div64_s64(9)

💅 div64_s64(9) — the kernel API manual, bestie edition

okay so real quick, the page header situation: this is div64_s64(9) straight out of the Kernel API Manual, and honestly? it's giving "small function, big responsibilities." let's get into it 🫶

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✨ NAME ✨

div64_s64 — signed 64bit divide with 64bit divisor

like yes, that's the whole vibe. it divides. it's signed. it's 64bit on both sides. slay. 💖

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🌸 SYNOPSIS 🌸

s64 div64_s64 (s64 dividend , s64 divisor );

no cap, that's the entire signature. two s64s walk in, one s64 walks out. iconic behavior only.

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🎀 ARGUMENTS 🎀

• dividend — a signed 64bit dividend. this is the one getting chopped up, bestie. it's the main character of this operation ngl 👑
• divisor — a signed 64bit divisor. this is the one doing the chopping. very "i'm the moment" of it.

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💀 RETURN 💀

dividend / divisor

literally just the division. that's the whole return value, no plot twist, no secret side quest. the dividend divided by the divisor. periodt. ✨

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🦋 SEE ALSO 🦋

okay so this is the friend group, and they're all math64.h girlies 💅 the kernel file is ./include/linux/math64.h and here's everyone:

• div_u64_rem(9)
• div_s64_rem(9)
• div64_u64_rem(9)
• div64_s64_rem(9)
• div64_u64(9)
• div_u64(9)
• div_s64(9)
• mul_u64_add_u64_div_u64(9)
• mul_u64_u64_div_u64(9)
• mul_u64_u64_div_u64_roundup(9)
• DIV64_U64_ROUND_UP(9)
• DIV_U64_ROUND_UP(9)
• DIV64_U64_ROUND_CLOSEST(9)
• DIV_U64_ROUND_CLOSEST(9)
• DIV_S64_ROUND_CLOSEST(9)
• roundup_u64(9)

go read those too, they're all lowkey obsessed with rounding and remainders and honestly same. 🌈

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ngl there's nothing dangerous on this page, it's literally just a divide. but the whole family above is worth a look if division alone isn't giving you what you need 🍓

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and that's the page, bestie!! 💜 this whole thing lives over in ./include/linux, dated October 2026, so go forth and divide your signed 64bit values with confidence. mwah. 😭🎀🧚