ENUM MEM_TYPE(9)

🌸 enum mem_type(9) 🌸

okay bestie, so this is the enum mem_type page from the Kernel API Manual — yes, the Kernel API one, that's the manual we're in 💅. It's all about memory types. And if you want the full deep-dive reference (like, the actual DRAM lore), the page points you at http://en.wikipedia.org/wiki/DRAM — go wild 🦋.

✨ SYNOPSIS ✨

enum mem_type {
    MEM_EMPTY ,
    MEM_RESERVED ,
    MEM_UNKNOWN ,
    MEM_FPM ,
    MEM_EDO ,
    MEM_BEDO ,
    MEM_SDR ,
    MEM_RDR ,
    MEM_DDR ,
    MEM_RDDR ,
    MEM_RMBS ,
    MEM_DDR2 ,
    MEM_FB_DDR2 ,
    MEM_RDDR2 ,
    MEM_XDR ,
    MEM_DDR3 ,
    MEM_RDDR3 ,
    MEM_LRDDR3 ,
    MEM_LPDDR3 ,
    MEM_DDR4 ,
    MEM_RDDR4 ,
    MEM_LRDDR4 ,
    MEM_LPDDR4 ,
    MEM_DDR5 ,
    MEM_RDDR5 ,
    MEM_LRDDR5 ,
    MEM_LPDDR5 ,
    MEM_NVDIMM ,
    MEM_WIO2 ,
    MEM_HBM2 ,
    MEM_HBM3

};

🎀 Constants 🎀

the whole alphabet of memory vibes, one by one, no skips 💖

• MEM_EMPTY — empty csrow. literally nothing in there, ghost town 👻
• MEM_RESERVED — a reserved csrow type. it's reserved, bestie, back off 🙈
• MEM_UNKNOWN — unknown csrow type. we simply do not know her 💀
• MEM_FPM — FPM — Fast Page Mode, and it was used on systems up to 1995. vintage, honestly 🕰️
• MEM_EDO — EDO — Extended data out, used on systems up to 1998. also vintage, also iconic ✨
• MEM_BEDO — BEDO — Burst Extended data out, which is an EDO variant. a little sequel moment 🍓
• MEM_SDR — SDR — Single data rate SDRAM, aka http://en.wikipedia.org/wiki/Synchronous_dynamic_random-access_memory. and here's the tea: they use 3 pins for chip select — pins 0 and 2 are for rank 0; pins 1 and 3 are for rank 1, if the memory is dual-rank 👑
• MEM_RDR — Registered SDR SDRAM. registered, fancy 🎀
• MEM_DDR — Double data rate SDRAM, see http://en.wikipedia.org/wiki/DDR_SDRAM 🔥
• MEM_RDDR — Registered Double data rate SDRAM. it's a variant of the DDR memories. a registered memory has a buffer inside it, hiding part of the memory details from the memory controller — sneaky little buffer, iykyk 🫶
• MEM_RMBS — Rambus DRAM, used on a few Pentium III/IV controllers. a few. not many. exclusive 💅
• MEM_DDR2 — DDR2 RAM, as described at JEDEC JESD79-2F. those memories are labeled as "PC2-" instead of "PC" to differentiate from DDR. branding, honestly 🦋
• MEM_FB_DDR2 — Fully-Buffered DDR2, as described at JEDEC Std No. 205 and JESD206. those memories are accessed per DIMM slot, and not by a chip select signal 👀
• MEM_RDDR2 — Registered DDR2 RAM. a variant of the DDR2 memories 💜
• MEM_XDR — Rambus XDR. it's an evolution of the original RAMBUS memories, created to compete with DDR2. weren't used on any x86 arch, but cell_edac PPC memory controller uses it. niche king 🌈
• MEM_DDR3 — DDR3 RAM ⭐
• MEM_RDDR3 — Registered DDR3 RAM. a variant of the DDR3 memories 💖
• MEM_LRDDR3 — Load-Reduced DDR3 memory 🎀
• MEM_LPDDR3 — Low-Power DDR3 memory 🌸
• MEM_DDR4 — Unbuffered DDR4 RAM 🔥
• MEM_RDDR4 — Registered DDR4 RAM. a variant of the DDR4 memories 🫶
• MEM_LRDDR4 — Load-Reduced DDR4 memory 🦋
• MEM_LPDDR4 — Low-Power DDR4 memory 🌿
• MEM_DDR5 — Unbuffered DDR5 RAM 👑
• MEM_RDDR5 — Registered DDR5 RAM ✨
• MEM_LRDDR5 — Load-Reduced DDR5 memory 💅
• MEM_LPDDR5 — Low-Power DDR5 memory 🧚
• MEM_NVDIMM — Non-volatile RAM. she persists 💾
• MEM_WIO2 — Wide I/O 2 😤
• MEM_HBM2 — High bandwidth Memory Gen 2 🚀
• MEM_HBM3 — High bandwidth Memory Gen 3 🚀🚀

🌈 SEE ALSO 🌈

kernel file ./include/linux/edac.h, plus the whole friend group: enum dev_type(9), enum hw_event_mc_err_type(9), enum edac_type(9), enum scrub_type(9), enum edac_mc_layer_type(9), struct edac_mc_layer(9), struct rank_info(9), struct edac_raw_error_desc(9), edac_get_dimm(9), struct edac_scrub_ops(9), struct edac_ecs_ops(9), struct edac_mem_repair_ops(9) — go read them all, no cap 💖

and that's the page!! this one lives under ./include/linux in the tree, and the manpage itself is dated October 2026 🗓️ — so yeah, future-coded AND iconic. mwah, see u in the next manpage bestie 🫶💅✨