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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 2E7C5C433E0 for ; Mon, 10 Aug 2020 03:30:45 +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 E94A8206A5 for ; Mon, 10 Aug 2020 03:30:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="F62TIQl+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E94A8206A5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.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:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=9v+o7PbW+L3q7E/GJQdDlkfLBx7f9OofW9pgCK/2UtI=; b=F62TIQl+4EADXEKvGWHmLOs/v A/Zk/2l+8aJauj8hPQHf2Y4X2b9BvdR5kL23zFPefjocHSX1brgBYyMmKHhPX0vlJq9KxnOE/KV4M RElwK4qEbW3z9rskq9+8BbRpGvBaHRqmaqirLTmSDZkd/TSAB3VIWISbg/vkwZaSr0ystctF+h4fI J3L5XyxXnlFon4BXDETy+MW1B0oxIczrxLhCkXNW8Jr55N0BsvmY384+AiFtRqNT5+uawuXnafFBF FtbHQ3oe8TSlhu+J6xUoR2qCB53GxAT74IZf3r3O8y6yUnxzr0XEFVC+n+P6O4ouGJi8kVy4J7CWK HRx0WGzrQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k4yUc-0002nr-3S; Mon, 10 Aug 2020 03:28:58 +0000 Received: from szxga06-in.huawei.com ([45.249.212.32] helo=huawei.com) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k4yUW-0002mj-FF; Mon, 10 Aug 2020 03:28:53 +0000 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 6375DE9F691D67B7F72E; Mon, 10 Aug 2020 11:28:32 +0800 (CST) Received: from [127.0.0.1] (10.174.176.220) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.487.0; Mon, 10 Aug 2020 11:28:24 +0800 Subject: Re: [PATCH v11 5/5] kdump: update Documentation about crashkernel To: Dave Young References: <20200801130856.86625-1-chenzhou10@huawei.com> <20200801130856.86625-6-chenzhou10@huawei.com> <20200808100239.GB60590@dhcp-128-65.nay.redhat.com> From: chenzhou Message-ID: <96d0da23-d484-7f66-1680-07b4b5984831@huawei.com> Date: Mon, 10 Aug 2020 11:28:22 +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: <20200808100239.GB60590@dhcp-128-65.nay.redhat.com> X-Originating-IP: [10.174.176.220] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200809_232852_779798_87E8ABD0 X-CRM114-Status: GOOD ( 24.14 ) 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, catalin.marinas@arm.com, bhsharma@redhat.com, huawei.libin@huawei.com, guohanjun@huawei.com, will@kernel.org, bhe@redhat.com, corbet@lwn.net, mingo@redhat.com, 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 2020/8/8 18:02, Dave Young wrote: > On 08/01/20 at 09:08pm, Chen Zhou wrote: >> Now the behavior of crashkernel=X has been changed, which tries low >> allocation in ZONE_DMA, and fall back to high allocation if it fails. >> >> If requized size X is too large and leads to very little free memory >> in ZONE_DMA after low allocation, the system may not work well. >> So add a threshold and go for high allocation directly if the required >> size is too large. The threshold is set as the half of low memory. >> >> If crash_base is outside 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. >> >> So update the Documentation. >> >> Signed-off-by: Chen Zhou >> --- >> Documentation/admin-guide/kdump/kdump.rst | 21 ++++++++++++++++--- >> .../admin-guide/kernel-parameters.txt | 11 ++++++++-- >> 2 files changed, 27 insertions(+), 5 deletions(-) >> >> 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 >> + 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). >> >> Load the Dump-capture Kernel >> ============================ >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index fb95fad81c79..d1b6016850d6 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -722,6 +722,10 @@ >> [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 ZONE_DMA, fall back >> + to high allocation if it fails when '@offset' hasn't been >> + specified. For non-RPi4 platforms, change ZONE_DMA to >> + ZONE_DMA32. >> See Documentation/admin-guide/kdump/kdump.rst for further details. >> >> crashkernel=range1:size1[,range2:size2,...][@offset] >> @@ -746,13 +750,16 @@ >> 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 under 4G. >> + This one let user to specify a low range in ZONE_DMA for >> + crash dump kernel. For non-RPi4 platforms, change ZONE_DMA >> + to ZONE_DMA32. >> cryptomgr.notests >> [KNL] Disable crypto self-tests >> >> -- >> 2.20.1 >> > Hi Chen, > > 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. Hi Dave, Did you mean this discuss: https://lkml.org/lkml/2019/12/27/122? This is about the different implementation instead of no low memory in arm64. On arm64 platform, if there is no low memory, system will boot fail. Thanks, Chen Zhou > > Acked-by: Dave Young > > Thanks > Dave > > > . > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel