7 files changed, 39 insertions, 8 deletions
diff --git a/usrp/host/lib/legacy/fusb.h b/usrp/host/lib/legacy/fusb.h
index da1b7c0ad..8116ed056 100644
--- a/usrp/host/lib/legacy/fusb.h
+++ b/usrp/host/lib/legacy/fusb.h
@@ -119,12 +119,17 @@ public:
   static fusb_devhandle *make_devhandle (usb_dev_handle *udh);
 
   /*!
-   * \brief returns max block size hard limit
+   * \brief Returns max block size in bytes (hard limit).
    */
   static int max_block_size ();
 
   /*!
-   * \brief returns the default buffer size
+   * \brief Returns default block size in bytes.
+   */
+  static int default_block_size ();
+
+  /*!
+   * \brief Returns the default buffer size in bytes.
    */
   static int default_buffer_size ();
 
diff --git a/usrp/host/lib/legacy/fusb_sysconfig_darwin.cc b/usrp/host/lib/legacy/fusb_sysconfig_darwin.cc
index f66c298db..54d008437 100644
--- a/usrp/host/lib/legacy/fusb_sysconfig_darwin.cc
+++ b/usrp/host/lib/legacy/fusb_sysconfig_darwin.cc
@@ -24,7 +24,7 @@
 #include <fusb_darwin.h>
 
 static const int MAX_BLOCK_SIZE = 32 * 1024;		// hard limit
-static const int FUSB_BUFFER_SIZE = 2 * (1L << 20);	// 2 MB (was 8 MB)
+static const int FUSB_BUFFER_SIZE = 2 * (1L << 20);	// 2 MB
 
 fusb_devhandle *
 fusb_sysconfig::make_devhandle (usb_dev_handle *udh)
@@ -37,6 +37,11 @@ int fusb_sysconfig::max_block_size ()
   return MAX_BLOCK_SIZE;
 }
 
+int fusb_sysconfig::default_block_size ()
+{
+  return fusb_sysconfig::max_block_size ();
+}
+
 int fusb_sysconfig::default_buffer_size ()
 {
   return FUSB_BUFFER_SIZE;
diff --git a/usrp/host/lib/legacy/fusb_sysconfig_generic.cc b/usrp/host/lib/legacy/fusb_sysconfig_generic.cc
index d336cb946..31022c14f 100644
--- a/usrp/host/lib/legacy/fusb_sysconfig_generic.cc
+++ b/usrp/host/lib/legacy/fusb_sysconfig_generic.cc
@@ -24,7 +24,7 @@
 #include <fusb_generic.h>
 
 static const int MAX_BLOCK_SIZE = 16 * 1024;		// hard limit
-static const int FUSB_BUFFER_SIZE = 2 * (1L << 20);	// 2 MB (was 8 MB)
+static const int FUSB_BUFFER_SIZE = 2 * (1L << 20);	// 2 MB
 
 fusb_devhandle *
 fusb_sysconfig::make_devhandle (usb_dev_handle *udh)
@@ -37,6 +37,11 @@ int fusb_sysconfig::max_block_size ()
   return MAX_BLOCK_SIZE;
 }
 
+int fusb_sysconfig::default_block_size ()
+{
+  return fusb_sysconfig::max_block_size ();
+}
+
 int fusb_sysconfig::default_buffer_size ()
 {
   return FUSB_BUFFER_SIZE;
diff --git a/usrp/host/lib/legacy/fusb_sysconfig_linux.cc b/usrp/host/lib/legacy/fusb_sysconfig_linux.cc
index 468fa9f82..e5dc1f457 100644
--- a/usrp/host/lib/legacy/fusb_sysconfig_linux.cc
+++ b/usrp/host/lib/legacy/fusb_sysconfig_linux.cc
@@ -23,8 +23,9 @@
 #include <fusb.h>
 #include <fusb_linux.h>
 
