Re: cross-compiling philosophy

[Ralf Corsepius]

On Thu, 2003-10-30 at 08:24, Bob Friesenhahn wrote:
> On Wed, 29 Oct 2003, Larry Doolittle wrote:
> 
> > I know this subject keeps coming up.  I hope my
> > suggestions are taken as constructive (presumably
> > for post-2.58).
> >
> > I ran into one more package (GNU screen-3.9.15) where
> > the authors used autoconf, and made no provision for
> > cross-compiling.  In fact, they use many detailed
> > run-time tests.  I was able to edit configure.in
> > to add ACTION-IF-CROSS-COMPILING arguments (tuned to
> > my special case) to their AC_TRY_RUN macros, and got
> > myself on the air.  Not very satisfying.
> >
> > There is an implicit assumption in autoconf that
> > people who cross-compile have no way to run the
> > executables from within the configure script.  So,
> > no provision is made for that possibility.
> 
> There are an infinite number of ways to run executables on a target.

Let me add that there also exists an infinite number of targets where no
possibility exists to run executables as part of autoconf checks.

> How is configure to know how to run executables on a target? Your
> example of a Unix-like system with NFS mounts to the build system is
> the most trivial case.
> 
> One possiblity that comes to mind is to use DejaGNU as the framework
> to execute the program on the target and require the user to write the
> code to download the exectuable to the target and run it.  The user
> would be responsible for writing the bit of Tcl code required to
> interface to the target.
Even if you can manage to get this working, this only helps in cases
where you have physical access to a target. 

In cross-compilation situations however, you often work off-line,
without any physical access to the target hardware.

Ralf