Running without Python

Running without Python

[Paul Smith]

I had a naive hope that if I built my own GDB (7.6) with Python support,
then I needed to copy it to another system to do some debugging (because
my code is compiled with GCC 4.8.1 and the other system doesn't have a
new-enough GDB to debug the new object file format) where that other
system didn't have an appropriate Python, that my GDB would still work.

Like, GDB would try to dlopen() the Python library, discover it wasn't
available, shrug, and continue on letting me debug using "classic"
commands with just some minor grumbling.

But, it pretty much just stops:

  $ my-gdb
  Could not find platform independent libraries <prefix>
  Could not find platform dependent libraries <exec_prefix>
  Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
  ImportError: No module named site
  $

Any thoughts about this?  I guess I need to build GDB twice, once with
Python for those systems that can use it and once without for those
systems that don't have it.  Is there any interest in making this work
"better"?

Cheers!

Re: Running without Python

[Tom Tromey]

>>>>> "Paul" == Paul Smith <psmith@gnu.org> writes:

Paul> But, it pretty much just stops:
Paul>   $ my-gdb
Paul>   Could not find platform independent libraries <prefix>
Paul>   Could not find platform dependent libraries <exec_prefix>
Paul>   Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
Paul>   ImportError: No module named site
Paul>   $

Paul> Any thoughts about this?  I guess I need to build GDB twice, once with
Paul> Python for those systems that can use it and once without for those
Paul> systems that don't have it.  Is there any interest in making this work
Paul> "better"?

This should be better in a more recent gdb.  Please try git master.
We've made it so that if Python initialization fails, then gdb still
works but disables all the Python functionality.

However, we haven't done the dlopen thing.  It's been discussed but I
think it is difficult to do sanely, and especially difficult to do in a
way that handles differences between versions of libpython.

Tom

Re: Running without Python

[Paul Smith]

On Mon, 2013-10-28 at 14:53 -0600, Tom Tromey wrote:
> >>>>> "Paul" == Paul Smith <psmith@gnu.org> writes:
> 
> Paul> But, it pretty much just stops:
> Paul>   $ my-gdb
> Paul>   Could not find platform independent libraries <prefix>
> Paul>   Could not find platform dependent libraries <exec_prefix>
> Paul>   Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
> Paul>   ImportError: No module named site
> Paul>   $
> 
> Paul> Any thoughts about this?  I guess I need to build GDB twice, once with
> Paul> Python for those systems that can use it and once without for those
> Paul> systems that don't have it.  Is there any interest in making this work
> Paul> "better"?
> 
> This should be better in a more recent gdb.  Please try git master.
> We've made it so that if Python initialization fails, then gdb still
> works but disables all the Python functionality.

Is this in 7.6.1, or just master?

> However, we haven't done the dlopen thing.  It's been discussed but I
> think it is difficult to do sanely, and especially difficult to do in a
> way that handles differences between versions of libpython.

That's OK with me, actually, because I've linked python statically so I
don't have to worry about it.  It's just the support .py stuff that's
missing when I copy GDB around.

Cheers!

Re: Running without Python

[Tom Tromey]

>> This should be better in a more recent gdb.  Please try git master.
>> We've made it so that if Python initialization fails, then gdb still
>> works but disables all the Python functionality.

Paul> Is this in 7.6.1, or just master?

Just master.

Tom