STRUCT EXTCONTEXT(9)

💅 NAME 💅

struct extcontext — the extended context header structure, aka the lil' header that kicks off every extended context block 🎀

oh and btw this page lives in the Kernel API Manual, section 9, bestie 🫶

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✨ SYNOPSIS ✨

struct extcontext {
    unsigned int            magic;
    unsigned int            size;
 };

like... that's it. two fields. iconic minimalism 💅

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🌸 Members 🌸

• magic — the magic value, and no it's not a vibe, it's literally what tells you which type of extended context you're looking at 🔮✨
• size — the size, in bytes, of the enclosing structure. yes the whole thing. she's measuring the fit 👑

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🦋 Description 🦋

okay so picture this: extended context structures are here to carry context that just does not fit inside struct sigcontext. she simply doesn't have the room, bestie 😭

so instead they get placed sequentially in memory, right at the end of struct ucontext and struct sigframe. and each one of those extended context structures starts with a header — and that header is literally this struct. main character energy 🌟

the type of context being represented? indicated by the magic field, periodt. userland can go through each extended context structure and check it against the magic values it recognises 👀✨

and the size field is the glow-up that makes the whole thing future-proof 💖 it lets any unrecognised context get skipped right over — so future expansion is totally fine, no cap 🚀

the end of the extended context data is indicated by the magic value END_EXTCONTEXT_MAGIC. that's the "we're done here" signal, iykyk 🎬

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🌈 SEE ALSO 🌈

• Kernel file ./arch/mips/include/uapi/asm/ucontext.h struct msa_extcontext(9)
• struct ucontext(9)

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okay that's the whole page bestie, go forth and check your magics 💜

source file: ./arch/mips/include/uapi/asm · version: Kernel API Manual · dated: October 2026 · titled struct extcontext(9) 🎀