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By default, Centos 7 doesn’t support Intel’s 10G SFP+ X520 module. When you look at the dmesg you find the following error: “failed to load because an unsupported SFP+ or QSFP module type was detected.” The workaround is to allow unsupported SFP modules in the kernel by enabling ixgbe kernel module. Let’s start by editing /etc/default/grub file and
change the line :



GRUB_CMDLINE_LINUX=" ixgbe.allow_unsupported_sfp=1" 
# note the space between " and ixgbe.

Now, we create the new grub configuration with the new option.

cp /boot/grub2/grub.cfg /boot/grub2/grub.cfg.bak
grub2-mkconfig -o /boot/grub2/grub.cfg

Next, the configuration file for the ixgbe kernel module must be created with the option to allow unsupported SFP. The file should not already exist. The one-liner command is:

echo "options ixgbe allow_unsupported_sfp=1" > /etc/modprobe.d/ixgbe.conf

The last step is to regenerate the initrd image with the new kernel configuration and reboot.

dracut --regenerate-all --force

After the reboot, the SFP should be recognized and ready for use.