tb_tunnel_event(9)

📦 version 7.3.1, in nixpkgs unstable

💅 tb_tunnel_event(9)

okay so this is a page from the Kernel API Manual — it's tb_tunnel_event(9), and bestie, it's a tiny little function with a big job: telling userspace that something happened in the tunnel world. let's get into it 🎀

✨ NAME ✨

tb_tunnel_event — notify userspace about a tunneling event

like, it's the messenger. it does not tunnel. it just tells people about tunneling. main character energy of the announcement, not the event 💅

🦋 SYNOPSIS 🦋

void tb_tunnel_event (struct tb *tb , enum tb_tunnel_event event , enum
       tb_tunnel_type type , const struct tb_port *src_port , const struct
       tb_port *dst_port );

five arguments, returns nothing (void), it's giving "I just do the thing and leave" 😌

🌸 ARGUMENTS 🌸

  • tb — the domain where the event occurred. like, the whole neighborhood 🏘️
  • event — the event that happened. the actual tea ☕
  • type — the type of the tunnel in question. what kind of tunnel we're talking about here 🚇
  • src_port — the tunnel source port. can be NULL (it's allowed to not know, no pressure) 🙈
  • dst_port — the tunnel destination port. also can be NULL (same vibe) 🫶

⭐ DESCRIPTION ⭐

so what it does is, it notifies userspace about a tunneling event in the domain. and here's the iconic part: the tunnel does not need to exist. fr fr. that's not a bug, that's the whole point — for example, the tunnel was not activated because there is not enough bandwidth 😭 so we still wanna tell userspace "hey, this was a thing that could've happened," and this function is how we do it.

now the detail work, and this is the bit you gotta remember:

  • if src_port and dst_port are given → it fills in the full TUNNEL_DETAILS environment variable 🔥 full send, all the details
  • otherwise → it uses the shorter one, which is just the tunnel type 🍓

that's it. that's the whole function. short, sweet, slays, periodt 👑

🌈 SEE ALSO 🌈

kernel file ./drivers/thunderbolt/tunnel.c — and the whole tunnel girlie friend group:

and that's the page!! sourced from ./drivers/thunderbolt, dated October 2026 — go read the source bestie, it's right there, and it's literally only a few lines 💜🦋✨

📦 where this page comes from