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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 0005CC433EA for ; Tue, 28 Jul 2020 12:22:51 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CE5AC206D4 for ; Tue, 28 Jul 2020 12:22:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE5AC206D4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 98FCB8840E; Tue, 28 Jul 2020 12:22:51 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id YOa6n2CYO3qP; Tue, 28 Jul 2020 12:22:50 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id E4F3588408; Tue, 28 Jul 2020 12:22:50 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id D8963C0050; Tue, 28 Jul 2020 12:22:50 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 31A76C004D for ; Tue, 28 Jul 2020 12:22:50 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 2086387D5A for ; Tue, 28 Jul 2020 12:22:50 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id p4d8VOlxS9oU for ; Tue, 28 Jul 2020 12:22:48 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by whitealder.osuosl.org (Postfix) with ESMTPS id A915687D4B for ; Tue, 28 Jul 2020 12:22:48 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id E2E8B68B05; Tue, 28 Jul 2020 14:22:44 +0200 (CEST) Date: Tue, 28 Jul 2020 14:22:44 +0200 From: Christoph Hellwig To: "Song Bao Hua (Barry Song)" Subject: Re: [PATCH v4 1/2] dma-direct: provide the ability to reserve per-numa CMA Message-ID: <20200728122244.GA3639@lst.de> References: <20200723131344.41472-1-song.bao.hua@hisilicon.com> <20200723131344.41472-2-song.bao.hua@hisilicon.com> <20200728115231.GA793@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: "catalin.marinas@arm.com" , Mike Rapoport , Steve Capper , "robin.murphy@arm.com" , Linuxarm , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "Zengtao \(B\)" , "ganapatrao.kulkarni@cavium.com" , Andrew Morton , huangdaode , "will@kernel.org" , Christoph Hellwig , "linux-arm-kernel@lists.infradead.org" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Tue, Jul 28, 2020 at 12:19:03PM +0000, Song Bao Hua (Barry Song) wrote: > I am sorry I haven't got your point yet. Do you mean something like the below? > > arch/arm64/Kconfig: > config CMDLINE > string "Default kernel command string" > - default "" > + default "pernuma_cma=16M" > help > Provide a set of default command-line options at build time by > entering them here. As a minimum, you should specify the the > root device (e.g. root=/dev/nfs). Yes. > A background of the current code is that Linux distributions can usually use arch/arm64/configs/defconfig > directly to build kernel. cmdline can be easily ignored during the generation of Linux distributions. I've not actually heard of a distro shipping defconfig yet.. > > > if a way to expose this in the device tree might be useful, but people > > more familiar with the device tree and the arm code will have to chime > > in on that. > > Not sure if it is an useful user case as we are using ACPI but not device tree since it is an ARM64 > server with NUMA. Well, than maybe ACPI experts need to chime in on this. > > This seems to have lost the dma_contiguous_default_area NULL check. > > cma_alloc() is doing the check by returning NULL if cma is NULL. > > struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, > bool no_warn) > { > ... > if (!cma || !cma->count) > return NULL; > } > > But I agree here the code can check before calling cma_alloc_aligned. Oh, indeed. Please split the removal of the NULL check in to a prep patch then. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu