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[PATCH] Kdump documentation update
o Kdump documentation update. - Update details for using relocatable kernel. - Start using kexec-tools-testing release as it is latest and old kexec-tools can't load relocatable bzImage file. - Also add kdump on ia64 specific details. Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Cc: Horms <horms@verge.net.au> Cc: Mohan Kumar M <mohan@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Vivek Goyal
Linus Torvalds
parent
b282b6f8a8
commit
9c61a446a1
1 changed files with 155 additions and 75 deletions
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@ -17,7 +17,7 @@ You can use common Linux commands, such as cp and scp, to copy the
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memory image to a dump file on the local disk, or across the network to
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a remote system.
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Kdump and kexec are currently supported on the x86, x86_64, and ppc64
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Kdump and kexec are currently supported on the x86, x86_64, ppc64 and IA64
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architectures.
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When the system kernel boots, it reserves a small section of memory for
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@ -54,59 +54,64 @@ memory," in two ways:
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Setup and Installation
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======================
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Install kexec-tools and the Kdump patch
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---------------------------------------
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Install kexec-tools
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-------------------
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1) Login as the root user.
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2) Download the kexec-tools user-space package from the following URL:
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http://www.xmission.com/~ebiederm/files/kexec/kexec-tools-1.101.tar.gz
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http://www.kernel.org/pub/linux/kernel/people/horms/kexec-tools/kexec-tools-testing-20061214.tar.gz
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Note: Latest kexec-tools-testing git tree is available at
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git://git.kernel.org/pub/scm/linux/kernel/git/horms/kexec-tools-testing.git
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or
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http://www.kernel.org/git/?p=linux/kernel/git/horms/kexec-tools-testing.git;a=summary
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3) Unpack the tarball with the tar command, as follows:
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tar xvpzf kexec-tools-1.101.tar.gz
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tar xvpzf kexec-tools-testing-20061214.tar.gz
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4) Download the latest consolidated Kdump patch from the following URL:
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4) Change to the kexec-tools-1.101 directory, as follows:
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http://lse.sourceforge.net/kdump/
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cd kexec-tools-testing-20061214
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(This location is being used until all the user-space Kdump patches
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are integrated with the kexec-tools package.)
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5) Change to the kexec-tools-1.101 directory, as follows:
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cd kexec-tools-1.101
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6) Apply the consolidated patch to the kexec-tools-1.101 source tree
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with the patch command, as follows. (Modify the path to the downloaded
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patch as necessary.)
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patch -p1 < /path-to-kdump-patch/kexec-tools-1.101-kdump.patch
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7) Configure the package, as follows:
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5) Configure the package, as follows:
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./configure
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8) Compile the package, as follows:
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6) Compile the package, as follows:
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make
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9) Install the package, as follows:
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7) Install the package, as follows:
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make install
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Download and build the system and dump-capture kernels
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------------------------------------------------------
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Build the system and dump-capture kernels
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-----------------------------------------
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There are two possible methods of using Kdump.
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Download the mainline (vanilla) kernel source code (2.6.13-rc1 or newer)
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from http://www.kernel.org. Two kernels must be built: a system kernel
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and a dump-capture kernel. Use the following steps to configure these
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kernels with the necessary kexec and Kdump features:
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1) Build a separate custom dump-capture kernel for capturing the
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kernel core dump.
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System kernel
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-------------
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2) Or use the system kernel binary itself as dump-capture kernel and there is
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no need to build a separate dump-capture kernel. This is possible
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only with the architecutres which support a relocatable kernel. As
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of today i386 and ia64 architectures support relocatable kernel.
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Building a relocatable kernel is advantageous from the point of view that
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one does not have to build a second kernel for capturing the dump. But
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at the same time one might want to build a custom dump capture kernel
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suitable to his needs.
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Following are the configuration setting required for system and
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dump-capture kernels for enabling kdump support.
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System kernel config options
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----------------------------
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1) Enable "kexec system call" in "Processor type and features."
