insn_decode_mmio(9)

✨ NAME ✨

insn_decode_mmio — Decode a MMIO instruction. This is the insn_decode_mmio(9) page in the Kernel API Manual, and yes bestie, we're decoding a Memory-mapped I/O instruction. 💅

🎀 SYNOPSIS 🎀

enum insn_mmio_type insn_decode_mmio (struct insn *insn , int *bytes );

💖 ARGUMENTS 💖

• insn — Structure to store decoded instruction. Like, this is where the decoded instruction gets stored. 🫶
• bytes — Returns size of memory operand. It hands you back the size of the memory operand. 📏

🦋 DESCRIPTION 🦋

okay so insn_decode_mmio decodes an instruction that's used for Memory-mapped I/O. That's the whole main character energy of this function. ✨

Type of the instruction. The size of the memory operand is stored in bytes. If decode failed, INSN_MMIO_DECODE_FAILED returned. No cap, that's the failure signal. 💀

🌈 SEE ALSO 🌈

Kernel file ./arch/x86/lib/insn-eval.c is over here being linked with all these besties:

• is_string_insn(9)
• insn_has_rep_prefix(9)
• get_seg_reg_override_idx(9)
• check_seg_overrides(9)
• resolve_default_seg(9)
• resolve_seg_reg(9)
• get_segment_selector(9)
• get_reg_offset_16(9)
• get_desc(9)
• insn_get_seg_base(9)
• get_seg_limit(9)
• insn_get_code_seg_params(9)
• insn_get_modrm_rm_off(9)
• insn_get_modrm_reg_off(9)
• insn_get_modrm_reg_ptr(9)
• get_seg_base_limit(9)
• get_eff_addr_reg(9)
• get_eff_addr_modrm(9)
• get_eff_addr_modrm_16(9)
• get_eff_addr_sib(9)
• get_addr_ref_16(9)
• get_addr_ref_32(9)
• get_addr_ref_64(9)
• insn_get_addr_ref(9)
• insn_fetch_from_user(9)
• insn_fetch_from_user_inatomic(9)
• insn_decode_from_regs(9)

source: ./arch/x86/lib · version/date: October 2026 · page: insn_decode_mmio(9) — mwah, go decode that MMIO bestie 💋🎀