From patchwork Mon Jan 11 16:05:28 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 8006491 Return-Path: X-Original-To: patchwork-xen-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 4FAE09F32E for ; Mon, 11 Jan 2016 16:15:18 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 63E7E20295 for ; Mon, 11 Jan 2016 16:15:17 +0000 (UTC) Received: from lists.xen.org (lists.xenproject.org [50.57.142.19]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 802D8200FE for ; Mon, 11 Jan 2016 16:15:16 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xen.org) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aIf4j-0003yh-Ru; Mon, 11 Jan 2016 16:12:10 +0000 Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aIf4c-0003xH-9h for xen-devel@lists.xenproject.org; Mon, 11 Jan 2016 16:12:02 +0000 Received: from [85.158.137.68] by server-16.bemta-3.messagelabs.com id 5F/3E-07451-154D3965; Mon, 11 Jan 2016 16:12:01 +0000 X-Env-Sender: prvs=811e07856=Paul.Durrant@citrix.com X-Msg-Ref: server-14.tower-31.messagelabs.com!1452528718!15140629!1 X-Originating-IP: [66.165.176.63] X-SpamReason: No, hits=0.0 required=7.0 tests=sa_preprocessor: VHJ1c3RlZCBJUDogNjYuMTY1LjE3Ni42MyA9PiAzMDYwNDg=\n, received_headers: No Received headers X-StarScan-Received: X-StarScan-Version: 7.35.1; banners=-,-,- X-VirusChecked: Checked Received: (qmail 16017 invoked from network); 11 Jan 2016 16:12:00 -0000 Received: from smtp02.citrix.com (HELO SMTP02.CITRIX.COM) (66.165.176.63) by server-14.tower-31.messagelabs.com with RC4-SHA encrypted SMTP; 11 Jan 2016 16:12:00 -0000 X-IronPort-AV: E=Sophos;i="5.20,553,1444694400"; d="scan'208";a="330422067" From: Paul Durrant To: Date: Mon, 11 Jan 2016 16:05:28 +0000 Message-ID: <1452528329-10952-2-git-send-email-paul.durrant@citrix.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1452528329-10952-1-git-send-email-paul.durrant@citrix.com> References: <1452528329-10952-1-git-send-email-paul.durrant@citrix.com> MIME-Version: 1.0 X-DLP: MIA2 Cc: Keir Fraser , Ian Campbell , Tim Deegan , Ian Jackson , Paul Durrant , Jan Beulich Subject: [Xen-devel] [PATCH v6 1/2] public/io/netif.h: clarifications to wire formats X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP My previous patch 03809ae7 "document transmit and receive wire formats separately" improved documentation of the receive and transmit wire formats but further clarifications were requested. This patch adds those clarifications. Signed-off-by: Paul Durrant Cc: Ian Campbell Cc: Ian Jackson Cc: Jan Beulich Cc: Keir Fraser Cc: Tim Deegan --- v6: - v4 of the original patch was committed so this is an incremental version of the patch in v5. v5: - Add extra clarifications. --- xen/include/public/io/netif.h | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h index 1790ea0..0a3272f 100644 --- a/xen/include/public/io/netif.h +++ b/xen/include/public/io/netif.h @@ -154,19 +154,29 @@ * Guest transmit * ============== * - * This is the 'wire' format for packets: + * This is the 'wire' format for transmit (frontend -> backend) packets: + * * Fragment 1: netif_tx_request_t - flags = NETTXF_* * size = total packet size * [Extra 1: netif_extra_info_t] - (only if fragment 1 flags include * NETTXF_extra_info) + * ... * [Extra N: netif_extra_info_t] - (only if extra N-1 flags include * XEN_NETIF_EXTRA_MORE) * ... * Fragment N: netif_tx_request_t - (only if fragment N-1 flags include - * NETTXF_more_data) + * NETTXF_more_data - flags on preceding + * extras are not relevent here) * flags = 0 * size = fragment size * + * NOTE: + * + * This format slightly is different from that used for receive + * (backend -> frontend) packets. Specifically, in a multi-fragment + * packet the actual size of fragment 1 can only be determined by + * subtracting the sizes of fragments 2..N from the total packet size. + * * Ring slot size is 12 octets, however not all request/response * structs use the full size. * @@ -202,19 +212,29 @@ * Guest receive * ============= * - * This is the 'wire' format for packets: + * This is the 'wire' format for receive (backend -> frontend) packets: + * * Fragment 1: netif_rx_request_t - flags = NETRXF_* * size = fragment size * [Extra 1: netif_extra_info_t] - (only if fragment 1 flags include * NETRXF_extra_info) + * ... * [Extra N: netif_extra_info_t] - (only if extra N-1 flags include * XEN_NETIF_EXTRA_MORE) * ... * Fragment N: netif_rx_request_t - (only if fragment N-1 flags include - * NETRXF_more_data) + * NETRXF_more_data - flags on preceding + * extras are not relevent here) * flags = 0 * size = fragment size * + * NOTE: + * + * This format slightly is different from that used for transmit + * (frontend -> backend) packets. Specifically, in a multi-fragment + * packet the size of the packet can only be determined by summing the + * sizes of fragments 1..N. + * * Ring slot size is 8 octets. * * rx request (netif_rx_request_t)