From: Bruce Richardson <bruce.richardson@intel.com>
To: Wenzhuo Lu <wenzhuo.lu@intel.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH] doc: more clarification for i40e 16 bytes desc
Date: Wed, 25 Oct 2017 09:36:35 +0100 [thread overview]
Message-ID: <20171025083635.GA13488@bricha3-MOBL3.ger.corp.intel.com> (raw)
In-Reply-To: <1508900093-9894-1-git-send-email-wenzhuo.lu@intel.com>
On Wed, Oct 25, 2017 at 10:54:53AM +0800, Wenzhuo Lu wrote:
> The description of i40e 16 bytes descriptor is not clear
> enough. Add more details.
>
> Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
> ---
Good idea to document this better.
> doc/guides/nics/i40e.rst | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
> index a0946e6..e0237a8 100644
> --- a/doc/guides/nics/i40e.rst
> +++ b/doc/guides/nics/i40e.rst
> @@ -398,13 +398,20 @@ 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 Bytes Descriptor setting on DPDK VF
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> +Until 2.1.26, the Linux i40e driver doesn't support 16 bytes RX descriptor.
I assume that 2.1.26 is referring to the i40e driver version, not the
linux kernel version. This should be made clearer, as it also could be
read as a very old kernel version.
> 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.
Can you explain - either on-list here, or actually in the docs - why
there is this restriction? Is it HW or SW? A reference to the section in
the datasheet for it would also be good. For example Table 8-10 in the
datasheet lists no restriction on the Dsize bit in the queue context.
> +In the future, if the Linux i40e driver supports 16 bytes RX descriptor, user
> +should make sure the DPDK VF uses the same RX descriptor mode, 16 bytes or 32
> +bytes, 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
>
Regards,
/Bruce
next prev parent reply other threads:[~2017-10-25 8:36 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-25 2:54 Wenzhuo Lu
2017-10-25 8:36 ` Bruce Richardson [this message]
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 ` [dpdk-dev] [PATCH v3] doc: more clarification for i40e 16 byte desc Wenzhuo Lu
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