From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1AAB746F; Tue, 28 Nov 2023 03:09:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VpOMdNtR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 28FD8C433C7; Tue, 28 Nov 2023 03:09:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701140980; bh=PxGteF7iO02cA2HMwpt9WIBm9CHhptr+zLzAIBnCTqc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VpOMdNtR7egI3mQ7P6K0P7LlWmbkEtwBR4l9E8yklT4Kznw9qsNb+OTrxC5WbSs03 Rq6GAFSQ4iMNl/KVRA+ngtyqiQ2Op1lqPcnnWNrNE4Wnd/6iCVhESVR2l1sJ5GWFZZ dlbbC/NIaz7Oo8PM2e3TGEgTz64Uas1N+DprHC9LuD4HT2u3IV1VZt3b7k+bQOUuzv Ol0BtXIVNBt1T22tqTKPBujAEjnYL/10c7x6MKRvUTxhmLSe5u1s+UPprXMAOKpI0w YKkPBGfHOl1Zmbb3QMYKH/Z40gKIqpql6SwhwFiy+LgbOWoehqOyw4TwlHh4CRuXKv hl3Tjmpreti2w== Date: Mon, 27 Nov 2023 19:09:38 -0800 From: Jakub Kicinski To: Stanislav Fomichev Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, haoluo@google.com, jolsa@kernel.org, toke@kernel.org, willemb@google.com, dsahern@kernel.org, magnus.karlsson@intel.com, bjorn@kernel.org, maciej.fijalkowski@intel.com, hawk@kernel.org, yoong.siang.song@intel.com, netdev@vger.kernel.org, xdp-hints@xdp-project.net Subject: Re: [PATCH bpf-next v6 01/13] xsk: Support tx_metadata_len Message-ID: <20231127190938.01005780@kernel.org> In-Reply-To: <20231127190319.1190813-2-sdf@google.com> References: <20231127190319.1190813-1-sdf@google.com> <20231127190319.1190813-2-sdf@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 27 Nov 2023 11:03:07 -0800 Stanislav Fomichev wrote: > For zerocopy mode, tx_desc->addr can point to an arbitrary offset > and carry some TX metadata in the headroom. For copy mode, there > is no way currently to populate skb metadata. > > Introduce new tx_metadata_len umem config option that indicates how many > bytes to treat as metadata. Metadata bytes come prior to tx_desc address > (same as in RX case). > > The size of the metadata has mostly the same constraints as XDP: > - less than 256 bytes > - 8-byte aligned (compared to 4-byte alignment on xdp, due to 8-byte > timestamp in the completion) > - non-zero > > This data is not interpreted in any way right now. Reviewed-by: Jakub Kicinski