Hi Bruce,
> -----Original Message----- > From: Richardson, Bruce > Sent: Tuesday, October 31, 2017 6:04 PM > To: Lu, Wenzhuo <wenzhuo...@intel.com> > Cc: dev@dpdk.org > Subject: Re: [dpdk-dev] [PATCH v2] doc: more clarification for i40e 16 bytes > desc > > On Tue, Oct 31, 2017 at 11:40:33AM +0800, Wenzhuo Lu wrote: > > The description of i40e 16 bytes descriptor is not clear enough. Add > > more details. > > > > Signed-off-by: Wenzhuo Lu <wenzhuo...@intel.com> > > Thanks for the clarification, it's better now. Couple of minor tweaks I would > suggest below. > > Otherwise: > Acked-by: Bruce Richardson <bruce.richard...@intel.com> > > > --- > > doc/guides/nics/i40e.rst | 21 ++++++++++++++++----- > > 1 file changed, 16 insertions(+), 5 deletions(-) > > > > diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst index > > a0946e6..771620c 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 Bytes Descriptor setting on DPDK VF > > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > We tend to refer to these as "16-byte" and "32-byte" descriptors in the > singular, not "16-bytes". > > > > > +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 nofify VF its own RX descriptor mode. > > +Until i40e 2.1.26, the Linux i40e driver doesn't support 16 bytes RX > descriptor. > > This implies that the 2.1.26 driver does support setting the descriptor size, > though later text implies that this is not the case. > Therefore, I suggest changing "Until i40e 2.1.26", to "For all available > versions of the i40e driver," and omit the version number, since it will soon > be out of date otherwise. The only time we should need to update this is > when/if there is a kernel version that does support reporting or seting the > descriptor size. Thanks for the review and comments. I'll send a V3 and add your ack :) > > > 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. > > +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 > > +bytes 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 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 > >
