MEMORY OBJECTS CONTROL STATE (MOCS)(9)

💅 MEMORY OBJECTS CONTROL STATE (MOCS) 💅

okay bestie, sit down, because we're about to talk about MOCS — that's Memory Objects Control State for the uninitiated — and it's from the Kernel API Manual, section 9, so you know it's gonna be a little nerdy but we're gonna make it cute 💖

🌸 MOTIVATION 🌸

So back in the day (like, previous Gens), the MOCS settings were just a value that was set by user land as part of the batch. simple. iconic. no drama.

But then Gen9 happened and everything changed, because now it's a single table (per ring) that all the batches reference by index instead of programming the MOCS directly. the way that's such a glow-up honestly ✨

The one wrinkle in this whole situation (and there's always a wrinkle, isn't there 😭) is that only PART of the MOCS tables are included in the context — specifically the GFX_MOCS_0 - GFX_MOCS_64 and the LNCFCMOCS0 - LNCFCMOCS32 registers. The rest are not included (that's the settings for the other rings, bestie, they're off doing their own thing 🙈).

This table has to be set at system start-up, and that's lowkey non-negotiable, because of the way the table interacts with the contexts and the GmmLib interface. it's giving foundational, fr fr 🫶

🦋 IMPLEMENTATION 🦋

So how does this actually work? The tables — one per supported platform — are defined in intel_mocs.c, and they get programmed in the first batch after the context is loaded (with the hardware workarounds, obviously, we're not savages 💅).

After that, the usual context handling just keeps the MOCS in step. that's it. that's the whole vibe. main character energy from start to finish 👑

🎀 SEE ALSO 🎀

• Kernel file ./drivers/gpu/drm/i915/gt/intel_mocs.h — go read it, iykyk 📖

and that's the whole page, bestie!! this one's from the Kernel API Manual, section 9, sourced from ./drivers/gpu/drm/i915/gt, dated October 2026 — so if you ever need to cite it, you're welcome, mwah 💋🦋⭐