X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=doc%2Fguides%2Fprog_guide%2Fkernel_nic_interface.rst;h=32d09ccf82008166891c27f5a012bf6b62e407fb;hb=5920d930837228649278ebe523503c94ac31d7f5;hp=7fcbd936f9a11a278f22ffe489581821fc34ca5e;hpb=ff1e35fb5f8330f89d13f58c9fb767b5bd188940;p=dpdk.git

diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/prog_guide/kernel_nic_interface.rst
index 7fcbd936f9..32d09ccf82 100644
--- a/doc/guides/prog_guide/kernel_nic_interface.rst
+++ b/doc/guides/prog_guide/kernel_nic_interface.rst
@@ -227,7 +227,7 @@ application functions:
 
 ``config_promiscusity``:
 
-    Called when the user changes the promiscusity state of the KNI
+    Called when the user changes the promiscuity state of the KNI
     interface.  For example, when the user runs ``ip link set promisc
     [on|off] dev <ifaceX>``. If the user sets this callback function to
     NULL, but sets the ``port_id`` field to a value other than -1, a default
@@ -235,6 +235,15 @@ application functions:
     will be called which calls ``rte_eth_promiscuous_<enable|disable>()``
     on the specified ``port_id``.
 
+``config_allmulticast``:
+
+    Called when the user changes the allmulticast state of the KNI interface.
+    For example, when the user runs ``ifconfig <ifaceX> [-]allmulti``. If the
+    user sets this callback function to NULL, but sets the ``port_id`` field to
+    a value other than -1, a default callback handler in the rte_kni library
+    ``kni_config_allmulticast()`` will be called which calls
+    ``rte_eth_allmulticast_<enable|disable>()`` on the specified ``port_id``.
+
 In order to run these callbacks, the application must periodically call
 the ``rte_kni_handle_request()`` function.  Any user callback function
 registered will be called directly from ``rte_kni_handle_request()`` so
@@ -245,7 +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
@@ -268,12 +277,16 @@ Use Case: Ingress
 -----------------
 
 On the DPDK RX side, the mbuf is allocated by the PMD in the RX thread context.
-This thread will enqueue the mbuf in the rx_q FIFO.
+This thread will enqueue the mbuf in the rx_q FIFO,
+and the next pointers in mbuf-chain will convert to physical address.
 The KNI thread will poll all KNI active devices for the rx_q.
 If an mbuf is dequeued, it will be converted to a sk_buff and sent to the net stack via netif_rx().
-The dequeued mbuf must be freed, so the same pointer is sent back in the free_q FIFO.
+The dequeued mbuf must be freed, so the same pointer is sent back in the free_q FIFO,
+and next pointers must convert back to virtual address if exists before put in the free_q FIFO.
 
 The RX thread, in the same main loop, polls this FIFO and frees the mbuf after dequeuing it.
+The address conversion of the next pointer is to prevent the chained mbuf
+in different hugepage segments from causing kernel crash.
 
 Use Case: Egress
 ----------------
@@ -287,10 +300,24 @@ 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
 -------
 
-Ethtool is a Linux-specific tool with corresponding support in the kernel
-where each net device must register its own callbacks for the supported operations.
-The current implementation uses the igb/ixgbe modified Linux drivers for ethtool support.
-Ethtool is not supported in i40e and VMs (VF or EM devices).
+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.