STRUCT HFI1_IPOIB_CIRC_BUF(9)

🦋 struct hfi1_ipoib_circ_buf(9) 🦋

okay so bestie, this is a page from the Kernel API Manual — like, the actual kernel, no cap — and it's all about one little struct. Sit down, grab a strawberry 🍓, we're doing this.

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✨ NAME ✨

struct hfi1_ipoib_circ_buf — literally just a list of items to be processed. that's the whole vibe. a whole struct whose entire personality is "here's some stuff, go deal with it" 💅

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✨ SYNOPSIS ✨

struct hfi1_ipoib_circ_buf {
    void *items;
    u32 max_items;
    u32 shift;
    u64 sent_txreqs;
    u32 avail;
    u32 tail;
    atomic_t stops;
    atomic_t ring_full;
    atomic_t no_desc;
    u64 complete_txreqs;
    u32 head;
 };

look at her. eleven fields. she's serving structure, she's serving organization, she's giving main character energy 👑

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✨ Members ✨

okay let's meet the cast, one by one, in the exact order the page serves them:

• items — the ring of items, and every single one is a power of two size. icons only. ✨
• max_items — max items + 1 that the ring can contain. yes, the plus one is real, don't come for me, that's what it says 🫶
• shift — log2 of size, used for getting the txreq. math girlies rise 🌸
• sent_txreqs — a count of txreqs that got posted to sdma. keeping receipts, fr fr 🧾
• tail — the ring tail. that's it. that's the whole description. 💀

wait — quick aside, bestie: avail is literally sitting right there in the struct up in the synopsis, but the Members list doesn't say a single word about it. not one. so I'm not gonna make something up, because that would be lying on the internet and we don't do that 🙈 just know avail is in the building.

okay continuing:

• stops — count of stops of the queue. how many times did we stop? this many. 😭
• ring_full — the ring has been filled. she's full. she cannot take any more. 💀
• no_desc — a descriptor shortage was seen. rough out here for a descriptor 😔
• complete_txreqs — count of txreqs completed by sdma. the glow-up arc, finished and accounted for 🔥
• head — the ring head. iconic, mysterious, to the point. 👑

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✨ SEE ALSO ✨

go look at these next, bestie, they're literally linked:

• Kernel file ./drivers/infiniband/hw/hfi1/ipoib.h
• struct ipoib_txreq(9)
• struct hfi1_ipoib_txq(9)

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💖 heads up: the members list and the struct in the synopsis don't line up one-to-one (avail says hi but nobody introduces her), so don't be shocked. that's the page, not me.

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okay that's the whole thing, you ate that 🍓✨ mwah 💋

sign-off time: this little beauty lives under ./drivers/infiniband/hw/hfi1, and the page is dated October 2026 — so yeah, she's from the future, we stan a forward-thinking struct 🌈👑. bye bestie, go process some items! 🦋💜