Cross-compilers _without_ copying all of include & lib

[Paul Smith]

%% "Kai Ruottu" <karuottu@mbnet.fi> writes:

  kr> Ok, you maybe didn't mean just the symlinking but what on earth is
  kr> so hard in it?

It requires a significant amount of trial and error to figure out what
parts you need to link.  I ended up rebuilding the cross-compiler about
9 times and finally came up with this makefile rule that populates a
"fake" sys-include and lib, then removes the extra stuff at the end.  It
turns out that the gcc build _DOES_ install some compiler-specific
things, like linker scripts, into the lib directory:

  $(extract_image):
	mkdir -p $(TARGINC) $(TARGLIB)
	ln -f -s $(IMAGEHDR)/* $(TARGINC)
	echo $(IMAGEHDR) > $(TARGINC)/COPIED
	ln -f -s $(IMAGELIB)/* $(TARGLIB)
	ln -f -s $(IMAGEUSRLIB)/*.o $(IMAGEUSRLIB)/*.so $(IMAGEUSRLIB)/lib*nonshared* $(TARGLIB)
	echo $(IMAGELIB) > $(TARGLIB)/COPIED
	echo $(IMAGEHDR)/* | sed 's:$(IMAGEHDR):$(TARGINC):g' > $@
	echo $(IMAGELIB)/* | sed 's:$(IMAGELIB):$(TARGLIB):g' >> $@
	echo $(IMAGEUSRLIB)/*.o $(IMAGEUSRLIB)/*.so $(IMAGEUSRLIB)/lib*nonshared* | sed 's:$(IMAGEUSRLIB):$(TARGLIB):g' >> $@

  # Clean up the crap we had to install
  $(postinst_image):
	rm -f `cat $(extract_image)`


Where TARGINC is the target sys-include, TARGLIB is the target lib,
and IMAGEHDR, IMAGELIB, and IMAGEUSRLIB are the include, lib, and
usr/lib directories in the root fs image, respectively.

  kr> Just never use the '--with-headers=' and '--with-libs' again!

So, how does one tell the cross-compiler build where to find the target
headers and libraries, without using those flags?

  kr> The '$prefix/$target/include' is AFAIK the de-facto standard place
  kr> for the target headers.

I don't want that either.  I don't want any part of the target system
_AT ALL_ installed into $prefix: not the target headers and not the
target libraries.

I will have a _SEPARATE_ directory structure that contains, as I said, a
complete filesystem image of the entire target system.  This will be
available to me both when I build the cross-compiler _AND_ when I'm
compiling my code using that cross-compiler.  Why should I have all that
content copied into two places?  That's just a huge headache in a
maintenance sense, not to mention a waste of resources.

  kr> By opinion is that the extra libraries, libiberty, libstdc++,
  kr> libffi,... whatever there are, belong to the specific
  kr> target/GCC-version, not only to the specific target!

So, use the --enable-version-specific-runtime-libs flag when you
configure GCC.  Where's the problem with that?

  kr> So putting them into the '$prefix/$target/lib' and maybe
  kr> overwriting the previous GCC install stuff there, is seriously
  kr> wrong.

That's not where they get put anyway: they go under $prefix/lib
somewhere not $prefix/$target/lib.

-- 
-------------------------------------------------------------------------------
 Paul D. Smith <psmith@nortelnetworks.com>   HASMAT--HA Software Mthds & Tools
 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist
-------------------------------------------------------------------------------
   These are my opinions---Nortel Networks takes no responsibility for them.

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