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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , Shuah Khan , Randy Dunlap , Alexander Duyck , kernel-team@meta.com, Andrew Lunn , Jesper Dangaard Brouer , Ilias Apalodimas , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Pavel Begunkov , Jens Axboe , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , netdev@vger.kernel.org, bpf@vger.kernel.org, io-uring@vger.kernel.org, "Mike Marciniszyn (Meta)" , Weiming Shi , Nikolay Aleksandrov , David Wei , Alexander Lobakin , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Mina Almasry Subject: Re: [RFC net-next 04/15] net: Let memory providers set RX buffer headroom Message-ID: References: <20261002190018.696925-1-bjorn@kernel.org> <20261002190018.696925-5-bjorn@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20261002190018.696925-5-bjorn@kernel.org> On 10/02, Björn Töpel wrote: > AF_XDP lets userspace choose a headroom in front of the packet data > in each UMEM chunk, and the kernel adds XDP_PACKET_HEADROOM to it. A > driver whose buffers come from an AF_XDP memory provider must put > packets after this headroom. The driver sees only the page pool, so > it has no generic way to learn the value, and nothing checks that > the driver supports it. > > Add rx_headroom to the provider parameters and to the queue > configuration. It is the full headroom, including > XDP_PACKET_HEADROOM; zero means the driver default. Add > QCFG_RX_HEADROOM. A provider that sets a headroom can only be > installed on a queue that supports it; otherwise the install fails > with -EOPNOTSUPP. The driver checks the value with the rest of the > queue configuration. > > Signed-off-by: Björn Töpel This is also a bit confusing to read on its own. Do we not need to convert existing users? The next patch does not seem to use this new rx_headroom?