Partial reconfiguration is done on a frame-by-frame basis. As such, when partial BIT files are created, they are built with a discrete number of configuration frames. The size of a partial bit file depends on the number and type of frames included. You can see this size in the header of a raw bit file (.rbt) created by write_bitstream -rawbitfile.
Partition boundaries do not have to align to reconfigurable frame boundaries, but the most efficient place and route results are achieved when this is done. Static logic is permitted to exist in a frame that will be reconfigured, as long as:
- It is outside the area group defined by the Pblock
- It does not contain dynamic elements such as block RAM, Distributed (LUT) RAM, or SRLs (7 series only).
When static logic is placed in a reconfigured frame, the exact functionality of the static logic is rewritten, and is guaranteed not to glitch.
Irregular shaped Partitions (such as a T or L shapes) are permitted but discouraged. Placement and routing in such regions can become challenging, because routing resources must be entirely contained within these regions. Boundaries of Partitions can touch, but this is not recommended, as some separation helps mitigate potential routing restriction issues as these partitions connect to the static design. Nested or overlapping RPs (partitions within partitions) are not permitted. Design rule checks () validate the Partitions and settings in a PR design.
Only one RP can exist per physical Reconfigurable Frame.
A Reconfigurable Frame is the smallest size physical region that can be reconfigured, and its height aligns with clock region or I/O bank boundaries. A Reconfigurable Frame cannot contain logic from more than one RP. If it were to contain logic from more than one RP, it would be very easy to reconfigure the region with information from an incorrect RM, thus creating contention. The software tools are designed to avoid that potentially dangerous occurrence.