Troubleshooting Core dumps

It is never nice when a project coredumps. With this tool. you might be able to figure out why it core dumps and what you can do about it.

Note that some coredumps are not caused by the Python or C code, but by instability of the microcontroller. For example, supplying not enough power or … will also generate a coredump.

  1. Install the ESP-IDF toolchain. You can find instructions here. If you already built our firmware from source once, you do not need to install the idf again.
  2. This will provide us with a tool called addr2line, which converts the stacktrace addresses to a line number in C sourcecode. From here, we might be able to determine the root cause of the coredump. You can find the tool in ../xtensa-esp32-elf/bin/xtensa-esp32-elf-addr2line.

Note: This is a command line tool only.

  1. Grab the .elf for your firmware version and board type here. From here on, we will call it application.elf

If you do not know your current firmware version, you can check it using:

>>> import os
>>> os.uname()
  1. Wait for your running code to coredump. I attached an example here. We are only interested in the top section.
Guru Meditation Error: Core  0 panic'ed (StoreProhibited). Exception was unhandled.
Core 0 register dump:
PC      : 0x40195846  PS      : 0x00060530  A0      : 0x801952fb  A1      : 0x3ffbaef0  
A2      : 0x00000000  A3      : 0x00000000  A4      : 0x00000005  A5      : 0xffffffff  
A6      : 0x0000336d  A7      : 0x3ffba1c4  A8      : 0x80194d84  A9      : 0x3ffbaeb0  
A10     : 0x00000028  A11     : 0x00000000  A12     : 0x3ffb9f28  A13     : 0x00000000  
A14     : 0x3ffb9f38  A15     : 0x00000001  SAR     : 0x00000000  EXCCAUSE: 0x0000001d  
EXCVADDR: 0x0000002d  LBEG    : 0x40093718  LEND    : 0x40093746  LCOUNT  : 0xffffffff  

ELF file SHA256: 0000000000000000000000000000000000000000000000000000000000000000

Backtrace: 0x40195846:0x3ffbaef0 0x401952f8:0x3ffbaf10 0x40184fe8:0x3ffbaf30

================= CORE DUMP START =================
  1. Navigate terminal to the folder where your application.elf file is located. From there, use the following command. replace [backtrace] with the numbers following the Backtrace: in the coredump.
xtensa-esp32-elf-addr2line -fe [application.elf] [backtrace]

In this case, the backtrace is 0x40195846:0x3ffbaef0 0x401952f8:0x3ffbaf10 0x40184fe8:0x3ffbaf30

  1. The output of this command will give you the files and line numbers of the last ran commands (stack trace), where the last command will have caused the error.

More Advanced
You can also use the xtensa-esp32-elf-gdb tool in the command line, which will return where in the code the processor crashed. You can use:

  • info symbol [PC] (where [PC] is the program counter found in the coredump) to get the section of the line that causes the coredump
  • disassemble [PC] to get the instructions of the specified line in assemble format.