Confusion on repository versions on

I built an SD card from scratch a few years ago, and now try to upgrade, because I need driver support introduced in a more recent kernel. My build is based on Yocto Poky (first ‘daisy’ 1,6, then ‘dizzy’ 1.7 and now ‘jethro’ 2.0). The kernel (version 4.4.0-altera) originates from the ‘meta-altera’ layer from branch angstrom-v2015.12-yocto2.0, which is the latest available. All builds nicely, but I have issues with Ethernet that I did not have with the previous build, and that don’t seem to caused by the .DTB (I added some changes related to the later kernel).

And now for the confusion:

My question is: what is the latest kernel version that is ‘officially’ supported, especially related to Ethernet (there is quite a lot of difference between stmmac.c and friends between kernel 3.10.31 and 4.4, dwmac-socfpga.c seems to be introduced somewhere around 3.18).