Received: by 2002:a05:6a10:206:0:0:0:0 with SMTP id 6csp2552943pxj; Mon, 14 Jun 2021 01:13:16 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxita3z6lm2npzrQwGY3rfjGHjViVJf2rrOvUe9fSZgnMNNmYLkfTQkgfAs2qI12h1dOmdp X-Received: by 2002:aa7:d284:: with SMTP id w4mr15938717edq.347.1623658396387; Mon, 14 Jun 2021 01:13:16 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1623658396; cv=none; d=google.com; s=arc-20160816; b=d4jxTh6nBwL75s/FcKFsPiqFRdbjzIWRvrD8XbH7dTtzKh7ZIAKOeyAGGeG5NIzOHH uYIKZiVL9rbYr8QIYxC+RPAKQZPwMK8v4VSjURmNbKI7sgESHr6tRJ/MIqaj5U8SdHoC dN3mhzyQhYWBb321hKgN69d3qvAX5EPRM4wq3giKohMAYxLEGxvgU51/H1PMDtgzd4H7 0r3Xf/7+zw61Iam+z3o/VXnHUtUMkWsdnwGIwP7ct/4fN4j4EbiPTCQO7i3njqfcJZXR +/gLzBkHVI+/pS6m3VP2WFMBmWJZWoYqwTs2f5eaf3YLKswYYjlIRcV3U3FLw7/KoXG+ 9Xig== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:content-language :in-reply-to:mime-version:user-agent:date:message-id:from:references :cc:to:subject; bh=ErBqmTOe94/oF95QCRl/uT/u01skWUgHS/IjNEHRmQ4=; b=lIkw6tQwtWcWWe2pLdowXWVEx2dCZ8iXP6vVpB4/M3CeZV8cAQTFqGy7PVS0BPKONW v26f0eOXG2u6eRfYMNSZeI3JAycipLmFdT+TOFkDGc9NTjuLpAKedf5zqAWJEYp/Rz0J KOUvcIK7kePRSzR0cwZS71J37Q60lN8b4bLZricH3uBQmJhpKPSoR17NJCIPdKlOjE9T glhdzXRYqriphDe4zjHQFpdgnkAv7KqGZkhxMAXl7LGhT/aCxWGHM0Wh44bO0dLkJaBZ +8ix4UA1u1hiKAO2I5NFM8nMEQZso5qA6V8aGoXYcfO3YB7M4p07bvr2YptzttIJhtMF xV/g== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=huawei.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id ce5si9845378ejc.305.2021.06.14.01.12.53; Mon, 14 Jun 2021 01:13:16 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=huawei.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232566AbhFNILv (ORCPT + 99 others); Mon, 14 Jun 2021 04:11:51 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:3228 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232528AbhFNILu (ORCPT ); Mon, 14 Jun 2021 04:11:50 -0400 Received: from fraeml705-chm.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4G3P0s5vvHz6H7n1; Mon, 14 Jun 2021 15:56:45 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml705-chm.china.huawei.com (10.206.15.54) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Mon, 14 Jun 2021 10:09:46 +0200 Received: from [10.47.95.26] (10.47.95.26) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Mon, 14 Jun 2021 09:09:46 +0100 Subject: Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options To: Lu Baolu , , , , CC: , , , , References: <1623414043-40745-1-git-send-email-john.garry@huawei.com> <1623414043-40745-4-git-send-email-john.garry@huawei.com> From: John Garry Message-ID: <03675e2f-c3a6-ce33-ef96-f9ae544b2d13@huawei.com> Date: Mon, 14 Jun 2021 09:03:43 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.47.95.26] X-ClientProxiedBy: lhreml725-chm.china.huawei.com (10.201.108.76) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/06/2021 03:14, Lu Baolu wrote: > On 2021/6/11 20:20, John Garry wrote: >> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig >> index 2a71347611d4..4467353f981b 100644 >> --- a/drivers/iommu/Kconfig >> +++ b/drivers/iommu/Kconfig >> @@ -94,6 +94,7 @@ choice >>       prompt "IOMMU default DMA mode" >>       depends on IOMMU_DMA >> +    default IOMMU_DEFAULT_LAZY if INTEL_IOMMU >>       default IOMMU_DEFAULT_STRICT > > If two default values are different. Which one will be overridden? If I understand your question correctly, I think you are asking if both are set: CONFIG_IOMMU_DEFAULT_LAZY=y CONFIG_IOMMU_DEFAULT_STRICT=y If this happens, then make defconfig complains about both being set, and selects the 2nd, whatever that is. If neither are set, then IOMMU_DEFAULT_LAZY is set if INTEL_IOMMU is set, otherwise IOMMU_DEFAULT_STRICT. Thanks, John