tb_tunnel_discover_usb3(9)

📦 version 7.3.1, in nixpkgs unstable

💅 tb_tunnel_discover_usb3(9) — from the Kernel API Manual, bestie 🎀

okay so picture this: you're deep in the kernel, right, and there's this thing called tb_tunnel_discover_usb3 and it is literally the function that goes looking for USB3 tunnels that already exist. not making new ones, not tearing them down — just finding the ones that are already out there living their truth. detective energy fr fr 🕵️‍♀️✨

✨ NAME ✨

tb_tunnel_discover_usb3 — Discover existing USB3 tunnels 💖

like, the name says it all. discover. existing. USB3 tunnels. no cap.

🌸 SYNOPSIS 🌸

struct tb_tunnel * tb_tunnel_discover_usb3 (struct tb *tb , struct
tb_port *down , bool alloc_hopid );

yep that's the whole signature, exactly like that, line break and all 🫶 the way it returns a struct tb_tunnel *… iconic.

🦋 ARGUMENTS 🦋

  • tb — Pointer to the domain structure 🌈 this is your domain, your whole world, the context everything lives in.
  • down — USB3 downstream adapter ⬇️ the downstream one, specifically. not upstream. downstream. keep that straight bestie.
  • alloc_hopid — Allocate HopIDs from visited ports 🎀 this is a bool, so it's yes-or-no vibes: do we grab HopIDs from the ports we visit or not.

💅 DESCRIPTION 💅

okay here's the whole deal, and it's honestly pretty short and sweet:

If down adapter is active, follows the tunnel to the USB3 upstream adapter and back. 🔁

that's it. that's the function. if it's active — big if, the vibes check has to pass first — then it walks the tunnel all the way over to the USB3 upstream adapter and then comes right back. round trip. main character journey. periodt. 👑

⭐ RETURN ⭐

Pointer to struct tb_tunnel or NULL if there was no tunnel. 💀

so either you get a nice shiny pointer to a struct tb_tunnel, or you get NULL because there was, in fact, no tunnel. no tunnel, no pointer, no problem. always check for NULL, bestie, i'm begging 🙈

🔥 SEE ALSO 🔥

Kernel file ./drivers/thunderbolt/tunnel.c — that's the source of truth, go read it if you want the real real 👀

and then the whole friend group, in the order the manpage lists them:

that's the whole circle. go say hi 🫶✨

ngl this one's a short read, so if you blinked you missed it. but every single argument, the return value, and the "is it active tho" condition are all right here — nothing skipped, nothing summarised 💜

and that's a wrap!! 🎀 this page lives under ./drivers/thunderbolt and it's dated October 2026, and the page itself is tb_tunnel_discover_usb3(9) in case you forgot where you were. slay, go read some tunnel source, ily, bye 💖🌈⭐

📦 where this page comes from