1.5 Built-in Self-Test
(Ask a Question)PolarFire devices have a built-in self-test mechanism that can be used (optionally) to check the reliability and security of a device automatically upon power-up, or on-demand. The contents of all the non-volatile configuration memory segments, including security keys, security settings, and the FPGA fabric configuration, plus any memory pages declared as ROM by the user (all the write-protected pages) are tested using digest check. This test provides assurance against both natural and maliciously induced failures.
Digests are used for protecting data integrity. In the factory and user security segment, each logical page contains an automatically generated digest calculated dynamically at the time of programming the data to be written. For the FPGA fabric, the digest includes an overall value covering the data to be programmed. In addition, digests are calculated and stored for the sNVM pages marked as ROM. The digests can be verified on-demand by the user, either internally using a system service, or externally using a programming instruction. In addition, the user can automatically run digest checks on each power-up. The following section describes various options to run the digest check.
An endurance limit specifies how many times a digest check of the FPGA fabric can be run. For more information about the FPGA configuration memory endurance limits, see PolarFire FPGA Datasheet. Therefore, depending on how the system is deployed and used (for example, how often it is powered-up), the on-demand digest check may be more appropriate for testing the integrity of the FPGA fabric.