drm_gem_create_mmap_offset(9)

📦 version 7.3.1, in nixpkgs unstable

💅 drm_gem_create_mmap_offset (kernel API manual, bestie edition) 🎀

okay so welcome to the group chat, the function we're stanning today is literally drm_gem_create_mmap_offset(9) — she lives in the Kernel API Manual and honestly she's giving backstage-pass energy for GEM objects. let's get into it ✨

🌸 NAME 🌸

drm_gem_create_mmap_offset — create a fake mmap offset for an object 🫶

no fr, "fake" is the official word here, it's iconic, we love a harmless little fiction 💅

✨ SYNOPSIS ✨

int drm_gem_create_mmap_offset (struct drm_gem_object *obj );

that's it, that's the whole vibe check — one argument, returns an int, slay 💖

🦋 ARGUMENTS 🦋

  • obj — the obj in question 👀 (yes, that's literally what the manual says, and honestly? valid. it's the object you're doing the whole fake-offset thing for.)

🔥 DESCRIPTION 🔥

so here's how GEM memory mapping works, bestie, listen up 🧚

it hands back to userspace a fake mmap offset that userspace can then use in a subsequent mmap(2) call. then the DRM core code does its little lookup moment — it looks up the object based on that offset and sets up all the various memory mapping structures. main character behaviour, no cap 👑

this routine allocates and attaches a fake offset for obj. periodt. that's the job 🌟

drivers can call drm_gem_free_mmap_offset before freeing obj to release the fake offset again — like returning your borrowed hoodie before you move out, please do this 🙈 💜

ngl the "fake" wording is doing a lot of heavy lifting here but it's exactly what the docs say, so we're keeping it fr fr 🍓

👑 SEE ALSO 👑

kernel file ./drivers/gpu/drm/drm_gem.c and honestly the whole extended friend group 😭 :

like, the whole roster. tag yourself, i'm drm_gem_free_mmap_offset(9) because i also clean up after everyone 💀 🫶

and that's the page!! source path ./drivers/gpu/drm, dated October 2026, from the Kernel API Manual — drm_gem_create_mmap_offset(9) out 💜✨

📦 where this page comes from