From: Wenzhuo Lu <wenzhuo.lu@intel.com>
To: dev@dpdk.org
Cc: Wenzhuo Lu <wenzhuo.lu@intel.com>
Subject: [dpdk-dev] [PATCH v3] doc: more clarification for i40e 16 byte desc
Date: Wed, 1 Nov 2017 10:45:28 +0800 [thread overview]
Message-ID: <1509504328-111123-1-git-send-email-wenzhuo.lu@intel.com> (raw)
In-Reply-To: <1508900093-9894-1-git-send-email-wenzhuo.lu@intel.com>
The description of i40e 16 byte descriptor is not clear
enough. Add more details.
Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
---
doc/guides/nics/i40e.rst | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
index a0946e6..05c1875 100644
--- a/doc/guides/nics/i40e.rst
+++ b/doc/guides/nics/i40e.rst
@@ -398,13 +398,24 @@ used to classify MPLS packet by using a command in testpmd like:
testpmd> ethertype_filter 0 add mac_ignr 00:00:00:00:00:00 ethertype \
0x8847 fwd queue <M>
-16 Byte Descriptor cannot be used on DPDK VF
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+16 Byte RX Descriptor setting on DPDK VF
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-If the Linux i40e kernel driver is used as host driver, while DPDK i40e PMD
-is used as the VF driver, DPDK cannot choose 16 byte receive descriptor. That
-is to say, user should keep ``CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC=n`` in
-config file.
+Currently the VF's RX descriptor mode is decided by PF. There's no PF-VF
+interface for VF to request the RX descriptor mode, also no interface to notify
+VF its own RX descriptor mode.
+For all available versions of the i40e driver, these drivers don't support 16
+byte RX descriptor. If the Linux i40e kernel driver is used as host driver,
+while DPDK i40e PMD is used as the VF driver, DPDK cannot choose 16 byte receive
+descriptor. The reason is that the RX descriptor is already set to 32 byte by
+the i40e kernel driver. That is to say, user should keep
+``CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC=n`` in config file.
+In the future, if the Linux i40e driver supports 16 byte RX descriptor, user
+should make sure the DPDK VF uses the same RX descriptor mode, 16 byte or 32
+byte, as the PF driver.
+
+The same rule for DPDK PF + DPDK VF. The PF and VF should use the same RX
+descriptor mode. Or the VF RX will not work.
Receive packets with Ethertype 0x88A8
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
1.9.3
prev parent reply other threads:[~2017-11-01 2:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-25 2:54 [dpdk-dev] [PATCH] doc: more clarification for i40e 16 bytes desc Wenzhuo Lu
2017-10-25 8:36 ` Bruce Richardson
2017-10-31 1:53 ` Lu, Wenzhuo
2017-10-31 3:40 ` [dpdk-dev] [PATCH v2] " Wenzhuo Lu
2017-10-31 10:04 ` Bruce Richardson
2017-11-01 2:03 ` Lu, Wenzhuo
2017-11-01 2:45 ` Wenzhuo Lu [this message]
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