It is complicated…
When Duo started up, only 3.4 worked for it, so we went with that one. When nand mainline support became a thing, we updated to that ASAP, which was 5.4.
Duo X has 4.4 because it is the official/vendor supported kernel for it by rockchip, and we needed to get the unit booting and working ASAP too. The rockchip 4.4 and mainline kernel have a few differences, and rockchip not officially supporting mainline means we need to stick with 4.4 for an initial release/testing as otherwise we can’t receive any support.
Dwarf has 5.10 because we had more time to develop for it, so we went straight to mainline from the get-go. Dwarf can use any kernel version really. 5.10 is the latest LTS so we are on that.
The Duo can very likely be updated to 5.10 without problems, we have only a few minor patches needed.
At some point yes, for sure. We want all devices to eventually be on the same kernel version.
It is a pain to maintain patches for many different kernel versions..