STRUCT APPLE_SMC(9)

💖 NAME 💖

okay so welcome to struct apple_smc(9) from the Kernel API Manual — literally the main character struct of this whole page. bestie, the original NAME line is kinda shy and gives us no description at all (it's just the name and a dash), so all the actual tea is down in the synopsis and the members list. no cap. 👑

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✨ SYNOPSIS ✨

here's the whole vibe, copied exactly so you can trust me:

struct apple_smc {
    struct device *dev;
    u32 key_count;
    smc_key first_key;
    smc_key last_key;
    struct blocking_notifier_head event_handlers;
    struct apple_rtkit *rtk;
    struct completion init_done;
    enum apple_smc_boot_stage boot_stage;
    struct resource *sram;
    void __iomem *sram_base;
    struct apple_rtkit_shmem shmem;
    unsigned int msg_id;
    bool atomic_mode;
    bool atomic_pending;
    struct completion cmd_done;
    u64 cmd_ret;
    struct mutex mutex;
    spinlock_t lock;
};

like, look at her. she's structured. she's organized. she contains multitudes. 🫶

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🎀 MEMBERS 🎀

every single field, explained, no gatekeeping:

• dev — the underlying struct device for the physical backend device. like, whose struct even is this? this one. 🏠
• key_count — how many SMC keys are available. the headcount, basically. 💅
• first_key — the first valid SMC key. the beginning of the alphabet era. ✨
• last_key — the last valid SMC key. the end of an era. 😭
• event_handlers — the notifier call chain for events received from SMC. she's got a whole group chat for events. 🦋
• rtk — pointer to the Apple RTKit instance. lowkey essential. 🔥
• init_done — a completion for initialization. she'll text you when she's ready, fr. 💌
• boot_stage — the current boot stage of SMC. where is she in her life rn. 🌱
• sram — pointer to the SRAM resource. ✨
• sram_base — the SRAM base address. the literal starting point, iykyk. 📍
• shmem — the RTKit shared memory structure for SRAM. sharing is caring bestie. 🫶
• msg_id — the current message id for commands — and heads up, it gets incremented for each command. number go up. 🔢
• atomic_mode — flag set when atomic mode is entered. she's in her atomic era. 💅
• atomic_pending — flag indicating a pending atomic command. the "seen at 3:14" of flags. 🙈
• cmd_done — completion for command execution in non-atomic mode. 🎀
• cmd_ret — return value from SMC for the last command. the receipts. 🧾
• mutex — mutex for non-atomic mode. one at a time, bestie. 🔒
• lock — spinlock for atomic mode. spin spin spin, iconic. 🌈

notice how mutex is for non-atomic and lock is for atomic? don't mix them up, that's the whole point of having both. periodt. 💀

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🌸 SEE ALSO 🌸

go read these next, they're all linked up and everything:

• the kernel file ./include/linux/mfd/macsmc.h 👀
• smc_key(9)
• SMC_KEY(9)
• struct apple_smc_key_info(9)
• enum apple_smc_boot_stage(9)
• apple_smc_read(9)
• apple_smc_write(9)
• apple_smc_enter_atomic(9)
• apple_smc_write_atomic(9)
• apple_smc_rw(9)
• apple_smc_get_key_by_index(9)
• apple_smc_get_key_info(9)
• apple_smc_key_exists(9)

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okay that's the whole page, go be a kernel dev now 💜

sign-off moment: this icon lives in ./include/linux/mfd, dated October 2026, and she's filed under struct apple_smc(9). slay. 🎀✨