Merge branch 'master' of ettus.sourcerepo.com:ettus/uhdpriv into usrp_e

Conflicts:
	host/examples/rx_timed_samples.cpp

20 files changed, 1277 insertions, 582 deletions

diff --git a/host/lib/transport/CMakeLists.txt b/host/lib/transport/CMakeLists.txt
index 872865d6c..bde2b72b9 100644
--- a/host/lib/transport/CMakeLists.txt
+++ b/host/lib/transport/CMakeLists.txt
@@ -18,6 +18,16 @@
 #This file will be included by cmake, use absolute paths!
 
 ########################################################################
+# Check for SIMD headers
+########################################################################
+INCLUDE(CheckIncludeFileCXX)
+CHECK_INCLUDE_FILE_CXX(emmintrin.h HAVE_EMMINTRIN_H)
+
+IF(HAVE_EMMINTRIN_H)
+    ADD_DEFINITIONS(-DHAVE_EMMINTRIN_H)
+ENDIF(HAVE_EMMINTRIN_H)
+
+########################################################################
 # Setup defines for interface address discovery
 ########################################################################
 MESSAGE(STATUS "Configuring interface address discovery...")
@@ -40,8 +50,8 @@ ENDIF(HAVE_IFADDRS_H)
 # Append to the list of sources for lib uhd
 ########################################################################
 LIBUHD_PYTHON_GEN_SOURCE(
-    ${CMAKE_SOURCE_DIR}/lib/transport/gen_vrt.py
-    ${CMAKE_BINARY_DIR}/lib/transport/vrt.cpp
+    ${CMAKE_SOURCE_DIR}/lib/transport/gen_vrt_if_packet.py
+    ${CMAKE_BINARY_DIR}/lib/transport/vrt_if_packet.cpp
 )
 
 LIBUHD_PYTHON_GEN_SOURCE(
@@ -49,6 +59,16 @@ LIBUHD_PYTHON_GEN_SOURCE(
     ${CMAKE_BINARY_DIR}/lib/transport/convert_types.cpp
 )
 
+# append this directory to the include path so the generated convert types
+# can include the implementation convert types file in the source directory
+INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/lib/transport)
+
+# make the generated convert types depend on the implementation header
+SET_SOURCE_FILES_PROPERTIES(
+    ${CMAKE_BINARY_DIR}/lib/transport/convert_types.cpp PROPERTIES
+    OBJECT_DEPENDS ${CMAKE_SOURCE_DIR}/lib/transport/convert_types_impl.hpp
+)
+
 LIBUHD_APPEND_SOURCES(
     ${CMAKE_SOURCE_DIR}/lib/transport/if_addrs.cpp
     ${CMAKE_SOURCE_DIR}/lib/transport/udp_simple.cpp
diff --git a/host/lib/transport/convert_types_impl.hpp b/host/lib/transport/convert_types_impl.hpp
new file mode 100644
index 000000000..5958b08cb
--- /dev/null
+++ b/host/lib/transport/convert_types_impl.hpp
@@ -0,0 +1,201 @@
+//
+// Copyright 2010 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+#ifndef INCLUDED_LIBUHD_TRANSPORT_CONVERT_TYPES_IMPL_HPP
+#define INCLUDED_LIBUHD_TRANSPORT_CONVERT_TYPES_IMPL_HPP
+
+#include <uhd/config.hpp>
+#include <uhd/utils/byteswap.hpp>
+#include <boost/cstdint.hpp>
+#include <cstring>
+#include <complex>
+
+#ifdef HAVE_EMMINTRIN_H
+    #define USE_EMMINTRIN_H //use sse2 intrinsics
+#endif
+
+/***********************************************************************
+ * Typedefs
+ **********************************************************************/
+typedef std::complex<float>          fc32_t;
+typedef std::complex<boost::int16_t> sc16_t;
+typedef boost::uint32_t              item32_t;
+
+/***********************************************************************
+ * Convert complex short buffer to items32
+ **********************************************************************/
+static UHD_INLINE void sc16_to_item32_nswap(
+    const sc16_t *input, item32_t *output, size_t nsamps
+){
+    std::memcpy(output, input, nsamps*sizeof(item32_t));
+}
+
+static UHD_INLINE void sc16_to_item32_bswap(
+    const sc16_t *input, item32_t *output, size_t nsamps
+){
+    const item32_t *item32_input = (const item32_t *)input;
+    for (size_t i = 0; i < nsamps; i++){
+        output[i] = uhd::byteswap(item32_input[i]);
+    }
+}
+
+/***********************************************************************
+ * Convert items32 buffer to complex short
+ **********************************************************************/
+static UHD_INLINE void item32_to_sc16_nswap(
+    const item32_t *input, sc16_t *output, size_t nsamps
+){
+    std::memcpy(output, input, nsamps*sizeof(item32_t));
+}
+
+static UHD_INLINE void item32_to_sc16_bswap(
+    const item32_t *input, sc16_t *output, size_t nsamps
+){
+    item32_t *item32_output = (item32_t *)output;
+    for (size_t i = 0; i < nsamps; i++){
+        item32_output[i] = uhd::byteswap(input[i]);
+    }
+}
+
+/***********************************************************************
+ * Convert complex float buffer to items32
+ **********************************************************************/
+static const float shorts_per_float = float(32767);
+
+static UHD_INLINE item32_t fc32_to_item32(fc32_t num){
+    boost::uint16_t real = boost::int16_t(num.real()*shorts_per_float);
+    boost::uint16_t imag = boost::int16_t(num.imag()*shorts_per_float);
+    return (item32_t(real) << 16) | (item32_t(imag) << 0);
+}
+
+static UHD_INLINE void fc32_to_item32_nswap(
+    const fc32_t *input, item32_t *output, size_t nsamps
+){
+    for (size_t i = 0; i < nsamps; i++){
+        output[i] = fc32_to_item32(input[i]);
+    }
+}
+
+#if defined(USE_EMMINTRIN_H)
+#include <emmintrin.h>
+
+static UHD_INLINE void fc32_to_item32_bswap(
+    const fc32_t *input, item32_t *output, size_t nsamps
+){
+    __m128 scalar = _mm_set_ps1(shorts_per_float);
+
+    //convert blocks of samples with intrinsics
+    size_t i = 0; for (; i < (nsamps & ~0x3); i+=4){
+        //load from input
+        __m128 tmplo = _mm_loadu_ps(reinterpret_cast<const float *>(input+i+0));
+        __m128 tmphi = _mm_loadu_ps(reinterpret_cast<const float *>(input+i+2));
+
+        //convert and scale
+        __m128i tmpilo = _mm_cvtps_epi32(_mm_mul_ps(tmplo, scalar));
+        __m128i tmpihi = _mm_cvtps_epi32(_mm_mul_ps(tmphi, scalar));
+
+        //pack + byteswap -> byteswap 32 bit words
+        __m128i tmpi = _mm_packs_epi32(tmpilo, tmpihi);
+        tmpi = _mm_or_si128(_mm_srli_epi16(tmpi, 8), _mm_slli_epi16(tmpi, 8));
+
+        //store to output
+        _mm_storeu_si128(reinterpret_cast<__m128i *>(output+i), tmpi);
+    }
+
+    //convert remainder
+    for (; i < nsamps; i++){
+        output[i] = uhd::byteswap(fc32_to_item32(input[i]));
+    }
+}
+
+#else
+static UHD_INLINE void fc32_to_item32_bswap(
+    const fc32_t *input, item32_t *output, size_t nsamps
+){
+    for (size_t i = 0; i < nsamps; i++){
+        output[i] = uhd::byteswap(fc32_to_item32(input[i]));
+    }
+}
+
+#endif
+
+/***********************************************************************
+ * Convert items32 buffer to complex float
+ **********************************************************************/
+static const float floats_per_short = float(1.0/shorts_per_float);
+
+static UHD_INLINE fc32_t item32_to_fc32(item32_t item){
+    return fc32_t(
+        float(boost::int16_t(item >> 16)*floats_per_short),
+        float(boost::int16_t(item >> 0)*floats_per_short)
+    );
+}
+
+static UHD_INLINE void item32_to_fc32_nswap(
+    const item32_t *input, fc32_t *output, size_t nsamps
+){
+    for (size_t i = 0; i < nsamps; i++){
+        output[i] = item32_to_fc32(input[i]);
+    }
+}
+
+#if defined(USE_EMMINTRIN_H)
+#include <emmintrin.h>
+
+static UHD_INLINE void item32_to_fc32_bswap(
+    const item32_t *input, fc32_t *output, size_t nsamps
+){
+    __m128 scalar = _mm_set_ps1(floats_per_short/(1 << 16));
+    __m128i zeroi = _mm_setzero_si128();
+
+    //convert blocks of samples with intrinsics
+    size_t i = 0; for (; i < (nsamps & ~0x3); i+=4){
+        //load from input
+        __m128i tmpi = _mm_loadu_si128(reinterpret_cast<const __m128i *>(input+i));
+
+        //byteswap + unpack -> byteswap 32 bit words
+        tmpi = _mm_or_si128(_mm_srli_epi16(tmpi, 8), _mm_slli_epi16(tmpi, 8));
+        __m128i tmpilo = _mm_unpacklo_epi16(zeroi, tmpi); //value in upper 16 bits
+        __m128i tmpihi = _mm_unpackhi_epi16(zeroi, tmpi);
+
+        //convert and scale
+        __m128 tmplo = _mm_mul_ps(_mm_cvtepi32_ps(tmpilo), scalar);
+        __m128 tmphi = _mm_mul_ps(_mm_cvtepi32_ps(tmpihi), scalar);
+
+        //store to output
+        _mm_storeu_ps(reinterpret_cast<float *>(output+i+0), tmplo);
+        _mm_storeu_ps(reinterpret_cast<float *>(output+i+2), tmphi);
+    }
+
+    //convert remainder
+    for (; i < nsamps; i++){
+        output[i] = item32_to_fc32(uhd::byteswap(input[i]));
+    }
+}
+
+#else
+static UHD_INLINE void item32_to_fc32_bswap(
+    const item32_t *input, fc32_t *output, size_t nsamps
+){
+    for (size_t i = 0; i < nsamps; i++){
+        output[i] = item32_to_fc32(uhd::byteswap(input[i]));
+    }
+}
+
+#endif
+
+#endif /* INCLUDED_LIBUHD_TRANSPORT_CONVERT_TYPES_IMPL_HPP */
diff --git a/host/lib/transport/gen_convert_types.py b/host/lib/transport/gen_convert_types.py
index af2bcc7cb..951b634d9 100755
--- a/host/lib/transport/gen_convert_types.py
+++ b/host/lib/transport/gen_convert_types.py
@@ -24,66 +24,15 @@ TMPL_TEXT = """
 
 \#include <uhd/config.hpp>
 \#include <uhd/transport/convert_types.hpp>
-\#include <uhd/utils/byteswap.hpp>
 \#include <boost/cstdint.hpp>
 \#include <boost/detail/endian.hpp>
 \#include <stdexcept>
-\#include <complex>
-
-//define the endian macros to convert integers
-\#ifdef BOOST_BIG_ENDIAN
-    \#define BE_MACRO(x) x
-    \#define LE_MACRO(x) uhd::byteswap(x)
-    static const bool is_big_endian = true;
-\#else
-    \#define BE_MACRO(x) uhd::byteswap(x)
-    \#define LE_MACRO(x) x
-    static const bool is_big_endian = false;
-\#endif
+\#include "convert_types_impl.hpp"
 
 using namespace uhd;
 
 /***********************************************************************
- * Constants
- **********************************************************************/
-typedef std::complex<float>          fc32_t;
-typedef std::complex<boost::int16_t> sc16_t;
-typedef boost::uint32_t              item32_t;
-
-static const float shorts_per_float = float(32767);
-static const float floats_per_short = float(1.0/shorts_per_float);
-
-/***********************************************************************
- * Single-sample converters
- **********************************************************************/
-static UHD_INLINE item32_t sc16_to_item32(sc16_t num){
-    boost::uint16_t real = boost::int16_t(num.real());
-    boost::uint16_t imag = boost::int16_t(num.imag());
-    return (item32_t(real) << 16) | (item32_t(imag) << 0);
-}
-
-static UHD_INLINE sc16_t item32_to_sc16(item32_t item){
-    return sc16_t(
-        boost::uint16_t(item >> 16),
-        boost::uint16_t(item >> 0)
-    );
-}
-
-static UHD_INLINE item32_t fc32_to_item32(fc32_t num){
-    boost::uint16_t real = boost::int16_t(num.real()*shorts_per_float);
-    boost::uint16_t imag = boost::int16_t(num.imag()*shorts_per_float);
-    return (item32_t(real) << 16) | (item32_t(imag) << 0);
-}
-
-static UHD_INLINE fc32_t item32_to_fc32(item32_t item){
-    return fc32_t(
-        float(boost::int16_t(item >> 16)*floats_per_short),
-        float(boost::int16_t(item >> 0)*floats_per_short)
-    );
-}
-
-/***********************************************************************
- * Sample-buffer converters
+ * Generate predicate for jump table
  **********************************************************************/
 UHD_INLINE boost::uint8_t get_pred(
     const io_type_t &io_type,
@@ -92,27 +41,34 @@ UHD_INLINE boost::uint8_t get_pred(
     boost::uint8_t pred = 0;
 
     switch(otw_type.byteorder){
-    case otw_type_t::BO_BIG_ENDIAN:    pred |= $ph.be_p; break;
-    case otw_type_t::BO_LITTLE_ENDIAN: pred |= $ph.le_p; break;
-    ##let the compiler determine the native byte order (we could use python sys.byteorder)
-    case otw_type_t::BO_NATIVE:        pred |= (is_big_endian)? $ph.be_p : $ph.le_p; break;
-    default: throw std::runtime_error("unhandled byteorder type");
+    \#ifdef BOOST_BIG_ENDIAN
+    case otw_type_t::BO_BIG_ENDIAN:    pred |= $ph.nswap_p; break;
+    case otw_type_t::BO_LITTLE_ENDIAN: pred |= $ph.bswap_p; break;
+    \#else
+    case otw_type_t::BO_BIG_ENDIAN:    pred |= $ph.bswap_p; break;
+    case otw_type_t::BO_LITTLE_ENDIAN: pred |= $ph.nswap_p; break;
+    \#endif
+    case otw_type_t::BO_NATIVE:        pred |= $ph.nswap_p; break;
+    default: throw std::runtime_error("unhandled otw byteorder type");
     }
 
-    switch(otw_type.width){
-    case 16: pred |= $ph.w16_p; break;
-    default: throw std::runtime_error("unhandled bit width");
+    switch(otw_type.get_sample_size()){
+    case sizeof(boost::uint32_t): pred |= $ph.item32_p; break;
+    default: throw std::runtime_error("unhandled otw sample size");
     }
 
     switch(io_type.tid){
-    case io_type_t::COMPLEX_INT16:   pred |= $ph.sc16_p; break;
     case io_type_t::COMPLEX_FLOAT32: pred |= $ph.fc32_p; break;
+    case io_type_t::COMPLEX_INT16:   pred |= $ph.sc16_p; break;
     default: throw std::runtime_error("unhandled io type id");
     }
 
     return pred;
 }
 
+/***********************************************************************
+ * Convert host type to device type
+ **********************************************************************/
 void transport::convert_io_type_to_otw_type(
     const void *io_buff, const io_type_t &io_type,
     void *otw_buff, const otw_type_t &otw_type,
@@ -123,16 +79,16 @@ void transport::convert_io_type_to_otw_type(
     case $pred:
         #set $out_type = $ph.get_dev_type($pred)
         #set $in_type = $ph.get_host_type($pred)
-        #set $converter = $in_type+"_to_"+$out_type
-        #set $xe_macro = $ph.get_xe_macro($pred)
-        for (size_t i = 0; i < num_samps; i++){
-            (($(out_type)_t *)otw_buff)[i] = $(xe_macro)($(converter)(((const $(in_type)_t *)io_buff)[i]));
-        }
+        #set $converter = '_'.join([$in_type, 'to', $out_type, $ph.get_swap_type($pred)])
+        $(converter)((const $(in_type)_t *)io_buff, ($(out_type)_t *)otw_buff, num_samps);
         break;
     #end for
     }
 }
 
