Re: where is doc for --host option ?

[Ethan M. <merritt@u.washington.edu>]

On Friday 08 May 2009 15:00:15 Allin Cottrell wrote:
> On Fri, 8 May 2009, Ethan Merritt wrote:
> 
> > On Friday 08 May 2009 10:34:51 pl...@pi... wrote:
> > > HI,
> > >
> > > I'm trying to cross-compile gnuplot for arm.
> > >
> > > I set CC= and CXX= but it got thrown out with a message saying I should
> > > use --host to cross-compile.
> > >
> > > The supposed "complete" list of options in ./configure --help and in
> > > INSTALL does not mention it or cross-compiling at all
> >
> > The --host=arm-linux option is not something that is part of
> > gnuplot, or gnuplot's autoconfigure scripts.  It is an option
> > for the gcc compiler. So you would need to look in the gcc docs.
> > I would guess the best source of help would be an arm-linux
> > forum.
> 
> 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.  

But I haven't tried it.  If someone confirms a benefit of having the
AC_PROG_CC in the configure script, that's certainly fine with me.

I have separately acknowledged that there should probably be a top
level build target that builds only the gnuplot executable.
Is there a standard name for such a target?