From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7781DC04EB9 for ; Mon, 3 Dec 2018 11:56:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 455402082F for ; Mon, 3 Dec 2018 11:56:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 455402082F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726432AbeLCL5Q (ORCPT ); Mon, 3 Dec 2018 06:57:16 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:43095 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725975AbeLCL5P (ORCPT ); Mon, 3 Dec 2018 06:57:15 -0500 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 4DAE0BF84CA14; Mon, 3 Dec 2018 19:56:24 +0800 (CST) Received: from [127.0.0.1] (10.202.226.41) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.408.0; Mon, 3 Dec 2018 19:56:16 +0800 Subject: Re: [PATCH] dma-debug: Kconfig for PREALLOC_DMA_DEBUG_ENTRIES To: Christoph Hellwig , Robin Murphy References: <20181130175449.2625-1-cai@gmx.us> <20181201163657.GA19557@lst.de> CC: Qian Cai , , , , , From: John Garry Message-ID: <53ab96d7-5dc9-e1a9-4cf2-bb8bf80a3acf@huawei.com> Date: Mon, 3 Dec 2018 11:56:11 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <20181201163657.GA19557@lst.de> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.226.41] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/12/2018 16:36, Christoph Hellwig wrote: > On Fri, Nov 30, 2018 at 07:39:50PM +0000, Robin Murphy wrote: >> I was assuming the point was to also add something like >> >> default 131072 if HNS_ENET >> >> so that DMA debug doesn't require too much thought from the user. If they >> still have to notice the overflow message and empirically figure out a >> value that does work, rebuilding the kernel each time is far less >> convenient than simply adding "dma_debug_entries=..." to their kernel >> command line and rebooting, which they can do today. If they do already >> know up-front that the default will need overriding and what the >> appropriate value is, then the command line still seems seems just as >> convenient. > > I'm not so fond of random drivers changing the defaults. My idea > was rather to have the config option so that the defconfig files for > the Hisilicon SOCs with this hardware could select a larger number > without making a total mess of the kernel configuration. > > If we really have to we could do different defaults, but I'd still > much rather do this on a arch/platform basis than specific drivers. As I understand, some drivers could even use much more than this (131072), to such a point where I can't imagine that we would want to set an arch default to support them. For this HNS_ENET case, it is arm64 specific so it would be an arch defconfig. Thanks, John > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu > > . >