memremap(9)

✨ memremap — the kernel API manual, but make it make sense ✨

okay so this is memremap(9) from the Kernel API Manual, and honestly bestie, if you've ever been like "hmm I need to map an iomem_resource but as cacheable memory," this is literally your girl 💅

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💖 NAME 💖

memremap — remap an iomem_resource as cacheable memory 🎀

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🦋 SYNOPSIS 🦋

void * memremap (resource_size_t offset , size_t size , unsigned long
flags );

like, that's the whole vibe. three args, one pointer out. slay.

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🌸 ARGUMENTS 🌸

• offset — the start address of the iomem resource. where the mapping begins, bestie 📍
• size — how big the remap is. the size of it. yep 🫶
• flags — any of MEMREMAP_WB, MEMREMAP_WT, MEMREMAP_WC, MEMREMAP_ENC, MEMREMAP_DEC 🚩

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💜 DESCRIPTION 💜

so memremap is basically ioremap for the cases where you already know the resource you're mapping doesn't have i/o side effects, and the __iomem annotation just isn't applicable. it's the chill, no-drama version 😌✨

and here's the tea about multiple flags: if you pass more than one, the different mapping types get attempted in the order listed below until one of them succeeds. first come, first served, periodt 🔥

🧚 the flags, one by one 🧚

• MEMREMAP_WB — matches the default mapping for System RAM on the architecture, and that's usually a read-allocate write-back cache. AND, key detail: if MEMREMAP_WB is specified and the requested remap region is RAM, memremap will bypass establishing a new mapping and instead just return a pointer into the direct map. no new mapping, no problem 💫
• MEMREMAP_WT — establishes a mapping where writes either bypass the cache or are written through to memory, and never exist in a cache-dirty state with respect to program visibility. very "clean hands" of it honestly. ⚠️ but attempts to map System RAM with this mapping type will fail. no cap.
• MEMREMAP_WC — establishes a writecombine mapping, where writes may be coalesced together (e.g. in the CPU's write buffers), but is otherwise uncached. also ⚠️ attempts to map System RAM with this mapping type will fail. it's giving picky, and we respect it.

lowkey important: MEMREMAP_ENC and MEMREMAP_DEC are listed up in the flags, but the description only breaks down the three above. don't come for me, I'm just telling you what the page says 🙈

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🌈 SEE ALSO 🌈

• Kernel file ./kernel/iomem.c — go read it, it's right there 👑

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and that's the whole page, bestie! no notes, go map something cacheable 🦋✨

this lil masterpiece came from the ./kernel source, dated October 2026 — mwah, sending you love from the Kernel API Manual 💖🎀🫶