message: doc: test: unittest segfault gdb
  Feedback from Jon Atack and Marco Falke.
diff: @@ -74,3 +74,29 @@ start debugging, just like you would with any other program:
  ```bash
  gdb src/test/test_bitcoin
  ```
  +
  +#### Segmentation faults
  +
  +If you hit a segmentation fault during a test run, you can diagnose where the fault
  +is happening by running `gdb ./src/test/test_bitcoin` and then using the `bt` command
  +within gdb.
  +
  +Another tool that can be used to resolve segmentation faults is
  +[valgrind](https://valgrind.org/).
  +
  +If for whatever reason you want to produce a core dump file for this fault, you can do
  +that as well. By default, the boost test runner will intercept system errors and not
  +produce a core file. To bypass this, add `--catch_system_errors=no` to the
  +`test_bitcoin` arguments and ensure that your ulimits are set properly (e.g. `ulimit -c
  +unlimited`).
  +
  +Running the tests and hitting a segmentation fault should now produce a file called `core`
  +(on Linux platforms, the file name will likely depend on the contents of
  +`/proc/sys/kernel/core_pattern`).
  +
  +You can then explore the core dump using
  +``` bash
  +gdb src/test/test_bitcoin core
  +
  +(gbd) bt # produce a backtrace for where a segfault occurred
  +```
  