,23 +298,17 @@ static void handle_rx_flowctrl(
 /***********************************************************************
  * TX Flow Control Functions
  **********************************************************************/
+#define DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL 0
+
 //! Stores the state of TX flow control
 struct tx_fc_cache_t
 {
-    tx_fc_cache_t(void):
-        stream_channel(0),
-        device_channel(0),
-        last_seq_out(0),
+    tx_fc_cache_t(size_t capacity):
         last_seq_ack(0),
-        last_seq_ack_cache(0) {}
+        space(capacity) {}
 
-    size_t stream_channel;
-    size_t device_channel;
-    size_t last_seq_out;
-    boost::atomic_size_t last_seq_ack;
-    size_t last_seq_ack_cache;
-    boost::shared_ptr<device3_impl::async_md_type> async_queue;
-    boost::shared_ptr<device3_impl::async_md_type> old_async_queue;
+    size_t last_seq_ack;
+    size_t space;
 };
 
 /*! Return the size of the flow control window in packets.
@@ -340,79 +334,74 @@ static size_t get_tx_flow_control_window(
     return window_in_pkts;
 }
 
-// TODO: Remove this function
-// This function only exists to make sure the transport is not destroyed
-// until it is no longer needed.
-static managed_send_buffer::sptr get_tx_buff(
-    zero_copy_if::sptr xport,
-    const double timeout
-){
-    return xport->get_send_buff(timeout);
-}
-
 static bool tx_flow_ctrl(
-    task::sptr /*holds ref*/,
     boost::shared_ptr<tx_fc_cache_t> fc_cache,
-    size_t fc_window,
+	zero_copy_if::sptr async_xport,
+    uint32_t (*endian_conv)(uint32_t),
+    void (*unpack)(const uint32_t *packet_buff, vrt::if_packet_info_t &),
     managed_buffer::sptr
 ) {
-    bool refresh_cache = false;
-
-    // Busy loop waiting for flow control update.  This is necessary because
-    // at this point there is data trying to be sent and it must be sent as
-    // quickly as possible when the flow control update arrives to avoid
-    // underruns at high rates.  This is also OK because it only occurs when
-    // data needs to be sent and flow control is holding it back.
     while (true)
     {
-        if (refresh_cache)
-        {
-            // update the cached value from the atomic
-            fc_cache->last_seq_ack_cache = fc_cache->last_seq_ack;
-        }
-
-        // delta is the amount of FC credit we've used up
-        const size_t delta = (fc_cache->last_seq_out & HW_SEQ_NUM_MASK) -
-            (fc_cache->last_seq_ack_cache & HW_SEQ_NUM_MASK);
-        // If we want to send another packet, we must have FC credit left
-        if ((delta & HW_SEQ_NUM_MASK) < fc_window)
+        // If there is space
+        if (fc_cache->space)
         {
-            // Packet will be sent
-            fc_cache->last_seq_out++; //update seq
+            // All is good - packet will be sent
+            fc_cache->space--;
             return true;
         }
-        else
-        {
-            if (refresh_cache)
-            {
-                // We have already refreshed the cache and still
-                // lack flow control permission to send new data.
-
-                // A true busy loop choked out the message handler
-                // thread on machines with processor limitations
-                // (too few cores).  Yield to allow flow control
-                // receiver thread to operate.
-                boost::this_thread::yield();
-            }
-            else
-            {
-                // Allow the cache to refresh and try again to
-                // see if the device has granted flow control permission.
-                refresh_cache = true;
-            }
-        }
+
+		// Look for a flow control message to update the space available in the buffer.
+        // A minimal timeout is used because larger timeouts can cause the thread to be
+        // scheduled out for too long at high data rates and result in underruns.
+		managed_recv_buffer::sptr buff = async_xport->get_recv_buff(0.000001);
+		if (buff)
+		{
+			vrt::if_packet_info_t if_packet_info;
+			if_packet_info.num_packet_words32 = buff->size()/sizeof(uint32_t);
+			const uint32_t *packet_buff = buff->cast<const uint32_t *>();
+			try {
+				unpack(packet_buff, if_packet_info);
+			}
+			catch(const std::exception &ex)
+			{
+				UHD_MSG(error) << "Error unpacking async flow control packet: " << ex.what() << std::endl;
+				continue;
+			}
+
+			if (if_packet_info.packet_type != vrt::if_packet_info_t::PACKET_TYPE_FC)
+			{
+				UHD_MSG(error) << "Unexpected packet type received by flow control handler: " << if_packet_info.packet_type << std::endl;
+				continue;
+			}
+
+			// update the amount of space
+			size_t seq_ack = endian_conv(packet_buff[if_packet_info.num_header_words32+1]);
+			fc_cache->space += (seq_ack - fc_cache->last_seq_ack) & HW_SEQ_NUM_MASK;
+			fc_cache->last_seq_ack = seq_ack;
+		}
     }
     return false;
 }
 
