irq_create_mapping(9)

💅 irq_create_mapping — a page from the Kernel API Manual, bestie

okay so picture this: you've got a hardware interrupt just vibing out there in hardware-land, and it has zero idea that linux irq space even exists. that's the whole crisis this function solves. it's giving matchmaker energy. 🎀

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✨ NAME ✨

irq_create_mapping — Map a hardware interrupt into linux irq space 🦋

like, literally, it takes your hardware interrupt and gets it a spot in linux irq space. no cap.

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🌸 SYNOPSIS 🌸

unsigned int irq_create_mapping (struct irq_domain *domain ,
irq_hw_number_t hwirq );

that's the whole thing. two args, one unsigned int coming back at you. iconic. 💅

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🫶 ARGUMENTS 🫶

• domain — the domain that owns this hardware interrupt, or NULL for the default domain. yes bestie, NULL is allowed, it's not a typo, it means "default domain, please" ✨
• hwirq — the hardware irq number in that domain space. important: it's in the domain's own numbering, not linux's. keep that straight or the vibe check fails 😭

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👑 DESCRIPTION 👑

okay so the number one rule, and I mean it, write it on your mirror:

Only one mapping per hardware interrupt is permitted.

one hardware interrupt → one mapping. that's it. that's the deal. don't come back later trying to double-book it, because it will not slay. 🙈

and then — and this is the part people forget — if the sense/trigger is to be specified, set_irq_type should be called on the number returned from that call. like, the number that comes back from irq_create_mapping. that's the handle you feed to set_irq_type. don't guess, don't invent your own number, use the returned one. 🔥

fr fr: this page does not say what happens if you try to map the same hwirq twice — it just says only one mapping per hardware interrupt is permitted. so don't. 💀

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🌈 RETURN 🌈

• Linux irq number — the good ending, you ate 🍓
• 0 on error — the bad ending, no irq for you, check your args bestie 😭

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🌟 SEE ALSO 🌟

Kernel file ./include/linux/irqdomain.h — plus the whole squad, all of them, in the order the page lists them:

• struct irq_fwspec(9)
• struct irq_fwspec_info(9)
• struct irq_domain_ops(9)
• struct irq_domain(9)
• struct irq_domain_info(9)
• irq_domain_create_linear(9)
• irq_resolve_mapping(9)
• irq_find_mapping(9)
• irq_domain_create_hierarchy(9)
• irq_domain_alloc_irqs(9)

that's a full friend group, honestly. go read them, they're all main character energy in their own way 💜

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and that's the tea 🧚 from ./include/linux, dated October 2026 — go map those interrupts responsibly, bestie, mwah 💖⭐