rdma_read_gids(9)

📦 version 7.3.1, in nixpkgs unstable

💖 rdma_read_gids(9) — like, the Kernel API Manual page, bestie 💖

okay so this is rdma_read_gids, and it lives in the rdma_read_gids(9) section of the Kernel API Manual — yes that's the manual name, I'm not making it up ✨. Sit down, grab a boba, and let me tell you about the little function that hands you your GIDs.

🎀 NAME 🎀

rdma_read_gids — returns the SGID and DGID that were used for establishing the connection, and honestly? iconic behaviour 💅.

so like, the way this works: you can use it after rdma_resolve_addr() on the client side. You can also use it on a new connection on the server side. It's applicable to IB, RoCE, and iWarp — it's giving versatile, fr fr 🦋.

big caveat though, don't skip this: if cm_id isn't bound yet to the RDMA device, it doesn't copy any SGID or DGID to the given pointers. Nothing. Nada. Ghosted 😭.

✨ SYNOPSIS ✨

void rdma_read_gids (struct rdma_cm_id *cm_id , union ib_gid *sgid ,
union ib_gid *dgid );

that's the whole signature, she's cute, she's small, she does exactly one thing 🫶

🌸 ARGUMENTS 🌸

  • cm_id — -- undescribed -- 💀 yeah that's literally what the page says, the docs really said "not me forgetting to describe this one." I'm not gonna invent lore for it, no cap.
  • sgid — pointer to SGID where the SGID will be returned. It is optional, so if you're not feeling it, pass on it, queen 👑.
  • dgid — pointer to DGID where the DGID will be returned. Also optional. Also can be skipped. We love a flexible parameter ✨.

⭐ NOTE ⭐

listen. listen. this API should not be used by any new ULPs or new code. nope. nope. not you. 🙈

If you're a user interested in querying GIDs, you should instead refer to the path record of the rdma_cm_id to query the GIDs. That's the move, that's the vibe, that's the current timeline 🌈.

This API is provided for compatibility for existing users — so it's like that one friend who's still on the old app version. We keep them around, we love them, but don't join them 💀.

🦋 SEE ALSO 🦋

okay this list is LONG and I'm obsessed with her for it — kernel file ./include/rdma/rdma_cm.h plus a whole entourage:

go read them all, iykyk 🧚‍♀️

fr fr reminder bestie: new code? don't touch this one. path record of the rdma_cm_id is the way. periodt. 💜

and that's the page!! 🎀 sign-off time: this came out of ./include/rdma, dated October 2026, and the whole thing is rdma_read_gids(9) — slay, bye, go resolve some addresses responsibly 💖🔥

📦 where this page comes from