-#define DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL 0
-/*! Handle incoming messages. If they're flow control, update the TX FC cache.
- * Otherwise, send them to the async message queue for the user to poll.
+/***********************************************************************
+ * TX Async Message Functions
+ **********************************************************************/
+struct async_tx_info_t
+{
+    size_t stream_channel;
+    size_t device_channel;
+    boost::shared_ptr<device3_impl::async_md_type> async_queue;
+    boost::shared_ptr<device3_impl::async_md_type> old_async_queue;
+};
+
+/*! Handle incoming messages.
+ *  Send them to the async message queue for the user to poll.
  *
  * This is run inside a uhd::task as long as this streamer lives.
  */
 static void handle_tx_async_msgs(
-        boost::shared_ptr<tx_fc_cache_t> fc_cache,
+        boost::shared_ptr<async_tx_info_t> async_info,
         zero_copy_if::sptr xport,
         endianness_t endianness,
         boost::function<double(void)> get_tick_rate
@@ -462,31 +451,21 @@ static void handle_tx_async_msgs(
             if_packet_info,
             packet_buff,
             tick_rate,
-            fc_cache->stream_channel
+            async_info->stream_channel
     );
 
-    // TODO: Shouldn't we be polling if_packet_info.packet_type == PACKET_TYPE_FC?
-    //       Thing is, on X300, packet_type == 0, so that wouldn't work. But it seems it should.
-    //The FC response and the burst ack are two indicators that the radio
-    //consumed packets. Use them to update the FC metadata
-    if (metadata.event_code == DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL) {
-        fc_cache->last_seq_ack = metadata.user_payload[0];
-    }
-
-    //FC responses don't propagate up to the user so filter them here
-    if (metadata.event_code != DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL) {
-        fc_cache->async_queue->push_with_pop_on_full(metadata);
-        metadata.channel = fc_cache->device_channel;
-        fc_cache->old_async_queue->push_with_pop_on_full(metadata);
+	// Filter out any flow control messages and cache the rest
+    if (metadata.event_code == DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL)
+    {
+        UHD_MSG(error) << "Unexpected flow control message found in async message handling" << std::endl;
+    } else {
+        async_info->async_queue->push_with_pop_on_full(metadata);
+        metadata.channel = async_info->device_channel;
+        async_info->old_async_queue->push_with_pop_on_full(metadata);
         standard_async_msg_prints(metadata);
     }
 }
 
-
-
-/***********************************************************************
- * Async Data
- **********************************************************************/
 bool device3_impl::recv_async_msg(
     async_metadata_t &async_metadata, double timeout
 )
@@ -726,6 +705,20 @@ void device3_impl::update_tx_streamers(double /* rate */)
     }
 }
 
+// This class manages the lifetime of the TX async message handler task and transports
+class device3_send_packet_streamer : public sph::send_packet_streamer
+{
+public:
+	device3_send_packet_streamer(const size_t max_num_samps) : sph::send_packet_streamer(max_num_samps) {};
+	~device3_send_packet_streamer() {
+		_tx_async_msg_task.reset();	// Make sure the async task is destroyed before the transports
+	};
+
+	both_xports_t _xport;
+	both_xports_t _async_xport;
+	task::sptr _tx_async_msg_task;
+};
+
 tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
 {
     boost::mutex::scoped_lock lock(_transport_setup_mutex);
@@ -741,7 +734,7 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
     boost::shared_ptr<async_md_type> async_md(new async_md_type(1000/*messages deep*/));
 
     // II. Iterate over all channels
-    boost::shared_ptr<sph::send_packet_streamer> my_streamer;
+    boost::shared_ptr<device3_send_packet_streamer> my_streamer;
     // The terminator's lifetime is coupled to the streamer.
     // There is only one terminator. If the streamer has multiple channels,
     // it will be connected to each downstream block.
@@ -753,6 +746,7 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
         args.args = chan_args[stream_i];
         size_t mb_index = block_id.get_device_no();
         size_t suggested_block_port = args.args.cast<size_t>("block_port", rfnoc::ANY_PORT);
+        uhd::endianness_t endianness = get_transport_endianness(mb_index);
 
