2011/5/14 Doug Evans <d...@google.com>: > On Sat, May 14, 2011 at 2:09 AM, Ruben Van Boxem > <vanboxem.ru...@gmail.com> wrote: >> 2011/5/14 Doug Evans <d...@google.com>: >>> On Thu, May 12, 2011 at 9:19 AM, Ruben Van Boxem >>> <vanboxem.ru...@gmail.com> wrote: >>>> (now in plain-text as required by gdb mailing list) >>>> >>>> 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. >>> >>> In a properly configured/built gdb on linux this isn't necessary, even >>> if python is installed in some random place. >>> I'm not sure about windows though. >>> Did you specify --with-python when you configured gdb, and if so did >>> you specify a value? >>> e.g., --with-python=SOME_VALUE >> >> I was cross-compiling a mingw toolchain+gdb from Linux, so I used >> --with-python without a value (because gdb configure tries to find the >> Python executabe), and I added -I"/path/to/python/includes" to CFLAGS >> and -L"/path/to/pythondll/importlib" to LDFLAGS, which built as it >> should. This is hacky though, and gdb configure should provide >> --with-python-libs and --with-python-include to make it more >> streamlined with any other build prerequisite (like >> gmp/mpfr/mpc/cloog/ppl in GCC for example). > > Ah. > Cross-compiling gdb with python is in need of improvement. > Alas python hasn't been designed with cross-compilation in mind (e.g. > build on linux, run on windows). > AIUI, the way to get the parameters required for compiling with > libpython is to get them from python's "distutils": kinda hard to do > in a cross-compile. Done correctly there's no need to run python. > > I haven't done anything more to support python in gdb's configure.ac > because it's not clear to me what the right thing to do is: distutils > provides more than just --libs and --includes (btw, we don't use > --libs though, we use --ldflags which includes all of: the directory > in which to find libpython, the -l for libpython, and the -l's for all > the other libraries python needs). [Which isn't to say that someone > else isn't free to tackle this.] > > In the meantime, what I've been doing is a hack: write a script that > responds to: > --includes > --ldflags > --exec-prefix > and pass that as --with-python. > > E.g. > bash$ cat $HOME/my-python-for-config > #! /bin/sh > > if [ $# -ne 2 ] > then > echo "Bad # args. Blech!" >&2 > exit 1 > fi > > # The first argument is the path to python-config.py, ignore it. > > case "$2" in > --includes) echo "-I/usr/include/python2.6 -I/usr/include/python2.6" ;; > --ldflags) echo "-L/usr/lib/python2.6/config -lpthread -ldl -lutil -lm > -lpython2.6" ;; > --exec-prefix) echo "/usr" ;; > *) echo "Bad arg $2. Blech!" >&2 ; exit 1 ;; > esac > > exit 0 > bash$ ./configure --with-python=$HOME/my-python-for-config [...] > [...] > > > Note that --exec-prefix is the runtime location of python. > GCC uses this to tell libpython where to find its support files. > [grep for Py_SetProgramName in gdb/python/python.c]
OK, I tried your script in a couple of variations. It gets rid of the traceback I had before, but still doesn't help the PYTHONPATH problem. My directory structure is as follows (this is not in root, "/" is just my main build directory, there are several levels below it): /gdb <-- gdb build dir /gdb/gdb <-- where the python configuration is done /python <-- temporary install dir for python files for build, extracted from the official Windows installer, also location of libpython2.7.a import library /python/include/python27 <-- python headers, found by gdb in both cases /mingw64 <-- toolchain sysroot prefix /mingw64/bin <-- install location of gdb and python27.dll /mingw64/lib/python27 <-- install location of all python scripts First variant: --includes) echo "-I../../python/include" ;; --ldflags) echo "-L../../python -lpython2.7" ;; --exec-prefix) echo "../../mingw64/lib/python27" ;; Here exec-prefix would be the relative path from where "configure" does its magic to the final location of the scripts on the build system. Second variant: --includes) echo "-I../../python/include" ;; --ldflags) echo "-L../../python -lpython2.7" ;; --exec-prefix) echo "../lib/python27" ;; I thought the second points gdb to the installed location of the python scripts, but it still needed PYTHONPATH for that. I used relative paths in an attempt to "do the right thing", hackwise... Remember that the whole "/mingw64" directory gets zipped and moved, then it gets extracted to a random location in the Windows filesystem. Thanks for the help so far, I think we might just get this worked out together. Ruben > >>>> 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. >>>> [...] >>> >>> Yeah. >>> There is a proposal to add GDB_PYTHONPATH (or some such IIRC) and have >>> gdb use that instead of PYTHONPATH if it exists, but there's been >>> resistance to it. >>> I think(!) what would happen is that gdb would set $PYTHONPATH to the >>> value of $GDB_PYTHONPATH. >>> [Inferiors started by gdb should still get the original value of >>> PYTHONPATH though.] >> >> That way would be almost ideal, but a hardcoded *relative* path to the >> python scripts (that is standardized within gdb) wouldn't hurt. > > See above re: --exec-prefix. > >> An >> extra environment variable would require a lot of explaining for >> Windows, and is not "plug-and-play", like the rest of a sysrooted >> toolchain is supposed to be like. I think this should work on all >> setups: >> >> 1. Check hardcoded path; my suggestion would be "<gdb >> executable>/../lib/python27" >> 2. If this fails to find the necessary files/scripts, find it like you >> described above in Linux, without PYTHONPATH set. >> 3. Check PYTHONPATH. > > The problem being solved by the proposed GDB_PYTHONPATH is "What if > the user has PYTHONPATH set and it points to an incompatible version > of python?". > Leaving such a value for PYTHONPATH set while gdb's python is running > feels wrong (and IIRC has caused some problems). > > The problem of telling python where to find itself is already solved > (or at least is intended to be solved) with gdb's calling > Py_SetProgramName with a value derived from the python-provided > --exec-prefix. > >> I would think only number one would change, and perhaps be only >> enabled with a special configure option. Nothing else would have to >> change, and Windows users would rejoice :) >> Again, this is only my suggestion, if there are problems with it in >> way I haven't thought of, please say so, and we can come up with >> another solution. > -- http://mail.python.org/mailman/listinfo/python-list