• Tandem PROM requires PERSIST to be set to reserve dual-purpose I/O for programming usage. Because of this, the configuration flash cannot be accessed by the user design after Tandem PROM configuration completes. Tandem PCIe should be used if configuration flash update from the FPGA user design is required.
• The use of Tandem PROM with PERSIST also disables the ICAP. This resource is not available post-configuration for DFX or other functions.
• Tandem with Field Updates is supported for UltraScale and UltraScale+ devices only. This solution will never support 7 series devices. For this type of approach in 7 series, a general Dynamic Function eXchange solution should be considered.
• General Tandem + Dynamic Function eXchange is also supported. To enable, simply use the standard Tandem option when generating the PCIe IP then add it to a DFX design to be compiled in non-project mode as described in Non-Project Flow , and the Vivado Design Suite User Guide: Dynamic Function eXchange (PG909) [Ref 19] .
• Bitstream compression, which is enabled by default for Tandem Configuration solutions, is not compatible with the Dynamic Function eXchange per-frame CRC feature. If per-frame CRC checking is desired for any of the “update” partial bitstreams, rerun bitstream generation with that feature enabled and bitstream compression disabled. The write_bitstream -cell option can be used to create only the partial and clearing bitstreams needed for each design image.