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@ -132,89 +137,161 @@ System kernel
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analysis tools require a vmlinux with debug symbols in order to read
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and analyze a dump file.
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4) Make and install the kernel and its modules. Update the boot loader
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(such as grub, yaboot, or lilo) configuration files as necessary.
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Dump-capture kernel config options (Arch Independent)
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-----------------------------------------------------
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5) Boot the system kernel with the boot parameter "crashkernel=Y@X",
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where Y specifies how much memory to reserve for the dump-capture kernel
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and X specifies the beginning of this reserved memory. For example,
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"crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
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starting at physical address 0x01000000 for the dump-capture kernel.
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1) Enable "kernel crash dumps" support under "Processor type and
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features":
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On x86 and x86_64, use "crashkernel=64M@16M".
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CONFIG_CRASH_DUMP=y
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On ppc64, use "crashkernel=128M@32M".
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2) Enable "/proc/vmcore support" under "Filesystems" -> "Pseudo filesystems".
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CONFIG_PROC_VMCORE=y
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(CONFIG_PROC_VMCORE is set by default when CONFIG_CRASH_DUMP is selected.)
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The dump-capture kernel
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-----------------------
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1) Under "General setup," append "-kdump" to the current string in
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"Local version."
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2) On x86, enable high memory support under "Processor type and
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Dump-capture kernel config options (Arch Dependent, i386)
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--------------------------------------------------------
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1) On x86, enable high memory support under "Processor type and
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features":
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CONFIG_HIGHMEM64G=y
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or
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CONFIG_HIGHMEM4G
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3) On x86 and x86_64, disable symmetric multi-processing support
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2) On x86 and x86_64, disable symmetric multi-processing support
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under "Processor type and features":
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CONFIG_SMP=n
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(If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
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when loading the dump-capture kernel, see section "Load the Dump-capture
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Kernel".)
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4) On ppc64, disable NUMA support and enable EMBEDDED support:
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3) If one wants to build and use a relocatable kernel,
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Enable "Build a relocatable kernel" support under "Processor type and
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features"
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CONFIG_NUMA=n
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CONFIG_EMBEDDED=y
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CONFIG_EEH=N for the dump-capture kernel
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CONFIG_RELOCATABLE=y
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5) Enable "kernel crash dumps" support under "Processor type and
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features":
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4) Use a suitable value for "Physical address where the kernel is
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loaded" (under "Processor type and features"). This only appears when
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"kernel crash dumps" is enabled. A suitable value depends upon
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whether kernel is relocatable or not.
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CONFIG_CRASH_DUMP=y
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If you are using a relocatable kernel use CONFIG_PHYSICAL_START=0x100000
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This will compile the kernel for physical address 1MB, but given the fact
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kernel is relocatable, it can be run from any physical address hence
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kexec boot loader will load it in memory region reserved for dump-capture
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kernel.
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6) Use a suitable value for "Physical address where the kernel is
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Otherwise it should be the start of memory region reserved for
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second kernel using boot parameter "crashkernel=Y@X". Here X is
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start of memory region reserved for dump-capture kernel.
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Generally X is 16MB (0x1000000). So you can set
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CONFIG_PHYSICAL_START=0x1000000
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5) Make and install the kernel and its modules. DO NOT add this kernel
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to the boot loader configuration files.
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Dump-capture kernel config options (Arch Dependent, x86_64)
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----------------------------------------------------------
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1) On x86 and x86_64, disable symmetric multi-processing support
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under "Processor type and features":
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CONFIG_SMP=n
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(If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
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when loading the dump-capture kernel, see section "Load the Dump-capture
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Kernel".)
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2) Use a suitable value for "Physical address where the kernel is
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loaded" (under "Processor type and features"). This only appears when
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"kernel crash dumps" is enabled. By default this value is 0x1000000
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(16MB). It should be the same as X in the "crashkernel=Y@X" boot
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parameter discussed above.