         // Access to this channel's block control
         uhd::rfnoc::sink_block_ctrl_base::sptr blk_ctrl =
@@ -779,6 +773,7 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
         uhd::sid_t stream_address = blk_ctrl->get_address(block_port);
         UHD_STREAMER_LOG() << "[TX Streamer] creating tx stream " << tx_hints.to_string() << std::endl;
         both_xports_t xport = make_transport(stream_address, TX_DATA, tx_hints);
+		both_xports_t async_xport = make_transport(stream_address, ASYNC_TX_MSG, device_addr_t(""));
         UHD_STREAMER_LOG() << std::hex << "[TX Streamer] data_sid = " << xport.send_sid << std::dec << std::endl;
 
         // To calculate the max number of samples per packet, we assume the maximum header length
@@ -790,8 +785,10 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
 
         //make the new streamer given the samples per packet
         if (not my_streamer)
-            my_streamer = boost::make_shared<sph::send_packet_streamer>(spp);
+            my_streamer = boost::make_shared<device3_send_packet_streamer>(spp);
         my_streamer->resize(chan_list.size());
+        my_streamer->_xport = xport;
+        my_streamer->_async_xport = async_xport;
 
         //init some streamer stuff
         std::string conv_endianness;
@@ -827,29 +824,30 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
                 block_port
         );
 
-        boost::shared_ptr<tx_fc_cache_t> fc_cache(new tx_fc_cache_t());
-        fc_cache->stream_channel = stream_i;
-        fc_cache->device_channel = mb_index;
-        fc_cache->async_queue = async_md;
-        fc_cache->old_async_queue = _async_md;
+        boost::shared_ptr<async_tx_info_t> async_tx_info(new async_tx_info_t());
+        async_tx_info->stream_channel = args.channels[stream_i];
+        async_tx_info->device_channel = mb_index;
+        async_tx_info->async_queue = async_md;
+        async_tx_info->old_async_queue = _async_md;
 
         boost::function<double(void)> tick_rate_retriever = boost::bind(
                 &rfnoc::tick_node_ctrl::get_tick_rate,
                 send_terminator,
                 std::set< rfnoc::node_ctrl_base::sptr >() // Need to specify default args with bind
         );
-        task::sptr task = task::make(
+
+        my_streamer->_tx_async_msg_task = task::make(
                 boost::bind(
                     &handle_tx_async_msgs,
-                    fc_cache,
-                    xport.recv,
-                    get_transport_endianness(mb_index),
+                    async_tx_info,
+                    my_streamer->_async_xport.recv,
+                    endianness,
                     tick_rate_retriever
                 )
         );
 
         blk_ctrl->sr_write(uhd::rfnoc::SR_CLEAR_RX_FC, 0xc1ea12, block_port);
-        blk_ctrl->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, xport.recv_sid.get_dst(), block_port);
+        blk_ctrl->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, my_streamer->_async_xport.recv_sid.get_dst(), block_port);
         UHD_STREAMER_LOG() << "[TX Streamer] resp_in_dst_sid == " << boost::format("0x%04X") % xport.recv_sid.get_dst() << std::endl;
 
         // FIXME: Once there is a better way to map the radio block and port
@@ -864,7 +862,7 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
             UHD_STREAMER_LOG() << "[TX Streamer] Number of downstream radio nodes: " << downstream_radio_nodes.size() << std::endl;
             BOOST_FOREACH(const boost::shared_ptr<uhd::rfnoc::radio_ctrl> &node, downstream_radio_nodes) {
                 if (node->get_block_id() == radio_id) {
-                    node->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, xport.send_sid.get_src(), radio_port);
+                    node->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, my_streamer->_async_xport.recv_sid.get_dst(), radio_port);
                 }
             }
         } else {
@@ -877,23 +875,27 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
             std::vector<boost::shared_ptr<uhd::rfnoc::radio_ctrl> > downstream_radio_nodes = blk_ctrl->find_downstream_node<uhd::rfnoc::radio_ctrl>();
             UHD_STREAMER_LOG() << "[TX Streamer] Number of downstream radio nodes: " << downstream_radio_nodes.size() << std::endl;
             BOOST_FOREACH(const boost::shared_ptr<uhd::rfnoc::radio_ctrl> &node, downstream_radio_nodes) {
-                node->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, xport.send_sid.get_src(), block_port);
+                node->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, my_streamer->_async_xport.recv_sid.get_dst(), block_port);
             }
         }
 
