View source for Kernel Panic


== Overview ==


You encounter a Kernel panic on boot up with an ASL kernel, disks are not detected


== Cause ==


This is almost always caused by a kernel design change. A module required for the system to see your disks is not being loaded in the initrd


== Diagnostics ==


Send the output from cat /etc/modprobe.conf and lspci to support


== Possible fixes (HARDWARE DEPENDENT) ==

Stub for various modprobe.confs go here

Step 1) Update your modprobe.conf
  vim /etc/modprobe.conf

Step 2) regenerate your initrd.img
  /sbin/new-kernel-pkg --package kernel --mkinitrd --depmod --install 2.6.23.1-2.art 

Step 3) Set the kernel to boot into your DEFAULT OS KERNEL. NOT THE ASL KERNEL. This is defined by the "default=" value, starting at 0 for the first position. This will set the system to fail "safe" back into the working kernel, without requiring you to power cycle or otherwise cold boot the system if there is a problem.

  vim /etc/grub.conf

example:

 # grub.conf generated by anaconda
 #
 # Note that you do not have to rerun grub after making changes to this file
 # NOTICE:  You have a /boot partition.  This means that
 #          all kernel and initrd paths are relative to /boot/, eg.
 #          root (hd0,0)
 #          kernel /vmlinuz-version ro root=/dev/md0
 #          initrd /initrd-version.img
 #boot=/dev/sda1
 default=1
 timeout=5
 serial --unit=0 --speed=57600
 terminal --timeout=5 serial console
 title CentOS (2.6.23.1-3.art)
        root (hd0,0)
        kernel /vmlinuz-2.6.23.1-3.art ro root=/dev/md0 console=tty0 console=ttyS0,57600n8 selinux=0 noapic
        initrd /initrd-2.6.23.1-3.art.img
 title CentOS (2.6.9-42.0.10.EL)
        root (hd0,0)
        kernel /vmlinuz-2.6.9-42.0.10.EL ro root=/dev/md0 console=tty0 console=ttyS0,57600n8
        initrd /initrd-2.6.9-42.0.10.EL.img



Step 4) Set the "panic" flag on the ASL kernel line

   title CentOS (2.6.23.1-3.art)
        root (hd0,0)
        kernel /vmlinuz-2.6.23.1-3.art ro root=/dev/md0 console=tty0 console=ttyS0,57600n8 selinux=0 panic=5
        initrd /initrd-2.6.23.1-3.art.img
 
Step 5) Set the ASL kernel to boot once, with the grub command

 [root@www2 ~]# grub

 grub> savedefault --default=0 --once
 grub> quit

Step 6) Reboot