title: Kdump can't reboot using 'echo c > /proc/sysrq-trigger'
body: <p>I can reload kernel by using 'kexec -e', that means the configuration of my kernel should be correct. However the kernel can't automatically reboot after crashes. The output of command 'kdump-config show' shows the environment is correct.</p>
  
  <pre><code>RAMDISK$ kdump-config show
  USE_KDUMP:        1
  KDUMP_SYSCTL:     kernel.panic_on_oops=1
  KDUMP_COREDIR:    /var/crash
  crashkernel addr: 0xf000000
  current state:    ready to kdump
  
  kernel link: 
  
  kexec command:
    /sbin/kexec -p --command-line="BOOT_IMAGE=/boot/vmlinuz-3.2.1 root=UUID=4989514c-5622-4cd7-9b75-f0e07f7c6f84 ro initrd=/install/initrd.gz quiet kgdboc=ttyS0,115200 irqpoll maxcpus=1 nousb" --initrd=/boot/initrd.img-3.2.1 /boot/vmlinuz-3.2.1
  RAMDISK$ 
  RAMDISK$ cat /proc/cmdline 
  BOOT_IMAGE=/boot/vmlinuz-3.2.1 root=UUID=4989514c-5622-4cd7-9b75-f0e07f7c6f84 ro initrd=/install/initrd.gz crashkernel=256M quiet kgdboc=ttyS0,115200
  RAMDISK$
  </code></pre>
  
  <p>The original kernel 3.2.0-4-amd64 build-in by debian 7.9 can work with kdump without any problem. 
  Can anyone figure out what's wrong to my kernel, or the error log when kdump is working?</p>