path: root/doc
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authorLiron Himi <>2019-03-26 20:40:10 +0200
committerThomas Monjalon <>2019-03-30 00:59:59 +0100
commitff1e35fb5f8330f89d13f58c9fb767b5bd188940 (patch)
treee848cbfe43222159104d43ccd6c807ad0af67ee1 /doc
parent23d5455517568966ca8cac216941128ed3d3a455 (diff)
kni: calculate MTU from mbuf size
- mbuf_size and mtu are now being calculated according to the given mb-pool. - max_mtu is now being set according to the given mtu the above two changes provide the ability to work with jumbo frames Signed-off-by: Liron Himi <> Acked-by: Ferruh Yigit <>
Diffstat (limited to 'doc')
3 files changed, 13 insertions, 1 deletions
diff --git a/doc/guides/nics/kni.rst b/doc/guides/nics/kni.rst
index 204fbd5..a66c595 100644
--- a/doc/guides/nics/kni.rst
+++ b/doc/guides/nics/kni.rst
@@ -55,7 +55,8 @@ configuration:
Interface name: kni#
force bind kernel thread to a core : NO
- mbuf size: MAX_PACKET_SZ
+ mbuf size: (rte_pktmbuf_data_room_size(pktmbuf_pool) - RTE_PKTMBUF_HEADROOM)
+ mtu: (conf.mbuf_size - ETHER_HDR_LEN)
KNI control path is not supported with the PMD, since there is no physical
backend device by default.
diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/prog_guide/kernel_nic_interface.rst
index 33ea980..7fcbd93 100644
--- a/doc/guides/prog_guide/kernel_nic_interface.rst
+++ b/doc/guides/prog_guide/kernel_nic_interface.rst
@@ -187,6 +187,8 @@ The ``struct rte_kni_conf`` structure contains fields which allow the
user to specify the interface name, set the MTU size, set an explicit or
random MAC address and control the affinity of the kernel Rx thread(s)
(both single and multi-threaded modes).
+By default the KNI sample example gets the MTU from the matching device,
+and in case of KNI PMD it is derived from mbuf buffer length.
The ``struct rte_kni_ops`` structure contains pointers to functions to
handle requests from the ``rte_kni`` kernel module. These functions
diff --git a/doc/guides/rel_notes/release_19_05.rst b/doc/guides/rel_notes/release_19_05.rst
index aae8ff6..4e99118 100644
--- a/doc/guides/rel_notes/release_19_05.rst
+++ b/doc/guides/rel_notes/release_19_05.rst
@@ -54,6 +54,15 @@ New Features
Also, make sure to start the actual text at the margin.
+* **Updated KNI module and PMD.**
+ Updated the KNI kernel module to set the max_mtu according to the given
+ initial MTU size. Without it, the maximum MTU was 1500.
+ Updated the KNI PMD driver to set the mbuf_size and MTU based on
+ the given mb-pool. This provide the ability to pass jumbo frames
+ if the mb-pool contains suitable buffers' size.
* **Updated Solarflare network PMD.**
Updated the sfc_efx driver including the following changes: