How to turn off PXE booting of ConnectX-4 Ethernet Cards from Linux?

It looks like I should be able to do it from mlxconfig, mlxburn, or flint, but I have found no documentation giving a specific method for this. We need to turn off PXE booting on a large number of RHEL 6.x / 7.x servers using MCX415A-GCAT and MCX416A-GCAT cards and doing it from the host OS could be easily automated.

Also, is there documentation on what all of the mlxconfig parameters mean? The MFT documentation only covers a few of the mlxconfig parameters.

The right command is

mlxconfig -d s LEGACY_BOOT_PROTOCOL=0

and it will be supported in the next comming MFT v4.7

Did you try to disable BOOT_OPTION_ROM_EN option?

Yes, I set BOOT_OPTION_ROM_EN to False using mlxconfig. The parameter was truly set to False, but it did not stop the interface from trying to netboot.