STRUCT EF4_RX_BUFFER(9)

💖 struct ef4_rx_buffer(9) 💖

okay so bestie, welcome to the Kernel API Manual ✨ — today's main character is struct ef4_rx_buffer, and honestly? she's giving "one little buffer, so much lore." let's get into it 🫶

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🌸 NAME 🌸

struct ef4_rx_buffer — an Efx RX data buffer 🎀

like, literally the struct that holds one receive buffer's info. that's her. that's the whole vibe check.

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✨ SYNOPSIS ✨

here's the whole glow-up, exactly as it lives in the kernel — no cap, copy it character for character:

struct ef4_rx_buffer {
    dma_addr_t dma_addr;
    struct page *page;
    u16 page_offset;
    u16 len;
    u16 flags;
 };

five fields. that's it. small struct, big energy 💅

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🦋 Members 🦋

• dma_addr — the DMA base address of the buffer. like, where it lives in DMA-land. lowkey the whole point 📍
• page — the associated page buffer. important: this will be NULL if the buffer slot is currently free. so if you see a NULL in here, don't panic — she's just off duty rn 🙈
• page_offset — okay this one changes based on the state, so listen up:
  • if pending: offset in page of the DMA base address
  • if completed: offset in page of the Ethernet header

two different meanings, same field. iykyk 😭

• len — also state-dependent, bestie:
  • if pending: length for DMA descriptor
  • if completed: received length, excluding the hash prefix

yes the exclusion matters. don't forget it 🔥

• flags — flags for buffer and packet state. but here's the tea ☕: these are only set on the first buffer of a scattered packet. so if you're looking at buffer #2 and wondering where the flags went… they were never there, bestie 💀

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👑 SEE ALSO 👑

go read these next, fr fr — the whole friend group:

• Kernel file ./drivers/net/ethernet/sfc/falcon/net_driver.h
• struct ef4_buffer(9)
• struct ef4_special_buffer(9)
• struct ef4_tx_buffer(9)
• struct ef4_tx_queue(9)
• struct ef4_rx_page_state(9)
• struct ef4_rx_queue(9)
• struct ef4_channel(9)
• struct ef4_msi_context(9)
• struct ef4_channel_type(9)
• struct ef4_link_state(9)
• struct ef4_phy_operations(9)
• enum ef4_phy_mode(9)
• struct ef4_hw_stat_desc(9)
• struct ef4_nic(9)
• struct ef4_nic_type(9)

that's sixteen refs. sixteen! she knows everybody 🌈

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remember: page = NULL when free, page_offset and len mean different things depending on pending vs completed, and flags only show up on the first buffer of a scattered packet. memorize that and you're golden ⭐

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mwah, that's the page! this lil gem lives in ./drivers/net/ethernet/sfc/falcon and the version vibes are dated October 2026 💜 slay, go read some kernel source, ily, bye 🧚💖