diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 474b8cb54899..7ffb6f4dea1c 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -862,6 +862,25 @@ do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 dotraplinkage void
 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 {
+	/*
+	 * This addresses a Pentium Pro Erratum:
+	 *
+	 * PROBLEM: If the APIC subsystem is configured in mixed mode with
+	 * Virtual Wire mode implemented through the local APIC, an
+	 * interrupt vector of 0Fh (Intel reserved encoding) may be
+	 * generated by the local APIC (Int 15).  This vector may be
+	 * generated upon receipt of a spurious interrupt (an interrupt
+	 * which is removed before the system receives the INTA sequence)
+	 * instead of the programmed 8259 spurious interrupt vector.
+	 *
+	 * IMPLICATION: The spurious interrupt vector programmed in the
+	 * 8259 is normally handled by an operating system's spurious
+	 * interrupt handler. However, a vector of 0Fh is unknown to some
+	 * operating systems, which would crash if this erratum occurred.
+	 *
+	 * In theory this could be limited to 32bit, but the handler is not
+	 * hurting and who knows which other CPUs suffer from this.
+	 */
 }
 
 dotraplinkage void