Linux 3.17 has a commit which supports hotplug of thunderbolt of non-chained thunderbolt devices. But what does "non-chained thunderbolt devices" mean? Is a thunderbolt to ethernet adapter a chained or non-chained device? How about a thunderbolt to display port adapter?
2 Answers
See Apple's promo page for info about Thunderbolt. It also describes how you can chain devices together instead of needing a hub or similar. My impression is that hot-plugging such daisy-chained devices are what are not supported by the linux commit; only single devices, whatever type they are.
Thunderbolt 3 is a beast of a protocol and hardware solution. In Linux, there is some support for Apple devices but nothing very generic currently, as I understand. For instance with kernel 4.9 (Debian 9) with the Lenovo Thunderbolt 3 docking station and Lenovo Thinkpad T470 everything worked if I booted while attached to the dock. Suspend/ resume would not work, just the power and the display would come online. With kernel 4.13 I can reliably suspend/ resume with everything coming back online. I cannot hot-plug though.
BTW the original Thunderbolt is really relevant only on Apple hardware from what I know. Thunderbolt 2 got deployed more widely on Dell and Lenovo hardware in addition to Apples.
Thunderbolt should work as DisplayPort (and in case of Thunderbolt 3 as charger) pretty much all the time. The switch to "Thunderbolt alternative mode" should be easy enough to be supported as one of the first things.
Thunderbolt also allows for networking, which should be present in all major operating systems including Linux kernel 4.15+ shortly.
