125. Vhost MTU Test Plan

The feature test the setting of MTU value of virtio-net and kernel driver.

125.1. Prerequisites:

The guests kernel should grand than 4.10 The qemu version should greater or equal to 2.9

125.2. Test Case: Test the MTU in virtio-net

1. Launch the testpmd by below commands on host, and config mtu:

   ./testpmd -c 0xc -n 4 --socket-mem 2048,2048 \
   --vdev 'net_vhost0,iface=vhost-net,queues=1' \
   -- -i --txd=512 --rxd=128 --nb-cores=1 --port-topology=chained
   testpmd> set fwd mac
   testpmd> start
   

2. Launch VM:

   Use the qemu_2.9 or qemu 2.10 to start the VM and the VM kernel should
   grand than 4.10, set the mtu value to 9000
   
   qemu-system-x86_64 \
   -chardev socket,id=char0,path=./vhost-net \
   -netdev type=vhost-user,id=netdev0,chardev=char0,vhostforce \
   -device virtio-net-pci,netdev=netdev0,mrg_rxbuf=on,host_mtu=9000
   

3. Check the MTU value in VM:

   Use the ifconfig command to check the MTU value of
   virtio kernel driver is 9000 in VM.
   

4. Bind the virtio driver to igb_uio, launch testpmd in VM, and verify the mtu in port info is 9000:

   ./testpmd -c 0x03 -n 3 \
   -- -i --txd=512 --rxd=128 --tx-offloads=0x0 --enable-hw-vlan-strip
   testpmd> set fwd mac
   testpmd> start
   testpmd> show port info 0
   

5. Check the MTU value of virtio in testpmd on host is 9000::

   testpmd> show port info 1

6. Repeat the step 2 ~ 5, change the mtu value to 68, 65535(the minimal value and maximum value), verify the value is changed.