STRUCT EFX_TX_BUFFER(9)

💖 struct efx_tx_buffer(9) 💖

okay so bestie, welcome to the Kernel API Manual — this lil' page is all about struct efx_tx_buffer, aka the buffer state for a TX descriptor. it's giving "small struct, big responsibilities" and honestly? we stan. 🎀

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✨ NAME ✨

struct efx_tx_buffer — buffer state for a TX descriptor. that's it, that's the whole vibe. 🦋

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🌸 SYNOPSIS 🌸

struct efx_tx_buffer {
    union {
      const struct sk_buff *skb;
      struct xdp_frame *xdpf;
    };
    union {
      efx_qword_t option;
      dma_addr_t dma_addr;
    };
    unsigned short flags;
    unsigned short len;
    unsigned short unmap_len;
    unsigned short dma_offset;
 };

no cap, that's the whole thing. two anonymous unions, four unsigned shorts, and a whole lotta main character energy. 👑

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💅 Members 💅

• {unnamed_union} — anonymous. yes babes, it literally just says anonymous and honestly same. 🙈 (this is the skb / xdpf union, and there's a matching one below — read on, i gotchu.)
• skb — when flags & EFX_TX_BUF_SKB, this is the associated socket buffer, and it gets freed once the descriptor completes. so like, it's the guest of honor at the free-the-skb party. 🎉
• xdpf — when flags & EFX_TX_BUF_XDP, this is the XDP frame info; its data member is the associated buffer that we drop a page reference on. lowkey important, don't forget the data member, iykyk. 💀
• {unnamed_union} — anonymous, again. second anonymous union, same energy. 🫶 (this one's the option / dma_addr union.)
• option — when flags & EFX_TX_BUF_OPTION, it's an EF10-specific option descriptor. EF10 girlies rise. ⭐
• dma_addr — DMA address of the fragment. 🎯
• flags — flags for allocation and DMA mapping type. that's the allocation type and the DMA mapping type, both in one. iconic. 🔥
• len — length of this fragment. heads up though: this field is zero when the queue slot is empty. like, literally 0. so if you see a zero, that slot's not home. 🏚️
• unmap_len — length of this fragment to unmap. 🌈
• dma_offset — offset of dma_addr from the address of the backing DMA mapping. ⚠️ only valid if unmap_len != 0 — so check that unmap_len != 0 first, babes, fr fr. don't be out here reading it when it's not valid. 😭

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🌟 SEE ALSO 🌟

the squad, the whole entire squad. 🧚 these all live in the kernel file ./drivers/net/ethernet/sfc/siena/net_driver.h:

• struct efx_buffer(9)
• struct efx_special_buffer(9)
• struct efx_tx_queue(9)
• struct efx_rx_buffer(9)
• struct efx_rx_page_state(9)
• struct efx_rx_queue(9)
• struct efx_channel(9)
• struct efx_msi_context(9)
• struct efx_channel_type(9)
• struct efx_link_state(9)
• enum efx_phy_mode(9)
• struct efx_hw_stat_desc(9)
• struct efx_rss_context(9)
• struct efx_arfs_rule(9)
• struct efx_async_filter_insertion(9)
• struct efx_nic(9)
• struct efx_nic_type(9)

go read them all, bestie. ttyl. 💜

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mwah 💋 that's a wrap! this page was brought to you by ./drivers/net/ethernet/sfc/siena and is dated way out there in October 2026 — slay, see you in the future, and remember: struct efx_tx_buffer(9) always ate. periodt. 🎀✨