STRUCT AMD_SHMEM_INFO(9)

🦋 struct amd_shmem_info 🦋

okay bestie, so this is a page from the Kernel API Manual — yes, the Kernel API Manual, we're literally in the big leagues today — and it's all about struct amd_shmem_info, aka the shared memory table for AMD HFI. slay. let's get into it ✨

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💖 NAME 💖

struct amd_shmem_info — the shared memory table for AMD HFI. that's the whole vibe, no notes. 🎀

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🌸 SYNOPSIS 🌸

here's the struct in all its glory, copied exactly so you know I'm not making anything up, bestie:

struct amd_shmem_info {
    struct acpi_pcct_ext_pcc_shared_memory header;
    u32 version_number          :8, n_logical_processors    :8,
    n_capabilities          :8, table_update_context    :8;
    u32 n_bitmaps               :8, reserved                :24;
    u32 table_data[];
 };

look at those bitfields. the way they're just sitting there being all compact and :8 and :24… obsessed. 🫶

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👑 Members 👑

every field, one by one, no skips, we do not leave anyone on read in this house 💅

• header — the PCCT table header, and it's carrying the signature, the length flags and the command. it's giving "main character with three jobs". 🌟
• version_number — the version number of the table. yes bestie, it's exactly what it sounds like. 💖
• n_logical_processors — the number of logical processors. keep counting, icon. ⭐
• n_capabilities — the number of ranking dimensions, like performance, efficiency, etc. multiple dimensions?? we stan a multidimensional queen. 🌈
• table_update_context — the command being sent over the subspace. subspace!! so sci-fi, so iconic. 🚀
• n_bitmaps — the number of 32-bit bitmaps used to enumerate all the APIC IDs, and this is based on the maximum APIC ID enumerated in the system. so it scales, periodt. 📈
• reserved — 24-bit spare. it's just vibing off to the side, not doing anything, and honestly? relatable. 🙈
• table_data — the Bit Map(s) of enabled logical processors, followed by the ranking data for each logical processor. maps first, then ranks, in that exact order, don't @ me. 🍓

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✨ SEE ALSO ✨

go read these next, bestie, they're all in the family 🫶

• Kernel file ./drivers/platform/x86/amd/hfi/hfi.c
• struct amd_hfi_classes(9)
• struct amd_hfi_cpuinfo(9)
• amd_hfi_online(9)
• amd_hfi_offline(9)

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ngl, the whole squad lives over in ./drivers/platform/x86/amd/hfi — that's the source, and this page is dated October 2026. 🗓️

kk that's the whole page!! you understood it, you ate it up, I'm so proud of you. now go read amd_hfi_online(9) and text me your thoughts 💜🧚‍♀️

./drivers/platform/x86/amd/hfi · October 2026 · struct amd_shmem_info(9) 💫