netdev - Re: [PATCH wpan-next 01/20] net: mac802154: Allow the creation of coordinator interfaces

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Date:   Sat, 3 Sep 2022 14:29:05 -0400
From:   Alexander Aring <aahringo@...hat.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Alexander Aring <alex.aring@...il.com>,
        Stefan Schmidt <stefan@...enfreihafen.org>,
        linux-wpan - ML <linux-wpan@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Network Development <netdev@...r.kernel.org>,
        David Girault <david.girault@...vo.com>,
        Romuald Despres <romuald.despres@...vo.com>,
        Frederic Blain <frederic.blain@...vo.com>,
        Nicolas Schodet <nico@...fr.eu.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH wpan-next 01/20] net: mac802154: Allow the creation of
 coordinator interfaces

Hi,

On Sat, Sep 3, 2022 at 2:21 PM Alexander Aring <aahringo@...hat.com> wrote:
...
>
> Assume you always get an ack back until somebody implements this
> feature in their driver (It's already implemented so as they return
> TX_SUCCESS). We cannot do much more I think... it is not robust but
> then somebody needs to update the driver/firmware.
>
> It's more weird if the otherside does not support AACK, because ARET
> will send them 3 times (by default) the same frame. That's why we have
> the policy to not set the ackreq bit if it's not required.
>
> > What is your "less worse" choice?
> >
> > > Btw: I can imagine that hwsim "fakes" such
> > > offload behaviours.
> >
> > My current implementation actually did handle all the acks (waiting for
> > them and sending them) from the MAC. I'm currently migrating the ack
> > sending part to the hw. For the reception, that's the big question.
> >
>
> In my opinion we should never deal with ack frames on mac802154 level,
> neither on hwsim, this is an offloaded functionality. What I have in

* except of course in cases of monitors, but monitors really aren't
part of the network and they are sniffers... A monitor can indeed send
frames out, which could cause a lot of trouble in the network if you
want to. It's a playground thing to do experiments... Here we never
analyze any payload received and forward it directly to the user, it's
also a kind of kernel bypass. I know people run some user space stacks
with it (including myself) but they get problems until it gets into
e.g. ackknowledge handling.

- Alex