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parameter.
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On x86 and x86_64, use "CONFIG_PHYSICAL_START=0x1000000".
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For x86_64, normally "CONFIG_PHYSICAL_START=0x1000000".
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On ppc64 the value is automatically set at 32MB when
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CONFIG_CRASH_DUMP is set.
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6) Optionally enable "/proc/vmcore support" under "Filesystems" ->
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"Pseudo filesystems".
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CONFIG_PROC_VMCORE=y
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(CONFIG_PROC_VMCORE is set by default when CONFIG_CRASH_DUMP is selected.)
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7) Make and install the kernel and its modules. DO NOT add this kernel
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3) Make and install the kernel and its modules. DO NOT add this kernel
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to the boot loader configuration files.
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Dump-capture kernel config options (Arch Dependent, ppc64)
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----------------------------------------------------------
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- Make and install the kernel and its modules. DO NOT add this kernel
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to the boot loader configuration files.
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Dump-capture kernel config options (Arch Dependent, ia64)
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----------------------------------------------------------
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(To be filled)
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Boot into System Kernel
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=======================
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1) Make and install the kernel and its modules. Update the boot loader
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(such as grub, yaboot, or lilo) configuration files as necessary.
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2) Boot the system kernel with the boot parameter "crashkernel=Y@X",
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where Y specifies how much memory to reserve for the dump-capture kernel
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and X specifies the beginning of this reserved memory. For example,
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"crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
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starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
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On x86 and x86_64, use "crashkernel=64M@16M".
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On ppc64, use "crashkernel=128M@32M".
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Load the Dump-capture Kernel
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============================
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After booting to the system kernel, load the dump-capture kernel using
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the following command:
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After booting to the system kernel, dump-capture kernel needs to be
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loaded.
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kexec -p <dump-capture-kernel> \
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Based on the architecture and type of image (relocatable or not), one
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can choose to load the uncompressed vmlinux or compressed bzImage/vmlinuz
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of dump-capture kernel. Following is the summary.
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For i386:
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- Use vmlinux if kernel is not relocatable.
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- Use bzImage/vmlinuz if kernel is relocatable.
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For x86_64:
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- Use vmlinux
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For ppc64:
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- Use vmlinux
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For ia64:
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(To be filled)
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If you are using a uncompressed vmlinux image then use following command
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to load dump-capture kernel.
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kexec -p <dump-capture-kernel-vmlinux-image> \
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--initrd=<initrd-for-dump-capture-kernel> --args-linux \
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--append="root=<root-dev> init 1 irqpoll"
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--append="root=<root-dev> <arch-specific-options>"
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If you are using a compressed bzImage/vmlinuz, then use following command
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to load dump-capture kernel.
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kexec -p <dump-capture-kernel-bzImage> \
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--initrd=<initrd-for-dump-capture-kernel> \
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--append="root=<root-dev> <arch-specific-options>"
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Following are the arch specific command line options to be used while
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loading dump-capture kernel.
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For i386 and x86_64:
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"init 1 irqpoll maxcpus=1"
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For ppc64:
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"init 1 maxcpus=1 noirqdistrib"
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For IA64
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(To be filled)
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Notes on loading the dump-capture kernel:
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* <dump-capture-kernel> must be a vmlinux image (that is, an
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uncompressed ELF image). bzImage does not work at this time.
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* By default, the ELF headers are stored in ELF64 format to support
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systems with more than 4GB memory. The --elf32-core-headers option can
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be used to force the generation of ELF32 headers. This is necessary
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@ -231,6 +308,9 @@ Notes on loading the dump-capture kernel:
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* "init 1" boots the dump-capture kernel into single-user mode without
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networking. If you want networking, use "init 3."
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* We generally don' have to bring up a SMP kernel just to capture the
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dump. Hence generally it is useful either to build a UP dump-capture
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kernel or specify maxcpus=1 option while loading dump-capture kernel.
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Kernel Panic
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============
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