[dpdk-users] TestPMD: Unable to create TAP interface

[Kandy Palanisamy]

 Hello Rami,
Thanks for your suggestion.
The /dev/net/tun device is automatically created, if I just insmod the kernel module 'tun' (I had not done that; that was the cause of the failure). After that, the testpmd command to create tuntap is successful.
Kandy

    On Monday, July 23, 2018, 12:38:36 PM PDT, Rosen, Rami <rami.rosen at intel.com> wrote:  
 
 Hi Kandy,
What is the output of 
ls -al /dev/net/tun 
on that host ? 
if it is empty, can you please try:

mkdir /dev/net (if it doesn't exist already)
mknod /dev/net/tun c 10 200

and then launch the same command you used for starting testpmd ? 

See:
https://www.kernel.org/doc/Documentation/networking/tuntap.txt

Regards,
Rami Rosen

-----Original Message-----
From: users [mailto:users-bounces at dpdk.org] On Behalf Of Kandy Palanisamy
Sent: Friday, July 20, 2018 01:22
To: users at dpdk.org
Subject: [dpdk-users] TestPMD: Unable to create TAP interface

Hi,
I tried to create a tap device using TestPMD as follows:
     testpmd -l 0-3 -n 4 --vdev=net_tap0 -- -i But, I get the error:
PMD: Initializing pmd_tap for net_tap0 as dtap0
PMD: Unable to create TAP interface
PMD: dtap0: tun_alloc() failed.

Appreciate if someone could help what I am missing.
Here is the complete log, and list of modules loaded and the ixgbe interface bound to dpdk.=====================================================================
root at intel-corei7-64:/tmp# /usr/bin/testpmd -l 0-3 -n 4 --vdev=net_tap0 -- -i
EAL: Detected 16 lcore(s)
EAL: Multi-process socket /var/run/.rte_unix
EAL: Probing VFIO support...
EAL: NUMA support not available consider that all memory is in socket_id 0
EAL: PCI device igb_uio 0000:04:00.0: uio device registered with irq 50
0000:04:00.0 on NUMA socket 0
EAL:   probe driver: 8086:15ac net_ixgbe
EAL: PCI device 0000:04:00.1 on NUMA socket 0
EAL:   probe driver: 8086:15ac net_ixgbe
EAL: PCI device 0000:0a:00.0 on NUMA socket 0
EAL:   probe driver: 8086:1533 net_e1000_igb
PMD: Initializing pmd_tap for net_tap0 as dtap0
PMD: Unable to create TAP interface
PMD: dtap0: tun_alloc() failed.
PMD: TAP Unable to initialize net_tap0
vdev_probe(): failed to initialize net_tap0 device

EAL: Bus (vdev) probe failed.
Interactive-mode selected
testpmd: create a new mbuf pool <mbuf_pool_socket_0>: n=171456, size=2176, socket=0
testpmd: preferred mempool ops selected: ring_mp_mc

Warning! port-topology=paired and odd forward ports number, the last port will pair with itself.

Configuring Port 0 (socket 0)
Port 0: 00:13:95:2B:DC:7E
Checking link statuses...
Done
testpmd> 

root at intel-corei7-64:/tmp# lsmod
Module                  Size  Used by
rte_kni                20480  0
igb_uio                16384  0
uio                    16384  1 igb_uio
8021q                  24576  0
nfc                    69632  0
bnep                   20480  2
intel_rapl             20480  0
igb                   167936  0
ixgbe                 249856  0
mei_me                 28672  0
x86_pkg_temp_thermal    16384  0
intel_powerclamp       16384  0
mei                    61440  1 mei_me
mdio                   16384  1 ixgbe
coretemp               16384  0
root at intel-corei7-64:/tmp#
root at intel-corei7-64:/tmp#
root at intel-corei7-64:/tmp# dpdk-devbind --status

Network devices using DPDK-compatible driver ============================================
0000:04:00.0 'Ethernet Connection X552 10 GbE SFP+ 15ac' drv=igb_uio unused=ixgbe

Network devices using kernel driver
===================================
0000:04:00.1 'Ethernet Connection X552 10 GbE SFP+ 15ac' if=eth2 drv=ixgbe unused=igb_uio
0000:0a:00.0 'I210 Gigabit Network Connection 1533' if=eth0 drv=igb unused=igb_uio *Active*

::Thanks for your help,Kandy