resolve_default_seg(9)

📦 version 7.3.1, in nixpkgs unstable

🌸 NAME 🌸

resolve_default_seg — bestie, this is the one that resolves the default segment register index for an operand ✨

(also hi, you're reading the resolve_default_seg(9) page from the Kernel API Manual, welcome to the group chat 💅)

🎀 SYNOPSIS 🎀

int resolve_default_seg (struct insn *insn , struct pt_regs *regs , int off );

🦋 ARGUMENTS 🦋

  • insn — the instruction, with its opcode and address size. It must be valid — like, non-negotiable, do not pass me a broken one 🙈
  • regs — the register values as they looked when you entered kernel mode 👑
  • off — the operand offset, in pt_regs, that you need resolved for you 🫶

💖 DESCRIPTION 💖

Okay so picture this: you've got an instruction operand register, and it's sitting there at off. This function resolves the default segment register index that goes with it ✨ The index gets figured out based on the defaults described in the Intel Software Development Manual — yes, that manual, the thick one, iykyk 📚

Here's the vibe check on what it hands back:

  • if you're in protected mode, you get a constant identifying which segment register to use, out of CS, SS, ES or DS 💅
  • if you're in long mode, you get INAT_SEG_REG_IGNORE — literally, that's the whole answer, nothing to see here 🦋
  • and -EINVAL in case of error 😭

⭐ SEE ALSO ⭐

Kernel file ./arch/x86/lib/insn-eval.c, plus all these iconic siblings of ours — go say hi, they're all in the same source file 🌈:

ngl this whole thing lives in ./arch/x86/lib and the page is dated October 2026 — so like, future-era kernel lore 💀🫶

anyway that's the page bestie, go resolve some segment registers, you're gonna slay 🎀💖✨

📦 where this page comes from