Python enabled gdb on Windows and relocation

[Ruben Van Boxem]

Hi,

I am currently trying to integrate Python support into my toolchain build
(including GDB of course). It is a sysrooted binutils+GCC+GDB+mingw-w64
toolchain.

I currently have the basic setup working: I can link gdb with my manually
generated import lib to the python dll from the official Windows install. If
there is anything I am missing or a very easy solution to the problems
decsribed below, please just say so. I am only suggesting what I would like
to happen.

Now on to the problems I'd like to discuss:

1. gdb.exe won't start without me having set PYTHONPATH manually. I
understand the need for this, but as gdb requires Python 2, and users of my
toolchain may have installed Python 3 or a 32-bit version python they want
to use from the same environment (without changing their own PYTHONPATH),
there is no way to run python-enabled gdb. What I suggest is perhaps a
Windows only change: a kind of "sysroot"ed gdb+python, so that the python
used by gdb is truly built in. I cannot require everyone using my toolchain
to install the correct python version for obvious reasons (Windows != Linux
in this regard). However way this is tackled, the gdb I want should look
relative to it's current (relocatable) directory for Python modules/*;py
files in a well-defined directory at build time. That would allow me to
distribute gdb in a very clear way:

<sysroot>
<sysroot>/bin
<sysroot>/bin/python27.dll
<sysroot>/bin/gdb.exe
<sysroot>/lib
<sysroot>/lib/python27
<sysroot>/lib/python27/<all *.py files from the official windows install>

Currently, this scheme only works if I manually set the PYTHONPATH
environment variable to <root>/lib/python27. This global environment
variable could conflict with existing Python installations, that may have
another bitness (I have 64- and 32-bit toolchains). I think you can see
there are problems enough with the current set up. I also read this old
discussion: http://comments.gmane.org/gmane.comp.gdb.patches/62811 that
might imply that the PYTHONPATH check is something built-in to the python
dll. Can anyone shed some light on this?

2. With PYTHONPATH set as a temporary workaround, gdb starts, but spits out
a traceback:
Traceback (most recent call last):
  File "<string>", line 35, in <module>
  File "m:\development\mingw64\share\gdb/python/gdb/__init__.py", line 18,
in <module>
    gdb.command.pretty_printers.register_pretty_printer_commands()
  File
"m:\development\mingw64\share\gdb/python/gdb\command\pretty_printers.py",
line 368, in register_pretty_printer_commands
    InfoPrettyPrinter()
  File
"m:\development\mingw64\share\gdb/python/gdb\command\pretty_printers.py",
line 100, in __init__
    gdb.COMMAND_DATA)
RuntimeError: Could not find command prefix info.

This is a minor problem I think, as "python import time" "python print
time.clock()" works as expected. What is wrong?

Thanks very much!

Ruben

PS: I've sent this to both the gdb and python mailing lists, as these issues
have a large overlap to both projects.
PS2: Please reply-to-all as I do not want daily mails from both mailing
lists on every issue brought up there. My apologies.
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