request_percpu_irq_affinity(9)

📦 version 7.3.1, in nixpkgs unstable

💖 request_percpu_irq_affinity(9) 💖

okay so bestie, welcome to the Kernel API Manual — today's main character is request_percpu_irq_affinity(9), and she is literally here to allocate a percpu interrupt line. mouthful of a name? yes. iconic? also yes. let's get into it. ✨

🌸 NAME 🌸

request_percpu_irq_affinity — allocate a percpu interrupt line. that's the vibe, no cap. 💅

✨ SYNOPSIS ✨

here's the signature, copied exactly so nobody gets creative with it:

       int request_percpu_irq_affinity (unsigned int irq , irq_handler_t
       handler , const char *devname , const cpumask_t *affinity , void
       __percpu *dev_id );

🎀 ARGUMENTS 🎀

the cast, in order — no skips, bestie:

  • irq — Interrupt line to allocate.
  • handler — Function to be called when the IRQ occurs.
  • devname — An ascii name for the claiming device.
  • affinity — A cpumask describing the target CPUs for this interrupt.
  • dev_id — A percpu cookie passed back to the handler function.

💅 DESCRIPTION 💅

so here's the key tea: this call allocates interrupt resources, but it doesn't enable the interrupt on any CPU, because all percpu-devid interrupts are flagged with IRQ_NOAUTOEN. so don't just sit there waiting for it to turn on by itself, bestie 😭 — it has to be done on each CPU using enable_percpu_irq.

also important: dev_id must be globally unique. it is a per-cpu variable, and the handler gets called with the interrupted CPU's instance of that variable. so yeah — the handler gets the right CPU's version, and that's the whole point. 🫶

🦋 SEE ALSO 🦋

the kernel file for this is ./kernel/irq/manage.c — that's where the lore lives — and here's the full SEE ALSO friend group, no skips, fr fr:

mwah 💋 — page source: ./kernel/irq; date: October 2026; function: request_percpu_irq_affinity(9). that's the footer, bestie, and we ate. 🎀✨

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