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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 0AEC6C43331 for ; Fri, 6 Sep 2019 14:01:31 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 DDD4D2070C for ; Fri, 6 Sep 2019 14:01:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DDD4D2070C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id A693A2352; Fri, 6 Sep 2019 14:01:30 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 0655D234A for ; Fri, 6 Sep 2019 14:01:29 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id D9D4C7DB for ; Fri, 6 Sep 2019 14:01:27 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id C476768B05; Fri, 6 Sep 2019 16:01:23 +0200 (CEST) Date: Fri, 6 Sep 2019 16:01:23 +0200 From: Christoph Hellwig To: Boris Ostrovsky Subject: Re: [PATCH 09/11] swiotlb-xen: simplify cache maintainance Message-ID: <20190906140123.GA9894@lst.de> References: <20190905113408.3104-1-hch@lst.de> <20190905113408.3104-10-hch@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Stefano Stabellini , Konrad Rzeszutek Wilk , x86@kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, gross@suse.com, xen-devel@lists.xenproject.org, Christoph Hellwig , linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Fri, Sep 06, 2019 at 09:52:12AM -0400, Boris Ostrovsky wrote: > We need nop definitions of these two for x86. > > Everything builds now but that's probably because the calls are under > 'if (!dev_is_dma_coherent(dev))' which is always false so compiler > optimized is out. I don't think we should rely on that. That is how a lot of the kernel works. Provide protypes only for code that is semantically compiled, but can't ever be called due to IS_ENABLED() checks. It took me a while to get used to it, but it actually is pretty nice as the linker does the work for you to check that it really is never called. Much better than say a BUILD_BUG_ON(). _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu