WOPCM LAYOUT(9)

💅 WOPCM Layout — section 9, bestie

okay so this is from the Kernel API Manual, and it's literally just the map of WOPCM. no cap.

🗺️ WOPCM Layout

so here's the tea: the layout of the WOPCM gets locked in (fixed, immovable, done-zo) right after you write to the GuC WOPCM size and offset registers. and those register values? they're not vibes-based — they get calculated and determined by the HuC/GuC firmware size plus whatever set of hardware requirements/restrictions is in play. it's giving very much calculated. as shown below:

:

   +=========> +====================+ <== WOPCM Top
   ^           |  HW contexts RSVD  |
   |     +===> +====================+ <== GuC WOPCM Top
   |     ^     |                    |
   |     |     |                    |
   |     |     |                    |
   |    GuC    |                    |
   |   WOPCM   |                    |
   |    Size   +--------------------+
 WOPCM   |     |    GuC FW RSVD     |
   |     |     +--------------------+
   |     |     |   GuC Stack RSVD   |
   |     |     +------------------- +
   |     v     |   GuC WOPCM RSVD   |
   |     +===> +====================+ <== GuC WOPCM base
   |           |     WOPCM RSVD     |
   |           +------------------- + <== HuC Firmware Top
   v           |      HuC FW        |
   +=========> +====================+ <== WOPCM Base

the GuC's accessible slice of WOPCM starts at GuC WOPCM base and ends at GuC WOPCM top. 🫶 and the top part of the WOPCM? that's reserved for hardware contexts (e.g. the RC6 context) — so hands off, that's their section. 💅

👀 SEE ALSO

• Kernel file ./drivers/gpu/drm/i915/gt/intel_wopcm.c
• intel_wopcm_init_early(9)
• intel_wopcm_init(9)

✨ that's the whole page, icon status. shoutout to the source tree at ./drivers/gpu/drm/i915/gt, dated October 2026, from the Kernel API Manual — WOPCM Layout(9), periodt. 🎀💖🦋