STRUCT RISCV_IOMMU_COMMAND(9)

💅 struct riscv_iommu_command(9) 💅

okay bestie, welcome to the Kernel API Manual entry for struct riscv_iommu_command — yes that's the whole title, she's a long one, we love her anyway 🫶

---

✨ NAME ✨

struct riscv_iommu_command — the generic IOMMU command structure. that's it. that's the vibe. 🎀

---

🌸 SYNOPSIS 🌸

here's the whole glow-up, literally the entire struct:

struct riscv_iommu_command {
    u64 dword0;
    u64 dword1;
 };

two u64s. that's the main character energy right there. no cap. 💖

---

🦋 Members 🦋

• dword0 — this one's got the opcode AND the function identifier living inside it. she contains multitudes ✨
• dword1 — and this one's the opcode specific data. whatever the opcode wants, she provides 🎀

---

💀 Description 💀

okay so here's the tea 🍓 — these commands get interpreted as two 64bit fields. and the layout? iconic, honestly:

• the first 7 bits of the first field are the opcode, and that opcode also defines the command's format (so like, the opcode is basically the vibe-setter for the whole thing 👑)
• then right after comes a 3bit field that specifies the function invoked by that command
• and the rest? opcode-specific. mystery. intrigue. iykyk 💅

so this is a generic struct — she's a blank canvas that gets populated differently according to each command. no two commands fill her in the same way fr fr 🌈

and if you want more infos on the commands and the command queue, go check section 3.1. that's where the lore lives 📖✨

---

🧚 SEE ALSO 🧚

the whole friend group, in order, no one left out 🫶:

• Kernel file ./drivers/iommu/riscv/iommu-bits.h enum
• riscv_iommu_igs_settings(9)
• enum riscv_iommu_ddtp_modes(9)
• enum riscv_iommu_hpmevent_id(9)
• struct riscv_iommu_dc(9)
• enum riscv_iommu_dc_iohgatp_modes(9)
• enum riscv_iommu_dc_fsc_atp_modes(9)
• struct riscv_iommu_pc(9)
• struct riscv_iommu_fq_record(9)
• enum riscv_iommu_fq_causes(9)
• enum riscv_iommu_fq_ttypes(9)
• struct riscv_iommu_pq_record(9)
• struct riscv_iommu_msipte(9)

---

lowkey a reminder bestie: it's giving "generic," so don't go assuming she behaves the same for every command — the format is defined by the opcode, periodt 💅

---

and that's the page!! 🌸 sourced from ./drivers/iommu/riscv, dated October 2026 — mwah, go read some more manpages, ily, bye 🎀💖✨