On a niche hardware note for Linux 4.21, should you be using a ZynqMP DDR controller, there will now be Error Detection And Correction (EDAC) ECC support.

The EDAC changes submitted for Linux 4.21 include support for the ZynqMP DDR controller within the Synopsys EDAC driver. This allows for ECC support for this ZynqMP DDR controller. Also enabled is error injection support via the hardware's data poisoning capabilities, which is exposed via sysfs and allows injecting data poison or data errors for testing.

The ZynqMP DDR controller is out of Xilinx and used by some of their ARM + FPGA platforms like the Zynq UltraScale+ MPSoC.