New upstream version 18.08

[deb_dpdk.git] / doc / guides / sample_app_ug / vhost.rst

diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst
index a4bdc6a..fd42cb3 100644 (file)
--- a/doc/guides/sample_app_ug/vhost.rst
+++ b/doc/guides/sample_app_ug/vhost.rst
@@ -147,7 +147,10 @@ retries on an RX burst, it takes effect only when rx retry is enabled. The
 default value is 15.
 
 **--dequeue-zero-copy**
 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 binded 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
 
 **--vlan-strip 0|1**
 VLAN strip option is removed, because different NICs have different behaviors


@@ -155,6 +158,10 @@ when disabling VLAN strip. Such feature, which heavily depends on hardware,
 should be removed from this example to reduce confusion. Now, VLAN strip is
 enabled and cannot be disabled.
 
 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
 -------------
 
 Common Issues
 -------------
 


@@ -175,15 +182,22 @@ Common Issues
   The command above indicates how many hugepages are free to support QEMU's
   allocation request.
 
   The command above indicates how many hugepages are free to support QEMU's
   allocation request.
 

-* vhost-user will not work with QEMU without the ``-mem-prealloc`` option
+* Failed to build DPDK in VM

 
 

-  The current implementation works properly only when the guest memory is
-  pre-allocated.
+  Make sure "-cpu host" QEMU option is given.

 
 

-* vhost-user will not work with a QEMU version without shared memory mapping:
+* Device start fails if NIC's max queues > the default number of 128

 
 

-  Make sure ``share=on`` QEMU option is given.
+  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.

 
 

-* Failed to build DPDK in VM
+  Change the default number to make it work as below, just set the number
+  according to the NIC's property. ::

 
 

-  Make sure "-cpu host" QEMU option is given.
+      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.