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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 49E57C43461 for ; Tue, 1 Sep 2020 17:14:40 +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 1970D20767 for ; Tue, 1 Sep 2020 17:14:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="jfXmV18V" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1970D20767 Authentication-Results: mail.kernel.org; dmarc=none (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=YLL9rGQelAbKjDyBLCt1t4H8E3N2Z264ysu0cP0Q9p4=; b=jfXmV18VpQCkQWP/yA+/FEqe3 vmMYIulBckrNd8t3XobxfYI2Pu/l/FzdmdyndbTkwqF/c72eRfUYzkmDiK6/KltR57/6y186tm5q8 q4udv0dw+4994oUuHUdsM4RSPdUHTWX0CxQ/1MP67jxKJrUfAKyfPKSYbTS24IzuJ+pnnPCdAVGZ+ LXe41ZlEzpsLhhhvu3PHgMtHiup+oLojjedp24Jx349CXPe2Fw6miaheopu/u+o8SeVJhmqck/T2+ nN4rRfWJbwfhkexjPke3bHcKSp0ImaN90RhVQbI0Nfi7YKaZy6QaPJ/620KzXjRKLrsYEoITmJ/N5 0HttotscQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kD9qP-0002vq-Rg; Tue, 01 Sep 2020 17:13:17 +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 1kD9qL-0002ud-QN; Tue, 01 Sep 2020 17:13:14 +0000 Received: from gaia (unknown [46.69.195.127]) (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 9625F2087D; Tue, 1 Sep 2020 17:13:09 +0000 (UTC) Date: Tue, 1 Sep 2020 18:13:07 +0100 From: Catalin Marinas To: chenzhou Subject: Re: [PATCH v11 5/5] kdump: update Documentation about crashkernel Message-ID: <20200901171306.GK5561@gaia> References: <20200801130856.86625-1-chenzhou10@huawei.com> <20200801130856.86625-6-chenzhou10@huawei.com> <20200808100239.GB60590@dhcp-128-65.nay.redhat.com> <96d0da23-d484-7f66-1680-07b4b5984831@huawei.com> <20200810060355.GB6988@dhcp-128-65.nay.redhat.com> <2e6aebf9-3765-5d8c-933c-698442db1d52@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <2e6aebf9-3765-5d8c-933c-698442db1d52@huawei.com> 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-20200901_131313_936781_09DCB85E X-CRM114-Status: GOOD ( 17.54 ) 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: wangkefeng.wang@huawei.com, linux-doc@vger.kernel.org, bhsharma@redhat.com, huawei.libin@huawei.com, guohanjun@huawei.com, will@kernel.org, bhe@redhat.com, corbet@lwn.net, mingo@redhat.com, Dave Young , John.P.donnelly@oracle.com, arnd@arndb.de, xiexiuqi@huawei.com, horms@verge.net.au, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, robh+dt@kernel.org, james.morse@arm.com, prabhakar.pkin@gmail.com, nsaenzjulienne@suse.de 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 Tue, Aug 18, 2020 at 03:07:04PM +0800, chenzhou wrote: > On 2020/8/10 14:03, Dave Young wrote: > >>> Previously I remember we talked about to use similar logic as X86, but I > >>> remember you mentioned on some arm64 platform there could be no low > >>> memory at all. Is this not a problem now for the fallback? Just be > >>> curious, thanks for the update, for the common part looks good. > >> > >> Did you mean this discuss: https://lkml.org/lkml/2019/12/27/122? > > I meant about this reply instead :) > > https://lkml.org/lkml/2020/1/16/616 > > Sorry for not repley in time, I was on holiday last week. > > The platform James mentioned may exist for which have no devices and > need no low memory. If there is no memory below 4GB, the arm64 kernel assumes that the 32-bit devices will have some DMA offsets shifting the addresses to the bottom of the available RAM. So even if RAM starts above 4GB, we ZONE_DMA32 will be allocated in the bottom 4GB of the high memory (and if the hardware designers forgot to shift those DMA accesses, we don't have to support the platform ;)). So the arm64 notion of low memory differs slightly from the x86 one. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel