The irqaffinity kernel parameter can be used to specify a set of CPUs which are allowed to handle the incoming IRQs. The parameter argument is a CPU list:

irqaffinity=<cpu number>,….,<cpu number>

• cpu lists in The kernel's command-line parameters
• kernel/irq/irqdesc.c
• see irq_default_affinity in the sources
• see /proc/irq/default_smp_affinity in SMP IRQ affinity
• smp_affinity in procfs