IOREMAP() AND IOREMAP_*() VARIANTS(9)

✨ ioremap() and ioremap_*() variants ✨

okay so bestie, this is the ioremap(9) page from the Kernel API Manual, and it's literally the whole vibe for ioremap() and every ioremap_*() variant. No cap, it's short but it matters. 💅

Architectures with an MMU are expected to provide ioremap and iounmap themselves, or rely on GENERIC_IOREMAP. For NOMMU architectures we provide a default nop-op implementation. That implementation expects the physical address used for MMIO to already be marked as uncached, and it can be used as kernel virtual addresses. 🦋

ioremap_wc and ioremap_wt can provide more relaxed caching attributes for specific drivers if the architecture chooses to implement them. If they are not implemented, we fall back to plain ioremap. Conversely, ioremap_np can provide stricter non-posted write semantics if the architecture implements them. ✨

🌈 SEE ALSO 🌈

• Kernel file ./include/asm-generic/io.h
• memset_io(9)
• memcpy_fromio(9)
• memcpy_toio(9)

💖 source/version ./include/asm-generic · date October 2026 · that's the cute sign-off, bestie — periodt. 🫶