OpenEmbedded "poky" with some sysmocom specific modifications. Mostly used only up to sysmocom release 201310, but the "pyro" branch is still used for 201705
* split out rtl-nic firmware from the big
linux-firmware package
[hfreyther: For whatever reasons the NIC works without
additional firmware as well. I couldn't see in the driver
source when that is the case and which features are missing]