[PATCH] Document an errata workaround in apic code.

arch/i386/kernel/apic.c

@@ -90,7 +90,7 @@ void clear_local_APIC(void)
 		apic_write_around(APIC_LVTPC, APIC_LVT_MASKED);
 	v = GET_APIC_VERSION(apic_read(APIC_LVR));
 	if (APIC_INTEGRATED(v)) {	/* !82489DX */
-		if (maxlvt > 3)
+		if (maxlvt > 3)		/* Due to Pentium errata 3AP and 11AP. */
 			apic_write(APIC_ESR, 0);
 		apic_read(APIC_ESR);
 	}