Due to a bug in the Intel® Quartus® Prime software versions 19.3 and older, you may see conflicting PRESERVE_UNUSED_XCVR_CHANNEL compilation messages when compiling with an OpenCL BSP flow on Intel Stratix® 10 L & H-Tile devices.
The following Quartus Settings File assignment is required to preserve the performance of unused channels that may be used in the future.
set_instance_assignment -name PRESERVE_UNUSED_XCVR_CHANNEL ON -to <pin_name>
In an Intel Quartus Prime software version 19.3 and older OpenCL flow project, you may see the following message in your quartus_sh_compile.log file.
Info (19365): Global preservation of unused transceiver channels is enabled. All unused transceiver channels will be preserved.
However, a critical warning similar to the following may be seen in the Intel Quartus Prime Fitter report
Critical Warning (19527): There are 88 unused RX channels and 88 unused TX channels in the design.
Info (19528): Add the QSF assignment 'set_instance_assignment -name PRESERVE_UNUSED_XCVR_CHANNEL ON -to <pin_name>' for each unused channel that will be used in future.
Info (19529): The above QSF assignment will preserve the performance of specified channels over time.
In this OpenCL flow case, your BTI channels are not preserved.
This problem is fixed in Intel Quartus Prime software version 19.4.