diff --git a/support/bin/rtcds.in b/support/bin/rtcds.in
index e904076b6041f1553bec9bb40960eece4c8b4441..43f1ebfdbc9cea5083500b836d88c9b6af479a40 100755
--- a/support/bin/rtcds.in
+++ b/support/bin/rtcds.in
@@ -4,6 +4,16 @@ log() {
     echo "$@" >&2
 }
 
+USE_KERNEL_MODELS=${USE_KERNEL_MODELS:-false}
+
+if $USE_KERNEL_MODELS ; then
+    log "Build kernel-mode models by default"
+else
+    log "Build user mode models by default"
+    USERLAND_FLAG=0
+    NOKERNELSPACE_FLAG=0
+fi
+
 # capture all command line flags as variables
 params=""
 ccmd=""
@@ -17,6 +27,14 @@ while (( "$#" )); do
             USERLAND_FLAG=0
             shift
             ;;
+        --no-user-space|--no-userland)
+            USERLAND_FLAG=''
+            shift
+            ;;
+        --kernel-space)
+            NOKERNELSPACE_FLAG=''
+            shift
+            ;;
         --no-kernel-space)
             NOKERNELSPACE_FLAG=0
             shift
@@ -415,11 +433,20 @@ global_status() {
 
 usage() {
 
+  if $USE_KERNEL_MODELS ; then
+      local udefault=""
+      local kdefault=" (default)"
+  else
+      local udefault=" (default)"
+      local kdefault=""
+  fi
+
   if $ALLOW_MODEL_ENABLE ; then
-    local enable_usage="enable <sys>...|--all      enable system start at boot
-  "
+    local enable_usage="
+  enable <sys>...|--all            enable system start at boot"
   else
-    local enable_usage=""
+    local enable_usage="
+"
   fi
 
     echo "Usage: $(basename $0) <command> [options] [args]
@@ -428,28 +455,30 @@ Advanced LIGO Real Time System control interface.
 
 Available commands:
 
-  build|make <sys>...|--all  build system
-    --user-space|--userland  build model in userland (user space)
-    --no-kernel-space        do not build kernel space model
-  install <sys>...|--all     install system
-
-  list|ls                    list systems for host
-
-  ${enable_usage}disable <sys>...|--all     disable system start at boot
-  start <sys>...|--all       start systems
-  restart <sys>...|--all     restart running systems
-  stop|kill <sys>...|--all   stop running systems
-
-  status [<sys>]             show status for system services
-
-  log                        show logs for system services
-    -f                         follow logs
-  blog <sys>                 show last build log for system
-    -i                         print log paths
-  lsmod                      list loaded RTS kernel modules
-  env                        print system environment info
-  version|--version|-v       print version
-  help|--help|-h             this help
+  build|make <sys>...|--all         build system
+    --user-space|--userland         build model in userland $udefault
+    --no-user-space|--no-userland   do not build model in userland $kdefault
+    --kernel-space                  build model in kernel space $kdefault
+    --no-kernel-space               do not build model in kernel space $udefault
+  install <sys>...|--all            install system
+
+  list|ls                           list systems for host
+  ${enable_usage}
+  disable <sys>...|--all            disable system start at boot
+  start <sys>...|--all              start systems
+  restart <sys>...|--all            restart running systems
+  stop|kill <sys>...|--all          stop running systems
+
+  status [<sys>]                    show status for system services
+
+  log                               show logs for system services
+    -f                              follow logs
+  blog <sys>                        show last build log for system
+    -i                              print log paths
+  lsmod                             list loaded RTS kernel modules
+  env                               print system environment info
+  version|--version|-v              print version
+  help|--help|-h                    this help
 "
 }