>Debug Kernel Panic

By | October 23, 2012

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Many of you may be already heard about kdump. Kdump is basically a crash debugging mechanism . Kernel Panic is one of such crashing scenario . Suppose , you got in situation where you need crash dump file of kernel panic error . Here I am discussing this in brief . The given below command tested on RHEL5

To get dump, you need to follow given below steps

1. Install kexec-tools and crash

 yum install kexec-tools crash

2. Enable crashkernel option  in grub.conf

 kernel /vmlinuz….. crashkernel=128M@16M  

This crashkernel parameter reserve memory for dump that is 128M while keeping initial memory allocation to 16M .

3. Reboot the system with crashkernel enabled and verify from command , if crashkernel activated successfully

cat /proc/iomem|grep Crash

4. Start kdump service . Also before starting kdump service you can have a look in /etc/kdump.conf . In /etc/kdump.conf file we can specify location where dump file get stored . Normally dump file get stored inside /var/crash folder.

  /etc/init.d/kdump start

5.  Send “c” to sysrq (http://en.wikipedia.org/wiki/System_request) using following command

 echo “c”>/proc/sysrq-trigger

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