STRUCT SPU_STATE(9)

🌸 struct spu_state — the whole vibe of an SPU context save area 🌸

okay so real talk, this is a page from the Kernel API Manual (that's the manual name, bestie, clocking in 😌) and the star of the show is struct spu_state. Let's get into it 💅

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✨ NAME ✨

struct spu_state — and ngl the original page just kinda leaves the description blank after the dash 😭 so like… the struct speaks for itself, iykyk. Keep reading, it gets so much better 🫶

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🦋 SYNOPSIS 🦋

here's the whole thing, copied exactly, no cap, every single field:

struct spu_state {
    struct spu_lscsa *lscsa;
    struct spu_problem_collapsed prob;
    struct spu_priv1_collapsed priv1;
    struct spu_priv2_collapsed priv2;
    u64 spu_chnlcnt_RW[32];
    u64 spu_chnldata_RW[32];
    u32 spu_mailbox_data[4];
    u32 pu_mailbox_data[1];
    u64 class_0_dar, class_0_pending;
    u64 class_1_dar, class_1_dsisr;
    unsigned long suspend_time;
    spinlock_t register_lock;
};

look at her. main character struct energy, periodt 👑

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🎀 Members 🎀

here's the rundown the page actually gives us, one by one, no skipping 🙈

• lscsa — Local Store Context Save Area. that's the big one, we'll get to her again in a sec 💖
• prob — Collapsed Problem State Area, w/o pads. yes "w/o pads" literally means without the padding, slay for saved bytes ✨
• priv1 — Collapsed Privileged 1 Area, w/o pads. same deal, no pads 🎀
• priv2 — Collapsed Privileged 2 Area, w/o pads. the sequel, also padless 🦋
• spu_chnlcnt_RW — Array of saved channel counts. it's an array, it's saved, it counts channels 💅
• spu_chnldata_RW — Array of saved channel data. the data half of the duo, iconic pairing fr fr
• suspend_time — Time stamp when decrementer disabled. a little timestamp moment ⏰

that's the member breakdown this page gives you, and we're moving on 🏃‍♀️

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💜 Description 💜

okay so here's the lore 📖 this structure represents the whole of the SPU context save area (CSA). like, the entirety of it. This struct contains all of the state necessary to suspend and then later optionally resume execution of an SPU context — suspend now, maybe resume later, your call bestie 😌

and the lscsa region? highkey the star of the size show — she is by far the largest, which is exactly why she's allocated separately. the whole point is that she may either be pinned or mapped to/from application memory, as appropriate for the OS environment. so like, flexible queen behavior 👑✨

fr fr this is the struct that holds everything you need to pause an SPU context and pick it back up later — don't lose track of it 💀

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🌈 SEE ALSO 🌈

• Kernel file ./arch/powerpc/include/asm/spu_csa.h
• struct spu_lscsa(9)

go read those too, they're literally right there and they're serving 🫶

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aaaand that's the whole page bestie 💖 huge thanks to ./arch/powerpc/include/asm for bringing us this one, dated October 2026, filed under struct spu_state(9) — mwah, iconic, no notes 🎀✨💅