+/***********************************************************************
+ * Convert device type to host type
+ **********************************************************************/
 void transport::convert_otw_type_to_io_type(
     const void *otw_buff, const otw_type_t &otw_type,
     void *io_buff, const io_type_t &io_type,
@@ -143,11 +99,8 @@ void transport::convert_otw_type_to_io_type(
     case $pred:
         #set $out_type = $ph.get_host_type($pred)
         #set $in_type = $ph.get_dev_type($pred)
-        #set $converter = $in_type+"_to_"+$out_type
-        #set $xe_macro = $ph.get_xe_macro($pred)
-        for (size_t i = 0; i < num_samps; i++){
-            (($(out_type)_t *)io_buff)[i] = $(converter)($(xe_macro)(((const $(in_type)_t *)otw_buff)[i]));
-        }
+        #set $converter = '_'.join([$in_type, 'to', $out_type, $ph.get_swap_type($pred)])
+        $(converter)((const $(in_type)_t *)otw_buff, ($(out_type)_t *)io_buff, num_samps);
         break;
     #end for
     }
@@ -160,29 +113,32 @@ def parse_tmpl(_tmpl_text, **kwargs):
     return str(Template(_tmpl_text, kwargs))
 
 class ph:
-    be_p   = 0b00001
-    le_p   = 0b00000
-    w16_p  = 0b00000
-    sc16_p = 0b00010
-    fc32_p = 0b00000
+    bswap_p  = 0b00001
+    nswap_p  = 0b00000
+    item32_p = 0b00000
+    sc16_p   = 0b00010
+    fc32_p   = 0b00000
 
     nbits = 2 #see above
 
     @staticmethod
-    def get_xe_macro(pred):
-        if (pred & ph.be_p) == ph.be_p: return 'BE_MACRO'
-        if (pred & ph.le_p) == ph.le_p: return 'LE_MACRO'
+    def has(pred, flag): return (pred & flag) == flag
+
+    @staticmethod
+    def get_swap_type(pred):
+        if ph.has(pred, ph.bswap_p): return 'bswap'
+        if ph.has(pred, ph.nswap_p): return 'nswap'
         raise NotImplementedError
 
     @staticmethod
     def get_dev_type(pred):
-        if (pred & ph.w16_p) == ph.w16_p: return 'item32'
+        if ph.has(pred, ph.item32_p): return 'item32'
         raise NotImplementedError
 
     @staticmethod
     def get_host_type(pred):
-        if (pred & ph.sc16_p) == ph.sc16_p: return 'sc16'
-        if (pred & ph.fc32_p) == ph.fc32_p: return 'fc32'
+        if ph.has(pred, ph.sc16_p): return 'sc16'
+        if ph.has(pred, ph.fc32_p): return 'fc32'
         raise NotImplementedError
 
 if __name__ == '__main__':
diff --git a/host/lib/transport/gen_vrt.py b/host/lib/transport/gen_vrt_if_packet.py
index 6cdd6645d..7910ff60d 100755
--- a/host/lib/transport/gen_vrt.py
+++ b/host/lib/transport/gen_vrt_if_packet.py
@@ -31,7 +31,7 @@ TMPL_TEXT = """
  * This file was generated by $file on $time.strftime("%c")
  **********************************************************************/
 
-\#include <uhd/transport/vrt.hpp>
+\#include <uhd/transport/vrt_if_packet.hpp>
 \#include <uhd/utils/byteswap.hpp>
 \#include <boost/detail/endian.hpp>
 \#include <stdexcept>
@@ -61,20 +61,22 @@ using namespace uhd::transport;
 #set $tsf_p = 0b01000
 #set $tlr_p = 0b10000
 
-void vrt::pack_$(suffix)(
-    const tx_metadata_t &metadata, //input
-    boost::uint32_t *header_buff,  //output
-    size_t &num_header_words32,    //output
-    size_t num_payload_words32,    //input
-    size_t &num_packet_words32,    //output
-    size_t packet_count,           //input
-    double tick_rate               //input
+static UHD_INLINE void pack_uint64_$(suffix)(boost::uint64_t num, boost::uint32_t *mem){
+    *(reinterpret_cast<boost::uint64_t *>(mem)) = $(XE_MACRO)(num);
+}
+
+void vrt::if_hdr_pack_$(suffix)(
+    boost::uint32_t *packet_buff,
+    if_packet_info_t &if_packet_info
 ){
     boost::uint32_t vrt_hdr_flags = 0;
 
     boost::uint8_t pred = 0;
-    if (metadata.has_stream_id) pred |= $hex($sid_p);
-    if (metadata.has_time_spec) pred |= $hex($tsi_p | $tsf_p);
+    if (if_packet_info.has_sid) pred |= $hex($sid_p);
+    if (if_packet_info.has_cid) pred |= $hex($cid_p);
+    if (if_packet_info.has_tsi) pred |= $hex($tsi_p);
+    if (if_packet_info.has_tsf) pred |= $hex($tsf_p);
+    if (if_packet_info.has_tlr) pred |= $hex($tlr_p);
 
     switch(pred){
     #for $pred in range(2**5)
@@ -83,81 +85,75 @@ void vrt::pack_$(suffix)(
         #set $flags = 0
         ########## Stream ID ##########
         #if $pred & $sid_p
-            header_buff[$num_header_words] = $(XE_MACRO)(metadata.stream_id);
+            packet_buff[$num_header_words] = $(XE_MACRO)(if_packet_info.sid);
             #set $num_header_words += 1
             #set $flags |= (0x1 << 28);
         #end if
         ########## Class ID ##########
         #if $pred & $cid_p
-            header_buff[$num_header_words] = 0;
-            #set $num_header_words += 1
-            header_buff[$num_header_words] = 0;
-            #set $num_header_words += 1
+            pack_uint64_$(suffix)(if_packet_info.cid, packet_buff+$num_header_words);
+            #set $num_header_words += 2
             #set $flags |= (0x1 << 27);
         #end if
         ########## Integer Time ##########
         #if $pred & $tsi_p
-            header_buff[$num_header_words] = $(XE_MACRO)(metadata.time_spec.secs);
+            packet_buff[$num_header_words] = $(XE_MACRO)(if_packet_info.tsi);
             #set $num_header_words += 1
             #set $flags |= (0x3 << 22);
         #end if
         ########## Fractional Time ##########
         #if $pred & $tsf_p
-            header_buff[$num_header_words] = 0;
-            #set $num_header_words += 1
-            header_buff[$num_header_words] = $(XE_MACRO)(metadata.time_spec.get_ticks(tick_rate));
-            #set $num_header_words += 1
+            pack_uint64_$(suffix)(if_packet_info.tsf, packet_buff+$num_header_words);
+            #set $num_header_words += 2
             #set $flags |= (0x1 << 20);
         #end if
         ########## Trailer ##########
         #if $pred & $tlr_p
+            //packet_buff[$num_header_words+if_packet_info.num_payload_words32] = $(XE_MACRO)(if_packet_info.tlr);
             #set $flags |= (0x1 << 26);
             #set $num_trailer_words = 1;
         #else
+            //packet_buff[$num_header_words+if_packet_info.num_payload_words32] = 0;
             #set $num_trailer_words = 0;
         #end if
         ########## Variables ##########
-            num_header_words32 = $num_header_words;
-            num_packet_words32 = $($num_header_words + $num_trailer_words) + num_payload_words32;
+            if_packet_info.num_header_words32 = $num_header_words;
+            if_packet_info.num_packet_words32 = $($num_header_words + $num_trailer_words) + if_packet_info.num_payload_words32;
             vrt_hdr_flags = $hex($flags);
         break;
     #end for
     }
 
     //set the burst flags
-    if (metadata.start_of_burst) vrt_hdr_flags |= $hex(0x1 << 25);
-    if (metadata.end_of_burst)   vrt_hdr_flags |= $hex(0x1 << 24);
+    if (if_packet_info.sob) vrt_hdr_flags |= $hex(0x1 << 25);
+    if (if_packet_info.eob) vrt_hdr_flags |= $hex(0x1 << 24);
 
     //fill in complete header word
-    header_buff[0] = $(XE_MACRO)(boost::uint32_t(0
+    packet_buff[0] = $(XE_MACRO)(boost::uint32_t(0
         | vrt_hdr_flags
-        | ((packet_count & 0xf) << 16)
-        | (num_packet_words32 & 0xffff)
+        | ((if_packet_info.packet_count & 0xf) << 16)
+        | (if_packet_info.num_packet_words32 & 0xffff)
     ));
 }
 
-void vrt::unpack_$(suffix)(
-    rx_metadata_t &metadata,            //output
-    const boost::uint32_t *header_buff, //input
-    size_t &num_header_words32,         //output
-    size_t &num_payload_words32,        //output
-    size_t num_packet_words32,          //input
-    size_t &packet_count,               //output
-    double tick_rate                    //input
-){
-    //clear the metadata
-    metadata = rx_metadata_t();
+static UHD_INLINE void unpack_uint64_$(suffix)(boost::uint64_t &num, const boost::uint32_t *mem){
+    num = $(XE_MACRO)(*reinterpret_cast<const boost::uint64_t *>(mem));
+}
 
+void vrt::if_hdr_unpack_$(suffix)(
+    const boost::uint32_t *packet_buff,
+    if_packet_info_t &if_packet_info
+){
     //extract vrt header
-    boost::uint32_t vrt_hdr_word = $(XE_MACRO)(header_buff[0]);
+    boost::uint32_t vrt_hdr_word = $(XE_MACRO)(packet_buff[0]);
     size_t packet_words32 = vrt_hdr_word & 0xffff;
-    packet_count = (vrt_hdr_word >> 16) & 0xf;
+    if_packet_info.packet_count = (vrt_hdr_word >> 16) & 0xf;
 
     //failure cases
-    if (packet_words32 == 0 or num_packet_words32 < packet_words32)
+    if (if_packet_info.num_packet_words32 < packet_words32)
         throw std::runtime_error("bad vrt header or packet fragment");
     if (vrt_hdr_word & (0x7 << 29))
-        throw std::runtime_error("unsupported vrt packet type");
+        throw std::runtime_error("bad vrt header or unsupported packet type");
 
     boost::uint8_t pred = 0;
     if(vrt_hdr_word & $hex(0x1 << 28)) pred |= $hex($sid_p);
@@ -169,45 +165,55 @@ void vrt::unpack_$(suffix)(
     switch(pred){
     #for $pred in range(2**5)
     case $pred:
-        #set $set_has_time_spec = False
+        #set $has_time_spec = False
         #set $num_header_words = 1
         ########## Stream ID ##########
         #if $pred & $sid_p
-            metadata.has_stream_id = true;
-            metadata.stream_id = $(XE_MACRO)(header_buff[$num_header_words]);
+            if_packet_info.has_sid = true;
+            if_packet_info.sid = $(XE_MACRO)(packet_buff[$num_header_words]);
             #set $num_header_words += 1
+        #else
+            if_packet_info.has_sid = false;
         #end if
         ########## Class ID ##########
         #if $pred & $cid_p
-            #set $num_header_words += 1
-            #set $num_header_words += 1
+            if_packet_info.has_cid = true;
+            unpack_uint64_$(suffix)(if_packet_info.cid, packet_buff+$num_header_words);
+            #set $num_header_words += 2
+        #else
+            if_packet_info.has_cid = false;
         #end if
         ########## Integer Time ##########
         #if $pred & $tsi_p
-            metadata.has_time_spec = true;
-            #set $set_has_time_spec = True
-            metadata.time_spec.secs = $(XE_MACRO)(header_buff[$num_header_words]);
+            if_packet_info.has_tsi = true;
+            if_packet_info.tsi = $(XE_MACRO)(packet_buff[$num_header_words]);
             #set $num_header_words += 1
+        #else
+            if_packet_info.has_tsi = false;
         #end if
         ########## Fractional Time ##########
         #if $pred & $tsf_p
-            #if not $set_has_time_spec
-            metadata.has_time_spec = true;
-                #set $set_has_time_spec = True
-            #end if
-            #set $num_header_words += 1
-            metadata.time_spec.set_ticks($(XE_MACRO)(header_buff[$num_header_words]), tick_rate);
-            #set $num_header_words += 1
+            if_packet_info.has_tsf = true;
+            unpack_uint64_$(suffix)(if_packet_info.tsf, packet_buff+$num_header_words);
+            #set $num_header_words += 2
+        #else
+            if_packet_info.has_tsf = false;
         #end if
         ########## Trailer ##########
         #if $pred & $tlr_p
+            if_packet_info.has_tlr = true;
+            if_packet_info.tlr = $(XE_MACRO)(packet_buff[$num_header_words+packet_words32]);
             #set $num_trailer_words = 1;
         #else
+            if_packet_info.has_tlr = false;
             #set $num_trailer_words = 0;
         #end if
         ########## Variables ##########
-            num_header_words32 = $num_header_words;
-            num_payload_words32 = packet_words32 - $($num_header_words + $num_trailer_words);
+            //another failure case
+            if (packet_words32 < $($num_header_words + $num_trailer_words))
+                throw std::runtime_error("bad vrt header or invalid packet length");
+            if_packet_info.num_header_words32 = $num_header_words;
+            if_packet_info.num_payload_words32 = packet_words32 - $($num_header_words + $num_trailer_words);
         break;
     #end for
     }
diff --git a/host/lib/transport/udp_zero_copy_asio.cpp b/host/lib/transport/udp_zero_copy_asio.cpp
index c3c02707e..7f9292d24 100644
--- a/host/lib/transport/udp_zero_copy_asio.cpp
+++ b/host/lib/transport/udp_zero_copy_asio.cpp
@@ -27,7 +27,8 @@ using namespace uhd::transport;
 /***********************************************************************
  * Constants
  **********************************************************************/
-static const size_t MIN_SOCK_BUFF_SIZE = size_t(100e3);
+//enough buffering for half a second of samples at full rate on usrp2
+static const size_t MIN_SOCK_BUFF_SIZE = size_t(sizeof(boost::uint32_t) * 25e6 * 0.5);
 static const size_t MAX_DGRAM_SIZE = 1500; //assume max size on send and recv
 static const double RECV_TIMEOUT = 0.1; //100 ms
 
@@ -159,6 +160,12 @@ template<typename Opt> static void resize_buff_helper(
     //otherwise, ensure that the buffer is at least the minimum size
     else if (udp_trans->get_buff_size<Opt>() < MIN_SOCK_BUFF_SIZE){
         resize_buff_helper<Opt>(udp_trans, MIN_SOCK_BUFF_SIZE, name);
+        if (udp_trans->get_buff_size<Opt>() < MIN_SOCK_BUFF_SIZE){
+            std::cerr << boost::format(
+                "Warning: the %s buffer size is smaller than the recommended size of %d bytes.\n"
+                "    See the USRP2 application notes on buffer resizing."
+            ) % name % MIN_SOCK_BUFF_SIZE << std::endl;
+        }
     }
 }
 
diff --git a/host/lib/transport/vrt_packet_handler.hpp b/host/lib/transport/vrt_packet_handler.hpp
index 8dfc7b3d0..68edeb1e1 100644
--- a/host/lib/transport/vrt_packet_handler.hpp
+++ b/host/lib/transport/vrt_packet_handler.hpp
@@ -20,48 +20,51 @@
 
