PR_GET_TSC(2const)

💖 PR_GET_TSC(2const) 💖

okay bestie, gather round, because we're about to ask the kernel the most nosy little question: can I read the timestamp counter or not? 🕰️✨

This one lives in the PR_GET_TSC(2const) chapter of the man pages, ngl the name is giving very "cryptic constant energy" and I am obsessed.

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🌸 NAME 🌸

PR_GET_TSC — get wether the timestamp counter can be read

(no I did not fix the typo, it's literally what the page says, we respect the source in this house 💅)

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🎀 LIBRARY 🎀

Standard C library (libc, -lc) — your everyday bestie, nothing exotic here 🫶

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✨ SYNOPSIS ✨

#include <linux/prctl.h>  /* Definition of PR_* constants */
#include <sys/prctl.h>

int prctl(PR_GET_TSC, int *flag);

like, that's it. one call. one little int *. go off 🦋

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💜 DESCRIPTION 💜

So here's the tea: this call returns the state of the flag that decides whether the timestamp counter can be read, and it drops that state right into the location pointed to by flag. 👑

That's the whole job. It reads the vibe of the flag. It does not set anything. (If you wanna change it, that's a whole different bestie — see PR_SET_TSC(2const) down in SEE ALSO 👀)

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🔥 RETURN VALUE 🔥

• On success, 0 is returned. slay ✨
• On error, -1 is returned, and errno is set to tell you exactly what went wrong. 😭

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💀 ERRORS 💀

• EFAULT — flag is an invalid address. bestie. bestie no. that pointer is not pointing anywhere real 🙈

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🌈 STANDARDS 🌈

Linux. x86 only. so if you're on some other architecture, this is not your moment, sorry babe 💔

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🧚 HISTORY 🧚

Linux 2.6.26 (x86). vintage. iconic. still serving 👑

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🍓 SEE ALSO 🍓

• prctl(2)
• PR_SET_TSC(2const)

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🫶 little reminder: flag has to be a real, valid address or you're getting EFAULT and a sad little -1. check your pointers, queen.

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k that's the whole page, ty for coming to my ted talk 💖 this was Linux man-pages 6.20, dated 2026-02-08 — mwah, bye, go read the timestamp counter (if the flag says you can) 🎀✨💅