Loosen timing on a net (xilinx)

[rodentje]

Hi,

I have a reset pulse "reset_clk1" generated on clock "clk1" which is held high for at least 16 clock cycles after a reset condition has occurred.

This reset also resets a FIFO which is used to cross clock domains from clock domain "clk2" to "clk1".

I want to loosen the timing from net "reset_clk1" to the resetting of the FIFO and some other nets (the FIFO is generated using coregen and has an asynchronous reset).

I don't want to do this using a timing ignore (TIG), but I want to specify how much margin can be taken.

How should I do this ?

Best regards,
RoDeNtJe