From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: From: Chen Zhou Subject: [PATCH v14 11/11] kdump: update Documentation about crashkernel Date: Sat, 30 Jan 2021 15:10:25 +0800 Message-ID: <20210130071025.65258-12-chenzhou10@huawei.com> In-Reply-To: <20210130071025.65258-1-chenzhou10@huawei.com> References: <20210130071025.65258-1-chenzhou10@huawei.com> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: mingo@redhat.com, tglx@linutronix.de, rppt@kernel.org, dyoung@redhat.com, bhe@redhat.com, catalin.marinas@arm.com, will@kernel.org, nsaenzjulienne@suse.de, corbet@lwn.net, John.P.donnelly@oracle.com, bhsharma@redhat.com, prabhakar.pkin@gmail.com Cc: John Donnelly , wangkefeng.wang@huawei.com, arnd@arndb.de, xiexiuqi@huawei.com, chenzhou10@huawei.com, linux-doc@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, robh+dt@kernel.org, horms@verge.net.au, james.morse@arm.com, huawei.libin@huawei.com, guohanjun@huawei.com, linux-arm-kernel@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 and "crashkernel=Y,low" can be used to allocate specified size low memory. So update the Documentation. Signed-off-by: Chen Zhou Tested-by: John Donnelly --- Documentation/admin-guide/kdump/kdump.rst | 22 ++++++++++++++++--- .../admin-guide/kernel-parameters.txt | 11 ++++++++-- 2 files changed, 28 insertions(+), 5 deletions(-) diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index 75a9dd98e76e..0877c76f8015 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 +325,15 @@ 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). Load the Dump-capture Kernel ============================ diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a10b545c2070..908e5c8b61ba 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -738,6 +738,9 @@ [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. crashkernel=range1:size1[,range2:size2,...][@offset] @@ -754,6 +757,8 @@ 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 @@ -762,13 +767,15 @@ 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. cryptomgr.notests [KNL] Disable crypto self-tests -- 2.20.1 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec