lookup_memtype(9)

📦 version 7.3.1, in nixpkgs unstable

💖 lookup_memtype(9) 💖

okay so welcome to the Kernel API Manual entry for lookup_memtype(9), bestie — this one is short, iconic, and literally about looking up the memory type for a physical address. 🎀

🌸 NAME 🌸

lookup_memtype — looks up the memory type for a physical address. periodt, that’s the whole name vibe. 💅

✨ SYNOPSIS ✨

enum page_cache_mode lookup_memtype (u64 paddr );

🫶 ARGUMENTS 🫶

  • paddr — the physical address whose memory type needs to be looked up. That’s it, that’s the assignment, bestie. 🦋

💜 DESCRIPTION 💜

⚠️ Only to be called when PAT is enabled.

Like, only. This is not a “call it whenever” situation, okay? 🚨

On the return side, it gives you one of these four constants:

  • _PAGE_CACHE_MODE_WB
  • _PAGE_CACHE_MODE_WC
  • _PAGE_CACHE_MODE_UC_MINUS
  • _PAGE_CACHE_MODE_WT

That’s the return squad, no cap. 🌈

🌈 SEE ALSO 🌈

Go check out the kernel file ./arch/x86/mm/pat/memtype.c and these besties too:

Cute sign-off: this page’s source/version is ./arch/x86/mm/pat, dated October 2026. Bye bestie, go look up those memory types responsibly 💖✨

📦 where this page comes from