12.1 Timing - I need a positive hold value, but a hold violation occurs on my input port

Description

I need a positive hold requirement for my input port, but the timing tools are reporting a hold violation.

Why am I receiving a hold violation, and how can I solve this issue?

Solution

If you have positive hold time requirements and you do not specify a data VALID duration with your OFFSET constraints, a hold error occurs (TRCE assumes VALID=OFFSET for a zero hold time check). 

For more details on timing constraints, see the Timing Constraints User Guide: http://www.xilinx.com/support/documentation/sw_manuals/xilinx12_1/ug612.pdf