Debugging signal 11

[Lucas Nali de Magalhães]

On Apr 18, 2021, at 4:18 PM, Ian Lepore <ian at freebsd.org> wrote:
> 
> On Sun, 2021-04-18 at 15:53 -0300, Lucas Nali de Magalhães wrote:
>> This also isn't the usual. Debugging a running process is possible but
>> the process you used is the wrong one. Debugging init, OTOH, is a
>> completely different story: init is the first process and is the most
>> important process of any unix. The actual command varies from
>> debugger to debugger but in gdb, "attach pid"  may do the trick for
>> you. You will need to be extra cautious because of you are aiming init.
>> Ideally, init is the process supposed to catch the signals and keep
>> the system running. So a break into it may cause your system to crash.
> 
> Given that it is init that is segfaulting, how to you propose that the
> OP lauch gdb in order to do an attach to init?  In other words: there
> is a reason the OP is trying to use the kernel debugger to examine
> what's going on here.

First the OP was able to modify init. Then it was asked the command
to do a stack trace. Thus the OP clearly hasn't the full knowledge of
the procedure and the risks. Besides this, kgdb is based on gdb. I
thought they should know.

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