x86: update description for memtest boot parameter

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index f6d5d5b..10c4b8b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1308,8 +1308,13 @@
 
 	memtest=	[KNL,X86] Enable memtest
 			Format: <integer>
-			range: 0,4 : pattern number
 			default : 0 <disable>
+			Specifies the number of memtest passes to be
+			performed. Each pass selects another test
+			pattern from a given set of patterns. Memtest
+			fills the memory with this pattern, validates
+			memory contents and reserves bad memory
+			regions that are detected.
 
 	meye.*=		[HW] Set MotionEye Camera parameters
 			See Documentation/video4linux/meye.txt.