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[23.128.96.18]) by mx.google.com with ESMTP id bi20si1820704edb.462.2021.06.16.01.43.25; Wed, 16 Jun 2021 01:43:48 -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=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232031AbhFPIoc (ORCPT + 99 others); Wed, 16 Jun 2021 04:44:32 -0400 Received: from mga05.intel.com ([192.55.52.43]:13682 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232012AbhFPIoa (ORCPT ); Wed, 16 Jun 2021 04:44:30 -0400 IronPort-SDR: ub69TCHkezbFX2XHupt/7iETjThXS7heEMI9+6G/vGcDA8dmAd4lQBxdppHWmcECO4/zi0U5sx A7+/L5P0Gh9w== X-IronPort-AV: E=McAfee;i="6200,9189,10016"; a="291770840" X-IronPort-AV: E=Sophos;i="5.83,277,1616482800"; d="scan'208";a="291770840" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jun 2021 01:42:23 -0700 IronPort-SDR: XkMrx79+dB/mNC/PtGc2214acDd1tQm3kKMHkMe7U42BlYgoA1S0+ARJaX4DmyEBki/aLU+Wte 49DGkPS1dyLg== X-IronPort-AV: E=Sophos;i="5.83,277,1616482800"; d="scan'208";a="484805084" Received: from hchan3-mobl1.gar.corp.intel.com (HELO [10.254.212.123]) ([10.254.212.123]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jun 2021 01:42:20 -0700 Cc: baolu.lu@linux.intel.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linuxarm@huawei.com, thunder.leizhen@huawei.com, chenxiang66@hisilicon.com Subject: Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options To: Robin Murphy , John Garry , joro@8bytes.org, will@kernel.org, dwmw2@infradead.org References: <1623414043-40745-1-git-send-email-john.garry@huawei.com> <1623414043-40745-4-git-send-email-john.garry@huawei.com> <03675e2f-c3a6-ce33-ef96-f9ae544b2d13@huawei.com> <824db374-dc82-a9ea-b162-2f51e70ef999@linux.intel.com> From: Lu Baolu Message-ID: Date: Wed, 16 Jun 2021 16:42:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/6/15 16:25, Robin Murphy wrote: > On 2021-06-15 08:26, Lu Baolu wrote: >> Hi John, >> >> On 6/14/21 4:03 PM, John Garry wrote: >>> 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. >> >> On x86, Intel or AMD, this will be >> >>      prompt "IOMMU default DMA mode" >>        depends on IOMMU_DMA >>        default IOMMU_DEFAULT_LAZY >>        default IOMMU_DEFAULT_STRICT >> >> which will be default, LAZY or STRICT? Will it cause complains? > > See Documentation/kbuild/kconfig-language.rst: > >   A config option can have any number of default values. If multiple >   default values are visible, only the first defined one is active. Get it. Thank you, Robin. Best regards, baolu