diff --git a/arch/x86/kernel/genapic_flat_64.c b/arch/x86/kernel/genapic_flat_64.c
index 9eca5ba..2ec2de8 100644
--- a/arch/x86/kernel/genapic_flat_64.c
+++ b/arch/x86/kernel/genapic_flat_64.c
@@ -179,8 +179,10 @@
 	 * is an example).
 	 */
 	if (acpi_gbl_FADT.header.revision > FADT2_REVISION_ID &&
-		(acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL))
+		(acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL)) {
+		printk(KERN_DEBUG "system APIC only can use physical flat");
 		return 1;
+	}
 #endif
 
 	return 0;