STRUCT NFP_NET_TX_RING(9)

📦 version 7.3.1, in nixpkgs unstable

💅 struct nfp_net_tx_ring(9) — the TX ring glow-up 🎀

okay bestie, welcome to the Kernel API Manual entry for struct nfp_net_tx_ring. this is the whole TX ring structure, and honestly? it's giving organized. every field, every union, every little pointer — we're covering it all, no skips, no cap. 🦋

✨ NAME ✨

struct nfp_net_tx_ring — the TX ring structure, periodt. this is the data structure, it's the whole vibe, it's the main character. 💜

🌸 SYNOPSIS 🌸

here's the whole thing laid out, character for character, exactly as it lives in the header. copy it, stare at it, memorize it — it's all here:

struct nfp_net_tx_ring {
    struct nfp_net_r_vector *r_vec;
    u16 idx;
    u16 data_pending;
    u8 __iomem *qcp_q;
    u64 *txrwb;
    u32 cnt;
    u32 wr_p;
    u32 rd_p;
    u32 qcp_rd_p;
    u32 wr_ptr_add;
    union {
      struct nfp_nfd3_tx_buf *txbufs;
      struct nfp_nfdk_tx_buf *ktxbufs;
    };
    union {
      struct nfp_nfd3_tx_desc *txds;
      struct nfp_nfdk_tx_desc *ktxds;
    };
    int qcidx;
    dma_addr_t dma;
    size_t size;
    bool is_xdp;
 };

🫶 MEMBERS 🫶

okay so this is the good part — every single field, explained. drink water, stay hydrated, and let's go field by field:

  • r_vec — back pointer to the ring vector structure. it's the "hey, this is my parent" link. every ring knows where it came from. 👑
  • idx — the ring index from Linux's perspective. that's the important qualifier, bestie, keep it.
  • data_pending — number of bytes added to the current block. NFDK only, so don't come for it if you're on NFD3.
  • qcp_q — pointer to the base of the QCP TX queue. that's the Queue Controller Peripheral queue, and it's an u8 __iomem *, iykyk.
  • txrwb — the TX pointer write back area. this is where the write-back happens. cute.
  • cnt — size of the queue, measured in number of descriptors. not bytes! descriptors. 📏
  • wr_p — the TX ring write pointer, and it's free running — meaning it just keeps on going, no wrapping drama here.
  • rd_p — the TX ring read pointer. also free running. matching set with wr_p, we love symmetry. 💖
  • qcp_rd_p — the local copy of the QCP TX queue read pointer. it's a copy, a little snapshot, a "just in case".
  • wr_ptr_add — the accumulated number of buffers to add to the QCP write pointer. it's used for .xmit_more delayed kick. yes, that dot is real, that's the name, don't touch it.

🧚 the anonymous unions 🧚

  • {unnamed_union} — anonymous. that's it, that's the label. it's a union with no name, living its best anonymous life.
  • txbufs — array of transmitted TX buffers, to free on transmit. NFD3 flavor. 🍓
  • ktxbufs — array of transmitted TX buffers, to free on transmit. NFDK flavor. same job, different name, different letter.
  • {unnamed_union} — anonymous again. second anonymous union, second chance at anonymity. iconic honestly.
  • txds — virtual address of the TX ring in host memory. NFD3 version.
  • ktxds — virtual address of the TX ring in host memory. NFDK version. same thing, k prefix, you get it. ✨

🌈 and the rest of the fields 🌈

  • qcidx — the Queue Controller Peripheral (QCP) queue index for the TX queue. spelled out in full because acronyms deserve lore.
  • dma — the DMA address of the TX ring. type is dma_addr_t, it's fancy.
  • size — size, in bytes, of the TX ring. and yes it's "needed to free" — that's the whole reason it's hanging around. lowkey essential. 💀
  • is_xdp — a bool asking the big question: is this a XDP TX ring? yes or no, no in-between.

🔥 SEE ALSO 🔥

go read these next, bestie, we're doing a whole study session:

ngl, if you skipped a field, go back. we said every detail and we meant every detail. no cap. 🙈

and that's the page! this one came from ./drivers/net/ethernet/netrono... (the footer truncates it, not me 🫶) and it's dated October 2026 — future-coded of it. big slay, thanks for reading, mwah. 💅🎀

📦 where this page comes from