From patchwork Thu Jul 30 19:48:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 11693597 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5E750912 for ; Thu, 30 Jul 2020 19:49:49 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3866920838 for ; Thu, 30 Jul 2020 19:49:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=xen.org header.i=@xen.org header.b="qM1rwFgs" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3866920838 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k1EY5-0003pV-Ok; Thu, 30 Jul 2020 19:49:05 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k1EY4-0003pM-Qz for xen-devel@lists.xenproject.org; Thu, 30 Jul 2020 19:49:04 +0000 X-Inumbo-ID: b8789c8a-d29d-11ea-ab18-12813bfff9fa Received: from mail.xenproject.org (unknown [104.130.215.37]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id b8789c8a-d29d-11ea-ab18-12813bfff9fa; Thu, 30 Jul 2020 19:49:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:MIME-Version:References: In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=8UnD14dYKCdyYi6YratGsYxZMEOmXUkZTQOXSnNy2ec=; b=qM1rwFgsvkvmFrUxckN5wRBlEU QVo9/7xQDlBETj2ZmEZsV/Ic5WufQEBs9w+8R4Bbt9P7YB1vwzGubUznHt6Od+KtzNnj5PnaeTOrj m/tNYypKBGzS8akFZFj43vmBx7YehsJ0s1+PygG/KASXi980e4mTT4iEwORXYL4m+KqQ=; Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k1EY3-0001L1-9z; Thu, 30 Jul 2020 19:49:03 +0000 Received: from host86-143-223-30.range86-143.btcentralplus.com ([86.143.223.30] helo=u2f063a87eabd5f.home) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1k1EY3-0004CS-2s; Thu, 30 Jul 2020 19:49:03 +0000 From: Paul Durrant To: xen-devel@lists.xenproject.org Subject: [PATCH 3/4] public/io/netif: specify MTU override node Date: Thu, 30 Jul 2020 20:48:57 +0100 Message-Id: <20200730194858.28523-4-paul@xen.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200730194858.28523-1-paul@xen.org> References: <20200730194858.28523-1-paul@xen.org> MIME-Version: 1.0 X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Paul Durrant Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" From: Paul Durrant There is currently no documentation to state what MTU a frontend should adertise to its network stack. It has however long been assumed that the default value of 1500 is correct. This patch specifies a mechanism to allow the tools to set the MTU via a xenstore node in the frontend area and states that the absence of that node means the frontend should assume an MTU of 1500 octets. NOTE: The Windows PV frontend has used an MTU sampled from the xenstore node specified in this patch. Signed-off-by: Paul Durrant Reviewed-by: Juergen Gross --- Cc: Juergen Gross --- xen/include/public/io/netif.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h index 9fcf91a2fe..00dd258712 100644 --- a/xen/include/public/io/netif.h +++ b/xen/include/public/io/netif.h @@ -204,6 +204,18 @@ * present). */ +/* + * MTU + * === + * + * The toolstack may set a value of MTU for the frontend by setting the + * /local/domain//device/vif//mtu node with the MTU value in + * octets. If this node is absent the frontend should assume an MTU value + * of 1500 octets. A frontend is also at liberty to ignore this value so + * it is only suitable for informing the frontend that a packet payload + * >1500 octets is permitted. + */ + /* * Hash types * ==========