On Fri, Feb 26, 2016 at 09:24:06AM +0000, Wang, Xiao W wrote: > Hi, > > > -----Original Message----- > > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com] > > Sent: Friday, February 26, 2016 5:06 PM > > To: Wang, Xiao W <xiao.w.wang at intel.com> > > Cc: Richardson, Bruce <bruce.richardson at intel.com>; Chen, Jing D > > <jing.d.chen at intel.com>; dev at dpdk.org > > Subject: Re: [dpdk-dev] [PATCH v3 1/3] fm10k: enable FTAG based forwarding > > > > 2016-02-26 04:31, Wang, Xiao W: > > > From: Richardson, Bruce > > > > On Thu, Feb 25, 2016 at 03:45:45PM +0000, Chen, Jing D wrote: > > > > > From: Richardson, Bruce > > > > > > On Thu, Feb 25, 2016 at 10:04:02AM +0000, Chen, Jing D wrote: > > > > > > > This feature is trying to use FTAG (a unique tech in fm10k) > > > > > > > instead of mac/vlan to forward packets. App need a way to tell > > > > > > > PMD driver that which forwarding style it would like to use. > > > > > > > > > > > > Why not just specify this in the port configuration at setup time? > > > > > > > > > > > > > > > > Please educate me. I think the port configuration flags are also > > > > > common to all PMD Drivers. Is it possible to add a flag like > > "RTE_USE_FTAG" > > > > and pass to PMD driver? > > > > > > > > > They are. > > > > For something PMD specific, like FTAG, it's always a challenge, and > > > > I don't know off the top of my head if there is a simple option. > > > > However, given the choice between an mbuf flag and a port config > > > > flag, I'd always choose the former. > > > > Other alternatives would be to have a fm10k specific API in the > > > > fm10k driver alone. > > > > > > > > I'll let Thomas as ethdev maintainer comment if he has other > > > > suggestions as to how to handle this case. I suspect this won't be > > > > the first device-specific piece of functionality we need to deal with. > > > > > > > > /Bruce > > > > > > Whatever method we choose, we have to find a way for the user to > > > express his need for FTAG, it maybe a build time config option, or a > > > port config flag (no such flag now), or a fast path flag in mbuf (no > > > such flag now) etc. For the customer Topsec's use case, they use FTAG > > > for all the TX packets, so all the above methods (per build config, > > > per port config, per mbuf config) can meet their need. Since the pmd > > > frame work is for common, it's hard to add new fields only for one > > > specific > > NIC, so I add a build time config and make an introduction in the doc. > > > > > > Thanks for the discussion, Thomas, do you have any suggestions? > > > > I don't understand why you say this feature is specific to fm10k. Can we > > imagine another NIC having this capability? > > As you know, fm10k has a switch logic between the Mac and Phy, every packets > Sent out from the host will be switched inside the NIC, other NICs don't have > a switch inside, and the FTAG feature is related to the switch function. > > As introduced in the second patch: > The FM10K family of NICs support the addition of a Fabric Tag (FTAG) to carry > special information. The FTAG is placed at the beginning of the frame, it > contains > information such as where the packet comes from and goes, and the vlan tag. In > FTAG based forwarding mode, the switch logic forwards packets according to > glort (global resource tag) information, rather than the mac and vlan table. > So this is a feature specific to fm10k. > > Best Regards, > Xiao
If it is fm10k specific, how about just adding a public function to the fm10k driver to turn it on. The user app will be non-portable across NICs, but that's the price of using nic-specific features. /Bruce > > I think it must be an port configuration, as Bruce suggested. > > What about a field in struct rte_eth_conf?
