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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19BBFC433EF for ; Mon, 21 Feb 2022 06:38:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345240AbiBUGjD (ORCPT ); Mon, 21 Feb 2022 01:39:03 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:40104 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344581AbiBUGjC (ORCPT ); Mon, 21 Feb 2022 01:39:02 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4BAA7205C3; Sun, 20 Feb 2022 22:38:38 -0800 (PST) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4K2CK22CRMzcfdn; Mon, 21 Feb 2022 14:37:26 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Mon, 21 Feb 2022 14:38:36 +0800 Received: from [10.174.178.55] (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Mon, 21 Feb 2022 14:38:35 +0800 Subject: Re: [PATCH v20 5/5] kdump: update Documentation about crashkernel To: Baoquan He CC: Thomas Gleixner , Ingo Molnar , Borislav Petkov , , "H . Peter Anvin" , , Dave Young , Vivek Goyal , Eric Biederman , , Catalin Marinas , Will Deacon , , Rob Herring , Frank Rowand , , "Jonathan Corbet" , , Randy Dunlap , Feng Zhou , Kefeng Wang , Chen Zhou , "John Donnelly" , Dave Kleikamp References: <20220124084708.683-1-thunder.leizhen@huawei.com> <20220124084708.683-6-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <8ada665b-1917-2f01-477f-baaa562f5502@huawei.com> Date: Mon, 21 Feb 2022 14:38:35 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 2022/2/21 11:48, Baoquan He wrote: > On 01/24/22 at 04:47pm, Zhen Lei wrote: >> From: Chen Zhou >> >> For arm64, the behavior of crashkernel=X has been changed, which >> tries low allocation in DMA zone and fall back to high allocation >> if it fails. >> >> We can also use "crashkernel=X,high" to select a high region above >> DMA zone, which also tries to allocate at least 256M low memory in >> DMA zone automatically and "crashkernel=Y,low" can be used to allocate >> specified size low memory. >> >> So update the Documentation. >> >> Signed-off-by: Chen Zhou >> Signed-off-by: Zhen Lei >> --- >> Documentation/admin-guide/kdump/kdump.rst | 11 +++++++++-- >> Documentation/admin-guide/kernel-parameters.txt | 11 +++++++++-- >> 2 files changed, 18 insertions(+), 4 deletions(-) >> >> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst >> index cb30ca3df27c9b2..d4c287044be0c70 100644 >> --- a/Documentation/admin-guide/kdump/kdump.rst >> +++ b/Documentation/admin-guide/kdump/kdump.rst >> @@ -361,8 +361,15 @@ Boot into System Kernel >> kernel will automatically locate the crash kernel image within the >> first 512MB of RAM if X is not given. >> >> - On arm64, use "crashkernel=Y[@X]". Note that the start address of >> - the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000). >> + On arm64, use "crashkernel=X" to try low allocation in DMA zone and >> + fall back to high allocation if it fails. >> + We can also use "crashkernel=X,high" to select a high region above >> + DMA zone, which also tries to allocate at least 256M low memory in >> + DMA zone automatically. >> + "crashkernel=Y,low" can be used to allocate specified size low memory. >> + Use "crashkernel=Y@X" if you really have to reserve memory from >> + specified start address X. Note that the start address of the kernel, >> + X if explicitly specified, must be aligned to 2MiB (0x200000). > > Hmm, we may not need the details related to crashkernel,high|low in this > section. This just gives examples of basic configation for each ARCH. > The detailed configuration of all crashkernel setting can be found in > "crashkernel syntax" section, I don't think arm64 is so special to need > a specific one. > >> >> Load the Dump-capture Kernel >> ============================ >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index f5a27f067db9ed9..65780c2ca830be0 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -792,6 +792,9 @@ >> [KNL, X86-64] Select a region under 4G first, and >> fall back to reserve region above 4G when '@offset' >> hasn't been specified. >> + [KNL, ARM64] Try low allocation in DMA zone and fall back >> + to high allocation if it fails when '@offset' hasn't been >> + specified. >> See Documentation/admin-guide/kdump/kdump.rst for further details. > > How about add ARM64 like below to avoid redundant words? > [KNL, X86-64, ARM64] Select a region under 4G first, and > fall back to reserve region above 4G when '@offset' > hasn't been specified. I agree very much, and I think that's the right thing to do. Thanks. I wanted to do the same before, just wasn't sure if the format was correct. I just looked at the other descriptions in kernel-parameters.txt and found that there are many precedents. "movablecore= [KNL,X86,IA-64,PPC]" > >> >> crashkernel=range1:size1[,range2:size2,...][@offset] >> @@ -808,6 +811,8 @@ >> Otherwise memory region will be allocated below 4G, if >> available. >> It will be ignored if crashkernel=X is specified. >> + [KNL, ARM64] range in high memory. >> + Allow kernel to allocate physical memory region from top. > > Ditto, please don't add redundent words if it's similar to x86_64 > handling. > >> crashkernel=size[KMG],low >> [KNL, X86-64] range under 4G. When crashkernel=X,high >> is passed, kernel could allocate physical memory region >> @@ -816,13 +821,15 @@ >> requires at least 64M+32K low memory, also enough extra >> low memory is needed to make sure DMA buffers for 32-bit >> devices won't run out. Kernel would try to allocate at >> - at least 256M below 4G automatically. >> + least 256M below 4G automatically. >> This one let user to specify own low range under 4G >> for second kernel instead. >> 0: to disable low allocation. >> It will be ignored when crashkernel=X,high is not used >> or memory reserved is below 4G. >> - >> + [KNL, ARM64] range in low memory. >> + This one let user to specify a low range in DMA zone for >> + crash dump kernel. > > Ditto. > >> cryptomgr.notests >> [KNL] Disable crypto self-tests >> >> -- >> 2.25.1 >> > > . > -- Regards, Zhen Lei