When you create a block design, the BD file (.bd extension) is saved to the project source file. IP integrator BD sources cannot be directly synthesized in the Vivado tools. There are two ways to instantiate a BD file:
- BD top
- Only the BD file is instantiated at the top-level. The top-level is usually the automatically generated BD HDL wrapper. This approach is recommended but not required for Versal ACAP designs.
- RTL top
- The BD file as well as custom logic and IP are instantiated at the top-level. In some cases, one or more BD files can also be instantiated in sub-levels of the hierarchy.