ixgbe driver hack for 3rd-party SFP+ transceivers compatibility

ixgbe_phy.c

// If both allow_unsupported_sfp=1 option and https://forums.servethehome.com/index.php?threads/patching-intel-x520-eeprom-to-unlock-all-sfp-transceivers.24634/ are not working,
// your SFP+ transceivers may be too old to support Transceiver Compliance Codes in EEPROM.
// Inspired from https://mails.dpdk.org/archives/dev/2019-May/131512.html.

// Looking for the following content in src/ixgbe_phy.c:
                status = hw->phy.ops.read_i2c_eeprom(hw,
                                                     IXGBE_SFF_10GBE_COMP_CODES,
                                                     &comp_codes_10g);
                if (status != IXGBE_SUCCESS)
                        goto err_read_i2c_eeprom;
                status = hw->phy.ops.read_i2c_eeprom(hw,
                                                     IXGBE_SFF_CABLE_TECHNOLOGY,
                                                     &cable_tech);
                if (status != IXGBE_SUCCESS)
                        goto err_read_i2c_eeprom;

// add the following lines
                if (comp_codes_10g == 0 && cable_tech == 0) {
                        printk(KERN_ALERT "yuxzhu: SPF+ transceiver may not support SFF compliance code. Set comp_codes_10g=32");
                        comp_codes_10g = 32;
                }

Thanks for this! Helped a ton. For future searchers: you can make this same patch for the pfsense/opnsense ix driver by:

1. setting up a FreeBSD VM (must choose to install src component when installing!)
2. adding the above fix to the latest intel ix driver for FreeBSD
3. compiling by running make in the src directory
4. copying the generated if_ix.ko file to the /boot/kernel/ directory in your pfsense machine.
5. running chmod 555 /boot/kernel/if_ix.ko
   6.if_ix_load="YES" to /boot/loader.conf

This process borrowed liberally from this gist for the Realtek driver here.

There are some small syntax changes you'll need to make. I believe I changed the code snippet to:

if (comp_codes_10g == 0 && cable_tech == 0) {
    printf("yuxzhu: SPF+ transceiver may not support SFF compliance code. Set comp_codes_10g=32");
    comp_codes_10g = 32;
}

Thank you both! I need both the Linux and FreeBSD fixes. ISP updated their infra to 10gbit and gave me their SFP+ modules which, of course, were incompatible with the Intel cards in the servers.