Note: If the I/O locations of "sys_clk_p/n" were modified in the top-level XDC constraint file prior to upgrading to 2015.1 then you will need to manually upgrade these constraints into the 2015.1 design.
For a proper upgrade of the MIG design into 2015.1, it is recommended to do the following:
MIG Software generates an <ip>_upgrade.xdc file and its path is given in the upgrade.log file for that IP
Customer should open the corresponding upgrade.xdc of the MIG IP for which the "sys_clk_p/n" I/O locations have been modified in the pre-2015.1 design
Comment out the PIN location constraints.
For example, if the I/O locations of "sys_clk_p/n" have been changed then the following lines should be commented out: