scripts/runqemu: show an error if /dev/net/tun is unusable

If /dev/net/tun is either not present or is not writable by the
user, then show an appropriate error message. (QEMU needs access to this
device in order to enable networking; it may be missing if it is not
enabled or loaded into the kernel, and some distributions such as CentOS
5.x set restrictive permissions upon it.)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>

diff --git a/scripts/runqemu b/scripts/runqemu
index 4adeacece1c60de9bad6d1056f041f2691b70b06..bed6a2948e808c765ef0e9829613d6748cf7d24e 100755 (executable)
--- a/scripts/runqemu
+++ b/scripts/runqemu
@@ -194,6 +194,14 @@ while [ $i -le $# ]; do
     i=$((i + 1))
 done
 
+if [ ! -c /dev/net/tun ] ; then
+       echo "TUN control device /dev/net/tun is unavailable; you may need to enable TUN (e.g. sudo modprobe tun)"
+       exit 1
+elif [ ! -w /dev/net/tun ] ; then
+       echo "TUN control device /dev/net/tun is not writable, please fix (e.g. sudo chmod 666 /dev/net/tun)"
+       exit 1
+fi
+
 YOCTO_KVM_WIKI="https://wiki.yoctoproject.org/wiki/How_to_enable_KVM_for_Poky_qemu"
 # Detect KVM configuration
 if [[ "x$KVM_ENABLED" == "xyes" ]]; then