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 87BF9C3DA7F for ; Tue, 6 Aug 2024 02:20:13 +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=YwiNyrAMyM4LU/ShbKM/5epc+KzYLNi3URhQdn+ZYf0=; b=mGUIi29RPccd2oMvqcxluBUTSQ ZOYJ1w33MzyddqNm/a0oL07y1cvjix85tjGj7u0w6kn4Om8aygtMB2FKymNtBcP6Ozt1iCFjH5T8u nhzcfDF9XNJm8jwXDjhp6hh+MqlcAolGXyS/Uq+25qCzFAuKlk+Sb9LGZniGZPakFzUiBkYr9K4OD /WCtydC1wLsz18sQEjj03UwklIHipvC08JX5G1vAmpa9MjMaHc+JMRtrTJpSBKufQqgjxvxFXXTzy 22CWsLmcp5wn5iZpZqWHsUHtbH47O+wfoI01kzQt6sm22mWaGR1zlyiV3ae8P71QW9DncFq5h+aqp qz+OHGXw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sb9nr-00000000FRd-3EPF; Tue, 06 Aug 2024 02:19:59 +0000 Received: from szxga07-in.huawei.com ([45.249.212.35]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sb9nK-00000000FIR-1ix2 for linux-arm-kernel@lists.infradead.org; Tue, 06 Aug 2024 02:19:29 +0000 Received: from mail.maildlp.com (unknown [172.19.162.112]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4WdH1k5m0mz1S75v; Tue, 6 Aug 2024 10:14:34 +0800 (CST) Received: from kwepemi100008.china.huawei.com (unknown [7.221.188.57]) by mail.maildlp.com (Postfix) with ESMTPS id 5E3911402CF; Tue, 6 Aug 2024 10:19:16 +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 10:19:15 +0800 Message-ID: <93bbedcd-2f6b-3124-6b54-01080efeb515@huawei.com> Date: Tue, 6 Aug 2024 10:19:14 +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: Catalin Marinas , "Russell King (Oracle)" CC: , , , References: <20240802092510.3915986-1-ruanjinjie@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: dggems702-chm.china.huawei.com (10.3.19.179) 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-20240805_191926_659180_6539E4B1 X-CRM114-Status: GOOD ( 15.92 ) 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 2024/8/5 21:18, Catalin Marinas wrote: > On Fri, Aug 02, 2024 at 12:01:43PM +0100, Russell King wrote: >> On Fri, Aug 02, 2024 at 05:25:10PM +0800, Jinjie Ruan wrote: >>> As ARM LPAE feature support accessing memory beyond the 4G limit, define >>> HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH macro to support reserving crash > > At least in 6.11-rc1, there's no trace of such macro anywhere. So not > sure this patch has any effect (I haven't checked linux-next though). Sorry, this macro is introduced in linux-next, the -next subject has been missed. > >>> memory above 4G for ARM32 LPAE. >>> >>> No test because there is no LPAE ARM32 hardware. >> >> Why are you submitting patches for features you can't test? >> >> I'm not going to apply this without it being properly tested, because I >> don't believe that this will work in the generic case. >> >> If the crash kernel is located in memory outside of the lower 4GiB of >> address space, and there is no alias within physical address space >> for that memory, then there is *no* *way* for such a kernel to boot. >> >> So, right now I believe this patch to be *fundamentally* wrong. > > Indeed. Even on arm64, we keep some crashkernel reservations in the > lower parts of the memory for ZONE_DMA allocations. Indeed, it is. > > On arch/arm with LPAE, we could do something similar like forcing some > lowmem reservation and allowing explicit allocation in the higher ranges > with crashkernel=,high. We should, of course, force the kdump In linux-next, with the HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH macro defined, it is ok. > image placement in the lower memory. The user kexec tools must be taught > to interpret this information and provide a DT accordingly to the crash > kernel. >