The current default value for the park register is 0. This means that if the park register is enabled in the control register, but no value is written to the park register, an invalid value exists in the register. This could cause problems with bus parking.
Another potential problem regarding the park register is that a value with multiple bits set can be written to this one-hot encoded register. While the Xilinx software driver will prevent the user from doing this, another user may choose to write their own driver. A change in the hardware to always use the most or least significant bit would be functionally more desirable.
This problem is fixed in the latest 6.2 EDK Service Pack, available at:
The first service pack containing the fix is EDK 6.2 Service Pack 2.