 #include <uhd/config.hpp>
 #include <uhd/device.hpp>
+#include <uhd/utils/assert.hpp>
 #include <uhd/types/io_type.hpp>
 #include <uhd/types/otw_type.hpp>
 #include <uhd/types/metadata.hpp>
-#include <uhd/transport/vrt.hpp>
+#include <uhd/transport/vrt_if_packet.hpp>
 #include <uhd/transport/convert_types.hpp>
 #include <uhd/transport/zero_copy.hpp>
-#include <boost/asio/buffer.hpp>
 #include <boost/function.hpp>
 #include <stdexcept>
 #include <iostream>
+#include <vector>
 
 namespace vrt_packet_handler{
 
 /***********************************************************************
  * vrt packet handler for recv
  **********************************************************************/
+    typedef std::vector<uhd::transport::managed_recv_buffer::sptr> managed_recv_buffs_t;
+    typedef boost::function<bool(managed_recv_buffs_t &)> get_recv_buffs_t;
+
     struct recv_state{
+        //width of the receiver in channels
+        size_t width;
+
         //init the expected seq number
-        size_t next_packet_seq;
+        std::vector<size_t> next_packet_seq;
 
         //state variables to handle fragments
-        uhd::transport::managed_recv_buffer::sptr managed_buff;
-        boost::asio::const_buffer copy_buff;
+        managed_recv_buffs_t managed_buffs;
+        std::vector<const boost::uint8_t *> copy_buffs;
+        size_t size_of_copy_buffs;
         size_t fragment_offset_in_samps;
 
-        recv_state(void){
-            //first expected seq is zero
-            next_packet_seq = 0;
-
-            //initially empty copy buffer
-            copy_buff = boost::asio::buffer("", 0);
+        recv_state(size_t width):
+            width(width),
+            next_packet_seq(width, 0),
+            managed_buffs(width),
+            copy_buffs(width, NULL),
+            size_of_copy_buffs(0),
+            fragment_offset_in_samps(0)
+        {
+            /* NOP */
         }
     };
 
-    typedef boost::function<uhd::transport::managed_recv_buffer::sptr(void)> get_recv_buff_t;
-
-    typedef boost::function<void(uhd::transport::managed_recv_buffer::sptr)> recv_cb_t;
-
-    static UHD_INLINE void recv_cb_nop(uhd::transport::managed_recv_buffer::sptr){
-        /* NOP */
-    }
-
     /*******************************************************************
      * Unpack a received vrt header and set the copy buffer.
      *  - helper function for vrt_packet_handler::_recv1
@@ -74,33 +77,39 @@ namespace vrt_packet_handler{
         vrt_unpacker_type vrt_unpacker,
         size_t vrt_header_offset_words32
     ){
-        size_t num_packet_words32 = state.managed_buff->size()/sizeof(boost::uint32_t);
+        size_t num_packet_words32 = state.managed_buffs[0]->size()/sizeof(boost::uint32_t);
         if (num_packet_words32 <= vrt_header_offset_words32){
-            state.copy_buff = boost::asio::buffer("", 0);
+            state.size_of_copy_buffs = 0;
             return; //must exit here after setting the buffer
         }
-        const boost::uint32_t *vrt_hdr = state.managed_buff->cast<const boost::uint32_t *>() + vrt_header_offset_words32;
-        size_t num_header_words32_out, num_payload_words32_out, packet_count_out;
-        vrt_unpacker(
-            metadata,                //output
-            vrt_hdr,                 //input
-            num_header_words32_out,  //output
-            num_payload_words32_out, //output
-            num_packet_words32,      //input
-            packet_count_out,        //output
-            tick_rate
-        );
 
-        //handle the packet count / sequence number
-        if (packet_count_out != state.next_packet_seq){
-            std::cerr << "S" << (packet_count_out - state.next_packet_seq)%16;
+        //vrt unpack each managed buffer
+        uhd::transport::vrt::if_packet_info_t if_packet_info;
+        for (size_t i = 0; i < state.width; i++){
+            const boost::uint32_t *vrt_hdr = state.managed_buffs[i]->cast<const boost::uint32_t *>() + vrt_header_offset_words32;
+            if_packet_info.num_packet_words32 = num_packet_words32 - vrt_header_offset_words32;
+            vrt_unpacker(vrt_hdr, if_packet_info);
+
+            //handle the packet count / sequence number
+            if (if_packet_info.packet_count != state.next_packet_seq[i]){
+                std::cerr << "S" << (if_packet_info.packet_count - state.next_packet_seq[i])%16;
+            }
+            state.next_packet_seq[i] = (if_packet_info.packet_count+1)%16;
+
+            //setup the buffer to point to the data
+            state.copy_buffs[i] = reinterpret_cast<const boost::uint8_t *>(vrt_hdr + if_packet_info.num_header_words32);
+
+            //store the minimum payload length into the copy buffer length
+            size_t num_payload_bytes = if_packet_info.num_payload_words32*sizeof(boost::uint32_t);
+            if (i == 0 or state.size_of_copy_buffs > num_payload_bytes){
+                state.size_of_copy_buffs = num_payload_bytes;
+            }
         }
-        state.next_packet_seq = (packet_count_out+1)%16;
 
-        //setup the buffer to point to the data
-        state.copy_buff = boost::asio::buffer(
-            vrt_hdr + num_header_words32_out,
-            num_payload_words32_out*sizeof(boost::uint32_t)
+        //store the last vrt info into the metadata
+        metadata.has_time_spec = if_packet_info.has_tsi and if_packet_info.has_tsf;
+        metadata.time_spec = uhd::time_spec_t(
+            time_t(if_packet_info.tsi), size_t(if_packet_info.tsf), tick_rate
         );
     }
 
@@ -111,24 +120,24 @@ namespace vrt_packet_handler{
     template<typename vrt_unpacker_type>
     static UHD_INLINE size_t _recv1(
         recv_state &state,
-        void *recv_mem,
+        const std::vector<void *> &buffs,
+        size_t offset_bytes,
         size_t total_samps,
         uhd::rx_metadata_t &metadata,
         const uhd::io_type_t &io_type,
         const uhd::otw_type_t &otw_type,
         double tick_rate,
         vrt_unpacker_type vrt_unpacker,
-        const get_recv_buff_t &get_recv_buff,
+        const get_recv_buffs_t &get_recv_buffs,
         //use these two params to handle a layer above vrt
-        size_t vrt_header_offset_words32,
-        const recv_cb_t &recv_cb
+        size_t vrt_header_offset_words32
     ){
+        metadata.has_time_spec = false; //false unless set in the helper
+
         //perform a receive if no rx data is waiting to be copied
-        if (boost::asio::buffer_size(state.copy_buff) == 0){
+        if (state.size_of_copy_buffs == 0){
             state.fragment_offset_in_samps = 0;
-            state.managed_buff = get_recv_buff();
-            if (state.managed_buff.get() == NULL) return 0;
-            recv_cb(state.managed_buff); //callback before vrt unpack
+            if (not get_recv_buffs(state.managed_buffs)) return 0;
             try{
                 _recv1_helper(
                     state, metadata, tick_rate, vrt_unpacker, vrt_header_offset_words32
@@ -141,28 +150,30 @@ namespace vrt_packet_handler{
 
         //extract the number of samples available to copy
         size_t bytes_per_item = otw_type.get_sample_size();
-        size_t bytes_available = boost::asio::buffer_size(state.copy_buff);
-        size_t num_samps = std::min(total_samps, bytes_available/bytes_per_item);
+        size_t bytes_available = state.size_of_copy_buffs;
+        size_t nsamps_to_copy = std::min(total_samps, bytes_available/bytes_per_item);
+        size_t bytes_to_copy = nsamps_to_copy*bytes_per_item;
+
+        for (size_t i = 0; i < state.width; i++){
+            //copy-convert the samples from the recv buffer
+            uhd::transport::convert_otw_type_to_io_type(
+                state.copy_buffs[i], otw_type,
+                reinterpret_cast<boost::uint8_t *>(buffs[i]) + offset_bytes,
+                io_type, nsamps_to_copy
+            );
+
+            //update the rx copy buffer to reflect the bytes copied
+            state.copy_buffs[i] += bytes_to_copy;
+        }
+        //update the copy buffer's availability
+        state.size_of_copy_buffs -= bytes_to_copy;
 
         //setup the fragment flags and offset
-        metadata.more_fragments = total_samps < num_samps;
+        metadata.more_fragments = state.size_of_copy_buffs != 0;
         metadata.fragment_offset = state.fragment_offset_in_samps;
-        state.fragment_offset_in_samps += num_samps; //set for next call
-
-        //copy-convert the samples from the recv buffer
-        uhd::transport::convert_otw_type_to_io_type(
-            boost::asio::buffer_cast<const void*>(state.copy_buff), otw_type,
-            recv_mem, io_type, num_samps
-        );
-
-        //update the rx copy buffer to reflect the bytes copied
-        size_t bytes_copied = num_samps*bytes_per_item;
-        state.copy_buff = boost::asio::buffer(
-            boost::asio::buffer_cast<const boost::uint8_t*>(state.copy_buff) + bytes_copied,
-            bytes_available - bytes_copied
-        );
+        state.fragment_offset_in_samps += nsamps_to_copy; //set for next call
 
-        return num_samps;
+        return nsamps_to_copy;
     }
 
     /*******************************************************************
@@ -171,21 +182,18 @@ namespace vrt_packet_handler{
     template<typename vrt_unpacker_type>
     static UHD_INLINE size_t recv(
         recv_state &state,
-        const boost::asio::mutable_buffer &buff,
+        const std::vector<void *> &buffs,
+        const size_t total_num_samps,
         uhd::rx_metadata_t &metadata,
         uhd::device::recv_mode_t recv_mode,
         const uhd::io_type_t &io_type,
         const uhd::otw_type_t &otw_type,
         double tick_rate,
         vrt_unpacker_type vrt_unpacker,
-        const get_recv_buff_t &get_recv_buff,
+        const get_recv_buffs_t &get_recv_buffs,
         //use these two params to handle a layer above vrt
-        size_t vrt_header_offset_words32 = 0,
-        const recv_cb_t& recv_cb = &recv_cb_nop
+        size_t vrt_header_offset_words32 = 0
     ){
-        metadata = uhd::rx_metadata_t(); //init the metadata
-        const size_t total_num_samps = boost::asio::buffer_size(buff)/io_type.size;
-
         switch(recv_mode){
 
         ////////////////////////////////////////////////////////////////
@@ -193,15 +201,14 @@ namespace vrt_packet_handler{
         ////////////////////////////////////////////////////////////////
             return _recv1(
                 state,
-                boost::asio::buffer_cast<void *>(buff),
+                buffs, 0,
                 total_num_samps,
                 metadata,
                 io_type, otw_type,
                 tick_rate,
                 vrt_unpacker,
-                get_recv_buff,
-                vrt_header_offset_words32,
-                recv_cb
+                get_recv_buffs,
+                vrt_header_offset_words32
             );
         }
 
@@ -213,15 +220,14 @@ namespace vrt_packet_handler{
             while(accum_num_samps < total_num_samps){
                 size_t num_samps = _recv1(
                     state,
-                    boost::asio::buffer_cast<boost::uint8_t *>(buff) + (accum_num_samps*io_type.size),
+                    buffs, accum_num_samps*io_type.size,
                     total_num_samps - accum_num_samps,
                     (accum_num_samps == 0)? metadata : tmp_md, //only the first metadata gets kept
                     io_type, otw_type,
                     tick_rate,
                     vrt_unpacker,
-                    get_recv_buff,
-                    vrt_header_offset_words32,
-                    recv_cb
+                    get_recv_buffs,
+                    vrt_header_offset_words32
                 );
                 if (num_samps == 0) break; //had a recv timeout or error, break loop
                 accum_num_samps += num_samps;
@@ -236,23 +242,18 @@ namespace vrt_packet_handler{
 /***********************************************************************
  * vrt packet handler for send
  **********************************************************************/
+    typedef std::vector<uhd::transport::managed_send_buffer::sptr> managed_send_buffs_t;
+    typedef boost::function<bool(managed_send_buffs_t &)> get_send_buffs_t;
+
     struct send_state{
         //init the expected seq number
         size_t next_packet_seq;
 
-        send_state(void){
-            next_packet_seq = 0;
+        send_state(void) : next_packet_seq(0){
+            /* NOP */
         }
     };
 
-    typedef boost::function<uhd::transport::managed_send_buffer::sptr(void)> get_send_buff_t;
-
-    typedef boost::function<void(uhd::transport::managed_send_buffer::sptr)> send_cb_t;
-
-    static UHD_INLINE void send_cb_nop(uhd::transport::managed_send_buffer::sptr){
-        /* NOP */
-    }
-
     /*******************************************************************
      * Pack a vrt header, copy-convert the data, and send it.
      *  - helper function for vrt_packet_handler::send
@@ -260,46 +261,42 @@ namespace vrt_packet_handler{
     template<typename vrt_packer_type>
     static UHD_INLINE void _send1(
         send_state &state,
-        const void *send_mem,
+        const std::vector<const void *> &buffs,
+        size_t offset_bytes,
         size_t num_samps,
-        const uhd::tx_metadata_t &metadata,
+        uhd::transport::vrt::if_packet_info_t &if_packet_info,
         const uhd::io_type_t &io_type,
         const uhd::otw_type_t &otw_type,
-        double tick_rate,
         vrt_packer_type vrt_packer,
-        const get_send_buff_t &get_send_buff,
-        size_t vrt_header_offset_words32,
-        const send_cb_t& send_cb
+        const get_send_buffs_t &get_send_buffs,
+        size_t vrt_header_offset_words32
     ){
-        //get a new managed send buffer
-        uhd::transport::managed_send_buffer::sptr send_buff = get_send_buff();
-        boost::uint32_t *tx_mem = send_buff->cast<boost::uint32_t *>() + vrt_header_offset_words32;
-
-        size_t num_header_words32, num_packet_words32;
-        size_t packet_count = state.next_packet_seq++;
-
-        //pack metadata into a vrt header
-        vrt_packer(
-            metadata,            //input
-            tx_mem,              //output
-            num_header_words32,  //output
-            num_samps,           //input
-            num_packet_words32,  //output
-            packet_count,        //input
-            tick_rate
-        );
-
-        //copy-convert the samples into the send buffer
-        uhd::transport::convert_io_type_to_otw_type(
-            send_mem, io_type,
-            tx_mem + num_header_words32, otw_type,
-            num_samps
-        );
-
-        send_cb(send_buff); //callback after memory filled
+        //load the rest of the if_packet_info in here
+        if_packet_info.num_payload_words32 = (num_samps*otw_type.get_sample_size())/sizeof(boost::uint32_t);
+        if_packet_info.packet_count = state.next_packet_seq++;
+
+        //get send buffers for each channel
+        managed_send_buffs_t send_buffs(buffs.size());
+        UHD_ASSERT_THROW(get_send_buffs(send_buffs));
+
+        for (size_t i = 0; i < buffs.size(); i++){
+            //calculate pointers with offsets to io and otw memory
+            const boost::uint8_t *io_mem = reinterpret_cast<const boost::uint8_t *>(buffs[i]) + offset_bytes;
+            boost::uint32_t *otw_mem = send_buffs[i]->cast<boost::uint32_t *>() + vrt_header_offset_words32;
+
+            //pack metadata into a vrt header
+            vrt_packer(otw_mem, if_packet_info);
+
+            //copy-convert the samples into the send buffer
+            uhd::transport::convert_io_type_to_otw_type(
+                io_mem, io_type,
+                otw_mem + if_packet_info.num_header_words32, otw_type,
+                num_samps
+            );
 
-        //commit the samples to the zero-copy interface
-        send_buff->commit(num_packet_words32*sizeof(boost::uint32_t));
+            //commit the samples to the zero-copy interface
+            send_buffs[i]->commit(if_packet_info.num_packet_words32*sizeof(boost::uint32_t));
+        }
     }
 
