From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ferruh Yigit Subject: Re: [PATCH] igb_uio: map dummy dma forcing iommu domain attachment Date: Tue, 7 Feb 2017 15:59:20 +0000 Message-ID: <67a9fd3b-b7f5-c641-9f59-590155cbd30b@intel.com> References: <1484742475-41005-1-git-send-email-alejandro.lucero@netronome.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit To: Alejandro Lucero , dev@dpdk.org Return-path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id 1DF349E3 for ; Tue, 7 Feb 2017 16:59:22 +0100 (CET) In-Reply-To: <1484742475-41005-1-git-send-email-alejandro.lucero@netronome.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi Alejandro, On 1/18/2017 12:27 PM, Alejandro Lucero wrote: > For using a DPDK app when iommu is enabled, it requires to > add iommu=pt to the kernel command line. But using igb_uio driver > makes DMAR errors because the device has not an IOMMU domain. Please help to understand the scope of the problem, 1- How can you re-produce the problem? 2- What happens get DMAR errors, is it prevents device work or some annoying error messages? 3- Can you please share the error messages? > > Since kernel 3.15, iommu=pt requires to use the internal kernel > DMA API for attaching the device to the IOMMU 1:1 mapping, aka > si_domain. Previous versions did attach the device to that > domain when intel iommu notifier was called. Again, what is not working since 3.15? > > This is not a problem if the driver does later some call to the > DMA API because the mapping can be done then. But DPDK apps do > not use that DMA API at all. Is this same/similar with: http://dpdk.org/dev/patchwork/patch/12654/ > > Doing this dma map and unmap is harmless even when iommu is not > enabled at all. > > Signed-off-by: Alejandro Lucero <...> Thanks, ferruh