Due to Avalon-ST x8 mode uses the SDM_IO bank, which is dedicated IO for configuration signal, AVSTx8 cannot place to userI/O pins.
In Intel Stratix10® pin connection guide page7, table3. Avalon-ST x8 mode uses the SDM_IO pins. SDM IO bank is dedicated IO for configuration signal, cannot locate user I/O.
In Stratix10 Configuraition User Guide page12, table4, it said AVSTx8 signals are dedicated, cannot use dual purpose user IO.
Only dual purpose configuration pins can user as user I/O during user mode. It describes in note15. AVST_DATA, AVST_VALID, and AVST_CLK.