Re: remote debugging stubs (EXC_BAD_ACCESS)

[Marco Gerards]

Greg Buchholz <sleepingsquirrel@sleepingsquirrel.org> writes:

[...]

> warning: Can't modify tracing state for pid 202: No signal thread

I'm not sure about how signals *exactly* work on the Hurd, but AFAIK
every task is also a server and listens for signal.  If there is no
thread (to listen for signals) you can't send signals to this thread.

> [Switching to thread 202.1]
> (gdb) info threads
> * 1 thread 202.1  0x0808d2dc in mach_msg_trap ()
> (gdb) break diskfs_init_diskfs
> Breakpoint 1 at 0x804b235: file init-init.c,
> (gdb) c
> Continuing.
> 
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> 0x080842ad in _hurd_exit ()

I haven't read its sourcecode, but I assume exit sends a signal to
itself (this is how exit usually works AFAIK).  If there is no signal
thread it can't send a signal to itself :).

So the question is: Why isn't there a signal thread?  I assume glibc
needs to start it if you are interested in debugging this you should
have a look there.

I have just one guess why there is no signal thread; exec wasn't
started yet.  Perhaps this is unrelated, I hope someone with more
knowledge about the Hurd can tell me how this works (Marcus? ;)).

[...]

Thanks,
Marco