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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5406BC3DA64 for ; Tue, 6 Aug 2024 11:11:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:CC:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=O9ED0oANOfrmtNlPzAhZUJkJo+jfrfrYQo1laU2SWco=; b=egxOF3Pi+AofAXd2Wrw7SsKIOH T9Xq75acDN6+Cig6UQtxe2QE+XYaFBn3RlEk2vdqtCk6tz6guzb9iEvvW0UP5QB0XmMXpMTlauxb8 nRLxa+kYh4FhrFWcBo4tnLR+qNckxw9SxnsEXa5lei6ZBB7eCtfKdg2p6vR/VYs4MZw96d8/IHpJX 6uRH/DYxa9k3TyLEDc7QpHdGyIxxC0EaYJ3oC3YxMAg0Q83MsU13EcnnzZSGzv3scgJk2RtOYzzVA sUwMwkEM0LGpE8Jl/Eu5g1EpLMIAMSNKFYtQbzSX+W4BF65YTkSSPDiStXg1hb5RuT8j7qS9nY2IR 0rNU1RfQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sbI5h-00000001JLt-3Hqx; Tue, 06 Aug 2024 11:10:57 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sbI5A-00000001JH3-3C6H for linux-arm-kernel@lists.infradead.org; Tue, 06 Aug 2024 11:10:26 +0000 Received: from mail.maildlp.com (unknown [172.19.163.174]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4WdVtZ2kmVzpSxD; Tue, 6 Aug 2024 19:09:10 +0800 (CST) Received: from kwepemi100008.china.huawei.com (unknown [7.221.188.57]) by mail.maildlp.com (Postfix) with ESMTPS id F373D140135; Tue, 6 Aug 2024 19:10:18 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by kwepemi100008.china.huawei.com (7.221.188.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Tue, 6 Aug 2024 19:10:18 +0800 Message-ID: <8912aec0-d47d-3574-1e57-b03abb8c7171@huawei.com> Date: Tue, 6 Aug 2024 19:10:17 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [RFC PATCH] ARM: Support allocating crashkernel above 4G for LPAE Content-Language: en-US To: "Russell King (Oracle)" , Baoquan He CC: , , References: <20240802092510.3915986-1-ruanjinjie@huawei.com> <6c0a45c3-08a2-f889-9e66-ab8aff66ae8c@huawei.com> <8f051483-46be-87b6-03bb-5e0d145a2ac3@huawei.com> From: Jinjie Ruan In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemi100008.china.huawei.com (7.221.188.57) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240806_041025_000371_4DD9DBDB X-CRM114-Status: GOOD ( 16.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2024/8/6 16:34, Russell King (Oracle) wrote: > On Tue, Aug 06, 2024 at 04:11:30PM +0800, Baoquan He wrote: >> I am fine with it. BUT have you addressed Russell's concern, e.g how to >> test it actually? > > Thanks for bringing that up. > > Let me reinforce my position on this. I will _not_ be accepting a patch > that allows the crash kernel to be placed into high memory on 32-bit > ARM unless it has been thoroughly tested to prove that it can actually > work. Thank you! I'm looking for an available environment to test, otherwise, the patch is invalid. > > Right now, I don't believe it can work as placing the kernel in highmem > likely means it will be located *outside* of the lower 4GiB of physical > memory which is all that will be accessible when the MMU is turned off. > This is a pre-condition to boot a kernel - the kernel image _must_ be > located within a region of memory which is exposed to the CPU when the > MMU is turned off. > > Unless it can be proven that placing the kernel in highmem means that > the kernel will be located in the lower 4GiB of physical memory space > with the MMU off, then further work on this patch is a waste of time. >