This patch contains the documentation for the kexec based crash dump tool.
Quick kdump-howto
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1) Download and build kexec-tools.
2) Download and build the latest kexec/kdump (-mm) kernel patchset.
Two kernels need to be built in order to get this feature working.
A) First kernel:
a) Enable "kexec system call" feature:
CONFIG_KEXEC=y
b) Physical load address (use default):
CONFIG_PHYSICAL_START=0x100000
c) Enable "sysfs file system support":
CONFIG_SYSFS=y
d) Boot into first kernel with the command line parameter "crashkernel=Y@X":
For example: "crashkernel=64M@16M".
B) Second kernel:
a) Enable "kernel crash dumps" feature:
CONFIG_CRASH_DUMP=y
b) Physical load addreess, use same load address as X in "crashkernel"
kernel parameter in d) above, e.g., 16 MB or 0x1000000.
CONFIG_PHYSICAL_START=0x1000000
c) Enable "/proc/vmcore support" (Optional, in Pseudo filesystems).
CONFIG_PROC_VMCORE=y
3) Boot into the first kernel.
4) Load the second kernel to be booted using:
kexec -p <second-kernel> --crash-dump --args-linux --append="root=<root-dev>
maxcpus=1 init 1"
5) System reboots into the second kernel when a panic occurs. A module can be
written to force the panic, for testing purposes.
6) See Documentation/kdump.txt for how to read the first kernel's
memory image and how to analyze it.
Signed-off-by: Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: randy_dunlap <rdunlap@xenotime.net>
Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Vivek Goyal