const_test_bit(9)

✨ NAME ✨

okay so this is const_test_bit(9) from the Kernel API Manual, and it’s here to determine whether a bit is set — that’s the whole serve, bestie. 💅

🌸 SYNOPSIS 🌸

bool const_test_bit (unsigned long nr , const volatile unsigned long
*addr );

🎀 ARGUMENTS 🎀

• nr — the bit number to test. 🔢
• addr — the address to start counting from. 📍

🦋 DESCRIPTION 🦋

It’s literally a version of generic_test_bit that discards the volatile qualifier so the compiler can optimize code harder. Iconic behavior, no cap. ✨

But bestie, read this twice: it is non-atomic, and it should be called only for testing compile-time constants, e.g. by the corresponding macros — not directly from "regular" code. 🫶

⚠️ non-atomic + compile-time-constants-only energy. Do not call it directly from "regular" code — it’s giving special-occasion macro behavior, not everyday code behavior. 💀

💜 SEE ALSO 💜

• Kernel file ./include/asm-generic/bitops/generic-non-atomic.h
• generic___set_bit(9)
• generic___change_bit(9)
• generic___test_and_set_bit(9)
• generic___test_and_clear_bit(9)
• generic_test_bit(9)
• generic_test_bit_acquire(9)

that’s the page, bestie — sourced from ./include/asm-generic/bitops, dated October 2026. mwah 💖🎀