1.12.1. Memory Blocks Initialization Requirement for PR Designs
For a non-PR design, the power up value for the contents of a M20K RAM or a MLAB RAM are all set at zero. However, at the end of performing a partial reconfiguration, the contents of a M20K or MLAB memory block are unknown. You must intentionally initialize the contents of all the memory to zero, if required by the functionality of the design, and not rely upon the power on values.