-static const int MAX_BLOCK_SIZE = 16 * 1024;		// hard limit
-static const int FUSB_BUFFER_SIZE = 2 * (1L << 20);	// 2 MB (was 8 MB)
+static const int MAX_BLOCK_SIZE     =  16 * 1024;	// hard limit
+static const int DEFAULT_BLOCK_SIZE =   4 * 1024;	// fewer kernel memory problems
+static const int FUSB_BUFFER_SIZE   =   1 * (1L << 20); // 1MB
 
 fusb_devhandle *
 fusb_sysconfig::make_devhandle (usb_dev_handle *udh)
@@ -37,6 +38,11 @@ int fusb_sysconfig::max_block_size ()
   return MAX_BLOCK_SIZE;
 }
 
+int fusb_sysconfig::default_block_size ()
+{
+  return DEFAULT_BLOCK_SIZE;
+}
+
 int fusb_sysconfig::default_buffer_size ()
 {
   return FUSB_BUFFER_SIZE;
diff --git a/usrp/host/lib/legacy/fusb_sysconfig_ra_wb.cc b/usrp/host/lib/legacy/fusb_sysconfig_ra_wb.cc
index 68eecedc5..c5ea7fff3 100644
--- a/usrp/host/lib/legacy/fusb_sysconfig_ra_wb.cc
+++ b/usrp/host/lib/legacy/fusb_sysconfig_ra_wb.cc
@@ -41,6 +41,11 @@ int fusb_sysconfig::max_block_size ()
   return MAX_BLOCK_SIZE;
 }
 
+int fusb_sysconfig::default_block_size ()
+{
+  return fusb_sysconfig::max_block_size ();
+}
+
 int fusb_sysconfig::default_buffer_size ()
 {
   return FUSB_BUFFER_SIZE;
diff --git a/usrp/host/lib/legacy/fusb_sysconfig_win32.cc b/usrp/host/lib/legacy/fusb_sysconfig_win32.cc
index 282e77ac4..02a3bf209 100644
--- a/usrp/host/lib/legacy/fusb_sysconfig_win32.cc
+++ b/usrp/host/lib/legacy/fusb_sysconfig_win32.cc
@@ -24,7 +24,7 @@
 #include <fusb_win32.h>
 
 static const int MAX_BLOCK_SIZE = 64 * 1024;		// Windows kernel hard limit
-static const int FUSB_BUFFER_SIZE = 2 * (1L << 20);	// 2 MB (was 8 MB)
+static const int FUSB_BUFFER_SIZE = 2 * (1L << 20);	// 2 MB
 	
 fusb_devhandle *
 fusb_sysconfig::make_devhandle (usb_dev_handle *udh)
@@ -37,6 +37,11 @@ int fusb_sysconfig::max_block_size ()
   return MAX_BLOCK_SIZE;
 }
 
+int fusb_sysconfig::default_block_size ()
+{
+  return fusb_sysconfig::max_block_size ();
+}
+
 int fusb_sysconfig::default_buffer_size ()
 {
   return FUSB_BUFFER_SIZE;
diff --git a/usrp/host/lib/legacy/usrp_basic.cc b/usrp/host/lib/legacy/usrp_basic.cc
index 2eef14727..0ac9e052a 100644
--- a/usrp/host/lib/legacy/usrp_basic.cc
+++ b/usrp/host/lib/legacy/usrp_basic.cc
@@ -475,7 +475,7 @@ usrp_basic_rx::usrp_basic_rx (int which_board, int fusb_block_size, int fusb_nbl
     throw std::out_of_range ("usrp_basic_rx: invalid fusb_nblocks");
   
   if (fusb_block_size == 0)
-    fusb_block_size = FUSB_BLOCK_SIZE;
+    fusb_block_size = fusb_sysconfig::default_block_size();
 
   if (fusb_nblocks == 0)
     fusb_nblocks = std::max (1, FUSB_BUFFER_SIZE / fusb_block_size);