Reading a Kernel Dump

If your application crashes with a kernel fault, the output tells you what happened at the time of the crash. Here's a sample:

Shutdown[0,0] S/C/F=11/1/11 C/D=f001517d/f00571ac state(c0)= now lock
QNX Version 6.6.0 Release 2014/02/22-18:29:37EST KSB:fe3f6000
[0]PID-TID= 1-1? P/T FL=00019001/08800000 "proc/boot/procnto-instr"
[0]ASPACE PID=7 PF=00001010 "proc/boot/devb-eide"
x86 context[efffcc28]:
0000: 08088cc8 b0359320 efff2c3c efffcc48 b0357f14 08088d10 efff2c10 000000f8
0020: b0323948 0000001d 00011296 efff2c24 00000099
ff 08 75 0e 8b 02 83 c4 f4 83 c0 08 50 e8 8e f5 fe ff 8b 5d e8 c9 c3 90
55 89
0000:>b0357f14 00000003 08088cc8 b0317d3d b0357f14 b0359320 efff2c6c b033f692
0000: 8088d10 b033f49c efff2c5c b033f678 b0357f14 00000003 00100102 00000003

Here's what each part means:

Signal, code, and fault codes; see these files:
  • signal: /usr/include/signal.h
  • code: /usr/include/sys/siginfo.h
  • fault: /usr/include/sys/fault.h

To find out what happened, search signal.h for the signal code. This tells you the name of the signal. Then, look in siginfo.h for the signal name. In this example, code 11 in signal.h is a SIGSEGV; in siginfo.h, code 1 in the SIGSEGV section is:

SEGV_MAPERR 1  // Address not mapped

See also the entry for siginfo_t in the QNX Neutrino C Library Reference.

Location of the kernel's code and data.
The state of the kernel:
  • now — in the kernel
  • lock — nonpreemptible
  • exit — leaving kernel
  • specret — special return processing
  • any number — the interrupt nesting level.
QNX Version
The version of the OS, followed by the date and time at which it was built.
The kernel stack base.
The process ID and thread ID. On CPU x (think SMP), process y was running thread z when the crash occurred.
Process and thread flags. To find out which flags are set, look in /usr/nto/include/sys/neutrino.h. The process flags are in the form _NTO_PF_*, and the thread flags are in the form _NTO_TF_*.
On CPU x, the address space for process y was active. This line appears only when the process is different from the one in the PID-TID line.
The process flags for the ASPACE PID. In the sample above, devb-eide wasn't running, but its address space was active.
The register set. You can find the list of registers in /usr/nto/include/cpu/context.h, where cpu is the appropriate CPU-specific directory.
The instruction on which the error occurred.
The contents of the stack. The location of the stack pointer is indicated by a greater-than sign (>) in the output; you can use the -S option for procnto to specify how many bytes of data before and after the stack pointer to include in the dump.