x86/kernel/irqinit.c

1 // SPDX-License-Identifier: GPL-2.0
34  * ISA PIC or low IO-APIC triggered (INTA-cycle or APIC) interrupts:
35  * (these are usually mapped to vectors 0x30-0x3f)
39  * The IO-APIC gives us many more interrupt sources. Most of these
44  * IO-APIC registers.
46  * (these are usually mapped into the 0x30-0xff vector range)
50 	[0 ... NR_VECTORS - 1] = VECTOR_UNUSED,
55 	struct irq_chip *chip = legacy_pic->chip;  in init_ISA_irqs()
59 	 * Try to set up the through-local-APIC virtual wire mode earlier.  in init_ISA_irqs()
61 	 * On some 32-bit UP machines, whose APIC has been disabled by BIOS  in init_ISA_irqs()
62 	 * and then got re-enabled by "lapic", it hangs at boot time without this.  in init_ISA_irqs()
66 	legacy_pic->init(0);  in init_ISA_irqs()
80 	 * If these IRQ's are handled by legacy interrupt-controllers like PIC,  in init_IRQ()
82 	 * these IRQs are handled by more modern controllers like IO-APIC,  in init_IRQ()
83 	 * then this vector space can be freed and re-used dynamically as the  in init_IRQ()