diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 05496622b4effb8212eb2175bea67f9a7bebe0d0..6b99c8b77c59105dac8cd4a52eaa7c026c4a1eca 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4194,6 +4194,9 @@
 			Used to run time disable IRQ_TIME_ACCOUNTING on any
 			platforms where RDTSC is slow and this accounting
 			can add overhead.
+			[x86] unstable: mark the TSC clocksource as unstable, this
+			marks the TSC unconditionally unstable at bootup and
+			avoids any further wobbles once the TSC watchdog notices.
 
 	turbografx.map[2|3]=	[HW,JOY]
 			TurboGraFX parallel port interface