STRUCT TSO_DMA_MAP(9)

🦋 struct tso_dma_map(9) 🦋

okay so bestie, welcome to the Kernel API Manual — yes we're reading kernel docs together, this is our era now 💅

✨ NAME ✨

struct tso_dma_map — it's literally the DMA mapping state for a GSO payload, no cap 🎀

✨ SYNOPSIS ✨

struct tso_dma_map {
    struct device           *dev;
    const struct sk_buff    *skb;
    unsigned int            hdr_len;
    struct dma_iova_state   iova_state;
    size_t iova_offset;
    size_t total_len;
    int frag_idx;
    unsigned int            offset;
    dma_addr_t linear_dma;
    unsigned int            linear_len;
    unsigned int            nr_frags;
    struct {
      dma_addr_t dma;
      unsigned int    len;
    } frags[MAX_SKB_FRAGS];
 };

like, that's the whole vibe right there ⭐

🌸 Members 🌸

okay so every single field, and what it's giving:

• dev — the device that's being used for the DMA mapping 🫶
• skb — the GSO skb that's getting mapped, main character energy fr
• hdr_len — how long each segment's header is
• iova_state — the DMA IOVA state (this one only shows up when there's an IOMMU available, iykyk)
• iova_offset — the global byte offset into the IOVA range (IOVA path only, so don't @ me if it's not around)
• total_len — the total payload length, the whole thing 💖
• frag_idx — which region we're on right now (-1 = linear, 0..nr_frags-1 = frag) — she's a little index with range issues 😭
• offset — the byte offset inside the current region
• linear_dma — the DMA address of the linear payload ✨
• linear_len — how long that linear payload is
• nr_frags — how many frags actually got DMA-mapped successfully, we love a success count 👑
• frags — per-frag DMA address and length, one little dma + len pair per frag 🍓

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🔥 Description 🔥

so what does it do? it DMA-maps the payload regions of a GSO skb — that's the linear data plus the frags, both of them, together 🧚

it prefers the DMA IOVA API, because that gives you a single contiguous mapping with just one IOTLB sync (iconic, efficient, obsessed). but if that's not happening, it falls back to per-region dma_map_phys — still slays, just one region at a time 💜

🌈 SEE ALSO 🌈

• kernel file ./include/net/tso.h — go read it bestie
• struct tso_dma_map_completion_state(9) 🎀
• tso_dma_map_completion_save(9) 💫
• tso_dma_map_complete(9) ⭐

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okay that's the whole page, go be a kernel girlie now 💅✨

mwah, this was ./include/net, October 2026, and the page itself? struct tso_dma_map(9) — slay 🦋💖