     /*******************************************************************
@@ -308,20 +305,27 @@ namespace vrt_packet_handler{
     template<typename vrt_packer_type>
     static UHD_INLINE size_t send(
         send_state &state,
-        const boost::asio::const_buffer &buff,
+        const std::vector<const void *> &buffs,
+        const size_t total_num_samps,
         const uhd::tx_metadata_t &metadata,
         uhd::device::send_mode_t send_mode,
         const uhd::io_type_t &io_type,
         const uhd::otw_type_t &otw_type,
         double tick_rate,
         vrt_packer_type vrt_packer,
-        const get_send_buff_t &get_send_buff,
+        const get_send_buffs_t &get_send_buffs,
         size_t max_samples_per_packet,
         //use these two params to handle a layer above vrt
-        size_t vrt_header_offset_words32 = 0,
-        const send_cb_t& send_cb = &send_cb_nop
+        size_t vrt_header_offset_words32 = 0
     ){
-        const size_t total_num_samps = boost::asio::buffer_size(buff)/io_type.size;
+        //translate the metadata to vrt if packet info
+        uhd::transport::vrt::if_packet_info_t if_packet_info;
+        if_packet_info.has_sid = false;
+        if_packet_info.has_cid = false;
+        if_packet_info.has_tlr = false;
+        if_packet_info.tsi = boost::uint32_t(metadata.time_spec.get_full_secs());
+        if_packet_info.tsf = boost::uint64_t(metadata.time_spec.get_tick_count(tick_rate));
+
         if (total_num_samps <= max_samples_per_packet) send_mode = uhd::device::SEND_MODE_ONE_PACKET;
         switch(send_mode){
 
@@ -329,17 +333,22 @@ namespace vrt_packet_handler{
         case uhd::device::SEND_MODE_ONE_PACKET:{
         ////////////////////////////////////////////////////////////////
             size_t num_samps = std::min(total_num_samps, max_samples_per_packet);
+
+            //fill in parts of the packet info overwrote in full buff mode
+            if_packet_info.has_tsi = metadata.has_time_spec;
+            if_packet_info.has_tsf = metadata.has_time_spec;
+            if_packet_info.sob = metadata.start_of_burst;
+            if_packet_info.eob = metadata.end_of_burst;
+
             _send1(
                 state,
-                boost::asio::buffer_cast<const void *>(buff),
+                buffs, 0,
                 num_samps,
-                metadata,
+                if_packet_info,
                 io_type, otw_type,
-                tick_rate,
                 vrt_packer,
-                get_send_buff,
-                vrt_header_offset_words32,
-                send_cb
+                get_send_buffs,
+                vrt_header_offset_words32
             );
             return num_samps;
         }
@@ -352,29 +361,25 @@ namespace vrt_packet_handler{
             static const size_t first_fragment_index = 0;
             const size_t final_fragment_index = num_fragments-1;
 
-            //make a rw copy of the metadata to re-flag below
-            uhd::tx_metadata_t md(metadata);
-
             //loop through the following fragment indexes
             for (size_t n = first_fragment_index; n <= final_fragment_index; n++){
 
                 //calculate new flags for the fragments
-                md.has_time_spec  = metadata.has_time_spec  and (n == first_fragment_index);
-                md.start_of_burst = metadata.start_of_burst and (n == first_fragment_index);
-                md.end_of_burst   = metadata.end_of_burst   and (n == final_fragment_index);
+                if_packet_info.has_tsi = metadata.has_time_spec  and (n == first_fragment_index);
+                if_packet_info.has_tsf = metadata.has_time_spec  and (n == first_fragment_index);
+                if_packet_info.sob     = metadata.start_of_burst and (n == first_fragment_index);
+                if_packet_info.eob     = metadata.end_of_burst   and (n == final_fragment_index);
 
                 //send the fragment with the helper function
                 _send1(
                     state,
-                    boost::asio::buffer_cast<const boost::uint8_t *>(buff) + (n*max_samples_per_packet*io_type.size),
+                    buffs, n*max_samples_per_packet*io_type.size,
                     (n == final_fragment_index)?(total_num_samps%max_samples_per_packet):max_samples_per_packet,
-                    md,
+                    if_packet_info,
                     io_type, otw_type,
-                    tick_rate,
                     vrt_packer,
-                    get_send_buff,
-                    vrt_header_offset_words32,
-                    send_cb
+                    get_send_buffs,
+                    vrt_header_offset_words32
                 );
             }
             return total_num_samps;
diff --git a/host/lib/types.cpp b/host/lib/types.cpp
index daf3be7f7..9cf2a2220 100644
--- a/host/lib/types.cpp
+++ b/host/lib/types.cpp
@@ -96,8 +96,6 @@ stream_cmd_t::stream_cmd_t(const stream_mode_t &stream_mode):
  * metadata
  **********************************************************************/
 rx_metadata_t::rx_metadata_t(void):
-    has_stream_id(false),
-    stream_id(0),
     has_time_spec(false),
     time_spec(time_spec_t()),
     more_fragments(false),
@@ -107,8 +105,6 @@ rx_metadata_t::rx_metadata_t(void):
 }
 
 tx_metadata_t::tx_metadata_t(void):
-    has_stream_id(false),
-    stream_id(0),
     has_time_spec(false),
     time_spec(time_spec_t()),
     start_of_burst(false),
@@ -120,19 +116,63 @@ tx_metadata_t::tx_metadata_t(void):
 /***********************************************************************
  * time spec
  **********************************************************************/
-time_spec_t::time_spec_t(boost::uint32_t secs, double nsecs):
-    secs(secs),
-    nsecs(nsecs)
+time_spec_t::time_spec_t(double secs):
+    _full_secs(0),
+    _frac_secs(secs)
 {
     /* NOP */
 }
 
-boost::uint32_t time_spec_t::get_ticks(double tick_rate) const{
-    return boost::math::iround(nsecs*tick_rate*1e-9);
+time_spec_t::time_spec_t(time_t full_secs, double frac_secs):
+    _full_secs(full_secs),
+    _frac_secs(frac_secs)
+{
+    /* NOP */
+}
+
+time_spec_t::time_spec_t(time_t full_secs, size_t tick_count, double tick_rate):
+    _full_secs(full_secs),
+    _frac_secs(double(tick_count)/tick_rate)
+{
+    /* NOP */
+}
+
+size_t time_spec_t::get_tick_count(double tick_rate) const{
+    return boost::math::iround(this->get_frac_secs()*tick_rate);
+}
+
+double time_spec_t::get_real_secs(void) const{
+    return this->_full_secs + this->_frac_secs;
+}
+
+time_t time_spec_t::get_full_secs(void) const{
+    return this->_full_secs + time_t(std::floor(this->_frac_secs));
+}
+
+double time_spec_t::get_frac_secs(void) const{
+    return std::fmod(this->_frac_secs, 1.0);
+}
+
+time_spec_t &time_spec_t::operator+=(const time_spec_t &rhs){
+    this->_full_secs += rhs.get_full_secs();
+    this->_frac_secs += rhs.get_frac_secs();
+    return *this;
+}
+
+time_spec_t &time_spec_t::operator-=(const time_spec_t &rhs){
+    this->_full_secs -= rhs.get_full_secs();
+    this->_frac_secs -= rhs.get_frac_secs();
+    return *this;
+}
+
+bool uhd::operator==(const time_spec_t &lhs, const time_spec_t &rhs){
+    return lhs.get_full_secs() == rhs.get_full_secs() and lhs.get_frac_secs() == rhs.get_frac_secs();
 }
 
-void time_spec_t::set_ticks(boost::uint32_t ticks, double tick_rate){
-    nsecs = double(ticks)*1e9/tick_rate;
+bool uhd::operator<(const time_spec_t &lhs, const time_spec_t &rhs){
+    if (lhs.get_full_secs() < rhs.get_full_secs()) return true;
+    if (lhs.get_full_secs() > rhs.get_full_secs()) return false;
+    return lhs.get_frac_secs() < rhs.get_frac_secs();
 }
 
 /***********************************************************************
diff --git a/host/lib/usrp/CMakeLists.txt b/host/lib/usrp/CMakeLists.txt
index 3e12c087e..814affdd0 100644
--- a/host/lib/usrp/CMakeLists.txt
+++ b/host/lib/usrp/CMakeLists.txt
@@ -23,6 +23,7 @@ LIBUHD_APPEND_SOURCES(
     ${CMAKE_SOURCE_DIR}/lib/usrp/dboard_id.cpp
     ${CMAKE_SOURCE_DIR}/lib/usrp/dboard_manager.cpp
     ${CMAKE_SOURCE_DIR}/lib/usrp/dsp_utils.hpp
+    ${CMAKE_SOURCE_DIR}/lib/usrp/mimo_usrp.cpp
     ${CMAKE_SOURCE_DIR}/lib/usrp/simple_usrp.cpp
     ${CMAKE_SOURCE_DIR}/lib/usrp/tune_helper.cpp
 )
diff --git a/host/lib/usrp/mimo_usrp.cpp b/host/lib/usrp/mimo_usrp.cpp
new file mode 100644
index 000000000..fd8225074
--- /dev/null
+++ b/host/lib/usrp/mimo_usrp.cpp
@@ -0,0 +1,291 @@
+//
+// Copyright 2010 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+#include <uhd/usrp/mimo_usrp.hpp>
+#include <uhd/usrp/tune_helper.hpp>
+#include <uhd/utils/assert.hpp>
+#include <uhd/utils/algorithm.hpp>
+#include <uhd/usrp/subdev_props.hpp>
+#include <uhd/usrp/mboard_props.hpp>
+#include <uhd/usrp/device_props.hpp>
+#include <uhd/usrp/dboard_props.hpp>
+#include <uhd/usrp/dsp_props.hpp>
+#include <boost/foreach.hpp>
+#include <boost/format.hpp>
+#include <boost/thread.hpp>
+#include <stdexcept>
+#include <iostream>
+
+using namespace uhd;
+using namespace uhd::usrp;
+
+/***********************************************************************
+ * MIMO USRP Implementation
+ **********************************************************************/
+class mimo_usrp_impl : public mimo_usrp{
+public:
+    mimo_usrp_impl(const device_addr_t &addr){
+        _dev = device::make(addr);
+
+        //extract each mboard and its sub-devices
+        BOOST_FOREACH(const std::string &name, (*_dev)[DEVICE_PROP_MBOARD_NAMES].as<prop_names_t>()){
+            _mboards.push_back((*_dev)[named_prop_t(DEVICE_PROP_MBOARD, name)]);
+            _rx_dsps.push_back(_mboards.back()[MBOARD_PROP_RX_DSP]);
+            _tx_dsps.push_back(_mboards.back()[MBOARD_PROP_TX_DSP]);
+
+            //extract rx subdevice
+            _rx_dboards.push_back(_mboards.back()[MBOARD_PROP_RX_DBOARD]);
+            std::string rx_subdev_in_use = _rx_dboards.back()[DBOARD_PROP_USED_SUBDEVS].as<prop_names_t>().at(0);
+            _rx_subdevs.push_back(_rx_dboards.back()[named_prop_t(DBOARD_PROP_SUBDEV, rx_subdev_in_use)]);
+
+            //extract tx subdevice
+            _tx_dboards.push_back(_mboards.back()[MBOARD_PROP_TX_DBOARD]);
+            std::string tx_subdev_in_use = _tx_dboards.back()[DBOARD_PROP_USED_SUBDEVS].as<prop_names_t>().at(0);
+            _tx_subdevs.push_back(_tx_dboards.back()[named_prop_t(DBOARD_PROP_SUBDEV, tx_subdev_in_use)]);
+        }
+
+        //set the clock config across all mboards (TODO set through api)
+        clock_config_t clock_config;
+        clock_config.ref_source = clock_config_t::REF_SMA;
+        clock_config.pps_source = clock_config_t::PPS_SMA;
+        BOOST_FOREACH(wax::obj mboard, _mboards){
+            mboard[MBOARD_PROP_CLOCK_CONFIG] = clock_config;
+        }
+    }
+
+    ~mimo_usrp_impl(void){
+        /* NOP */
+    }
+
+    device::sptr get_device(void){
+        return _dev;
+    }
+
+    std::string get_pp_string(void){
+        std::string buff = str(boost::format(
+            "MIMO USRP:\n"
+            "  Device: %s\n"
+        )
+            % (*_dev)[DEVICE_PROP_NAME].as<std::string>()
+        );
+        for (size_t i = 0; i < get_num_channels(); i++){
+            buff += str(boost::format(
+                "  Channel: %u\n"
+                "    Mboard: %s\n"
+                "    RX DSP: %s\n"
+                "    RX Dboard: %s\n"
+                "    RX Subdev: %s\n"
+                "    TX DSP: %s\n"
+                "    TX Dboard: %s\n"
+                "    TX Subdev: %s\n"
+            ) % i
+                % _mboards.at(i)[MBOARD_PROP_NAME].as<std::string>()
+                % _rx_dsps.at(i)[DSP_PROP_NAME].as<std::string>()
+                % _rx_dboards.at(i)[DBOARD_PROP_NAME].as<std::string>()
+                % _rx_subdevs.at(i)[SUBDEV_PROP_NAME].as<std::string>()
+                % _tx_dsps.at(i)[DSP_PROP_NAME].as<std::string>()
+                % _tx_dboards.at(i)[DBOARD_PROP_NAME].as<std::string>()
+                % _tx_subdevs.at(i)[SUBDEV_PROP_NAME].as<std::string>()
+            );
+        }
+        return buff;
+    }
+
+    size_t get_num_channels(void){
+        return _mboards.size();
+    }
+
+    /*******************************************************************
+     * Misc
+     ******************************************************************/
+    time_spec_t get_time_now(void){
+        //the time on the first mboard better be the same on all
+        return _mboards.front()[MBOARD_PROP_TIME_NOW].as<time_spec_t>();
+    }
+
+    void set_time_next_pps(const time_spec_t &time_spec){
+        BOOST_FOREACH(wax::obj mboard, _mboards){
+            mboard[MBOARD_PROP_TIME_NEXT_PPS] = time_spec;
+        }
+    }
+
+    void set_time_unknown_pps(const time_spec_t &time_spec){
+        std::cout << "Set time with unknown pps edge:" << std::endl;
+        std::cout << "  1) set times next pps (race condition)" << std::endl;
+        set_time_next_pps(time_spec);
+        boost::this_thread::sleep(boost::posix_time::seconds(1));
+
+        std::cout << "  2) catch seconds rollover at pps edge" << std::endl;
+        time_t last_secs = 0, curr_secs = 0;
+        while(curr_secs == last_secs){
+            last_secs = curr_secs;
+            curr_secs = get_time_now().get_full_secs();
+        }
+
+        std::cout << "  3) set times next pps (synchronously)" << std::endl;
+        set_time_next_pps(time_spec);
+        boost::this_thread::sleep(boost::posix_time::seconds(1));
+    }
+
+    void issue_stream_cmd(const stream_cmd_t &stream_cmd){
+        BOOST_FOREACH(wax::obj mboard, _mboards){
+            mboard[MBOARD_PROP_STREAM_CMD] = stream_cmd;
+        }
+    }
+
+    /*******************************************************************
+     * RX methods
+     ******************************************************************/
+    void set_rx_rate_all(double rate){
+        std::vector<double> _actual_rates;
+        BOOST_FOREACH(wax::obj rx_dsp, _rx_dsps){
+            rx_dsp[DSP_PROP_HOST_RATE] = rate;
+            _actual_rates.push_back(rx_dsp[DSP_PROP_HOST_RATE].as<double>());
+        }
+        _rx_rate = _actual_rates.front();
+        if (std::count(_actual_rates, _rx_rate) != _actual_rates.size()) throw std::runtime_error(
+            "MIMO configuratio error: rx rate inconsistent across mboards"
+        );
+    }
+
+    double get_rx_rate_all(void){
+        return _rx_rate;
+    }
+
+    tune_result_t set_rx_freq(size_t chan, double target_freq){
+        return tune_rx_subdev_and_ddc(_rx_subdevs.at(chan), _rx_dsps.at(chan), target_freq);
+    }
+
+    tune_result_t set_rx_freq(size_t chan, double target_freq, double lo_off){
+        return tune_rx_subdev_and_ddc(_rx_subdevs.at(chan), _rx_dsps.at(chan), target_freq, lo_off);
+    }
+
+    freq_range_t get_rx_freq_range(size_t chan){
+        return _rx_subdevs.at(chan)[SUBDEV_PROP_FREQ_RANGE].as<freq_range_t>();
+    }
+
+    void set_rx_gain(size_t chan, float gain){
+        _rx_subdevs.at(chan)[SUBDEV_PROP_GAIN] = gain;
+    }
+
+    float get_rx_gain(size_t chan){
+        return _rx_subdevs.at(chan)[SUBDEV_PROP_GAIN].as<float>();
+    }
+
+    gain_range_t get_rx_gain_range(size_t chan){
+        return _rx_subdevs.at(chan)[SUBDEV_PROP_GAIN_RANGE].as<gain_range_t>();
+    }
+
+    void set_rx_antenna(size_t chan, const std::string &ant){
+        _rx_subdevs.at(chan)[SUBDEV_PROP_ANTENNA] = ant;
+    }
+
+    std::string get_rx_antenna(size_t chan){
+        return _rx_subdevs.at(chan)[SUBDEV_PROP_ANTENNA].as<std::string>();
+    }
+
+    std::vector<std::string> get_rx_antennas(size_t chan){
+        return _rx_subdevs.at(chan)[SUBDEV_PROP_ANTENNA_NAMES].as<prop_names_t>();
+    }
+
+    bool get_rx_lo_locked(size_t chan){
+        return _rx_subdevs.at(chan)[SUBDEV_PROP_LO_LOCKED].as<bool>();
+    }
+
+    float read_rssi(size_t chan){
+        return _rx_subdevs.at(chan)[SUBDEV_PROP_RSSI].as<float>();
+    }
+
+    /*******************************************************************
+     * TX methods
+     ******************************************************************/
+    void set_tx_rate_all(double rate){
+        std::vector<double> _actual_rates;
+        BOOST_FOREACH(wax::obj tx_dsp, _tx_dsps){
+            tx_dsp[DSP_PROP_HOST_RATE] = rate;
+            _actual_rates.push_back(tx_dsp[DSP_PROP_HOST_RATE].as<double>());
+        }
+        _tx_rate = _actual_rates.front();
+        if (std::count(_actual_rates, _tx_rate) != _actual_rates.size()) throw std::runtime_error(
+            "MIMO configuratio error: tx rate inconsistent across mboards"
+        );
+    }
+
+    double get_tx_rate_all(void){
+        return _tx_rate;
+    }
+
+    tune_result_t set_tx_freq(size_t chan, double target_freq){
+        return tune_tx_subdev_and_duc(_tx_subdevs.at(chan), _tx_dsps.at(chan), target_freq);
+    }
+
+    tune_result_t set_tx_freq(size_t chan, double target_freq, double lo_off){
+        return tune_tx_subdev_and_duc(_tx_subdevs.at(chan), _tx_dsps.at(chan), target_freq, lo_off);
+    }
+
+    freq_range_t get_tx_freq_range(size_t chan){
+        return _tx_subdevs.at(chan)[SUBDEV_PROP_FREQ_RANGE].as<freq_range_t>();
+    }
+
+    void set_tx_gain(size_t chan, float gain){
+        _tx_subdevs.at(chan)[SUBDEV_PROP_GAIN] = gain;
+    }
+
+    float get_tx_gain(size_t chan){
+        return _tx_subdevs.at(chan)[SUBDEV_PROP_GAIN].as<float>();
+    }
+
+    gain_range_t get_tx_gain_range(size_t chan){
+        return _tx_subdevs.at(chan)[SUBDEV_PROP_GAIN_RANGE].as<gain_range_t>();
+    }
+
+    void set_tx_antenna(size_t chan, const std::string &ant){
+        _tx_subdevs.at(chan)[SUBDEV_PROP_ANTENNA] = ant;
+    }
+
+    std::string get_tx_antenna(size_t chan){
+        return _tx_subdevs.at(chan)[SUBDEV_PROP_ANTENNA].as<std::string>();
+    }
+
+    std::vector<std::string> get_tx_antennas(size_t chan){
+        return _tx_subdevs.at(chan)[SUBDEV_PROP_ANTENNA_NAMES].as<prop_names_t>();
+    }
+
+    bool get_tx_lo_locked(size_t chan){
+        return _tx_subdevs.at(chan)[SUBDEV_PROP_LO_LOCKED].as<bool>();
+    }
+
+private:
+    device::sptr _dev;
+    std::vector<wax::obj> _mboards;
+    std::vector<wax::obj> _rx_dsps;
+    std::vector<wax::obj> _tx_dsps;
+    std::vector<wax::obj> _rx_dboards;
+    std::vector<wax::obj> _tx_dboards;
+    std::vector<wax::obj> _rx_subdevs;
+    std::vector<wax::obj> _tx_subdevs;
+
+    //shadows
+    double _rx_rate, _tx_rate;
+};
+
+/***********************************************************************
+ * The Make Function
+ **********************************************************************/
+mimo_usrp::sptr mimo_usrp::make(const device_addr_t &dev_addr){
+    return sptr(new mimo_usrp_impl(dev_addr));
+}
diff --git a/host/lib/usrp/simple_usrp.cpp b/host/lib/usrp/simple_usrp.cpp
index f4aa82669..56e82d7ee 100644
--- a/host/lib/usrp/simple_usrp.cpp
+++ b/host/lib/usrp/simple_usrp.cpp
@@ -31,7 +31,7 @@ using namespace uhd;
 using namespace uhd::usrp;
 
 /***********************************************************************
- * Simple Device Implementation
+ * Simple USRP Implementation
  **********************************************************************/
 class simple_usrp_impl : public simple_usrp{
 public:
@@ -60,7 +60,7 @@ public:
         return _dev;
     }
 
-    std::string get_name(void){
+    std::string get_pp_string(void){
         return str(boost::format(
             "Simple USRP:\n"
             "  Device: %s\n"
@@ -86,6 +86,10 @@ public:
     /*******************************************************************
      * Misc
      ******************************************************************/
+    time_spec_t get_time_now(void){
+        return _mboard[MBOARD_PROP_TIME_NOW].as<time_spec_t>();
+    }
+
     void set_time_now(const time_spec_t &time_spec){
         _mboard[MBOARD_PROP_TIME_NOW] = time_spec;
     }
@@ -102,10 +106,6 @@ public:
         _mboard[MBOARD_PROP_CLOCK_CONFIG] = clock_config;
     }
 
-    float read_rssi(void){
-        return _rx_subdev[SUBDEV_PROP_RSSI].as<float>();
-    }
-
     /*******************************************************************
      * RX methods
      ******************************************************************/
@@ -157,6 +157,10 @@ public:
         return _rx_subdev[SUBDEV_PROP_LO_LOCKED].as<bool>();
     }
 
+    float read_rssi(void){
+        return _rx_subdev[SUBDEV_PROP_RSSI].as<float>();
+    }
+
     /*******************************************************************
      * TX methods
      ******************************************************************/
diff --git a/host/lib/usrp/usrp2/dboard_impl.cpp b/host/lib/usrp/usrp2/dboard_impl.cpp
index fef486771..fa8d1a674 100644
--- a/host/lib/usrp/usrp2/dboard_impl.cpp
+++ b/host/lib/usrp/usrp2/dboard_impl.cpp
@@ -33,7 +33,7 @@ using namespace uhd::usrp;
 /***********************************************************************
  * Helper Methods
  **********************************************************************/
-void usrp2_impl::dboard_init(void){
+void usrp2_mboard_impl::dboard_init(void){
     //read the dboard eeprom to extract the dboard ids
     _rx_db_eeprom = dboard_eeprom_t(_iface->read_eeprom(I2C_ADDR_RX_DB, 0, dboard_eeprom_t::num_bytes()));
     _tx_db_eeprom = dboard_eeprom_t(_iface->read_eeprom(I2C_ADDR_TX_DB, 0, dboard_eeprom_t::num_bytes()));
@@ -46,12 +46,12 @@ void usrp2_impl::dboard_init(void){
 
     //load dboards
     _rx_dboard_proxy = wax_obj_proxy::make(
-        boost::bind(&usrp2_impl::rx_dboard_get, this, _1, _2),
-        boost::bind(&usrp2_impl::rx_dboard_set, this, _1, _2)
+        boost::bind(&usrp2_mboard_impl::rx_dboard_get, this, _1, _2),
+        boost::bind(&usrp2_mboard_impl::rx_dboard_set, this, _1, _2)
     );
     _tx_dboard_proxy = wax_obj_proxy::make(
-        boost::bind(&usrp2_impl::tx_dboard_get, this, _1, _2),
-        boost::bind(&usrp2_impl::tx_dboard_set, this, _1, _2)
+        boost::bind(&usrp2_mboard_impl::tx_dboard_get, this, _1, _2),
+        boost::bind(&usrp2_mboard_impl::tx_dboard_set, this, _1, _2)
     );
 
     //init the subdevs in use (use the first subdevice)
@@ -62,7 +62,7 @@ void usrp2_impl::dboard_init(void){
 /***********************************************************************
  * RX DBoard Properties
  **********************************************************************/
-void usrp2_impl::rx_dboard_get(const wax::obj &key_, wax::obj &val){
+void usrp2_mboard_impl::rx_dboard_get(const wax::obj &key_, wax::obj &val){
     wax::obj key; std::string name;
     boost::tie(key, name) = extract_named_prop(key_);
 
@@ -96,7 +96,7 @@ void usrp2_impl::rx_dboard_get(const wax::obj &key_, wax::obj &val){
     }
 }
 
-void usrp2_impl::rx_dboard_set(const wax::obj &key, const wax::obj &val){
+void usrp2_mboard_impl::rx_dboard_set(const wax::obj &key, const wax::obj &val){
     switch(key.as<dboard_prop_t>()){
     case DBOARD_PROP_USED_SUBDEVS:{
             _rx_subdevs_in_use = val.as<prop_names_t>();
@@ -122,7 +122,7 @@ void usrp2_impl::rx_dboard_set(const wax::obj &key, const wax::obj &val){
 /***********************************************************************
  * TX DBoard Properties
  **********************************************************************/
-void usrp2_impl::tx_dboard_get(const wax::obj &key_, wax::obj &val){
+void usrp2_mboard_impl::tx_dboard_get(const wax::obj &key_, wax::obj &val){
     wax::obj key; std::string name;
     boost::tie(key, name) = extract_named_prop(key_);
 
@@ -156,7 +156,7 @@ void usrp2_impl::tx_dboard_get(const wax::obj &key_, wax::obj &val){
     }
 }
 
-void usrp2_impl::tx_dboard_set(const wax::obj &key, const wax::obj &val){
+void usrp2_mboard_impl::tx_dboard_set(const wax::obj &key, const wax::obj &val){
     switch(key.as<dboard_prop_t>()){
     case DBOARD_PROP_USED_SUBDEVS:{
             _tx_subdevs_in_use = val.as<prop_names_t>();
diff --git a/host/lib/usrp/usrp2/dsp_impl.cpp b/host/lib/usrp/usrp2/dsp_impl.cpp
index 367cde2e1..c315a2eec 100644
--- a/host/lib/usrp/usrp2/dsp_impl.cpp
+++ b/host/lib/usrp/usrp2/dsp_impl.cpp
@@ -41,11 +41,11 @@ pick_closest_rate(double exact_rate, const std::vector<rate_t> &rates){
     return closest_match;
 }
 
-void usrp2_impl::init_ddc_config(void){
+void usrp2_mboard_impl::init_ddc_config(void){
     //create the ddc in the rx dsp dict
     _rx_dsp_proxy = wax_obj_proxy::make(
-        boost::bind(&usrp2_impl::ddc_get, this, _1, _2),
-        boost::bind(&usrp2_impl::ddc_set, this, _1, _2)
+        boost::bind(&usrp2_mboard_impl::ddc_get, this, _1, _2),
+        boost::bind(&usrp2_mboard_impl::ddc_set, this, _1, _2)
     );
 
     //initial config and update
@@ -56,7 +56,7 @@ void usrp2_impl::init_ddc_config(void){
 /***********************************************************************
  * DDC Properties
  **********************************************************************/
-void usrp2_impl::ddc_get(const wax::obj &key, wax::obj &val){
+void usrp2_mboard_impl::ddc_get(const wax::obj &key, wax::obj &val){
     switch(key.as<dsp_prop_t>()){
     case DSP_PROP_NAME:
         val = std::string("usrp2 ddc0");
@@ -82,7 +82,7 @@ void usrp2_impl::ddc_get(const wax::obj &key, wax::obj &val){
     }
 }
 
-void usrp2_impl::ddc_set(const wax::obj &key, const wax::obj &val){
+void usrp2_mboard_impl::ddc_set(const wax::obj &key, const wax::obj &val){
     switch(key.as<dsp_prop_t>()){
 
     case DSP_PROP_FREQ_SHIFT:{
@@ -116,11 +116,11 @@ void usrp2_impl::ddc_set(const wax::obj &key, const wax::obj &val){
 /***********************************************************************
  * DUC Helper Methods
  **********************************************************************/
-void usrp2_impl::init_duc_config(void){
+void usrp2_mboard_impl::init_duc_config(void){
     //create the duc in the tx dsp dict
     _tx_dsp_proxy = wax_obj_proxy::make(
-        boost::bind(&usrp2_impl::duc_get, this, _1, _2),
-        boost::bind(&usrp2_impl::duc_set, this, _1, _2)
+        boost::bind(&usrp2_mboard_impl::duc_get, this, _1, _2),
+        boost::bind(&usrp2_mboard_impl::duc_set, this, _1, _2)
     );
 
     //initial config and update
@@ -131,7 +131,7 @@ void usrp2_impl::init_duc_config(void){
 /***********************************************************************
  * DUC Properties
  **********************************************************************/
-void usrp2_impl::duc_get(const wax::obj &key, wax::obj &val){
+void usrp2_mboard_impl::duc_get(const wax::obj &key, wax::obj &val){
     switch(key.as<dsp_prop_t>()){
     case DSP_PROP_NAME:
         val = std::string("usrp2 duc0");
@@ -157,7 +157,7 @@ void usrp2_impl::duc_get(const wax::obj &key, wax::obj &val){
     }
 }
 
-void usrp2_impl::duc_set(const wax::obj &key, const wax::obj &val){
+void usrp2_mboard_impl::duc_set(const wax::obj &key, const wax::obj &val){
     switch(key.as<dsp_prop_t>()){
 
     case DSP_PROP_FREQ_SHIFT:{
diff --git a/host/lib/usrp/usrp2/fw_common.h b/host/lib/usrp/usrp2/fw_common.h
index 242d268ec..4c66aa41e 100644
--- a/host/lib/usrp/usrp2/fw_common.h
+++ b/host/lib/usrp/usrp2/fw_common.h
@@ -38,7 +38,7 @@ extern "C" {
 
 //defines the protocol version in this shared header
 //increment this value when the protocol is changed
-#define USRP2_PROTO_VERSION 4
+#define USRP2_PROTO_VERSION 5
 
 //used to differentiate control packets over data port
 #define USRP2_INVALID_VRT_HEADER 0
@@ -111,7 +111,9 @@ typedef struct{
         struct {
             _SINS_ uint32_t addr;
             _SINS_ uint32_t data;
-            _SINS_ uint8_t num_bytes; //1, 2, 4
+            _SINS_ uint32_t addrhi;
+            _SINS_ uint32_t datahi;
+            _SINS_ uint8_t num_bytes; //1, 2, 4, 8
         } poke_args;
     } data;
 } usrp2_ctrl_data_t;
diff --git a/host/lib/usrp/usrp2/io_impl.cpp b/host/lib/usrp/usrp2/io_impl.cpp
index aa0f63321..c96528694 100644
--- a/host/lib/usrp/usrp2/io_impl.cpp
+++ b/host/lib/usrp/usrp2/io_impl.cpp
@@ -20,7 +20,7 @@
 #include "usrp2_regs.hpp"
 #include <uhd/utils/thread_priority.hpp>
 #include <uhd/transport/convert_types.hpp>
-#include <uhd/transport/bounded_buffer.hpp>
+#include <uhd/transport/alignment_buffer.hpp>
 #include <boost/format.hpp>
 #include <boost/asio.hpp> //htonl and ntohl
 #include <boost/bind.hpp>
@@ -34,56 +34,81 @@ namespace asio = boost::asio;
 
 /***********************************************************************
  * io impl details (internal to this file)
+ * - pirate crew
+ * - alignment buffer
+ * - thread loop
+ * - vrt packet handler states
  **********************************************************************/
 struct usrp2_impl::io_impl{
+    typedef alignment_buffer<managed_recv_buffer::sptr, time_spec_t> alignment_buffer_type;
 
-    io_impl(zero_copy_if::sptr zc_if);
-    ~io_impl(void);
+    io_impl(size_t num_frames, size_t width):
+        packet_handler_recv_state(width),
+        recv_pirate_booty(alignment_buffer_type::make(num_frames, width))
+    {
+        /* NOP */
+    }
+
+    ~io_impl(void){
+        recv_pirate_crew_raiding = false;
+        recv_pirate_crew.interrupt_all();
+        recv_pirate_crew.join_all();
+    }
 
-    managed_recv_buffer::sptr get_recv_buff(void);
+    bool get_recv_buffs(vrt_packet_handler::managed_recv_buffs_t &buffs){
+        boost::this_thread::disable_interruption di; //disable because the wait can throw
+        return recv_pirate_booty->pop_elems_with_timed_wait(buffs, boost::posix_time::milliseconds(100));
+    }
 
     //state management for the vrt packet handler code
     vrt_packet_handler::recv_state packet_handler_recv_state;
     vrt_packet_handler::send_state packet_handler_send_state;
 
-    //methods and variables for the recv pirate
-    void recv_pirate_loop(zero_copy_if::sptr zc_if);
-    boost::thread *recv_pirate_thread; bool recv_pirate_running;
-    bounded_buffer<managed_recv_buffer::sptr>::sptr recv_pirate_booty;
+    //methods and variables for the pirate crew
+    void recv_pirate_loop(zero_copy_if::sptr, usrp2_mboard_impl::sptr, size_t);
+    boost::thread_group recv_pirate_crew;
+    bool recv_pirate_crew_raiding;
+    alignment_buffer_type::sptr recv_pirate_booty;
 };
 
-usrp2_impl::io_impl::io_impl(zero_copy_if::sptr zc_if){
-    //create a large enough booty
-    size_t num_frames = zc_if->get_num_recv_frames();
-    std::cout << "Recv pirate num frames: " << num_frames << std::endl;
-    recv_pirate_booty = bounded_buffer<managed_recv_buffer::sptr>::make(num_frames);
-
-    //create a new pirate thread (yarr!!)
-    recv_pirate_thread = new boost::thread(
-        boost::bind(&usrp2_impl::io_impl::recv_pirate_loop, this, zc_if)
-    );
-}
-
-usrp2_impl::io_impl::~io_impl(void){
-    recv_pirate_running = false;
-    recv_pirate_thread->interrupt();
-    recv_pirate_thread->join();
-    delete recv_pirate_thread;
-}
-
-managed_recv_buffer::sptr usrp2_impl::io_impl::get_recv_buff(void){
-    managed_recv_buffer::sptr buff;
-    boost::this_thread::disable_interruption di; //disable because the wait can throw
-    recv_pirate_booty->pop_with_timed_wait(buff, boost::posix_time::milliseconds(100));
-    return buff; //a timeout means that we return a null sptr...
-}
-
-void usrp2_impl::io_impl::recv_pirate_loop(zero_copy_if::sptr zc_if){
+/***********************************************************************
+ * Receive Pirate Loop
+ * - while raiding, loot for recv buffers
+ * - put booty into the alignment buffer
+ **********************************************************************/
+void usrp2_impl::io_impl::recv_pirate_loop(
+    zero_copy_if::sptr zc_if,
+    usrp2_mboard_impl::sptr mboard,
+    size_t index
+){
     set_thread_priority_safe();
-    recv_pirate_running = true;
-    while(recv_pirate_running){
+    recv_pirate_crew_raiding = true;
+    while(recv_pirate_crew_raiding){
         managed_recv_buffer::sptr buff = zc_if->get_recv_buff();
-        if (buff->size()) recv_pirate_booty->push_with_pop_on_full(buff);
+        if (buff->size() == 0) continue; //ignore timeout buffers
+
+        try{
+            //extract the vrt header packet info
+            vrt::if_packet_info_t if_packet_info;
+            if_packet_info.num_packet_words32 = buff->size()/sizeof(boost::uint32_t);
+            vrt::if_hdr_unpack_be(buff->cast<const boost::uint32_t *>(), if_packet_info);
+
+            //extract the timespec and round to the nearest packet
+            UHD_ASSERT_THROW(if_packet_info.has_tsi and if_packet_info.has_tsf);
+
+            //size_t pkt_dur_ticks = mboard->get_master_clock_freq() * 1; //TODO FIXME
+            //size_t(if_packet_info.tsf) - size_t(if_packet_info.tsf)%pkt_dur_ticks
+            //the idea is to round the time specs to packet boundaries to avoid the issue
+            //of never getting alignment when things are not locked properly
+            time_spec_t time(
+                time_t(if_packet_info.tsi), size_t(if_packet_info.tsf), mboard->get_master_clock_freq()
+            );
+
+            //push the packet into the buffer with the new time
+            recv_pirate_booty->push_with_pop_on_full(buff, time, index);
+        }catch(const std::exception &e){
+            std::cerr << "Error (usrp2 recv pirate loop): " << e.what() << std::endl;
+        }
     }
 }
 
@@ -91,58 +116,64 @@ void usrp2_impl::io_impl::recv_pirate_loop(zero_copy_if::sptr zc_if){
  * Helper Functions
  **********************************************************************/
 void usrp2_impl::io_init(void){
-    //setup rx otw type
-    _rx_otw_type.width = 16;
-    _rx_otw_type.shift = 0;
-    _rx_otw_type.byteorder = otw_type_t::BO_BIG_ENDIAN;
+    //send a small data packet so the usrp2 knows the udp source port
+    for(size_t i = 0; i < _data_transports.size(); i++){
+        managed_send_buffer::sptr send_buff = _data_transports[i]->get_send_buff();
+        boost::uint32_t data = htonl(USRP2_INVALID_VRT_HEADER);
+        memcpy(send_buff->cast<void*>(), &data, sizeof(data));
+        send_buff->commit(sizeof(data));
+    }
 
-    //setup tx otw type
-    _tx_otw_type.width = 16;
-    _tx_otw_type.shift = 0;
-    _tx_otw_type.byteorder = otw_type_t::BO_BIG_ENDIAN;
+    //the number of recv frames is the number for the first transport
+    //the assumption is that all data transports should be identical
+    size_t num_frames = _data_transports.front()->get_num_recv_frames();
 
-    //send a small data packet so the usrp2 knows the udp source port
-    managed_send_buffer::sptr send_buff = _data_transport->get_send_buff();
-    boost::uint32_t data = htonl(USRP2_INVALID_VRT_HEADER);
-    memcpy(send_buff->cast<void*>(), &data, sizeof(data));
-    send_buff->commit(sizeof(data));
+    //create new io impl
+    _io_impl = UHD_PIMPL_MAKE(io_impl, (num_frames, _data_transports.size()));
+
+    //create a new pirate thread for each zc if (yarr!!)
+    for (size_t i = 0; i < _data_transports.size(); i++){
+        _io_impl->recv_pirate_crew.create_thread(boost::bind(
+            &usrp2_impl::io_impl::recv_pirate_loop,
+            _io_impl, _data_transports.at(i),
+            _mboards.at(i), i
+        ));
+    }
 
-    //setup RX DSP regs
     std::cout << "RX samples per packet: " << get_max_recv_samps_per_packet() << std::endl;
-    _iface->poke32(U2_REG_RX_CTRL_NSAMPS_PER_PKT, get_max_recv_samps_per_packet());
-    _iface->poke32(U2_REG_RX_CTRL_NCHANNELS, 1);
-    _iface->poke32(U2_REG_RX_CTRL_CLEAR_OVERRUN, 1); //reset
-    _iface->poke32(U2_REG_RX_CTRL_VRT_HEADER, 0
-        | (0x1 << 28) //if data with stream id
-        | (0x1 << 26) //has trailer
-        | (0x3 << 22) //integer time other
-        | (0x1 << 20) //fractional time sample count
-    );
-    _iface->poke32(U2_REG_RX_CTRL_VRT_STREAM_ID, 0);
-    _iface->poke32(U2_REG_RX_CTRL_VRT_TRAILER, 0);
-
     std::cout << "TX samples per packet: " << get_max_send_samps_per_packet() << std::endl;
-
-    //create new io impl
-    _io_impl = UHD_PIMPL_MAKE(io_impl, (_data_transport));
+    std::cout << "Recv pirate num frames: " << num_frames << std::endl;
 }
 
 /***********************************************************************
  * Send Data
  **********************************************************************/
+bool get_send_buffs(
+    const std::vector<udp_zero_copy::sptr> &trans,
+    vrt_packet_handler::managed_send_buffs_t &buffs
+){
+    UHD_ASSERT_THROW(trans.size() == buffs.size());
+    for (size_t i = 0; i < buffs.size(); i++){
+        buffs[i] = trans[i]->get_send_buff();
+    }
+    return true;
+}
+
 size_t usrp2_impl::send(
-    const asio::const_buffer &buff,
+    const std::vector<const void *> &buffs,
+    size_t num_samps,
     const tx_metadata_t &metadata,
     const io_type_t &io_type,
     send_mode_t send_mode
 ){
     return vrt_packet_handler::send(
-        _io_impl->packet_handler_send_state, //last state of the send handler
-        buff, metadata, send_mode,  //buffer to empty and samples metadata
-        io_type, _tx_otw_type,      //input and output types to convert
-        get_master_clock_freq(),    //master clock tick rate
-        uhd::transport::vrt::pack_be,
-        boost::bind(&zero_copy_if::get_send_buff, _data_transport),
+        _io_impl->packet_handler_send_state,       //last state of the send handler
+        buffs, num_samps,                          //buffer to fill
+        metadata, send_mode,                       //samples metadata
+        io_type, _io_helper.get_tx_otw_type(),     //input and output types to convert
+        _mboards.front()->get_master_clock_freq(), //master clock tick rate
+        uhd::transport::vrt::if_hdr_pack_be,
+        boost::bind(&get_send_buffs, _data_transports, _1),
         get_max_send_samps_per_packet()
     );
 }
@@ -151,17 +182,19 @@ size_t usrp2_impl::send(
  * Receive Data
  **********************************************************************/
 size_t usrp2_impl::recv(
-    const asio::mutable_buffer &buff,
+    const std::vector<void *> &buffs,
+    size_t num_samps,
     rx_metadata_t &metadata,
     const io_type_t &io_type,
     recv_mode_t recv_mode
 ){
     return vrt_packet_handler::recv(
-        _io_impl->packet_handler_recv_state, //last state of the recv handler
-        buff, metadata, recv_mode,  //buffer to fill and samples metadata
-        io_type, _rx_otw_type,      //input and output types to convert
-        get_master_clock_freq(),    //master clock tick rate
-        uhd::transport::vrt::unpack_be,
-        boost::bind(&usrp2_impl::io_impl::get_recv_buff, _io_impl)
+        _io_impl->packet_handler_recv_state,       //last state of the recv handler
+        buffs, num_samps,                          //buffer to fill
+        metadata, recv_mode,                       //samples metadata
+        io_type, _io_helper.get_rx_otw_type(),     //input and output types to convert
+        _mboards.front()->get_master_clock_freq(), //master clock tick rate
+        uhd::transport::vrt::if_hdr_unpack_be,
+        boost::bind(&usrp2_impl::io_impl::get_recv_buffs, _io_impl, _1)
     );
 }
diff --git a/host/lib/usrp/usrp2/mboard_impl.cpp b/host/lib/usrp/usrp2/mboard_impl.cpp
index 78fc5dc23..952954286 100644
--- a/host/lib/usrp/usrp2/mboard_impl.cpp
+++ b/host/lib/usrp/usrp2/mboard_impl.cpp
@@ -25,21 +25,77 @@
 #include <boost/bind.hpp>
 #include <boost/asio/ip/address_v4.hpp>
 #include <boost/assign/list_of.hpp>
+#include <iostream>
 
 using namespace uhd;
 using namespace uhd::usrp;
 
 /***********************************************************************
- * Helper Methods
+ * Structors
  **********************************************************************/
-void usrp2_impl::mboard_init(void){
-    _mboard_proxy = wax_obj_proxy::make(
-        boost::bind(&usrp2_impl::mboard_get, this, _1, _2),
-        boost::bind(&usrp2_impl::mboard_set, this, _1, _2)
+usrp2_mboard_impl::usrp2_mboard_impl(
+    size_t index,
+    transport::udp_simple::sptr ctrl_transport,
+    const usrp2_io_helper &io_helper
+):
+    _index(index),
+    _io_helper(io_helper)
+{
+    //make a new interface for usrp2 stuff
+    _iface = usrp2_iface::make(ctrl_transport);
+    _clock_ctrl = usrp2_clock_ctrl::make(_iface);
+    _codec_ctrl = usrp2_codec_ctrl::make(_iface);
+    _serdes_ctrl = usrp2_serdes_ctrl::make(_iface);
+
+    //TODO move to dsp impl...
+    //load the allowed decim/interp rates
+    //_USRP2_RATES = range(4, 128+1, 1) + range(130, 256+1, 2) + range(260, 512+1, 4)
+    _allowed_decim_and_interp_rates.clear();
+    for (size_t i = 4; i <= 128; i+=1){
+        _allowed_decim_and_interp_rates.push_back(i);
+    }
+    for (size_t i = 130; i <= 256; i+=2){
+        _allowed_decim_and_interp_rates.push_back(i);
+    }
+    for (size_t i = 260; i <= 512; i+=4){
+        _allowed_decim_and_interp_rates.push_back(i);
+    }
+
+    //setup the vrt rx registers
+    _iface->poke32(U2_REG_RX_CTRL_NSAMPS_PER_PKT, _io_helper.get_max_recv_samps_per_packet());
+    _iface->poke32(U2_REG_RX_CTRL_NCHANNELS, 1);
+    _iface->poke32(U2_REG_RX_CTRL_CLEAR_OVERRUN, 1); //reset
+    _iface->poke32(U2_REG_RX_CTRL_VRT_HEADER, 0
+        | (0x1 << 28) //if data with stream id
+        | (0x1 << 26) //has trailer
+        | (0x3 << 22) //integer time other
+        | (0x1 << 20) //fractional time sample count
     );
+    _iface->poke32(U2_REG_RX_CTRL_VRT_STREAM_ID, 0);
+    _iface->poke32(U2_REG_RX_CTRL_VRT_TRAILER, 0);
+    _iface->poke32(U2_REG_TIME64_TPS, size_t(get_master_clock_freq()));
+
+    //init the ddc
+    init_ddc_config();
+
+    //init the duc
+    init_duc_config();
+
+    //initialize the clock configuration
+    init_clock_config();
+
+    //init the tx and rx dboards (do last)
+    dboard_init();
 }
 
