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Date: Fri, 26 Feb 2016 16:33:09 +0000
From: Bruce Richardson <bruce.richardson@intel.com>
To: David Marchand <david.marchand@6wind.com>
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Subject: Re: [dpdk-dev] [PATCH v3 1/3] fm10k: enable FTAG based forwarding
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On Fri, Feb 26, 2016 at 04:00:49PM +0100, David Marchand wrote:
> On Fri, Feb 26, 2016 at 3:48 PM, Bruce Richardson
> <bruce.richardson@intel.com> wrote:
> > On Fri, Feb 26, 2016 at 09:24:06AM +0000, Wang, Xiao W wrote:
> >> Hi,
> >> > > 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.
> >
> > 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.
> 
> What about using a devargs ?
> Something like :
> -w xxxx:xx:xx.x,enable_ftag=1
> 
> The application still needs to know about this to enable it, but that
> sounds better to me.
> The only issue is that it can't work with hotplug at the moment.
>
Seems a good enough solution to me. Xiao, any other thoughts?

/Bruce