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Date:   Mon, 30 Jan 2023 20:12:24 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Jamal Hadi Salim <jhs@mojatatu.com>
Cc:     John Fastabend <john.fastabend@gmail.com>,
        "Singhai, Anjali" <anjali.singhai@intel.com>,
        Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNlbg==?= <toke@redhat.com>,
        Jamal Hadi Salim <hadi@mojatatu.com>,
        Jiri Pirko <jiri@resnulli.us>,
        Willem de Bruijn <willemb@google.com>,
        Stanislav Fomichev <sdf@google.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "kernel@mojatatu.com" <kernel@mojatatu.com>,
        "Chatterjee, Deb" <deb.chatterjee@intel.com>,
        "Limaye, Namrata" <namrata.limaye@intel.com>,
        "khalidm@nvidia.com" <khalidm@nvidia.com>,
        "tom@sipanda.io" <tom@sipanda.io>,
        "pratyush@sipanda.io" <pratyush@sipanda.io>,
        "xiyou.wangcong@gmail.com" <xiyou.wangcong@gmail.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "edumazet@google.com" <edumazet@google.com>,
        "pabeni@redhat.com" <pabeni@redhat.com>,
        "vladbu@nvidia.com" <vladbu@nvidia.com>,
        "simon.horman@corigine.com" <simon.horman@corigine.com>,
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        "seong.kim@amd.com" <seong.kim@amd.com>,
        "mattyk@nvidia.com" <mattyk@nvidia.com>,
        "Daly, Dan" <dan.daly@intel.com>,
        "Fingerhut, John Andy" <john.andy.fingerhut@intel.com>
Subject: Re: [PATCH net-next RFC 00/20] Introducing P4TC
Message-ID: <20230130201224.435a4b5e@kernel.org>
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On Mon, 30 Jan 2023 19:26:05 -0500 Jamal Hadi Salim wrote:
> > Didn't see this as it was top posted but, the answer is you don't program
> > hardware the ebpf when your underlying target is a MAT.
> >
> > Use devlink for the runtime programming as well, its there to program
> > hardware. This "Devlink is NOT for the runtime programming" is
> > just an artificate of the design here which I disagree with and it feels
> > like many other folks also disagree.
> 
> We are going to need strong justification to use devlink for
> programming the binary interface to begin with

We may disagree on direction, but we should agree status quo / reality.

What John described is what we suggested to Intel to do (2+ years ago),
and what is already implemented upstream. Grep for DDP.

IIRC my opinion back then was that unless kernel has any use for
whatever the configuration exposes - we should stay out of it.

> - see the driver models discussion. 
> 
> And let me get this clear: you are suggesting we
> use it for runtime and redo all that tc ndo and associated infra?