I'm not looking forward to documenting cli arguments that may or may not show depending on what plugins / drviers you choose

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@fosiki.com> (github: SvenDowideit)

docs/sources/reference/commandline/cli.rst

@@ -1145,7 +1145,7 @@ image is removed.
       --volumes-from="": Mount all volumes from the given container(s)
       --entrypoint="": Overwrite the default entrypoint set by the image
       -w, --workdir="": Working directory inside the container
-      --lxc-conf=[]: Add custom lxc options --lxc-conf="lxc.cgroup.cpuset.cpus = 0,1"
+      --lxc-conf=[]: (lxc exec-driver only) Add custom lxc options --lxc-conf="lxc.cgroup.cpuset.cpus = 0,1"
       --sig-proxy=true: Proxify all received signal to the process (even in non-tty mode)
       --expose=[]: Expose a port from the container without publishing it to your host
       --link="": Add link to another container (name:alias)

docs/sources/reference/run.rst

@@ -194,7 +194,7 @@ Runtime Privilege and LXC Configuration
 ::
 
    --privileged=false: Give extended privileges to this container
-   --lxc-conf=[]: Add custom lxc options --lxc-conf="lxc.cgroup.cpuset.cpus = 0,1"
+   --lxc-conf=[]: (lxc exec-driver only) Add custom lxc options --lxc-conf="lxc.cgroup.cpuset.cpus = 0,1"
 
 By default, Docker containers are "unprivileged" and cannot, for
 example, run a Docker daemon inside a Docker container. This is
@@ -211,12 +211,13 @@ host. Additional information about running with ``--privileged`` is
 available on the `Docker Blog
 <http://blog.docker.io/2013/09/docker-can-now-run-within-docker/>`_.
 
-An operator can also specify LXC options using one or more
-``--lxc-conf`` parameters. These can be new parameters or override
-existing parameters from the lxc-template.go_. Note that in the
-future, a given host's Docker daemon may not use LXC, so this is an
-implementation-specific configuration meant for operators already
-familiar with using LXC directly.
+If the Docker daemon was started using the ``lxc`` exec-driver
+(``docker -d --exec-driver=lxc``) then the operator can also specify
+LXC options using one or more ``--lxc-conf`` parameters. These can be
+new parameters or override existing parameters from the lxc-template.go_.
+Note that in the future, a given host's Docker daemon may not use LXC,
+so this is an implementation-specific configuration meant for operators
+already familiar with using LXC directly.
 
 .. _lxc-template.go: https://github.com/dotcloud/docker/blob/master/execdriver/lxc/lxc_template.go