.. code-block:: console
modprobe uio_pci_generic
- $RTE_SDK/usertools/dpdk-devbind.py -b=uio_pci_generic 0000:00:04.0
+ $RTE_SDK/usertools/dpdk-devbind.py -b uio_pci_generic 0000:00:04.0
Then start testpmd for packet forwarding testing.
The vm2vm parameter sets the mode of packet switching between guests in
the host.
-- 0 disables vm2vm, impling that VM's packets will always go to the NIC port.
+- 0 disables vm2vm, implying that VM's packets will always go to the NIC port.
- 1 means a normal mac lookup packet routing.
- 2 means hardware mode packet forwarding between guests, it allows packets
go to the NIC port, hardware L2 switch will determine which guest the
default value is 15.
**--dequeue-zero-copy**
-Dequeue zero copy will be enabled when this option is given.
+Dequeue zero copy will be enabled when this option is given. it is worth to
+note that if NIC is bound to driver with iommu enabled, dequeue zero copy
+cannot work at VM2NIC mode (vm2vm=0) due to currently we don't setup iommu
+dma mapping for guest memory.
**--vlan-strip 0|1**
VLAN strip option is removed, because different NICs have different behaviors
should be removed from this example to reduce confusion. Now, VLAN strip is
enabled and cannot be disabled.
+**--builtin-net-driver**
+A very simple vhost-user net driver which demonstrates how to use the generic
+vhost APIs will be used when this option is given. It is disabled by default.
+
Common Issues
-------------
* Failed to build DPDK in VM
Make sure "-cpu host" QEMU option is given.
+
+* Device start fails if NIC's max queues > the default number of 128
+
+ mbuf pool size is dependent on the MAX_QUEUES configuration, if NIC's
+ max queue number is larger than 128, device start will fail due to
+ insufficient mbuf.
+
+ Change the default number to make it work as below, just set the number
+ according to the NIC's property. ::
+
+ make EXTRA_CFLAGS="-DMAX_QUEUES=320"
+
+* Option "builtin-net-driver" is incompatible with QEMU
+
+ QEMU vhost net device start will fail if protocol feature is not negotiated.
+ DPDK virtio-user pmd can be the replacement of QEMU.