STRUCT GUC_MMIO_REG(9)

💅 struct guc_mmio_reg(9) — from the Kernel API Manual, bestie 🎀

okay so picture this: you're deep in the kernel docs, the manual name is Kernel API Manual, and this little icon walks in — 💫 struct guc_mmio_reg — the GuC MMIO reg state struct. that's it, that's the vibe. let's get into it ✨

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🌸 NAME 🌸

struct guc_mmio_reg — the GuC MMIO reg state struct, no cap 💖

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✨ SYNOPSIS ✨

here's the whole shape of it, literally copy-paste this into your brain, iykyk:

struct guc_mmio_reg {
    u32 offset;
    u32 value;
    u32 flags;
    u32 mask;
  #define GUC_REGSET_MASKED               BIT(0);
  #define GUC_REGSET_STEERING_NEEDED      BIT(1);
  #define GUC_REGSET_MASKED_WITH_VALUE    BIT(2);
  #define GUC_REGSET_RESTORE_ONLY         BIT(3);
  #define GUC_REGSET_STEERING_GROUP       GENMASK(16, 12);
  #define GUC_REGSET_STEERING_INSTANCE    GENMASK(23, 20);
 };

those #defines are living inside the struct body btw. she contains multitudes 🫶

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🦋 Members 🦋

bestie the glow-up is in the details, here's every member and what she does:

• offset — the MMIO Offset, and it gets filled in by the Host. that's the Host's job, not yours, periodt 💅
• value — the MMIO Value, and this one's used by Firmware to store value. firmwares' little storage unit 😌
• flags — flags for accessing the MMIO. the whole vibe-check bitfield, iconic
• mask — the value of a mask to apply if mask with value is set. yes, "if mask with value is set" — that's the condition, don't come for me, that's literally the doc 💀

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🎀 Description 🎀

GuC MMIO reg state struct. that's the whole description. she said "my work here is done" and honestly? respect. 👑

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💜 SEE ALSO 💜

go read these next, they're the friend group 🧚:

• the kernel file ./drivers/gpu/drm/xe/abi/guc_capture_abi.h
• struct guc_mmio_reg_set(9)
• struct guc_debug_capture_list_header(9)
• struct guc_debug_capture_list(9)
• struct guc_state_capture_header_t(9)
• struct guc_state_capture_t(9)
• struct guc_state_capture_group_header_t(9)
• struct guc_state_capture_group_t(9)

like, that's the entire group chat right there, highkey obsessed 🌈

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and that's the page!! sourced straight from ./drivers/gpu/drm/xe/abi, dated October 2026 — mwah, kiss the docs, they're beautiful 😭💖 periodt. 🍓