cross compiling thoughts

[Jim Wilson]

Axel Scheepers wrote:
> The above procedure produces a nice set of cross compiling tools to 
> build c and c++ sources. But... I was wondering if this was the right 
> way to do it; This time I could easily get the needed includes and libs 
> from the freebsd target host, but what if I wanted to use a platform 
> which I didn't have access too?

There is a good reference on cross compilers builds at
	http://www.kegel.com/crosstool
It mostly concerns building linux crosses.

If you already have libraries and header files, then you can tell gcc to 
use them.  The old scheme is to use --with-headers=/--with-libs= options 
to point to the targets headers and libraries.  The new scheme is to use 
--with-sys-root= which points to a file system root for the target. 
This allows support for targets with headers/libraries in multiple 
directories.

If you don't already have libraries and header files, then you have to 
build them in parallel with gcc somehow.  This can be a bit complicated 
for glibc.  The kegel.com site has info on a good way to do it.  For 
other targets, like freebsd, you would have to work up a similar procedure.

> I did some googling, and it seems there is also a 'newlib'. Is this 
> compatible with glibc? e.g. Can I cross build files for a host which 
> only has glibc? Never had a look at it, I should.

newlib was designed for embedded targets which have no library of their 
own.  It is unlikely that you would want to use newlib for any unix like 
OS.  newlib does build fairly easily in parallel with gcc.
-- 
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com