doc: update bbdev guide

[dpdk.git] / doc / guides / prog_guide / kernel_nic_interface.rst

diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/prog_guide/kernel_nic_interface.rst
index 2fd58e1..de5d75b 100644 (file)
--- a/doc/guides/prog_guide/kernel_nic_interface.rst
+++ b/doc/guides/prog_guide/kernel_nic_interface.rst
@@ -65,7 +65,7 @@ disabled, and the default carrier state of KNI interfaces is set to *off*.
 
 .. code-block:: console
 
-    # insmod kmod/rte_kni.ko
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko
 
 .. _kni_loopback_mode:
 
@@ -77,14 +77,14 @@ by specifying the ``lo_mode`` parameter:
 
 .. code-block:: console
 
-    # insmod kmod/rte_kni.ko lo_mode=lo_mode_fifo
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko lo_mode=lo_mode_fifo
 
 The ``lo_mode_fifo`` loopback option will loop back ring enqueue/dequeue
 operations in kernel space.
 
 .. code-block:: console
 
-    # insmod kmod/rte_kni.ko lo_mode=lo_mode_fifo_skb
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko lo_mode=lo_mode_fifo_skb
 
 The ``lo_mode_fifo_skb`` loopback option will loop back ring enqueue/dequeue
 operations and sk buffer copies in kernel space.
@@ -105,7 +105,7 @@ Single kernel thread mode is enabled as follows:
 
 .. code-block:: console
 
-    # insmod kmod/rte_kni.ko kthread_mode=single
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko kthread_mode=single
 
 This mode will create only one kernel thread for all KNI interfaces to
 receive data on the kernel side.  By default, this kernel thread is not
@@ -122,7 +122,7 @@ kernel thread mode is enabled as follows:
 
 .. code-block:: console
 
-    # insmod kmod/rte_kni.ko kthread_mode=multiple
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko kthread_mode=multiple
 
 This mode will create a separate kernel thread for each KNI interface to
 receive data on the kernel side.  The core affinity of each ``kni_thread``
@@ -163,13 +163,13 @@ To set the default carrier state to *on*:
 
 .. code-block:: console
 
-    # insmod kmod/rte_kni.ko carrier=on
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko carrier=on
 
 To set the default carrier state to *off*:
 
 .. code-block:: console
 
-    # insmod kmod/rte_kni.ko carrier=off
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko carrier=off
 
 If the ``carrier`` parameter is not specified, the default carrier state
 of KNI interfaces will be set to *off*.
@@ -254,7 +254,7 @@ to create a separate thread or secondary process to periodically call
 
 The KNI interfaces can be deleted by a DPDK application with
 ``rte_kni_release()``.  All KNI interfaces not explicitly deleted will be
-deleted when the the ``/dev/kni`` device is closed, either explicitly with
+deleted when the ``/dev/kni`` device is closed, either explicitly with
 ``rte_kni_close()`` or when the DPDK application is closed.
 
 DPDK mbuf Flow
@@ -300,6 +300,20 @@ The sk_buff is then freed and the mbuf sent in the tx_q FIFO.
 The DPDK TX thread dequeues the mbuf and sends it to the PMD via ``rte_eth_tx_burst()``.
 It then puts the mbuf back in the cache.
 
+IOVA = VA: Support
+------------------
+
+KNI operates in IOVA_VA scheme when
+
+- LINUX_VERSION_CODE >= KERNEL_VERSION(4, 10, 0) and
+- EAL option `iova-mode=va` is passed or bus IOVA scheme in the DPDK is selected
+  as RTE_IOVA_VA.
+
+Due to IOVA to KVA address translations, based on the KNI use case there
+can be a performance impact. For mitigation, forcing IOVA to PA via EAL
+"--iova-mode=pa" option can be used, IOVA_DC bus iommu scheme can also
+result in IOVA as PA.
+
 Ethtool
 -------
 
@@ -307,4 +321,3 @@ Ethtool is a Linux-specific tool with corresponding support in the kernel.
 The current version of kni provides minimal ethtool functionality
 including querying version and link state. It does not support link
 control, statistics, or dumping device registers.
-