qman_create_fq(9)

📦 version 7.3.1, in nixpkgs unstable

💅 qman_create_fq — the Kernel API Manual, bestie edition ✨

Okay so we're in the Kernel API Manual today, and the star of the show is qman_create_fq(9). Buckle up, this one's actually kinda iconic.

✨ NAME ✨

qman_create_fq — literally just allocates a FQ. That's it. That's the whole vibe. 🎀

🦋 SYNOPSIS 🦋

int qman_create_fq (u32 fqid , u32 flags , struct qman_fq *fq );

🌸 ARGUMENTS 🌸

  • fqid — the index of the FQD to encapsulate, and no cap it must be "Out of Service". Like, non-negotiable. 💀
  • flags — a bit-mask of QMAN_FQ_FLAG_*** options. Mix and match, bestie.
  • fq — the memory for storing the 'fq', with callbacks filled in. You bring the memory, it brings the callbacks. 🫶

💖 DESCRIPTION 💖

So what it does: it creates a frame queue object for the given fqid — unless the QMAN_FQ_FLAG_DYNAMIC_FQID flag is set in flags, in which case a FQID gets dynamically allocated instead (or, plot twist, the function fails if none are available 😭).

Once it's created, the caller should not touch the memory at 'fq' — the only exception is adjacent memory that's been extended for user-defined fields (peep the definition of "struct qman_fq" for more info on that). Hands off, it's giving main character energy and doesn't need your help. 🙈

Now, NO_MODIFY — that one's only intended for enqueuing to pre-existing frame-queues that aren't supposed to be otherwise interfered with. It prevents all other modifications to the frame queue. All of them. Periodt. 👑

Then there's the TO_DCPORTAL flag, which causes the driver to honour any context_b modifications requested in the qm_init_fq API. Why? Because that indicates the frame queue will be consumed by a direct-connect portal (PME, CAAM, or Fman). ✨

Lowkey important: when frame queues are consumed by software portals, the context_b field is controlled by the driver and can't be modified by the caller. So don't even try it. 💅

🔥 SEE ALSO 🔥

Kernel file ./include/soc/fsl/qman.h and honestly the whole squad:

Okay bestie, that's the page! 🧚 Coming to you from ./include/soc/fsl, dated October 2026 — screenshot it, memorize it, slay the day. 💜⭐

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