clflush_cache_range(9)

💅 clflush_cache_range(9) — like, the Kernel API Manual one, bestie

Okay so bestie, sit down, because today we're talking about clflush_cache_range, which lives in the Kernel API Manual and is genuinely one of those tiny functions that's doing the absolute most behind the scenes. 🎀

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✨ NAME ✨

clflush_cache_range — flush a cache range with clflush 🧹✨

Like, it flushes. A range. Of cache. With clflush. The name is honestly giving exactly-what-it-says-on-the-tin and I respect that so much.

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🌸 SYNOPSIS 🌸

void clflush_cache_range (void *vaddr , unsigned int size );

No return value, no drama, just vibes and a void. 💜

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🦋 ARGUMENTS 🦋

• vaddr — the virtual start address, aka where the whole thing kicks off 💫
• size — number of bytes to flush, aka how much of the cache we're clearing out 🫶

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🔥 DESCRIPTION 🔥

So here's the tea, and it's important tea: CLFLUSHOPT is an unordered instruction. Not me explaining that it needs fencing with MFENCE or SFENCE to avoid ordering issues 😭

Like, it will genuinely do its own thing in its own order if you don't fence it properly, and that's the whole cautionary tale. Fence it. Periodt. 👑

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🌈 SEE ALSO 🌈

• Kernel file ./arch/x86/mm/pat/set_memory.c — go read it, iykyk 📖✨

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Lowkey a tiny page but highkey every single word is load-bearing. The unordered-instruction warning is not decorative, bestie — do not skip the fencing. 💀

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okay that's the whole page, love u, bye 💖 — brought to you by ./arch/x86/mm/pat, dated October 2026, straight from the source/version line at the bottom. Mwah. 🫶🌷