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=-10.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,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 593D9C43461 for ; Thu, 3 Sep 2020 15:13:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4276520716 for ; Thu, 3 Sep 2020 15:13:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728665AbgICMDA (ORCPT ); Thu, 3 Sep 2020 08:03:00 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:55842 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728718AbgICL4W (ORCPT ); Thu, 3 Sep 2020 07:56:22 -0400 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 491F1DC3B52B4ED5FE93; Thu, 3 Sep 2020 19:56:21 +0800 (CST) Received: from [127.0.0.1] (10.174.176.220) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.487.0; Thu, 3 Sep 2020 19:56:10 +0800 Subject: Re: [PATCH v11 5/5] kdump: update Documentation about crashkernel To: Catalin Marinas References: <20200801130856.86625-1-chenzhou10@huawei.com> <20200801130856.86625-6-chenzhou10@huawei.com> <20200902171341.GC16673@gaia> CC: , , , , , , , , , , , , , , , , , , , , , From: chenzhou Message-ID: <84bb1cbb-c19e-9006-07b5-044eac5ecd4f@huawei.com> Date: Thu, 3 Sep 2020 19:56:09 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20200902171341.GC16673@gaia> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.220] X-CFilter-Loop: Reflected Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 2020/9/3 1:13, Catalin Marinas wrote: > On Sat, Aug 01, 2020 at 09:08:56PM +0800, Chen Zhou wrote: >> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst >> index 2da65fef2a1c..4b58f97351d5 100644 >> --- a/Documentation/admin-guide/kdump/kdump.rst >> +++ b/Documentation/admin-guide/kdump/kdump.rst >> @@ -299,7 +299,15 @@ Boot into System Kernel >> "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory >> starting at physical address 0x01000000 (16MB) for the dump-capture kernel. >> >> - On x86 and x86_64, use "crashkernel=64M@16M". >> + On x86 use "crashkernel=64M@16M". >> + >> + On x86_64, use "crashkernel=X" to select a region under 4G first, and >> + fall back to reserve region above 4G. >> + We can also use "crashkernel=X,high" to select a region above 4G, which >> + also tries to allocate at least 256M below 4G automatically and >> + "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. >> >> On ppc64, use "crashkernel=128M@32M". >> >> @@ -316,8 +324,15 @@ 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 ZONE_DMA, and >> + fall back to high allocation if it fails. And go for high allocation >> + directly if the required size is too large. If crash_base is outside > I wouldn't mention crash_base in the admin guide. That's an > implementation detail really and admins are not supposed to read the > source code to make sense of the documentation. ZONE_DMA is also a > kernel internal, so you'd need to define what it is for arm64. At least > the DMA and DMA32 zones are printed during kernel boot. Ok, i will fix this in next version. > >> + ZONE_DMA, try to allocate at least 256M in ZONE_DMA automatically. >> + "crashkernel=Y,low" can be used to allocate specified size low memory. >> + For non-RPi4 platforms, change ZONE_DMA memtioned above to ZONE_DMA32. >> + 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).