-void usrp2_impl::init_clock_config(void){
+usrp2_mboard_impl::~usrp2_mboard_impl(void){
+    /* NOP */
+}
+
+/***********************************************************************
+ * Helper Methods
+ **********************************************************************/
+void usrp2_mboard_impl::init_clock_config(void){
     //setup the clock configuration settings
     _clock_config.ref_source = clock_config_t::REF_INT;
     _clock_config.pps_source = clock_config_t::PPS_SMA;
@@ -49,7 +105,7 @@ void usrp2_impl::init_clock_config(void){
     update_clock_config();
 }
 
-void usrp2_impl::update_clock_config(void){
+void usrp2_mboard_impl::update_clock_config(void){
     boost::uint32_t pps_flags = 0;
 
     //translate pps source enums
@@ -82,19 +138,19 @@ void usrp2_impl::update_clock_config(void){
     _clock_ctrl->enable_external_ref(use_external);
 }
 
-void usrp2_impl::set_time_spec(const time_spec_t &time_spec, bool now){
+void usrp2_mboard_impl::set_time_spec(const time_spec_t &time_spec, bool now){
     //set the ticks
-    _iface->poke32(U2_REG_TIME64_TICKS, time_spec.get_ticks(get_master_clock_freq()));
+    _iface->poke32(U2_REG_TIME64_TICKS, time_spec.get_tick_count(get_master_clock_freq()));
 
     //set the flags register
     boost::uint32_t imm_flags = (now)? U2_FLAG_TIME64_LATCH_NOW : U2_FLAG_TIME64_LATCH_NEXT_PPS;
     _iface->poke32(U2_REG_TIME64_IMM, imm_flags);
 
     //set the seconds (latches in all 3 registers)
-    _iface->poke32(U2_REG_TIME64_SECS, time_spec.secs);
+    _iface->poke32(U2_REG_TIME64_SECS, boost::uint32_t(time_spec.get_full_secs()));
 }
 
-void usrp2_impl::issue_ddc_stream_cmd(const stream_cmd_t &stream_cmd){
+void usrp2_mboard_impl::issue_ddc_stream_cmd(const stream_cmd_t &stream_cmd){
     UHD_ASSERT_THROW(stream_cmd.num_samps <= U2_REG_RX_CTRL_MAX_SAMPS_PER_CMD);
 
     //setup the mode to instruction flags
@@ -113,19 +169,19 @@ void usrp2_impl::issue_ddc_stream_cmd(const stream_cmd_t &stream_cmd){
 
     //issue the stream command
     _iface->poke32(U2_REG_RX_CTRL_STREAM_CMD, U2_REG_RX_CTRL_MAKE_CMD(
-        (inst_samps)? stream_cmd.num_samps : ((inst_chain)? get_max_recv_samps_per_packet() : 1),
+        (inst_samps)? stream_cmd.num_samps : ((inst_chain)? _io_helper.get_max_recv_samps_per_packet() : 1),
         (stream_cmd.stream_now)? 1 : 0,
         (inst_chain)? 1 : 0,
         (inst_reload)? 1 : 0
     ));
-    _iface->poke32(U2_REG_RX_CTRL_TIME_SECS,  stream_cmd.time_spec.secs);
-    _iface->poke32(U2_REG_RX_CTRL_TIME_TICKS, stream_cmd.time_spec.get_ticks(get_master_clock_freq()));
+    _iface->poke32(U2_REG_RX_CTRL_TIME_SECS,  boost::uint32_t(stream_cmd.time_spec.get_full_secs()));
+    _iface->poke32(U2_REG_RX_CTRL_TIME_TICKS, stream_cmd.time_spec.get_tick_count(get_master_clock_freq()));
 }
 
 /***********************************************************************
  * MBoard Get Properties
  **********************************************************************/
-void usrp2_impl::mboard_get(const wax::obj &key_, wax::obj &val){
+void usrp2_mboard_impl::get(const wax::obj &key_, wax::obj &val){
     wax::obj key; std::string name;
     boost::tie(key, name) = extract_named_prop(key_);
 
@@ -148,7 +204,7 @@ void usrp2_impl::mboard_get(const wax::obj &key_, wax::obj &val){
     //handle the get request conditioned on the key
     switch(key.as<mboard_prop_t>()){
     case MBOARD_PROP_NAME:
-        val = std::string("usrp2 mboard");
+        val = str(boost::format("usrp2 mboard %d") % _index);
         return;
 
     case MBOARD_PROP_OTHERS:{
@@ -200,6 +256,16 @@ void usrp2_impl::mboard_get(const wax::obj &key_, wax::obj &val){
         val = _clock_config;
         return;
 
+    case MBOARD_PROP_TIME_NOW:{
+            usrp2_iface::pair64 time64(
+                _iface->peek64(U2_REG_TIME64_SECS_RB, U2_REG_TIME64_TICKS_RB)
+            );
+            val = time_spec_t(
+                time64.first, time64.second, get_master_clock_freq()
+            );
+        }
+        return;
+
     default: UHD_THROW_PROP_GET_ERROR();
     }
 }
@@ -207,7 +273,7 @@ void usrp2_impl::mboard_get(const wax::obj &key_, wax::obj &val){
 /***********************************************************************
  * MBoard Set Properties
  **********************************************************************/
-void usrp2_impl::mboard_set(const wax::obj &key, const wax::obj &val){
+void usrp2_mboard_impl::set(const wax::obj &key, const wax::obj &val){
     //handle the other props
     if (key.type() == typeid(std::string)){
         if (key.as<std::string>() == "mac-addr"){
diff --git a/host/lib/usrp/usrp2/usrp2_iface.cpp b/host/lib/usrp/usrp2/usrp2_iface.cpp
index 83e98904e..faf4a5c7e 100644
--- a/host/lib/usrp/usrp2/usrp2_iface.cpp
+++ b/host/lib/usrp/usrp2/usrp2_iface.cpp
@@ -59,6 +59,20 @@ public:
         return this->peek<boost::uint16_t>(addr);
     }
 
+    pair64 peek64(boost::uint32_t addrlo, boost::uint32_t addrhi){
+        //setup the out data
+        usrp2_ctrl_data_t out_data;
+        out_data.id = htonl(USRP2_CTRL_ID_PEEK_AT_THIS_REGISTER_FOR_ME_BRO);
+        out_data.data.poke_args.addr = htonl(addrlo);
+        out_data.data.poke_args.addrhi = htonl(addrhi);
+        out_data.data.poke_args.num_bytes = sizeof(boost::uint64_t);
+
+        //send and recv
+        usrp2_ctrl_data_t in_data = this->ctrl_send_and_recv(out_data);
+        UHD_ASSERT_THROW(ntohl(in_data.id) == USRP2_CTRL_ID_WOAH_I_DEFINITELY_PEEKED_IT_DUDE);
+        return pair64(ntohl(in_data.data.poke_args.data), ntohl(in_data.data.poke_args.datahi));
+    }
+
 /***********************************************************************
  * SPI
  **********************************************************************/
@@ -86,7 +100,7 @@ public:
 
         //send and recv
         usrp2_ctrl_data_t in_data = this->ctrl_send_and_recv(out_data);
-        UHD_ASSERT_THROW(htonl(in_data.id) == USRP2_CTRL_ID_OMG_TRANSACTED_SPI_DUDE);
+        UHD_ASSERT_THROW(ntohl(in_data.id) == USRP2_CTRL_ID_OMG_TRANSACTED_SPI_DUDE);
 
         return ntohl(in_data.data.spi_args.data);
     }
@@ -109,7 +123,7 @@ public:
 
         //send and recv
         usrp2_ctrl_data_t in_data = this->ctrl_send_and_recv(out_data);
-        UHD_ASSERT_THROW(htonl(in_data.id) == USRP2_CTRL_ID_COOL_IM_DONE_I2C_WRITE_DUDE);
+        UHD_ASSERT_THROW(ntohl(in_data.id) == USRP2_CTRL_ID_COOL_IM_DONE_I2C_WRITE_DUDE);
     }
 
     byte_vector_t read_i2c(boost::uint8_t addr, size_t num_bytes){
@@ -124,7 +138,7 @@ public:
 
         //send and recv
         usrp2_ctrl_data_t in_data = this->ctrl_send_and_recv(out_data);
-        UHD_ASSERT_THROW(htonl(in_data.id) == USRP2_CTRL_ID_HERES_THE_I2C_DATA_DUDE);
+        UHD_ASSERT_THROW(ntohl(in_data.id) == USRP2_CTRL_ID_HERES_THE_I2C_DATA_DUDE);
         UHD_ASSERT_THROW(in_data.data.i2c_args.addr = num_bytes);
 
         //copy out the data
@@ -187,7 +201,7 @@ private:
 
         //send and recv
         usrp2_ctrl_data_t in_data = this->ctrl_send_and_recv(out_data);
-        UHD_ASSERT_THROW(htonl(in_data.id) == USRP2_CTRL_ID_OMG_POKED_REGISTER_SO_BAD_DUDE);
+        UHD_ASSERT_THROW(ntohl(in_data.id) == USRP2_CTRL_ID_OMG_POKED_REGISTER_SO_BAD_DUDE);
     }
 
     template <class T> T peek(boost::uint32_t addr){
@@ -199,8 +213,8 @@ private:
 
         //send and recv
         usrp2_ctrl_data_t in_data = this->ctrl_send_and_recv(out_data);
-        UHD_ASSERT_THROW(htonl(in_data.id) == USRP2_CTRL_ID_WOAH_I_DEFINITELY_PEEKED_IT_DUDE);
-        return T(ntohl(out_data.data.poke_args.data));
+        UHD_ASSERT_THROW(ntohl(in_data.id) == USRP2_CTRL_ID_WOAH_I_DEFINITELY_PEEKED_IT_DUDE);
+        return T(ntohl(in_data.data.poke_args.data));
     }
 
 };
diff --git a/host/lib/usrp/usrp2/usrp2_iface.hpp b/host/lib/usrp/usrp2/usrp2_iface.hpp
index 7b2a3a89d..9cc32104e 100644
--- a/host/lib/usrp/usrp2/usrp2_iface.hpp
+++ b/host/lib/usrp/usrp2/usrp2_iface.hpp
@@ -23,6 +23,7 @@
 #include <boost/shared_ptr.hpp>
 #include <boost/utility.hpp>
 #include <boost/cstdint.hpp>
+#include <utility>
 #include "fw_common.h"
 
 ////////////////////////////////////////////////////////////////////////
@@ -49,6 +50,7 @@
 class usrp2_iface : public uhd::i2c_iface, boost::noncopyable{
 public:
     typedef boost::shared_ptr<usrp2_iface> sptr;
+    typedef std::pair<boost::uint32_t, boost::uint32_t> pair64;
 
     /*!
      * Make a new usrp2 interface with the control transport.
@@ -65,6 +67,14 @@ public:
     virtual usrp2_ctrl_data_t ctrl_send_and_recv(const usrp2_ctrl_data_t &data) = 0;
 
     /*!
+     * Read a dual register (64 bits)
+     * \param addrlo the address for the low-32 bits
+     * \param addrhi the address for the high-32 bits
+     * \return a pair of 32 bit integers lo, hi
+     */
+    virtual pair64 peek64(boost::uint32_t addrlo, boost::uint32_t addrhi) = 0;
+
+    /*!
      * Write a register (32 bits)
      * \param addr the address
      * \param data the 32bit data
diff --git a/host/lib/usrp/usrp2/usrp2_impl.cpp b/host/lib/usrp/usrp2/usrp2_impl.cpp
index 36c264c3c..3402c26b1 100644
--- a/host/lib/usrp/usrp2/usrp2_impl.cpp
+++ b/host/lib/usrp/usrp2/usrp2_impl.cpp
@@ -21,6 +21,7 @@
 #include <uhd/usrp/device_props.hpp>
 #include <uhd/utils/assert.hpp>
 #include <uhd/utils/static.hpp>
+#include <boost/algorithm/string.hpp>
 #include <boost/assign/list_of.hpp>
 #include <boost/format.hpp>
 #include <boost/foreach.hpp>
@@ -34,14 +35,23 @@ using namespace uhd::usrp;
 using namespace uhd::transport;
 namespace asio = boost::asio;
 
-UHD_STATIC_BLOCK(register_usrp2_device){
-    device::register_device(&usrp2::find, &usrp2::make);
+/***********************************************************************
+ * Helper Functions
+ **********************************************************************/
+std::vector<std::string> split_addrs(const std::string &addrs_str){
+    std::vector<std::string> addrs;
+    boost::split(addrs, addrs_str, boost::is_any_of("\t "));
+    return addrs;
+}
+
+template <class T> std::string num2str(T num){
+    return boost::lexical_cast<std::string>(num);
 }
 
 /***********************************************************************
  * Discovery over the udp transport
  **********************************************************************/
-uhd::device_addrs_t usrp2::find(const device_addr_t &hint){
+static uhd::device_addrs_t usrp2_find(const device_addr_t &hint){
     device_addrs_t usrp2_addrs;
 
     //return an empty list of addresses when type is set to non-usrp2
@@ -58,7 +68,7 @@ uhd::device_addrs_t usrp2::find(const device_addr_t &hint){
             new_hint["addr"] = if_addrs.bcast;
 
             //call discover with the new hint and append results
-            device_addrs_t new_usrp2_addrs = usrp2::find(new_hint);
+            device_addrs_t new_usrp2_addrs = usrp2_find(new_hint);
             usrp2_addrs.insert(usrp2_addrs.begin(),
                 new_usrp2_addrs.begin(), new_usrp2_addrs.end()
             );
@@ -66,6 +76,16 @@ uhd::device_addrs_t usrp2::find(const device_addr_t &hint){
         return usrp2_addrs;
     }
 
+    //if there are multiple addresses, just return good, dont test
+    std::vector<std::string> addrs = split_addrs(hint["addr"]);
+    if (addrs.size() > 1){
+        device_addr_t new_addr;
+        new_addr["type"] = "usrp2";
+        new_addr["addr"] = hint["addr"];
+        usrp2_addrs.push_back(new_addr);
+        return usrp2_addrs;
+    }
+
     //create a udp transport to communicate
     std::string ctrl_port = boost::lexical_cast<std::string>(USRP2_UDP_CTRL_PORT);
     udp_simple::sptr udp_transport = udp_simple::make_broadcast(
@@ -107,16 +127,7 @@ uhd::device_addrs_t usrp2::find(const device_addr_t &hint){
 /***********************************************************************
  * Make
  **********************************************************************/
-template <class T> std::string num2str(T num){
-    return boost::lexical_cast<std::string>(num);
-}
-
-device::sptr usrp2::make(const device_addr_t &device_addr){
-    //create a control transport
-    udp_simple::sptr ctrl_transport = udp_simple::make_connected(
-        device_addr["addr"], num2str(USRP2_UDP_CTRL_PORT)
-    );
-
+static device::sptr usrp2_make(const device_addr_t &device_addr){
     //extract the receive and send buffer sizes
     size_t recv_buff_size = 0, send_buff_size= 0 ;
     if (device_addr.has_key("recv_buff_size")){
@@ -126,62 +137,48 @@ device::sptr usrp2::make(const device_addr_t &device_addr){
         send_buff_size = size_t(boost::lexical_cast<double>(device_addr["send_buff_size"]));
     }
 
-    //create a data transport
-    udp_zero_copy::sptr data_transport = udp_zero_copy::make(
-        device_addr["addr"],
-        num2str(USRP2_UDP_DATA_PORT),
-        recv_buff_size,
-        send_buff_size
-    );
+    //create a ctrl and data transport for each address
+    std::vector<udp_simple::sptr> ctrl_transports;
+    std::vector<udp_zero_copy::sptr> data_transports;
+
+    BOOST_FOREACH(const std::string &addr, split_addrs(device_addr["addr"])){
+        ctrl_transports.push_back(udp_simple::make_connected(
+            addr, num2str(USRP2_UDP_CTRL_PORT)
+        ));
+        data_transports.push_back(udp_zero_copy::make(
+            addr, num2str(USRP2_UDP_DATA_PORT),
+            recv_buff_size, send_buff_size
+        ));
+    }
 
     //create the usrp2 implementation guts
     return device::sptr(
-        new usrp2_impl(ctrl_transport, data_transport)
+        new usrp2_impl(ctrl_transports, data_transports)
     );
 }
 
+UHD_STATIC_BLOCK(register_usrp2_device){
+    device::register_device(&usrp2_find, &usrp2_make);
+}
+
 /***********************************************************************
  * Structors
  **********************************************************************/
 usrp2_impl::usrp2_impl(
-    udp_simple::sptr ctrl_transport,
-    udp_zero_copy::sptr data_transport
-){
-    _data_transport = data_transport;
-
-    //make a new interface for usrp2 stuff
-    _iface = usrp2_iface::make(ctrl_transport);
-    _clock_ctrl = usrp2_clock_ctrl::make(_iface);
-    _codec_ctrl = usrp2_codec_ctrl::make(_iface);
-    _serdes_ctrl = usrp2_serdes_ctrl::make(_iface);
-
-    //load the allowed decim/interp rates
-    //_USRP2_RATES = range(4, 128+1, 1) + range(130, 256+1, 2) + range(260, 512+1, 4)
-    _allowed_decim_and_interp_rates.clear();
-    for (size_t i = 4; i <= 128; i+=1){
-        _allowed_decim_and_interp_rates.push_back(i);
+    std::vector<udp_simple::sptr> ctrl_transports,
+    std::vector<udp_zero_copy::sptr> data_transports
+):
+    _data_transports(data_transports)
+{
+    //create a new mboard handler for each control transport
+    for(size_t i = 0; i < ctrl_transports.size(); i++){
+        _mboards.push_back(usrp2_mboard_impl::sptr(
+            new usrp2_mboard_impl(i, ctrl_transports[i], _io_helper)
+        ));
+        //use an empty name when there is only one mboard
+        std::string name = (ctrl_transports.size() > 1)? boost::lexical_cast<std::string>(i) : "";
+        _mboard_dict[name] = _mboards.back();
     }
-    for (size_t i = 130; i <= 256; i+=2){
-        _allowed_decim_and_interp_rates.push_back(i);
-    }
-    for (size_t i = 260; i <= 512; i+=4){
-        _allowed_decim_and_interp_rates.push_back(i);
-    }
-
-    //init the mboard
-    mboard_init();
-
-    //init the ddc
-    init_ddc_config();
-
-    //init the duc
-    init_duc_config();
-
-    //initialize the clock configuration
-    init_clock_config();
-
-    //init the tx and rx dboards (do last)
-    dboard_init();
 
     //init the send and recv io
     io_init();
@@ -202,16 +199,16 @@ void usrp2_impl::get(const wax::obj &key_, wax::obj &val){
     //handle the get request conditioned on the key
     switch(key.as<device_prop_t>()){
     case DEVICE_PROP_NAME:
-        val = std::string("usrp2 device");
+        if (_mboards.size() > 1) val = std::string("usrp2 mimo device");
+        else                     val = std::string("usrp2 device");
         return;
 
     case DEVICE_PROP_MBOARD:
-        UHD_ASSERT_THROW(name == "");
-        val = _mboard_proxy->get_link();
+        val = _mboard_dict[name]->get_link();
         return;
 
     case DEVICE_PROP_MBOARD_NAMES:
-        val = prop_names_t(1, "");
+        val = prop_names_t(_mboard_dict.keys());
         return;
 
     default: UHD_THROW_PROP_GET_ERROR();
diff --git a/host/lib/usrp/usrp2/usrp2_impl.hpp b/host/lib/usrp/usrp2/usrp2_impl.hpp
index 2126b9565..42630a3e4 100644
--- a/host/lib/usrp/usrp2/usrp2_impl.hpp
+++ b/host/lib/usrp/usrp2/usrp2_impl.hpp
@@ -22,7 +22,7 @@
 #include "clock_ctrl.hpp"
 #include "codec_ctrl.hpp"
 #include "serdes_ctrl.hpp"
-#include <uhd/usrp/usrp2.hpp>
+#include <uhd/device.hpp>
 #include <uhd/utils/pimpl.hpp>
 #include <uhd/types/dict.hpp>
 #include <uhd/types/otw_type.hpp>
@@ -31,7 +31,7 @@
 #include <uhd/usrp/dboard_eeprom.hpp>
 #include <boost/shared_ptr.hpp>
 #include <boost/function.hpp>
-#include <uhd/transport/vrt.hpp>
+#include <uhd/transport/vrt_if_packet.hpp>
 #include <uhd/transport/udp_zero_copy.hpp>
 #include <uhd/usrp/dboard_manager.hpp>
 
@@ -62,73 +62,84 @@ public:
         return sptr(new wax_obj_proxy(get, set));
     }
 
-    ~wax_obj_proxy(void){
-        /* NOP */
+private:
+    get_t _get; set_t _set;
+    wax_obj_proxy(const get_t &get, const set_t &set): _get(get), _set(set){};
+    void get(const wax::obj &key, wax::obj &val){return _get(key, val);}
+    void set(const wax::obj &key, const wax::obj &val){return _set(key, val);}
+};
+
+/*!
+ * The io helper class encapculates the max packet sizes and otw types.
+ * The otw types are read-only for now, this will be reimplemented
+ * when it becomes possible to change the otw type in the usrp2.
+ */
+class usrp2_io_helper{
+public:
+    usrp2_io_helper(void){
+        //setup rx otw type
+        _rx_otw_type.width = 16;
+        _rx_otw_type.shift = 0;
+        _rx_otw_type.byteorder = uhd::otw_type_t::BO_BIG_ENDIAN;
+
+        //setup tx otw type
+        _tx_otw_type.width = 16;
+        _tx_otw_type.shift = 0;
+        _tx_otw_type.byteorder = uhd::otw_type_t::BO_BIG_ENDIAN;
     }
 
-private:
-    get_t _get;
-    set_t _set;
+    inline size_t get_max_send_samps_per_packet(void) const{
+        return _max_tx_bytes_per_packet/_tx_otw_type.get_sample_size();
+    }
 
-    wax_obj_proxy(const get_t &get, const set_t &set){
-        _get = get;
-        _set = set;
-    };
+    inline size_t get_max_recv_samps_per_packet(void) const{
+        return _max_rx_bytes_per_packet/_rx_otw_type.get_sample_size();
+    }
 
-    void get(const wax::obj &key, wax::obj &val){
-        return _get(key, val);
+    inline const uhd::otw_type_t &get_rx_otw_type(void) const{
+        return _rx_otw_type;
     }
 
-    void set(const wax::obj &key, const wax::obj &val){
-        return _set(key, val);
+    inline const uhd::otw_type_t &get_tx_otw_type(void) const{
+        return _tx_otw_type;
     }
+
+private:
+    uhd::otw_type_t _rx_otw_type, _tx_otw_type;
+    static const size_t _max_rx_bytes_per_packet =
+        USRP2_UDP_BYTES -
+        USRP2_HOST_RX_VRT_HEADER_WORDS32*sizeof(boost::uint32_t) -
+        USRP2_HOST_RX_VRT_TRAILER_WORDS32*sizeof(boost::uint32_t)
+    ;
+    static const size_t _max_tx_bytes_per_packet =
+        USRP2_UDP_BYTES -
+        uhd::transport::vrt::max_if_hdr_words32*sizeof(boost::uint32_t) -
+        sizeof(uhd::transport::vrt::if_packet_info_t().cid) //no class id ever used
+    ;
 };
 
 /*!
- * USRP2 implementation guts:
+ * USRP2 mboard implementation guts:
  * The implementation details are encapsulated here.
  * Handles properties on the mboard, dboard, dsps...
  */
-class usrp2_impl : public uhd::device{
+class usrp2_mboard_impl : public wax::obj{
 public:
-    /*!
-     * Create a new usrp2 impl base.
-     * \param ctrl_transport the udp transport for control
-     * \param data_transport the udp transport for data
-     */
-    usrp2_impl(
-        uhd::transport::udp_simple::sptr ctrl_transport,
-        uhd::transport::udp_zero_copy::sptr data_transport
-    );
+    typedef boost::shared_ptr<usrp2_mboard_impl> sptr;
 
-    ~usrp2_impl(void);
+    //structors
+    usrp2_mboard_impl(size_t index, uhd::transport::udp_simple::sptr, const usrp2_io_helper &);
+    ~usrp2_mboard_impl(void);
 
-    //the io interface
-    size_t get_max_send_samps_per_packet(void) const{
-        return _max_tx_bytes_per_packet/_tx_otw_type.get_sample_size();
-    }
-    size_t send(
-        const boost::asio::const_buffer &,
-        const uhd::tx_metadata_t &,
-        const uhd::io_type_t &,
-        uhd::device::send_mode_t
-    );
-    size_t get_max_recv_samps_per_packet(void) const{
-        return _max_rx_bytes_per_packet/_rx_otw_type.get_sample_size();
-    }
-    size_t recv(
-        const boost::asio::mutable_buffer &,
-        uhd::rx_metadata_t &,
-        const uhd::io_type_t &,
-        uhd::device::recv_mode_t
-    );
-
-private:
     inline double get_master_clock_freq(void){
         return _clock_ctrl->get_master_clock_rate();
     }
 
-    //device properties interface
+private:
+    size_t _index;
+    const usrp2_io_helper &_io_helper;
+
+    //properties for this mboard
     void get(const wax::obj &, wax::obj &);
     void set(const wax::obj &, const wax::obj &);
 
@@ -138,25 +149,10 @@ private:
     usrp2_codec_ctrl::sptr _codec_ctrl;
     usrp2_serdes_ctrl::sptr _serdes_ctrl;
 
-    /*******************************************************************
-     * Deal with the rx and tx packet sizes
-     ******************************************************************/
-    static const size_t _max_rx_bytes_per_packet =
-        USRP2_UDP_BYTES -
-        USRP2_HOST_RX_VRT_HEADER_WORDS32*sizeof(boost::uint32_t) -
-        USRP2_HOST_RX_VRT_TRAILER_WORDS32*sizeof(boost::uint32_t)
-    ;
-    static const size_t _max_tx_bytes_per_packet =
-        USRP2_UDP_BYTES -
-        uhd::transport::vrt::max_header_words32*sizeof(boost::uint32_t)
-    ;
-
-    uhd::otw_type_t _rx_otw_type, _tx_otw_type;
-    UHD_PIMPL_DECL(io_impl) _io_impl;
-    void io_init(void);
-
-    //udp transports for control and data
-    uhd::transport::udp_zero_copy::sptr _data_transport;
+    //rx and tx dboard methods and objects
+    uhd::usrp::dboard_manager::sptr _dboard_manager;
+    uhd::usrp::dboard_iface::sptr _dboard_iface;
+    void dboard_init(void);
 
     //methods and shadows for clock configuration
     uhd::clock_config_t _clock_config;
@@ -164,17 +160,6 @@ private:
     void update_clock_config(void);
     void set_time_spec(const uhd::time_spec_t &time_spec, bool now);
 
-    //rx and tx dboard methods and objects
-    uhd::usrp::dboard_manager::sptr _dboard_manager;
-    uhd::usrp::dboard_iface::sptr _dboard_iface;
-    void dboard_init(void);
-
-    //properties for the mboard
-    void mboard_init(void);
-    void mboard_get(const wax::obj &, wax::obj &);
-    void mboard_set(const wax::obj &, const wax::obj &);
-    wax_obj_proxy::sptr _mboard_proxy;
-
     //properties interface for rx dboard
     void rx_dboard_get(const wax::obj &, wax::obj &);
     void rx_dboard_set(const wax::obj &, const wax::obj &);
@@ -213,4 +198,59 @@ private:
 
 };
 
+/*!
+ * USRP2 implementation guts:
+ * The implementation details are encapsulated here.
+ * Handles device properties and streaming...
+ */
+class usrp2_impl : public uhd::device{
+public:
+    /*!
+     * Create a new usrp2 impl base.
+     * \param ctrl_transports the udp transports for control
+     * \param data_transports the udp transports for data
+     */
+    usrp2_impl(
+        std::vector<uhd::transport::udp_simple::sptr> ctrl_transports,
+        std::vector<uhd::transport::udp_zero_copy::sptr> data_transports
+    );
+
+    ~usrp2_impl(void);
+
+    //the io interface
+    size_t get_max_send_samps_per_packet(void) const{
+        return _io_helper.get_max_send_samps_per_packet();
+    }
+    size_t send(
+        const std::vector<const void *> &, size_t,
+        const uhd::tx_metadata_t &,
+        const uhd::io_type_t &,
+        uhd::device::send_mode_t
+    );
+    size_t get_max_recv_samps_per_packet(void) const{
+        return _io_helper.get_max_recv_samps_per_packet();
+    }
+    size_t recv(
+        const std::vector<void *> &, size_t,
+        uhd::rx_metadata_t &,
+        const uhd::io_type_t &,
+        uhd::device::recv_mode_t
+    );
+
+private:
+    //device properties interface
+    void get(const wax::obj &, wax::obj &);
+    void set(const wax::obj &, const wax::obj &);
+
+    //pointers to mboards on this device (think mimo setup)
+    std::vector<usrp2_mboard_impl::sptr> _mboards;
+    uhd::dict<std::string, usrp2_mboard_impl::sptr> _mboard_dict;
+
+    //io impl methods and members
+    std::vector<uhd::transport::udp_zero_copy::sptr> _data_transports;
+    const usrp2_io_helper _io_helper;
+    UHD_PIMPL_DECL(io_impl) _io_impl;
+    void io_init(void);
+};
+
 #endif /* INCLUDED_USRP2_IMPL_HPP */
diff --git a/host/lib/usrp/usrp2/usrp2_regs.hpp b/host/lib/usrp/usrp2/usrp2_regs.hpp
index 589fa71a3..c859d3603 100644
--- a/host/lib/usrp/usrp2/usrp2_regs.hpp
+++ b/host/lib/usrp/usrp2/usrp2_regs.hpp
@@ -18,8 +18,6 @@
 #ifndef INCLUDED_USRP2_REGS_HPP
 #define INCLUDED_USRP2_REGS_HPP
 
-#include <boost/cstdint.hpp>
-
 ////////////////////////////////////////////////////
 // Settings Bus, Slave #7, Not Byte Addressable!
 //
@@ -46,7 +44,7 @@
 #define SR_SIMTIMER 198
 #define SR_LAST 255
 
-#define _SR_ADDR(sr)    (MISC_OUTPUT_BASE + (sr) * sizeof(boost::uint32_t))
+#define _SR_ADDR(sr)    ((MISC_OUTPUT_BASE) + (4*(sr)))
 
 /////////////////////////////////////////////////
 // SPI Slave Constants
@@ -104,7 +102,11 @@
 #define U2_REG_TIME64_SECS  _SR_ADDR(SR_TIME64 + 0)  // value to set absolute secs to on next PPS
 #define U2_REG_TIME64_TICKS _SR_ADDR(SR_TIME64 + 1)  // value to set absolute ticks to on next PPS
 #define U2_REG_TIME64_FLAGS _SR_ADDR(SR_TIME64 + 2)  // flags - see chart above
-#define U2_REG_TIME64_IMM   _SR_ADDR(SR_TIME64 + 3) // set immediate (0=latch on next pps, 1=latch immediate, default=0)
+#define U2_REG_TIME64_IMM   _SR_ADDR(SR_TIME64 + 3)  // set immediate (0=latch on next pps, 1=latch immediate, default=0)
+#define U2_REG_TIME64_TPS   _SR_ADDR(SR_TIME64 + 4)  // the ticks per second rollover count
+
+#define U2_REG_TIME64_SECS_RB  (0xCC00 + 4*10)
+#define U2_REG_TIME64_TICKS_RB (0xCC00 + 4*11)
 
 //pps flags (see above)
 #define U2_FLAG_TIME64_PPS_NEGEDGE (0 << 0)