From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amerigo Wang Date: Wed, 12 Aug 2009 08:16:32 +0000 Subject: [Patch 7/8] doc: update the kdump document Message-Id: <20090812081854.5757.88620.sendpatchset@localhost.localdomain> List-Id: References: <20090812081731.5757.25254.sendpatchset@localhost.localdomain> In-Reply-To: <20090812081731.5757.25254.sendpatchset@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel@vger.kernel.org Cc: tony.luck@intel.com, linux-ia64@vger.kernel.org, Neil Horman , "Eric W. Biederman" , Andi Kleen , Amerigo Wang , akpm@linux-foundation.org, bernhard.walle@gmx.de, Fenghua Yu , Ingo Molnar , Anton Vorontsov Update the document for kdump. Signed-off-by: WANG Cong --- Index: linux-2.6/Documentation/kdump/kdump.txt =================================--- linux-2.6.orig/Documentation/kdump/kdump.txt +++ linux-2.6/Documentation/kdump/kdump.txt @@ -147,6 +147,15 @@ System kernel config options analysis tools require a vmlinux with debug symbols in order to read and analyze a dump file. +4) Enable "automatically reserve memory for kexec kernel" in + "Processor type and features." + + CONFIG_KEXEC_AUTO_RESERVE=y + + This will let you to use "crashkernel=auto", instead of specifying + numbers for "crashkernel=". Note, you need to have enough memory. + The threshold and reserved memory size are arch-dependent. + Dump-capture kernel config options (Arch Independent) ----------------------------------------------------- @@ -266,6 +275,25 @@ This would mean: 2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M 3) if the RAM size is larger than 2G, then reserve 128M +Or you can use: + + crashkernel=auto + +if you have enough memory. The threshold is 4G, below which this won't work. + +The automatically reserved memory size would be 128M on x86_32, 256M on +ppc, 1/32 of your physical memory size on x86_64 and ppc64 (but it will not +exceed 1TB/32 if you have more). IA64 has its own policy, shown below: + + Memory size Reserved memory + ====== =======+ [4G, 12G) 256M + [12G, 128G) 512M + [128G, 256G) 768M + [256G, 378G) 1024M + [378G, 512G) 1536M + [512G, 768G) 2048M + [768G, ) 3072M Boot into System Kernel