         // Add flow control
-        xport.send = zero_copy_flow_ctrl::make(
-            xport.send,
-            boost::bind(&tx_flow_ctrl, task, fc_cache, fc_window, _1),
+        boost::shared_ptr<tx_fc_cache_t> fc_cache(new tx_fc_cache_t(fc_window));
+        my_streamer->_xport.send = zero_copy_flow_ctrl::make(
+            my_streamer->_xport.send,
+            boost::bind(
+				&tx_flow_ctrl,
+				fc_cache,
+				my_streamer->_xport.recv,
+				(endianness == ENDIANNESS_BIG ? uhd::ntohx<uint32_t> : uhd::wtohx<uint32_t>),
+				(endianness == ENDIANNESS_BIG ? vrt::chdr::if_hdr_unpack_be : vrt::chdr::if_hdr_unpack_le),
+				 _1),
             NULL);
 
         //Give the streamer a functor to get the send buffer
-        //get_tx_buff is static so bind has no lifetime issues
-        //xport.send (sptr) is required to add streamer->data-transport lifetime dependency
-        //task (sptr) is required to add  a streamer->async-handler lifetime dependency
         my_streamer->set_xport_chan_get_buff(
             stream_i,
-            boost::bind(&get_tx_buff, xport.send, _1)
+            boost::bind(&zero_copy_if::get_send_buff, my_streamer->_xport.send, _1)
         );
         //Give the streamer a functor handled received async messages
         my_streamer->set_async_receiver(
diff --git a/host/lib/usrp/x300/x300_impl.cpp b/host/lib/usrp/x300/x300_impl.cpp
index 4f3870357..934e2eaa5 100644
--- a/host/lib/usrp/x300/x300_impl.cpp
+++ b/host/lib/usrp/x300/x300_impl.cpp
@@ -511,6 +511,8 @@ void x300_impl::setup_mb(const size_t mb_i, const uhd::device_addr_t &dev_addr)
     eth_addrs.push_back(eth0_addr);
 
     mb.next_src_addr = 0;   //Host source address for blocks
+    mb.next_tx_src_addr = 0;
+    mb.next_rx_src_addr = 0;
     if (dev_addr.has_key("second_addr")) {
         std::string eth1_addr = dev_addr["second_addr"];
 
@@ -1136,12 +1138,16 @@ uhd::both_xports_t x300_impl::make_transport(
 
     } else if (mb.xport_path == "eth") {
         // Decide on the IP/Interface pair based on the endpoint index
-        std::string interface_addr = mb.eth_conns[mb.next_src_addr].addr;
+        size_t &next_src_addr =
+            xport_type == TX_DATA ? mb.next_tx_src_addr :
+            xport_type == RX_DATA ? mb.next_rx_src_addr :
+            mb.next_src_addr;
+        std::string interface_addr = mb.eth_conns[next_src_addr].addr;
         const uint32_t xbar_src_addr =
-            mb.next_src_addr==0 ? X300_SRC_ADDR0 : X300_SRC_ADDR1;
+            next_src_addr==0 ? X300_SRC_ADDR0 : X300_SRC_ADDR1;
         const uint32_t xbar_src_dst =
-            mb.eth_conns[mb.next_src_addr].type==X300_IFACE_ETH0 ? X300_XB_DST_E0 : X300_XB_DST_E1;
-        mb.next_src_addr = (mb.next_src_addr + 1) % mb.eth_conns.size();
+            mb.eth_conns[next_src_addr].type==X300_IFACE_ETH0 ? X300_XB_DST_E0 : X300_XB_DST_E1;
+        next_src_addr = (next_src_addr + 1) % mb.eth_conns.size();
 
         xports.send_sid = this->allocate_sid(mb, address, xbar_src_addr, xbar_src_dst);
         xports.recv_sid = xports.send_sid.reversed();
diff --git a/host/lib/usrp/x300/x300_impl.hpp b/host/lib/usrp/x300/x300_impl.hpp
index 14120bd1f..8f4f81156 100644
--- a/host/lib/usrp/x300/x300_impl.hpp
+++ b/host/lib/usrp/x300/x300_impl.hpp
@@ -162,6 +162,8 @@ private:
 
         std::vector<x300_eth_conn_t> eth_conns;
         size_t next_src_addr;
+        size_t next_tx_src_addr;
+        size_t next_rx_src_addr;
 
         // Discover the ethernet connections per motherboard
         void discover_eth(const uhd::usrp::mboard_eeprom_t mb_eeprom,