The expansion ROM image presents itself to the BIOS as a boot device. As a result, the BIOS will add to the list of boot devices "MLNX FlexBoot <ver>" for a ConnectX family device. The priority of this list can be modified through BIOS setup.
The expansion ROM image presents itself to the BIOS as a boot device. If BIOS is set to UEFI Boot mode it will add to the list of boot devices "UEFI Network X \[Device Name\]" for each available port of ConnectX family devices. The priority of this list can be modified through BIOS setup.