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=-8.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 CA92BC433DF for ; Mon, 12 Oct 2020 11:26:19 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 6A69D2076E for ; Mon, 12 Oct 2020 11:26:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="v17vP5Vr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6A69D2076E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=gnon2Qx9BSWWRuHEGosIuPUGL3qluLWR9oz5WGlcDxc=; b=v17vP5VrNgpfAN2LBu/PXCHTA emNgUcm3TCRVOBsGTWu8w4+JUppMn2fOHZvbClyCvIFEKJ3gowpcKRf3J6/aKNZVMJzqkv8XrHHnn +5PaAaTwtwau/64Z+VPnnBqyIAUIfgBdhUpp5LonfOE1A9IgzvdmhGivn0/yzAmhcQ1OXEZEYWvBQ flEMHbSr4fpYzYC/ydiVfXAain/9954fL7y4KiacahWgUF0e3FOd1gDjE/rcM18oH000YXI9H6nTh 5PDSnmncyrnABiQAVfCZf8vVGwkPFUCfFdFoHv5mKbNSA5nrN6nYnwIf7XFZ4H7HXPdF4IJ9UHmF8 t8MjUdKHA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kRvwr-0007Hm-B7; Mon, 12 Oct 2020 11:25:01 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kRvwp-0007Gh-0V for linux-arm-kernel@lists.infradead.org; Mon, 12 Oct 2020 11:25:00 +0000 Received: from gaia (unknown [95.149.105.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DC4912076E; Mon, 12 Oct 2020 11:24:55 +0000 (UTC) Date: Mon, 12 Oct 2020 12:24:53 +0100 From: Catalin Marinas To: Ard Biesheuvel Subject: Re: [PATCH] arm64: mm: set ZONE_DMA size based on early IORT scan Message-ID: <20201012112453.GD9844@gaia> References: <20201010093153.30177-1-ardb@kernel.org> <20201012092821.GB9844@gaia> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201012_072459_137670_7A0F8FE7 X-CRM114-Status: GOOD ( 27.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lorenzo Pieralisi , Anshuman Khandual , Robin Murphy , Sudeep Holla , Jeremy Linton , ACPI Devel Maling List , Rob Herring , Linux ARM , Hanjun Guo , Will Deacon , Christoph Hellwig , Nicolas Saenz Julienne Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Oct 12, 2020 at 12:43:05PM +0200, Ard Biesheuvel wrote: > On Mon, 12 Oct 2020 at 11:30, Ard Biesheuvel wrote: > > On Mon, 12 Oct 2020 at 11:28, Catalin Marinas wrote: > > > On Sat, Oct 10, 2020 at 11:31:53AM +0200, Ard Biesheuvel wrote: > > > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > > > > index f0599ae73b8d..829fa63c3d72 100644 > > > > --- a/arch/arm64/mm/init.c > > > > +++ b/arch/arm64/mm/init.c > > > > @@ -191,6 +191,14 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) > > > > unsigned long max_zone_pfns[MAX_NR_ZONES] = {0}; > > > > > > > > #ifdef CONFIG_ZONE_DMA > > > > + if (IS_ENABLED(CONFIG_ACPI)) { > > > > + extern unsigned int acpi_iort_get_zone_dma_size(void); > > > > > > Nitpick: can we add this prototype to include/linux/acpi_iort.h? > > > > > > > + > > > > + zone_dma_bits = min(zone_dma_bits, > > > > + acpi_iort_get_zone_dma_size()); > > > > + arm64_dma_phys_limit = max_zone_phys(zone_dma_bits); > > > > + } > > > > + > > > > max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit); > > > > > > I think we should initialise zone_dma_bits slightly earlier via > > > arm64_memblock_init(). We'll eventually have reserve_crashkernel() > > > called before this and it will make use of arm64_dma_phys_limit for > > > "low" reservations: > > > > > > https://lore.kernel.org/linux-arm-kernel/20200907134745.25732-7-chenzhou10@huawei.com/ > > > > > > > We don't have access to the ACPI tables yet at that point. > > Also, could someone give an executive summary of why it matters where > the crashkernel is loaded? As far as I can tell, reserve_crashkernel() > only allocates memory for the kernel's executable image itself, which > can usually be loaded anywhere in memory. I could see how a > crashkernel might need some DMA'able memory if it needs to use the > hardware, but I don't think that is what is going on here. I thought the crashkernel needs some additional reserved RAM as well to be able to run. It should not touch the original kernel's memory as it usually needs to dump it. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel