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AR# 32184

10.1 XST - WARNING:Xst:819 - Why do I get this message when I include all signals in the process sensitivity list?


Keywords: XST, WARNING:Xst:819, 10.1

I am getting the following warning from XST even though I have verified that all signals are in the process sensitivity list.

WARNING:Xst:819: "your_file_name.vhd" line 25: One or more signals are missing in the process sensitivity list. To enable synthesis of FPGA/CPLD hardware, XST will assume that all necessary signal are present in the sensitivity list. Please note that the result of the synthesis may differ from the initial design specification. The signals missing are:


This is a known issue with XST if one of your signals is a record type of another record type. Below is an example:

type my_desk is
wood : std_logic;
end record;

type my_office
desk : my_desk;
end record

If you declare a signal of type "my_office" and include the signal in the process sensitivity list, you will get the Xst:819 warning. You can either ignore the warning or change it as demonstrated below:


signal office : my_office;// signal declaration

process(office) // issues the warning

process(office.desk.wood) //issues no warning
AR# 32184
Date Created 04/06/2009
Last Updated 04/06/2009
Status Active
Type General Article