Re: where is doc for --host option ?

[Allin C. <cot...@wf...>]

On Fri, 8 May 2009, Ethan Merritt wrote:

> On Friday 08 May 2009 15:00:15 Allin Cottrell wrote:
> > plotter does have a point.  I just checked the configure script
> > for my program, gretl, and part of the boiler-plate output from
> > ./configure --help is:
> >
> > System types:
> >   --build=BUILD     configure for building on BUILD [guessed]
> >   --host=HOST       cross-compile to build programs to run on HOST [BUILD]
> >
> > I certainly didn't add that explicitly; it's the output from some
> > standard autoconf macro (not sure which; maybe AC_PROG_CC?).
> > It's a bit surprising that it's not present in gnuplot's
> > "configure --help" output.
>
> I have not done cross-compilation, so take this with a grain of salt,
> but as I read the autoconf man pages, the idea is that if you use one of
> the cross-compilation macros like AC_PROG_CC in the ./configure script
> two things happen.  First, it tests for successful use of the CC=foo
> compiler flags.  Second, if the test succeeds it allows you to define
> conditional code options based on the knowledge that this is a
> cross-compiled build.
>
> So far as I know, the gnuplot source has no conditional code that would
> be triggered by AC_PROG_CC.  So I would have expected that setting
> CC to "--host=arm-linux" explicitly was sufficient; i.e. you wouldn't
> have to do it via the AC_PROG_CC macro.

I think one benefit of using AC_PROG_CC is simply that it displays
help for such compiler-related options in response to configure
--help.

Also -- though I'm on less firm ground here -- it's possible that
autoconf is in some ways cleverer than we think (although
sometimes it can seem inordinately stupid).  That is, using
AC_PROG_CC _may_ cause some things to work out correctly for
cross-compilation without requiring any intervention by the
writer of configure.in or Makefile.*  But, as with your comment,
apply a grain of salt.

Allin Cottrell