From patchwork Mon Sep 7 13:47:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: chenzhou X-Patchwork-Id: 11761083 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7EA3B746 for ; Mon, 7 Sep 2020 13:50:02 +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 2E4D320757 for ; Mon, 7 Sep 2020 13:50:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="wqbeTh15" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2E4D320757 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+patchwork-linux-arm=patchwork.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:MIME-Version:References:In-Reply-To:Message-ID:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=DPznaHng5SVwXngzqTTJF0mYNb4y5HiMPc6JV4QGNxM=; b=wqbeTh15VIAhk+1WQpSLrybog SoyoCWp1rOynmFN1q2KMmBkIJx7gNX2w93exXt4FclQlFxiJ14tHV2ZqoMGURZIZCjzflSpTZckA1 o6elsfgyvbc96mlzrFb+szq4zSICQjQXUZ3jLIfeIHX7TEmSSu4ozSO+ojTvtZGj5gjOqiqub2q9h vLUhMVxL+gLITgR8X3Fnjd+4+Q2ozxpSyC4YdkBRSntaYqOTobNwUZhc9RgAfKPivvBNjbSfAPCAD WlhvCG/r/SCIlOpMzUZiXYtcb9cIpWjo4k5vFk8UsZ0CBmajNoo9+oy23yrJNRVvPdTC+De9PkoE8 OwFzNT0fg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kFHVD-0006HJ-ON; Mon, 07 Sep 2020 13:48:11 +0000 Received: from szxga07-in.huawei.com ([45.249.212.35] helo=huawei.com) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kFHUC-0005rR-OF; Mon, 07 Sep 2020 13:47:11 +0000 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 37044B73E2F5FB36280A; Mon, 7 Sep 2020 21:47:04 +0800 (CST) Received: from localhost.localdomain.localdomain (10.175.113.25) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.487.0; Mon, 7 Sep 2020 21:46:55 +0800 From: Chen Zhou To: , , , , , , , , , , Subject: [PATCH v12 9/9] kdump: update Documentation about crashkernel Date: Mon, 7 Sep 2020 21:47:45 +0800 Message-ID: <20200907134745.25732-10-chenzhou10@huawei.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200907134745.25732-1-chenzhou10@huawei.com> References: <20200907134745.25732-1-chenzhou10@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.113.25] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200907_094709_080245_91D7633C X-CRM114-Status: GOOD ( 14.30 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 RCVD_IN_MSPIKE_H4 RBL: Very Good reputation (+4) [45.249.212.35 listed in wl.mailspike.net] -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [45.249.212.35 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.0 SPF_HELO_PASS SPF: HELO matches SPF record 0.0 RCVD_IN_MSPIKE_WL Mailspike good senders 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, arnd@arndb.de, linux-doc@vger.kernel.org, chenzhou10@huawei.com, xiexiuqi@huawei.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, robh+dt@kernel.org, horms@verge.net.au, nsaenzjulienne@suse.de, huawei.libin@huawei.com, guohanjun@huawei.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org 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. "crashkernel=Y,low" can be used to allocate specified size low memory in DMA zone. For non-RPi4 platforms, change DMA zone memtioned above to DMA32 zone. For x86 and arm64, we introduce threshold for the required memory. if required size X is too large and leads to very little free low memory 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. So update the Documentation. Signed-off-by: Chen Zhou --- Documentation/admin-guide/kdump/kdump.rst | 25 ++++++++++++++++--- .../admin-guide/kernel-parameters.txt | 13 ++++++++-- 2 files changed, 33 insertions(+), 5 deletions(-) diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index 2da65fef2a1c..549611abc581 100644 --- a/Documentation/admin-guide/kdump/kdump.rst +++ b/Documentation/admin-guide/kdump/kdump.rst @@ -299,7 +299,16 @@ 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. And go for high allocation + directly if the required size is too large. + 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 +325,18 @@ 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. And go for high allocation + directly if the required size is too large. + 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 + in DMA zone. + For non-RPi4 platforms, change DMA zone memtioned above to DMA32 zone. + 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 a1068742a6df..f7df572d8f64 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -727,6 +727,10 @@ [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 DMA zone, fall back + to high allocation if it fails when '@offset' hasn't been + specified. For non-RPi4 platforms, change DMA zone to + DMA32 zone. See Documentation/admin-guide/kdump/kdump.rst for further details. crashkernel=range1:size1[,range2:size2,...][@offset] @@ -743,6 +747,8 @@ 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. crashkernel=size[KMG],low [KNL, X86-64] range under 4G. When crashkernel=X,high is passed, kernel could allocate physical memory region @@ -751,13 +757,16 @@ 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 in low memory. + This one let user to specify a low range in DMA zone for + crash dump kernel. For non-RPi4 platforms, change DMA zone + to DMA32 zone. cryptomgr.notests [KNL] Disable crypto self-tests