Possible missing firmware for module tg3

When recently updating my Debian 9 Stretch’s boot image, it produced the following warning:

W: Possible missing firmware /lib/firmware/tigon/tg3_tso5.bin for module tg3
W: Possible missing firmware /lib/firmware/tigon/tg3_tso.bin for module tg3
W: Possible missing firmware /lib/firmware/tigon/tg3.bin for module tg3

That doesn’t look good! Without this module, I suspect my network card will not work after reboot. What’s needed is the package firmware-linux-nonfree but it’s not available in the standard Debian free repos – you need the nonfree repo.

Edit your /etc/apt/sources.list and add the following:

deb http://ftp.de.debian.org/debian stretch main non-free

You can install firmware-linux-nonfree with apt-get, which will allow your adapter requiring the tg3 module to continue working.