From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: From: Chen Zhou Subject: [PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64 Date: Sun, 28 Jun 2020 16:34:58 +0800 Message-ID: <20200628083458.40066-6-chenzhou10@huawei.com> In-Reply-To: <20200628083458.40066-1-chenzhou10@huawei.com> References: <20200628083458.40066-1-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: tglx@linutronix.de, mingo@redhat.com, dyoung@redhat.com, bhe@redhat.com, catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, robh+dt@kernel.org, arnd@arndb.de, John.P.donnelly@oracle.com, prabhakar.pkin@gmail.com, nsaenzjulienne@suse.de, corbet@lwn.net, bhsharma@redhat.com, horms@verge.net.au Cc: xiexiuqi@huawei.com, chenzhou10@huawei.com, linux-doc@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, huawei.libin@huawei.com, guohanjun@huawei.com, linux-arm-kernel@lists.infradead.org Now we support crashkernel=X,[low] on arm64, update the Documentation. We could use parameters "crashkernel=X crashkernel=Y,low" to reserve memory above 4G. Signed-off-by: Chen Zhou Tested-by: John Donnelly Tested-by: Prabhakar Kushwaha --- Documentation/admin-guide/kdump/kdump.rst | 13 +++++++++++-- Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++-- 2 files changed, 26 insertions(+), 4 deletions(-) diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index 2da65fef2a1c..6ba294d425c9 100644 --- a/Documentation/admin-guide/kdump/kdump.rst +++ b/Documentation/admin-guide/kdump/kdump.rst @@ -299,7 +299,13 @@ 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=Y[@X]" to select a region under 4G first, and + fall back to reserve region above 4G when '@offset' hasn't been specified. + 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. On ppc64, use "crashkernel=128M@32M". @@ -316,8 +322,11 @@ 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 + On arm64, use "crashkernel=Y[@X]". Note that the start address of the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000). + If crashkernel=Z,low is specified simultaneously, reserve spcified size + low memory for crash kdump kernel devices firstly and then reserve memory + above 4G. Load the Dump-capture Kernel ============================ diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb95fad81c79..335431a351c0 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -722,6 +722,9 @@ [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] If crashkernel=X,low is specified, reserve + spcified size low memory for crash kdump kernel devices + firstly, and then reserve memory above 4G. See Documentation/admin-guide/kdump/kdump.rst for further details. crashkernel=range1:size1[,range2:size2,...][@offset] @@ -746,13 +749,23 @@ 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 own low range under 4G + for crash dump kernel instead. + Different with x86_64, kernel allocates specified size + physical memory region only when this parameter is specified + instead of trying to allocate at least 256M below 4G + automatically. + This parameter is used along with crashkernel=X when we + want to reserve crashkernel above 4G. If there are devices + need to use ZONE_DMA in crash dump kernel, it is also + a good choice. cryptomgr.notests [KNL] Disable crypto self-tests -- 2.20.1 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec