[ptx]

Who made it up, then?

The official-looking website at https://varlink.org doesn't give any information about who the authors are, as far as I can tell, but the screenshots show the username "kay". There's a git repo for libvarlink [1] where the first commits (from 2017) are by Kay Sievers, who is one of the systemd developers.

An announcement post [2] from later in 2017, by Harald Hoyer, says that the varlink protocol was created by Kay Sievers and Lars Karlitski in "our team", presumably referring to the systemd team.

So the systemd developers "adopted" their own thing from themselves?

[1] https://github.com/varlink/libvarlink

[2] https://harald.hoyer.xyz/2017/12/18/varlink/

[NekkoDroid]

While I guess you aren't wrong, I also wouldn't say you are entirely correct that Kay is a systemd developer. He use to work on udev, but hasn't been active in any meaningful way on it for 2 years before varlinks release[1]. For what it was made I can't really say, but Lennart hadn't start integrating Varlink until a while after its release (I think I remember it being like 2021 or so when he started making use of it, after another check it seems the start of varlink stuff in systemd was 2019[2]).

[1]: https://github.com/systemd/systemd/commits/main/?author=kays...

[2]: https://github.com/search?q=repo%3Asystemd%2Fsystemd+varlink...

[ptx]

Kay Sievers' Wikipedia page cites a blog post by Lennart Poettering [1] which says that systemd was designed in "close cooperation" with Kay Sievers and that Harald Hoyer was also involved, so it seems pretty clear that he's on the team that develops systemd, the team that Harald Hoyer referred to as "our team". All three of them gave a talk [2] together in 2013 about what they were developing.

If Lennart Poettering "adopted" varlink, he seems to have done so from members of his own team ("our team") who created varlink and who are also fellow co-creators of systemd.

[1] https://0pointer.de/blog/projects/systemd.html#faqs

[2] https://www.youtube.com/watch?v=_rrpjYD373A