processed review comments

libraries/io/tr_10GbE/src/vhdl/tr_10GbE.vhd

@@ -49,7 +49,15 @@
 --   g_xon_backpressure can be enabled to set xon = 0 when the TX fill fifo is
 --   full. This also makes use of an extra fifo of size g_tx_fifo_size to 
 --   buffer the last incoming frame when xon = 0 to prevent corrupting the frame.
---  
+-- 
+-- Remark
+--  . Note that the snk_out_arr().xon is used to indicate when the MAC cannot
+--    receive new frames. If xon = 0 is ignored, the TX FIFO can overflow.
+--  . xon can become low when the MAC has no link. When g_xon_backpressure
+--    = TRUE, xon = 0 can also occur when the ready of the MAC is 0 for a long
+--    time filling up the TX fifo. If this fifo is almost full xon is set to 0,
+--    the remainder of the incoming frame is captured by an extra fifo. Therefore
+--    using g_xon_backpressure = TRUE uses extra RAM.
 
 LIBRARY IEEE, common_lib, dp_lib, diag_lib, technology_lib, tech_mac_10g_lib, tech_eth_10g_lib, tr_xaui_lib;
 USE IEEE.std_logic_1164.ALL;