[Python-Dev] Using SCons for cross-compilation
chris at kateandchris.net
Thu Nov 9 17:29:37 CET 2006
On Thu, Nov 09, 2006 at 04:42:48PM +0100, David Boddie wrote:
> On Thu Nov 9 07:45:30 CET 2006, Anthony Baxter wrote:
> > On Thursday 09 November 2006 16:30, Martin v. Löwis wrote:
> > > Patch #841454 takes a stab at cross-compilation
> > > (for MingW32 on a Linux system, in this case),
> > > and proposes to use SCons instead of setup.py
> > > to compile extension modules. Usage of SCons
> > > would be restricted to cross-compilation (for
> > > the moment).
> > >
> > > What do you think?
> > So we'd now have 3 places to update when things change (setup.py, PCbuild
> > area, SCons)? How does this deal with the problems that autoconf has with
> > cross-compilation? It would seem to me that just fixing the extension module
> > building is a tiny part of the problem... or am I missing something?
> I've been working on adding cross-compiling support to Python's build system,
> too, though I've had the luxury of building on Linux for a target platform
> that also runs Linux. Since the build system originally came from the GCC
> project, it shouldn't surprise anyone that there's already a certain level
> of support for cross-compilation built in. Simply setting the --build and
> --host options is a good start, for example.
> It seems that Martin's patch solves some problems I encountered more cleanly
> (in certain respects) than the solutions I came up with. Here are some
> issues I encountered (from memory):
> * The current system assumes that Parser/pgen will be built using the
> compiler being used for the rest of the build. This obviously isn't
> going to work when the executable is meant for the target platform.
> At the same time, the object files for pgen need to be compiled for
> the interpreter for the target platform.
> * The newly-compiled interpreter is used to compile the standard library,
> run tests and execute the setup.py file. Some of these things should
> be done by the interpreter, but it won't work on the host platform.
> On the other hand, the setup.py script should be run by the host's
> Python interpreter, but using information about the target interpreter's
> * There are various extensions defined in the setup.py file that are
> found and erroneously included if you execute it using the host's
> interpreter. Ideally, it would be possible to use the target's
> configuration to disable extensions, but a more configurable build
> process would also be welcome.
This pretty much covers the difficulties I encountered. For what it's worth,
my experiences with Python 2.5 are documented here:
I am also interested in pursuing solutions that make it easier to both build
python and third party extensions in cross compile environment.
> I'll try to look at Martin's patch at some point. I hope these observations
> and suggestions help explain the current issues with the build system when
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