diff --git a/arch/x86/include/asm/irqdomain.h b/arch/x86/include/asm/irqdomain.h
index 1d9091ffa140f01369704cb1d03844665b0d9ae0..73e9c42ce63be1470120e40d80804571d4fd9c8f 100644
--- a/arch/x86/include/asm/irqdomain.h
+++ b/arch/x86/include/asm/irqdomain.h
@@ -8,6 +8,7 @@
 enum {
 	/* Allocate contiguous CPU vectors */
 	X86_IRQ_ALLOC_CONTIGUOUS_VECTORS		= 0x1,
+	X86_IRQ_ALLOC_LEGACY				= 0x2,
 };
 
 extern struct irq_domain *x86_vector_domain;
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 81f35ae3f884a671f2b07884613bdfb435ff1df4..a4b0c60ab8e1b06fa6966596b9b22ce9dc41a9a8 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1013,6 +1013,7 @@ static int alloc_isa_irq_from_domain(struct irq_domain *domain,
 					  info->ioapic_pin))
 			return -ENOMEM;
 	} else {
+		info->flags |= X86_IRQ_ALLOC_LEGACY;
 		irq = __irq_domain_alloc_irqs(domain, irq, 1, node, info, true,
 					      NULL);
 		if (irq >= 0) {