STRUCT DDCB_QUEUE(9)

🌸 struct ddcb_queue(9) 🌸

okay so bestie, welcome to the Kernel API Manual — section 9, the kernel API one — and today's main character is literally a struct called ddcb_queue. it's giving "the queue data structure that holds ALL the DDCB vibes" 💅

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✨ NAME ✨

struct ddcb_queue — DDCB queue data 💖

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🦋 SYNOPSIS 🦋

like, here's the whole thing, every single field, no skips, no edits:

struct ddcb_queue {
    int ddcb_max;
    int ddcb_next;
    int ddcb_act;
    u16 ddcb_seq;
    unsigned int ddcbs_in_flight;
    unsigned int ddcbs_completed;
    unsigned int ddcbs_max_in_flight;
    unsigned int return_on_busy;
    unsigned int wait_on_busy;
    dma_addr_t ddcb_daddr;
    struct ddcb *ddcb_vaddr;
    struct ddcb_requ **ddcb_req;
    wait_queue_head_t *ddcb_waitqs;
    spinlock_t ddcb_lock;
    wait_queue_head_t busy_waitq;
    u32 IO_QUEUE_CONFIG;
    u32 IO_QUEUE_STATUS;
    u32 IO_QUEUE_SEGMENT;
    u32 IO_QUEUE_INITSQN;
    u32 IO_QUEUE_WRAP;
    u32 IO_QUEUE_OFFSET;
    u32 IO_QUEUE_WTIME;
    u32 IO_QUEUE_ERRCNTS;
    u32 IO_QUEUE_LRW;
};

that's the whole squad, right there 👑

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🎀 Members 🎀

like, the field-by-field tour. buckle up 🫶

• ddcb_max — the number of DDCBs sitting on the queue. the headcount. 💫
• ddcb_next — the next free DDCB, aka who's up next, no cap.
• ddcb_act — the next DDCB that's supposed to finish. manifesting its completion energy ✨
• ddcb_seq — the sequence number of the last DDCB. tracking, iconically.
• ddcbs_in_flight — DDCBs that are currently enqueued. they're out there, in the air, doing their thing 🦋
• ddcbs_completed — how many DDCBs have already been completed. the success counter, ate 💅
• return_on_busy — the number of -EBUSY returns on a full queue. yes, that's a real counter for the busy-ness 😭
• wait_on_busy — the number of waits on a full queue. she waits, she counts, she keeps receipts.
• ddcb_daddr — the DMA address of the first DDCB in the queue. memory address realness 🔥
• ddcb_vaddr — the kernel virtual address of the first DDCB in the queue. same first DDCB, but the virtual view, iykyk.
• ddcb_req — the associated requests, one per DDCB. a whole matching set, we love a one-to-one 💜
• ddcb_waitqs — the associated wait queues, one per DDCB. again: one per DDCB. consistent queen 🌈
• ddcb_lock — the lock that protects queuing operations. DO NOT skip the lock bestie, that's the whole safety vibe 🔒

ngl the struct up top also has ddcbs_max_in_flight, busy_waitq, and all the IO_QUEUE_* fields (IO_QUEUE_CONFIG, IO_QUEUE_STATUS, IO_QUEUE_SEGMENT, IO_QUEUE_INITSQN, IO_QUEUE_WRAP, IO_QUEUE_OFFSET, IO_QUEUE_WTIME, IO_QUEUE_ERRCNTS, IO_QUEUE_LRW) — this page doesn't describe those, so I'm not out here making stuff up about them 🙈 they're in the struct, that's what we know, periodt.

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👑 SEE ALSO 👑

go read these too, fr fr — all of them, from the kernel file ./drivers/misc/genwqe/card_base.h:

• struct genwqe_reg(9)
• struct dma_mapping(9)
• struct genwqe_dev(9)
• enum genwqe_requ_state(9)
• struct genwqe_sgl(9)
• struct ddcb_requ(9)
• struct genwqe_file(9)
• genwqe_get_slu_id(9)
• genwqe_write_vreg(9)
• genwqe_read_vreg(9)
• __genwqe_execute_ddcb(9)
• __genwqe_execute_raw_ddcb(9)
• genwqe_is_privileged(9)

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that's the whole page, bestie 💖✨🎀🦋 this lil masterpiece lives in ./drivers/misc/genwqe and it's dated October 2026 — so like, future iconic. mwah 💋