diff options
Diffstat (limited to 'doc/guides/sample_app_ug/vhost.rst')
| -rw-r--r-- | doc/guides/sample_app_ug/vhost.rst | 30 |
1 files changed, 22 insertions, 8 deletions
diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst index a4bdc6a4..fd42cb3f 100644 --- 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** -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 @@ -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. +**--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 ------------- @@ -175,15 +182,22 @@ Common Issues 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. |