diff --git a/etc/rc.conf.Linux b/etc/rc.conf.Linux
index cb24b897..9b030a5f 100644
--- a/etc/rc.conf.Linux
+++ b/etc/rc.conf.Linux
@@ -36,5 +36,6 @@ rc_tty_number=12
 
 # This is the number of CPU shares a service is allowed to use. The
 # default value, set by the kernel, is 1024.
+# This requires CONFIG_FAIR_GROUP_SCHED to be set in the kernel.
 # Also, this setting is not preserved if you suspend your computer.
 #rc_cgroup_cpu_shares=1024