--- b/usr.sbin/config/config.5	
+++ b/usr.sbin/config/config.5	
@@ -329,7 +329,9 @@ A value of 0 indicates that the kernel should configure
 its data structures according to the size of available
 physical memory.
 If auto configuration is requested, the kernel will set
-this tunable to a value between 32 and 384.
+this tunable to a value between 32 and 384 for 32-bit systems,
+or scale the value higher based on available memory for 64-bit
+systems.
 .Pp
 As explained in
 .Xr tuning 7 ,