> -----Original Message-----
> From: python-dev-bounces+mhammond=
keypoint.com.au@python.org
> [mailto:
python-dev-bounces+mhammond=keypoint.com.au@python.org] On
> Behalf Of Mark Hammond
> Sent: Tuesday, 22 January 2008 9:06 PM
> To: '"Martin v. Löwis"'
> Cc:
distutils-sig@python.org;
python-dev@python.org
> Subject: Re: [Python-Dev] Adventures with x64, VS7 and VS8 on Windows
>
> Hi Martin,
>
> Way back on Monday, 21 May 2007, you wrote:
>
> > This is an issue to be discussed for Python 2.6. I'm personally
> > hesitant to have the "official" build infrastructure deviate
> > from the layout that has been in-use for so many years, as a lot
> > of things depend on it.
> >
> > I don't find the need to have separate object directories convincing:
> > For building the Win32/Win64 binaries, I have separate checkouts
> > *anyway*, since all the add-on libraries would have to support
> > multi-arch builds, but I think they don't.
> ...
> > > * Re the x64 directory used by the PCBuild8 process. IMO, it makes
> > > sense to generate x64 binaries to their own directory - my
> expectation
> > > is that cross-compiling between platforms is a reasonable use-case,
> > > and we should support multiple achitectures for the same compiler
> > > version.
> >
> > See above; I disagree.
>
> [For additional context; the question was regarding where the output
> binaries were created for each platform, and specifically if x64 build
> should use something like 'PCBuild/x64']
>
> I'm bringing this topic up again as I noticed the AMD64 builds for
> Python
> 2.6 create their output in the PCBuild/x64 directory, not directly into
> the
> PCBuild directory. When I raised this with Christian, he also
> expressed a
> desire to be able to cross-compile in the same directory structure and
> was
> unaware of this discussion (but I made him aware of it :)
>
> You made excellent points about how tools currently recognize the
> PCBuild
> directory, and we can't break them, and I agree. I'd like to propose a
> compromise that might be able to keep everyone happy.
>
> The main problem I see with all platforms using 'PCBuild' is that in a
> cross-compilation scenario, it is impossible for the distutils to
> determine
> the location of the correct Python libraries to link with (stuff in its
> own
> PYTHONHOME is no good; it's for the wrong platform). Obviously, we can
> change the distutils so that the location of the correct libraries can
> be
> specified, but that implies all other build systems that currently
> assume
> PCBuild must also change to work in a cross-compilation scenario.
> While
> those external tools *will* work today in a native build on x64,
> eventually
> they may need to be upgraded to deal with cross-compilation - and this
> means
> that all such tools will also be unable to automatically determine the
> location of the libraries. They will all need to take the library dir
> as a
> user-specified option, which seems a pain (eg, buildbots would seem to
> need
> site-specific configuration information to make this work). If
> eventually
> all such tools are likely to upgrade, it would be ideal if we can offer
> them
> a way to upgrade so the correct libraries can be determined
> automatically,
> as they can now for native builds.
>
> My compromise proposal is this: Each platform builds in its own
> directory
> (ie, PCBuild/x86_64, PCBuild/x86). Every single build configuration
> has a
> post-build step that copies the result of the build to the PCBuild
> directory. We then add an option to the distutils so that a cross-
> compile
> platform can be specified and when it is, to use 'PCBuild/{platform}"
> instead of PCBuild, and we encourage other tools to use the same
> directory
> should they want to support "configure-less" cross-compilation (if
> distutils
> on the trunk is not still trying to maintain b/w compat, it should just
> *always* look in PCBuild/{platform}, and I'd suggest py3k not bother
> with
> PCBuild at all; build systems will be touched to upgrade to py3k, so
> that
> change isn't painful. But I digress :)
>
> The main advantage of the compromise is that it allows for the status
> quo to
> remain in place - just continue to use separate source trees for each
> platform, and only ever build a single platform in each tree, and tools
> are
> free to have ways of specifying which directory should be used. The
> official build process need not change. However, it also supports a
> way to
> do cross-compilation in a way that build tools can *automatically*
> locate
> the correct platform's libraries, and this will be particularly useful
> for
> extension authors.
>
> Would something like that be acceptable?
>
> Thanks,
>
> Mark
>
>
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