Date:   Fri, 17 Mar 2023 21:03:06 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Richard Cochran <richardcochran@gmail.com>
Cc:     Vladimir Oltean <vladimir.oltean@nxp.com>,
        =?UTF-8?B?S8O2cnk=?= Maincent <kory.maincent@bootlin.com>,
        Oleksij Rempel <o.rempel@pengutronix.de>,
        Horatiu Vultur <horatiu.vultur@microchip.com>,
        Michael Walle <michael@walle.cc>, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Heiner Kallweit <hkallweit1@gmail.com>, netdev@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-omap@vger.kernel.org,
        Maxime Chevallier <maxime.chevallier@bootlin.com>,
        thomas.petazzoni@bootlin.com, Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Jay Vosburgh <j.vosburgh@gmail.com>,
        Veaceslav Falico <vfalico@gmail.com>,
        Andy Gospodarek <andy@greyhouse.net>,
        Claudiu Manoil <claudiu.manoil@nxp.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        UNGLinuxDriver@microchip.com, Minghao Chi <chi.minghao@zte.com.cn>,
        Jie Wang <wangjie125@huawei.com>,
        Oleksij Rempel <linux@rempel-privat.de>,
        Sean Anderson <sean.anderson@seco.com>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Alexander Lobakin <alexandr.lobakin@intel.com>,
        Marco Bonelli <marco@mebeim.net>
Subject: Re: [PATCH v3 3/5] net: Let the active time stamping layer be
 selectable.
Message-ID: <20230317210306.346e80ea@kernel.org>
In-Reply-To: <ZBUyST3kDP1ZE1lF@hoboy.vegasvil.org>
References: <20230308135936.761794-4-kory.maincent@bootlin.com>
        <20230308230321.liw3v255okrhxg6s@skbuf>
        <20230310114852.3cef643d@kmaincent-XPS-13-7390>
        <20230310113533.l7flaoli7y3bmlnr@skbuf>
        <b4ebfd3770ffa5ad1233d2b5e79499ee@walle.cc>
        <20230310131529.6bahmi4obryy5dsx@soft-dev3-1>
        <20230310164451.ls7bbs6pdzs4m6pw@skbuf>
        <20230313084059.GA11063@pengutronix.de>
        <20230316160920.53737d1c@kmaincent-XPS-13-7390>
        <20230317152150.qahrr6w5x4o3eysz@skbuf>
        <ZBUyST3kDP1ZE1lF@hoboy.vegasvil.org>
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On Fri, 17 Mar 2023 20:38:49 -0700 Richard Cochran wrote:
> On Fri, Mar 17, 2023 at 05:21:50PM +0200, Vladimir Oltean wrote:
> > On Thu, Mar 16, 2023 at 04:09:20PM +0100, K=C3=B6ry Maincent wrote: =20
> > > Was there any useful work that could be continued on managing timesta=
mp through
> > > NDOs. As it seem we will made some change to the timestamp API, maybe=
 it is a
> > > good time to also take care of this. =20
> >=20
> > Not to my knowledge. Yes, I agree that it would be a good time to add an
> > NDO for hwtimestamping (while keeping the ioctl fallback), then
> > transitioning as many devices as we can, and removing the fallback when
> > the transition is complete. =20
>=20
> Um, user space ABI cannot be removed.

NDO meaning a dedicated callback in struct net_device_ops, so at least
for netdevs we can copy the data from user space, validate in the core
and then call the driver with a normal kernel pointer. So just an
internal refactoring, no uAPI changes.