From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rT5rT2FFDzDqcp for ; Tue, 14 Jun 2016 07:43:52 +1000 (AEST) Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u5DLho6r044744 for ; Mon, 13 Jun 2016 17:43:50 -0400 Received: from e24smtp03.br.ibm.com (e24smtp03.br.ibm.com [32.104.18.24]) by mx0a-001b2d01.pphosted.com with ESMTP id 23gf58wnx9-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 13 Jun 2016 17:43:49 -0400 Received: from localhost by e24smtp03.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 13 Jun 2016 18:43:45 -0300 Received: from d24relay02.br.ibm.com (d24relay02.br.ibm.com [9.13.184.26]) by d24dlp01.br.ibm.com (Postfix) with ESMTP id 836E8352006E for ; Mon, 13 Jun 2016 17:43:26 -0400 (EDT) Received: from d24av05.br.ibm.com (d24av05.br.ibm.com [9.18.232.44]) by d24relay02.br.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u5DLhgrt27263378 for ; Mon, 13 Jun 2016 18:43:42 -0300 Received: from d24av05.br.ibm.com (localhost [127.0.0.1]) by d24av05.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u5DLhgm2004790 for ; Mon, 13 Jun 2016 18:43:42 -0300 Subject: Re: [PATCH] powerpc: convert 'iommu_alloc failed' messages to dynamic debug To: Benjamin Herrenschmidt , linuxppc-dev@lists.ozlabs.org References: <1465563831-6565-1-git-send-email-mauricfo@linux.vnet.ibm.com> <1465686148.19533.28.camel@kernel.crashing.org> <575EB4DE.9080807@linux.vnet.ibm.com> <1465853216.3022.26.camel@kernel.crashing.org> From: Mauricio Faria de Oliveira Date: Mon, 13 Jun 2016 18:43:38 -0300 MIME-Version: 1.0 In-Reply-To: <1465853216.3022.26.camel@kernel.crashing.org> Content-Type: text/plain; charset=utf-8; format=flowed Message-Id: <575F290A.2070902@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Ben, On 06/13/2016 06:26 PM, Benjamin Herrenschmidt wrote: > I've been thinking about this a bit... it might be worthwhile adding > a dma_* call to query the approximate size of the IOMMU window, as > a way for the device to adjust its requirements dynamically. Ok, cool; something like it was one of the options being discussed here. What do you mean by 'approximate'? Maybe the size of 'free regions' in the pools? -- not sure because iiuic the window size is static / 2 gig, so didn't get why (or of what) to provide an approximation (for). > Another option would be to use a dma_attr for silencing mapping errors > which NVME could use provided it does handle them gracefully ... Ah, that's new. Interesting. Thanks for suggestion! -- Mauricio Faria de Oliveira IBM Linux Technology Center