title: Debugging kernel panic error
body: <p>I have a arm board on which I am running yocto with kernel 4.1.15. While I am running my python program I get following kernel error frequently but randomly</p>
  
  <pre><code>Unable to handle kernel paging request at virtual address 7f101f7c 
  pgd = 80004000 
  [7f101f7c] *pgd=8c6c4811, *pte=00000000, *ppte=00000000 
  Internal error: Oops: 80000007 [#1] PREEMPT SMP ARM 
  Modules linked in: wilc3000(O) at_pwr_dev(O) pn5xx_i2c [last unloaded: at_pwr_dev] 
  CPU: 0 PID: 1336 Comm: DebugThread Tainted: G O 4.1.15-1.2.0+g77f6154 
  Hardware name: Freescale i.MX6 Ultralite (Device Tree) 
  task: 8c73b900 ti: 8c8d6000 task.ti: 8c8d6000 
  PC is at 0x7f101f7c 
  LR is at _raw_spin_unlock_irqrestore+0x28/0x54 
  pc : [&lt;7f101f7c&gt;] lr : [&lt;807e1238&gt;] psr: 600f0013 
  sp : 8c8d7f30 ip : 00000000 fp : 00000000 
  r10: 7f107d30 r9 : 7f107d20 r8 : 7f107f48 
  r7 : 00000000 r6 : 8c57b000 r5 : 7f107f48 r4 : 8c54aa00 
  r3 : 00000000 r2 : 00000000 r1 : 20000013 r0 : ffffffc2 
  Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel 
  Control: 10c53c7d Table: 8c52c06a DAC: 00000015 
  Process DebugThread (pid: 1336, stack limit = 0x8c8d6210) 
  Stack: (0x8c8d7f30 to 0x8c8d8000) 7f20: 8c8063a0 00000000 8c8d6000 00000000 
  7f40: 00000000 00000000 00000000 8c975c40 8c54aa00 7f101f28 00000000 00000000 
  7f60: 00000000 8004d070 00000000 00000000 7ee95a5c 8c54aa00 00000000 00000000 
  7f80: 8c8d7f80 8c8d7f80 00000000 00000000 8c8d7f90 8c8d7f90 8c8d7fac 8c975c40 
  7fa0: 8004cf94 00000000 00000000 8000f528 00000000 00000000 00000000 00000000 
  7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
  7fe0: 00000000 00000000 00000000 00000000 00000013 00000000 7a9ce301 72611f00 
  [&lt;807e1238&gt;] (_raw_spin_unlock_irqrestore) from [&lt;00000000&gt;] ( (null)) 
  Code: bad PC value
  </code></pre>
  
  <p>How can I debug this error considering the fact that I don't have access to JTAG on this board. What is the meaning of <code>Code: bad PC value</code>? If there any to find anything regarding problem from this log?</p>