STRUCT NVRAM_OPS(9)

💾 struct nvram_ops(9) — the kernel API manual, but make it make sense

okay so bestie, this is a page from the Kernel API Manual (that's the manual name, iykyk 💅) and it's all about one little struct. buckle up.

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✨ NAME ✨

struct nvram_ops — NVRAM functionality made available to drivers 🫶

like, it's the official handshake between NVRAM hardware and the drivers that wanna talk to it. iconic behavior honestly.

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🌸 SYNOPSIS 🌸

struct nvram_ops {
    ssize_t (*get_size)(void);
    unsigned char   (*read_byte)(int);
    void (*write_byte)(unsigned char, int);
    ssize_t (*read)(char *, size_t, loff_t *);
    ssize_t (*write)(char *, size_t, loff_t *);
  #if defined(CONFIG_X86) || defined(CONFIG_M68K);
    long (*initialize)(void);
    long (*set_checksum)(void);
  #endif;
 };

no cap, that #if block is doing a lot of heavy lifting — those last two members show up only on CONFIG_X86 or CONFIG_M68K. everybody else? they're not invited.

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🎀 Members 🎀

• get_size — returns the fixed number of bytes in the NVRAM. that's it. that's the vibe check.
• read_byte — loads a single byte from NVRAM. one (1) byte. tiny but mighty 🦋
• write_byte — stores a single byte to NVRAM. also one byte. also iconic.
• read — validates the checksum (if there even is one) and then loads a range of bytes from NVRAM. it's giving responsible main character energy.
• write — stores a range of bytes to NVRAM and then updates the checksum (again, only if there is one). periodt.

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💜 Description 💜

so here's the tea ☕ — architectures that provide an nvram_ops struct do not have to implement all of these methods. it's not a contract, it's a menu. lowkey generous of them.

if the NVRAM hardware can only be accessed one byte at a time, then it may be sufficient to provide just .read_byte and .write_byte. that's your whole setup. cute, minimal, done.

but if your NVRAM has a checksum (and yes, it's actually going to be checked), then the .read and .write methods are the ones to use — they implement that checksum thing efficiently. work smarter not harder bestie 💅

portable drivers may use the wrapper functions defined here. the nvram_read and nvram_write functions call the .read and .write methods when those are available, and fall back on the .read_byte and .write_byte methods otherwise. so like… it figures it out for you. bestie behavior fr fr 🔥

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🦋 SEE ALSO 🦋

• Kernel file ./include/linux/nvram.h — go look, it's right there 🌈

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ok that's the whole page 🫶 no members were skipped, no flags were harmed, and every single detail is still in there. you're welcome.

— signed off with love from the ./include/linux girlies, dated October 2026, bringing you struct nvram_ops(9) ✨💖🎀