UNIMPLEMENTED(2)

✨ UNIMPLEMENTED ✨ (section 2, the system calls manual bestie)

okay so real talk — this page is literally just a ✨group chat of ghosts✨. Every single one of these syscalls is a name that exists, a legend that was foretold, and a function that does not exist in the Linux kernel. It's giving "invited to the party but never showed up." 💀

🌸 NAME 🌸

the full roster of unimplemented system calls, alphabetically, no skips, no cuts:

• afs_syscall
• break
• fattach
• fdetach
• ftime
• getmsg
• getpmsg
• gtty
• isastream
• lock
• madvise1
• mpx
• prof
• profil
• putmsg
• putpmsg
• security
• stty
• tuxcall
• ulimit
• vserver

twenty-one names. all of them unimplemented system calls. that's the whole vibe. 🎀

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🦋 SYNOPSIS 🦋

Unimplemented system calls.

yeah. that's it. the synopsis is literally just the sentence "Unimplemented system calls." no arguments, no flags, no nothing. iconic honestly. 👑

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💖 DESCRIPTION 💖

bestie listen. These system calls are not implemented in the Linux kernel. Not "partially implemented." Not "maybe implemented on your distro." Not there. They're vibes. They're lore. If you try to call them you're basically texting someone who changed their number. 😭

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💅 RETURN VALUE 💅

here's the part you actually need for your error handling, so pay attention:

• These system calls always return -1
• and they set errno to ENOSYS

that's it. every time. no cap. so if you see ENOSYS you already know what the tea is — that thing you called? does not exist. 🫶

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🌈 NOTES 🌈

important ✨plot twists✨ so you don't get caught lacking:

• Note that ftime(3), profil(3), and ulimit(3) are implemented as library functions. so the syscall is a ghost, but the library version is very much alive and thriving. don't @ them.
• Some system calls, like alloc_hugepages(2), free_hugepages(2), ioperm(2), iopl(2), and vm86(2), exist only on certain architectures. so if you're on the wrong one... they simply aren't there. arch-dependent behavior, we love her.
• Some system calls, like ipc(2), create_module(2), init_module(2), and delete_module(2), exist only when the Linux kernel was built with support for them. so it depends on how your kernel was compil—yeah, config-time decisions, iykyk.

🫧 quick reality check: "not implemented," "not implemented on this architecture," and "not compiled in" are three completely different flavors of "it's not there." don't confuse them bestie.

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🎀 SEE ALSO 🎀

• syscalls(2)

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and that's the whole page, periodt. 💜 this little masterpiece came from the Linux man-pages 6.20 collection, dated 2026-02-08 — so if anyone asks, that's the source and the version and the date, all bundled up with a bow. 🎁 run along now, and go call something that actually exists. 🦋✨