From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id D2AA0A034F; Wed, 6 May 2020 12:19:01 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 6DA751D6E5; Wed, 6 May 2020 12:19:01 +0200 (CEST) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by dpdk.org (Postfix) with ESMTP id 41F661D658 for ; Wed, 6 May 2020 12:18:59 +0200 (CEST) IronPort-SDR: YL3icpOIsk/kWU2petx3YL4OmJ3jCKV+CLDpAO16pTL3dyHIiP7x7uo65891+2s9SaatB0Wd8J GM+Pvo1ujYeg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 May 2020 03:18:58 -0700 IronPort-SDR: dduo0/kBxZZRicCcZJ1c2r+Icu4m4ntIPE0Z3eSbrkZOGSth0L4v55B0m8SZ/72FbaVPOTUBek vfyJhM7C1Rag== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,358,1583222400"; d="scan'208";a="338960926" Received: from aburakov-mobl.ger.corp.intel.com (HELO [10.209.121.37]) ([10.209.121.37]) by orsmga001.jf.intel.com with ESMTP; 06 May 2020 03:18:57 -0700 To: David Christensen , dev@dpdk.org References: <20200429232931.87233-1-drc@linux.vnet.ibm.com> <20200429232931.87233-3-drc@linux.vnet.ibm.com> <6cbb170a-3f13-47ba-e0ad-4a86cd6cb352@intel.com> <6763793c-265b-c5cf-228a-b2c177574c84@linux.vnet.ibm.com> <58df8aa5-e9b5-7f9a-2aee-fcb19b6dea04@intel.com> <782d6f04-f476-93d6-1a8f-2ed0b39dde10@linux.vnet.ibm.com> <8f83778f-fe74-6c69-e2d0-73b9a6e7ca79@intel.com> <4e7fa5f1-e2c7-a2e0-72d8-293c1cbc607b@linux.vnet.ibm.com> From: "Burakov, Anatoly" Message-ID: Date: Wed, 6 May 2020 11:18:56 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <4e7fa5f1-e2c7-a2e0-72d8-293c1cbc607b@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [PATCH 2/2] vfio: modify spapr iommu support to use static window sizing X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 05-May-20 5:26 PM, David Christensen wrote: >>>>>> That's not even mentioning the fact that the user may register >>>>>> external memory for DMA which may cause the window to be of >>>>>> insufficient size to cover said external memory. > > Regarding external memory, I can think of two obvious options: > > 1) Skip window sizing altogether if external memory is detected and > assume the user has set things up appropriately. A third option is just to caution users that external memory might not work on PPC64, and rely on my patch and the DMA mask infrastructure to ensure that any IOVA user requests, we can satisfy. If they can't be, user can adjust their IOVA request accordingly. > 2) Add an EAL command line option --iova-len that would allow the > external memory requirements to be considered it required. > I'm not keen on an additional platform-specific EAL option, to be honest, and i don't think others would be either. > I'll work on a new patch with (2) along with the other changes discussed > and resubmit.  Thanks for the feedback. > > Dave -- Thanks, Anatoly