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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 D2E1FC433E1 for ; Thu, 4 Jun 2020 07:14:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABC352074B for ; Thu, 4 Jun 2020 07:14:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591254873; bh=pQiZ65/cUBUWSQ69Pq08Vdl1ay+BjdbFbkajb1aT1Ec=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=lDb/4SsN3jciIOnwX6D/eJzSdW4tCO4OwY1Nli4RHfmSPm+kAs/IdIpy01tsl2bbx +V1E9YrluPvCoysHkwTkoRu+cwKRazqKIZfBvLjtVvIjFTNPzgxUONBMcyz/1boDyS DR33k3mHBONoFqAsRtyoHAue+DN0COa/z3aPQCj8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727786AbgFDHOc (ORCPT ); Thu, 4 Jun 2020 03:14:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:50058 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725959AbgFDHOc (ORCPT ); Thu, 4 Jun 2020 03:14:32 -0400 Received: from willie-the-truck (unknown [217.169.31.236]) (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 E9169206DC; Thu, 4 Jun 2020 07:14:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591254871; bh=pQiZ65/cUBUWSQ69Pq08Vdl1ay+BjdbFbkajb1aT1Ec=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IUcXCOKg4TAj9iHXF8yeI1elrDXEEOp/4uPhjL9xePaNoUijZ0Xw57hLkjCd6K0Ji MF/F1DTXZPJa4cak++xV07+8vXwvrMiMNiR89fi8bUUIn2Yr8MPrUKieaS2ja6M+Wj XtO6FKhx9/TE3nEhuVik1in0DW+6fQq0DVqKhuu8= Date: Thu, 4 Jun 2020 08:14:11 +0100 From: Will Deacon To: Bhupesh Sharma Cc: John Donnelly , chenzhou , Simon Horman , Devicetree List , Arnd Bergmann , Baoquan He , Linux Doc Mailing List , Catalin Marinas , guohanjun@huawei.com, kexec mailing list , Linux Kernel Mailing List , Rob Herring , James Morse , nsaenzjulienne@suse.de, Prabhakar Kushwaha , Thomas Gleixner , Prabhakar Kushwaha , RuiRui Yang , Ingo Molnar , linux-arm-kernel Subject: Re: [PATCH v8 0/5] support reserving crashkernel above 4G on arm64 kdump Message-ID: <20200604071410.GA30155@willie-the-truck> References: <303695cc-d3ea-9f51-1489-07d27d4253d4@oracle.com> <6EA47B07-5119-49DF-9980-12A2066F22CA@oracle.com> <8463464e-5461-f328-621c-bacc6a3b88dd@huawei.com> <8E0D45DC-12BF-437D-A342-03E974D9C6D4@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 04, 2020 at 01:17:06AM +0530, Bhupesh Sharma wrote: > On Wed, Jun 3, 2020 at 9:03 PM John Donnelly wrote: > > > On Jun 3, 2020, at 8:20 AM, chenzhou wrote: > > > On 2020/6/3 19:47, Prabhakar Kushwaha wrote: > > >>>> diff --git a/kernel/crash_core.c b/kernel/crash_core.c > > >>>> index 7f9e5a6dc48c..bd67b90d35bd 100644 > > >>>> --- a/kernel/crash_core.c > > >>>> +++ b/kernel/crash_core.c > > >>>> @@ -354,7 +354,7 @@ int __init reserve_crashkernel_low(void) > > >>>> return 0; > > >>>> } > > >>>> > > >>>> - low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN); > > >>>> + low_base = memblock_find_in_range(0,0xc0000000, low_size, CRASH_ALIGN); > > >>>> if (!low_base) { > > >>>> pr_err("Cannot reserve %ldMB crashkernel low memory, > > >>>> please try smaller size.\n", > > >>>> (unsigned long)(low_size >> 20)); > > >>>> > > >>>> > > >>> I suspect 0xc0000000 would need to be a CONFIG item and not hard-coded. > > >>> > > >> if you consider this as valid change, can you please incorporate as > > >> part of your patch-set. > > > > > > After commit 1a8e1cef7 ("arm64: use both ZONE_DMA and > > > ZONE_DMA32")，the 0-4G memory is splited to DMA [mem > > > 0x0000000000000000-0x000000003fffffff] and DMA32 [mem > > > 0x0000000040000000-0x00000000ffffffff] on arm64. > > > > > > From the above discussion, on your platform, the low crashkernel fall > > > in DMA32 region, but your environment needs to access DMA region, so > > > there is the call trace. > > > > > > I have a question, why do you choose 0xc0000000 here? > > > > > > Besides, this is common code, we also need to consider about x86. > > > > > > > + nsaenzjulienne@suse.de > > > > Exactly . This is why it needs to be a CONFIG option for Raspberry > > .., or device tree option. > > > > > > We could revert 1a8e1cef7 since it broke Arm kdump too. > > Well, unfortunately the patch for commit 1a8e1cef7603 ("arm64: use > both ZONE_DMA and ZONE_DMA32") was not Cc'ed to the kexec mailing > list, thus we couldn't get many eyes on it for a thorough review from > kexec/kdump p-o-v. > > Also we historically never had distinction in common arch code on the > basis of the intended end use-case: embedded, server or automotive, so > I am not sure introducing a Raspberry specific CONFIG option would be > a good idea. Right, we need a fix that works for everybody, since we try hard for a single Image that works for all platforms. What I don't really understand is why, with Chen's patches applied, we can't just keep the crashkernel out of the DMA zones altogether when no base is specified. I guess I'll just look out for your patch! Will