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[23.128.96.18]) by mx.google.com with ESMTP id y6si17508652ilq.94.2021.06.15.00.28.40; Tue, 15 Jun 2021 00:28:54 -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 S229898AbhFOHaM (ORCPT + 99 others); Tue, 15 Jun 2021 03:30:12 -0400 Received: from mga05.intel.com ([192.55.52.43]:2501 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229493AbhFOHaJ (ORCPT ); Tue, 15 Jun 2021 03:30:09 -0400 IronPort-SDR: m9j6sfytZgW/aQrWbkFRpR6p5vFRpvNbf7QTGOh0h0YbFzR5xQ2Qet9nIrilewS8rGPVjGghgV /lMUfbiSPUCw== X-IronPort-AV: E=McAfee;i="6200,9189,10015"; a="291572678" X-IronPort-AV: E=Sophos;i="5.83,275,1616482800"; d="scan'208";a="291572678" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jun 2021 00:27:53 -0700 IronPort-SDR: NhPtFRnH3Fzy5OVQxBazWhogkyHcuZquz8oQL1Qi6xEiNOXLelQQ3/bGTsFOjDJYnIzoy2wska cSHMVG53fLEw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.83,275,1616482800"; d="scan'208";a="554359035" Received: from unknown (HELO [10.239.159.118]) ([10.239.159.118]) by fmsmga001.fm.intel.com with ESMTP; 15 Jun 2021 00:27:51 -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: John Garry , joro@8bytes.org, will@kernel.org, dwmw2@infradead.org, robin.murphy@arm.com 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> From: Lu Baolu Message-ID: <824db374-dc82-a9ea-b162-2f51e70ef999@linux.intel.com> Date: Tue, 15 Jun 2021 15:26:26 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <03675e2f-c3a6-ce33-ef96-f9ae544b2d13@huawei.com> 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 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? > > If neither are set, then IOMMU_DEFAULT_LAZY is set if INTEL_IOMMU is > set, otherwise IOMMU_DEFAULT_STRICT. > > Thanks, > John Best regards, baolu