From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21C98C433ED for ; Mon, 3 May 2021 14:46:54 +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 AC8636023C for ; Mon, 3 May 2021 14:46:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC8636023C Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.121660.229448 (Exim 4.92) (envelope-from ) id 1ldZqL-0004i1-5D; Mon, 03 May 2021 14:46:41 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 121660.229448; Mon, 03 May 2021 14:46:41 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ldZqL-0004hu-1y; Mon, 03 May 2021 14:46:41 +0000 Received: by outflank-mailman (input) for mailman id 121660; Mon, 03 May 2021 14:46:39 +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 1ldZqJ-0004hp-Ew for xen-devel@lists.xenproject.org; Mon, 03 May 2021 14:46:39 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 3c2a5f07-55ae-437a-8979-a7c9b3462e92; Mon, 03 May 2021 14:46:38 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4FE0FB19B; Mon, 3 May 2021 14:46:37 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 3c2a5f07-55ae-437a-8979-a7c9b3462e92 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1620053197; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=eT4aP9mmfvbYpaF/Aa54jjFTrk212r7i0SUa9wwU5SU=; b=Yp0BSqJe/c5j4RNr/AdhmeWekomtajcLiggsSOCB3hXmaRwKW3gdVSj5ipJsRZTeqZU85U RJPTBRfYsS9b911uCOQTC8wK5VBeynkKbgL/shzKrD/JUTSVYC48ymB8mAWIiT3UnDuE8O VDOsccTwyekXRzC5fs38t/7oyWb9Dwo= Subject: Re: [PATCH v4 3/3] xen/pci: Refactor MSI code that implements MSI functionality within XEN To: Rahul Singh Cc: bertrand.marquis@arm.com, Paul Durrant , Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , Daniel De Graaf , xen-devel@lists.xenproject.org References: <60b4c33fdcc2f7ad68d383ffae191e22b0b32f1c.1619707144.git.rahul.singh@arm.com> From: Jan Beulich Message-ID: Date: Mon, 3 May 2021 16:46:36 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <60b4c33fdcc2f7ad68d383ffae191e22b0b32f1c.1619707144.git.rahul.singh@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 29.04.2021 16:46, Rahul Singh wrote: > MSI code that implements MSI functionality to support MSI within XEN is > not usable on ARM. Move the code under CONFIG_HAS_PCI_MSI_INTERCEPT flag > to gate the code for ARM. > > Currently, we have no idea how MSI functionality will be supported for > other architecture therefore we have decided to move the code under > CONFIG_PCI_MSI_INTERCEPT. We know this is not the right flag to gate the > code but to avoid an extra flag we decided to use this. My objection remains: Actively putting code under the wrong gating CONFIG_* is imo quite a bit worse than keeping it under a too wide one (e.g. CONFIG_X86), if introducing a separate CONFIG_HAS_PCI_MSI is deemed undesirable for whatever reason. Otherwise every abuse of CONFIG_PCI_MSI_INTERCEPT ought to get a comment to the effect of this being an abuse, which in particular for code you move into xen/drivers/passthrough/msi-intercept.c would end up sufficiently odd. (As a minor extra remark, putting deliberately misplaced code at the top of a file rather than at its bottom is likely to add to possible confusion down the road.) Jan