[OOT]: crash / kdump query

Mon Feb 6 06:03:58 EST 2012

Hi List,

I am new to crash / kdump tool and failing some problem as mentioned below.

I am referring the Linux Kernel Crash Book (http://www.dedoimedo.com/)
and URL http://www.dedoimedo.com/computers/crash.html.
I am building modified kernel source (2.6.32 based) and added my
modules (for study purpose). Building, installing and booting kernel
is successful. I have enabled the options for kdump as mentioned in
the book:

Enable Kexec system call:
CONFIG_KEXEC=y

Enable kernel crash dumps:
CONFIG_CRASH_DUMP=y

Optional: Disable Symmetric Multi-Processing (SMP) support
CONFIG_SMP=y

Enable sysfs file system support:
CONFIG_SYSFS=y

Enable /proc/vmcore support:
CONFIG_PROC_VMCORE=y

Configure the kernel with debug info:
CONFIG_DEBUG_INFO=y

Configure the start section for reserved RAM for the crash kernel:
CONFIG_PHYSICAL_START=0x200000             (2MB)

Configure kdump kernel so it can be identified:
CONFIG_LOCALVERSION="-crash"

Kdump configuration /etc/sysconfig/kdump:
KDUMP_KERNELVER=""

KDUMP_COMMANDLINE=""

KDUMP_COMMANDLINE_APPEND="maxcpus=1 "

KEXEC_OPTIONS=""

KDUMP_IMMEDIATE_REBOOT="yes"

KDUMP_TRANSFER=""

KDUMP_SAVEDIR="file:///var/crash"

KDUMP_KEEP_OLD_DUMPS="5"

KDUMP_FREE_DISK_SIZE="64"

KDUMP_VERBOSE="3"

KDUMP_DUMPLEVEL="0"

KDUMP_DUMPFORMAT="compressed"

There is no option KDUMP_DUMPDEV option
There is no option KDUMP_RUNLEVEL

I booted successfully with this kernel and tried to crash it by
module. After rebooting, I found that vmcore is generated under
/var/crash/ But I am not able to analyze it with crash command.

linux:/home/adil # cat /proc/cmdline
root=/dev/disk/by-id/ata-WDC_WD800BD-22LRA1_WD-WMAM9ZS19445-part1
resume=/dev/disk/by-id/ata-WDC_WD800BD-22LRA1_WD-WMAM9ZS19445-part2
splash=silent crashkernel=256M-:128M vga=0x31a
linux:/home/adil #

linux:/home/adil # crash /boot/System.map-2.6.32.12-crash-crash
/boot/vmlinuz-2.6.32.12-crash-crash

crash 5.0.1
Copyright (C) 2002-2010  Red Hat, Inc.
Copyright (C) 2004, 2005, 2006  IBM Corporation
Copyright (C) 1999-2006  Hewlett-Packard Co
Copyright (C) 2005, 2006  Fujitsu Limited
Copyright (C) 2006, 2007  VA Linux Systems Japan K.K.
Copyright (C) 2005  NEC Corporation
Copyright (C) 1999, 2002, 2007  Silicon Graphics, Inc.
Copyright (C) 1999, 2000, 2001, 2002  Mission Critical Linux, Inc.
This program is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under
certain conditions.  Enter "help copying" to see the conditions.
This program has absolutely no warranty.  Enter "help warranty" for details.

crash: /boot/vmlinuz-2.6.32.12-crash-crash: not a supported file format

Usage:
  crash [-h [opt]][-v][-s][-i file][-d num] [-S] [mapfile] [namelist] [dumpfile]

Enter "crash -h" for details.
linux:/home/adil #

The URL http://www.dedoimedo.com/computers/crash.html mentioned that
"The newer versions of Kdump can work with compressed kernel images.
Furthermore, they copy the System map file and the kernel image into
the crash directory, making the use of crash utility somewhat
simpler."

linux:/home/adil # ls -al /var/crash/2012-01-30-18\:08/
total 1335536
drwxr-xr-x 2 root root       4096 2012-01-30 18:13 .
drwxr-xr-x 8 root root       4096 2012-01-31 12:17 ..
-rw-r--r-- 1 root root        187 2012-01-30 18:13 README.txt
-rw-r--r-- 1 root root    1716605 2012-01-30 18:13
System.map-2.6.32.12-0.7-default
-rw------- 1 root root 1360732590 2012-01-30 18:13 vmcore
-rw-r--r-- 1 root root    3774506 2012-01-30 18:13
vmlinux-2.6.32.12-0.7-default.gz
linux:/home/adil # ls -al /var/crash/2012-01-31-12\:17/
total 1343860
drwxr-xr-x 2 root root       4096 2012-01-31 12:24 .
drwxr-xr-x 8 root root       4096 2012-01-31 12:17 ..
-rw-r--r-- 1 root root        187 2012-01-31 12:24 README.txt
-rw------- 1 root root 1374748735 2012-01-31 12:24 vmcore
linux:/home/adil #

linux:/home/adil # ls /boot/
backup_mbr
boot
boot.readme
config-2.6.32.12-0.7-default
config-2.6.32.12-0.7-xen
grub
initrd
initrd-2.6.32.12-0.7-default
initrd-2.6.32.12-0.7-default-kdump
initrd-2.6.32.12-0.7-xen
initrd-2.6.32.12-crash-crash
initrd-2.6.32.12-crash-crash-kdump
initrd-xen
message
symsets-2.6.32.12-0.7-default.tar.gz
symtypes-2.6.32.12-0.7-default.gz
symvers-2.6.32.12-0.7-default.gz
symvers-2.6.32.12-0.7-xen.gz
System.map-2.6.32.12-0.7-default
System.map-2.6.32.12-0.7-xen
System.map-2.6.32.12-crash-crash
vmlinux-2.6.32.12-0.7-xen.gz
vmlinuz
vmlinuz-2.6.32.12-0.7-default
vmlinuz-2.6.32.12-0.7-xen
vmlinuz-2.6.32.12-crash-crash
vmlinuz-xen
vmlinux-2.6.32.12-0.7-default.gz
linux:/home/adil #

Another observation is boot.kdump seems to on but manually start
giving me error:

linux:/home/adil # chkconfig boot.kdump
boot.kdump  on
linux:/home/adil #

linux:/home/adil # /etc/init.d/boot.kdump start
Loading kdump
Regenerating kdump initrd ...
Can't find kernel text map area from kcore
Cannot load /boot/vmlinuz-2.6.32.12-crash-crash

                                                    failed
linux:/home/adil #

Other Query: Following is not clear mentioned in the book under
"section 11.2 Crash (capture) kernel":
--------------
This means that while your production kernels will most likely be
named vmlinuz, the Kdump crash kernels need to be uncompressed,
hence named vmlinux, or rather vmlinux-kdump.
---------------

Please help how to correctly setup and use crash on my machine.

Thank you,
Adil