STRUCT AXIDMA_BD(9)

💖 NAME 💖

struct axidma_bd — the Axi Dma buffer descriptor layout, aka the blueprint bestie, the literal map of where everything lives 🗺️✨

🌸 SYNOPSIS 🌸

struct axidma_bd {
    u32 next;
    u32 next_msb;
    u32 phys;
    u32 phys_msb;
    u32 reserved3;
    u32 reserved4;
    u32 cntrl;
    u32 status;
    u32 app0;
    u32 app1;
    u32 app2;
    u32 app3;
    u32 app4;
    struct sk_buff *skb;
 };

That's the whole squad right there, no cap 🫶

✨ Members ✨

Okay so like, one field at a time, because every single one matters and we are not skipping anybody:

• next — the MM2S/S2MM Next Descriptor Pointer 👉 like, where we go next, the link in the chain.
• next_msb — the MM2S/S2MM Next Descriptor Pointer, but the high 32 bits 🧚 the upper half of the same vibe.
• phys — the MM2S/S2MM Buffer Address 📍 where the actual buffer lives in memory.
• phys_msb — the MM2S/S2MM Buffer Address again, high 32 bits 💅 yep, the top half, iconic.
• reserved3 — Reserved and not used 🙈 lowkey just sitting there. Ignore her.
• reserved4 — Reserved and not used 💀 same energy, also ignore. Periodt.
• cntrl — the MM2S/S2MM Control value 🎛️ the knobs, the buttons, the command energy.
• status — the MM2S/S2MM Status value 📊 how's it going, what's the tea.
• app0 — MM2S/S2MM User Application Field 0. 🍓 yours to play with.
• app1 — MM2S/S2MM User Application Field 1. 🍓 next one, also yours.
• app2 — MM2S/S2MM User Application Field 2. 🍓 keep going bestie.
• app3 — MM2S/S2MM User Application Field 3. 🍓 almost through the app fam.
• app4 — MM2S/S2MM User Application Field 4. 🍓 last one, slay.
• skb — pointer to SKB transferred using DMA 🌈 the main character pointer, carrying the packet through the DMA journey.

Ngl, reserved3 and reserved4 are literally just Reserved and not used — do not try to make them happen, they're not going to happen 💅

🦋 SEE ALSO 🦋

Go check these out, they're all in the same friend group 🫶

The kernel file ./drivers/net/ethernet/xilinx/xilinx_axienet.h, plus:

• struct skbuf_dma_descriptor(9)
• struct axienet_local(9)
• struct axienet_option(9)
• axienet_ior(9)
• axienet_iow(9)
• axienet_dma_out32(9)
• axienet_dma_out64(9)

And that's the whole page, bestie 🎀 this one comes from ./drivers/net/ethernet/xilinx, dated October 2026, straight out of the Kernel API Manual ✨ ily, go read your structs 💜