Merge branch 'fix-71' into 'stable-1.5'

Verbose error message in case no device is configured

See merge request etherlab.org/ethercat!90

devices/device_drivers_template.md

@@ -5,3 +5,17 @@ This table contains a list of all available native drivers,
 depending on the kernel version.
 
 The `generic` and the `ccat` driver are independent of the kernel version.
+
+To find out which native driver is required for your network card,
+you can use `lspci -vv` or look in `/sys`:
+```sh
+admin@ipc:~> ls -l /sys/class/net/eth5/device/driver
+lrwxrwxrwx 1 root root 0  6. Nov 15:35 /sys/class/net/eth5/device/driver -> ../../../../bus/pci/drivers/e1000
+```
+or
+```sh
+admin@ipc:~> basename $(readlink /sys/class/net/eth5/device/driver)
+e1000
+```
+
+In this example, `eth5` uses the `e1000` driver.

script/ethercatctl.in

@@ -102,6 +102,14 @@ start)
         MASTER_INDEX=$((${MASTER_INDEX} + 1))
     done
 
+    if [ -z "${DEVICES}" ]; then
+        echo "ERROR: No network cards for EtherCAT specified."
+        echo -n "Please edit ${ETHERCAT_CONFIG} with root permissions"
+        echo -n " and set MASTER0_DEVICE variable to either a "
+        echo "network interface name (like eth0) or to a MAC address."
+        exit 1
+    fi
+
     # load master module
     if ! ${MODPROBE} ${MODPROBE_FLAGS} ec_master \
             main_devices="${DEVICES}" backup_devices="${BACKUPS}"; then