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Building RTEMS Canadian Cross
=============================

RTEMS now contains experimental and yet incomplete support for building
it Canadian Cross.

1. Introduction
---------------
If you don't know what Canadian Cross Building means, you probably don't want
to apply it and should consider stop reading here. 

Interested readers might want to read Ian Lance Taylor's article at 
http://www.airs.com/ian/configure for underlaying details and working 
principles.


2. RTEMS
--------
Example: Building RTEMS for sparc-rtems under i386-pc-linux-gnu to be hosted 
on a i386-cygwin platform.

2.1 Required tools
------------------
* A i386-pc-linux-gnu cross sparc-rtems toolchain.
* A i386-pc-linux-gnu cross i386-cygwin toolchain.
* A i386-pc-linux-gnu native toolchain.

We further on assume these to be installed to these locations:
/opt/rtems .. linux cross sparc-rtems toolchain
/opt/cygwin .. linux cross i386-cygwin cross-toolchain
/usr .. linux native toolchain and further tools. 

2.2 Building sparc-rtems
------------------------
The first step is to build RTEMS for sparc-rtems under linux. 

mkdir build
cd build
<path>/rtems/configure [options] \
--target=sparc-rtems \
--prefix=/opt/cygwin/rtems/sparc-rtems
make
make install

This will build a standard sparc-rtems RTEMS and install it to the given 
PREFIX.

2.3 Building i386-cygwin host support
-------------------------------------
The next step is to build RTEMS host support for i386-cygwin.
This basically means to cross-build the host tools contained in RTEMS.

mkdir host
cd host
<path>/rtems/configure [options] \
--target=sparc-rtems \
--build=`<path>/rtems/config.guess` \
--host=i386-cygwin \
--prefix=/opt/cygwin/rtems
make
make install

This will build RTEMS host-tools for i386-cygwin and install it to the given
PREFIX.


3. Known issues
---------------

* At present time, building RTEMS Canadian Cross is known to be immature, and
to require additional work. Do not expect this to work.

* The configure scripts expect to find a native c-compiler called "cc". If
your host doesn't have such a "cc" (e.g. Cygwin) or has a non-functional
"cc" (eg. Solaris) try introducing a symlink <functional-cc> -> cc
(E.g.: ln -s <path-to>/gcc /opt/rtems/bin/cc) and make sure this cc can be
found on $PATH.

* It will *not* work for all BSPs requiring BSP-specific host-tools 
(Unfortunately, this comprizes i386-rtems/pcx86 and all powerpc BSPs).

* Incomplete support for *_FOR_TARGET, *_FOR_HOST, *_FOR_BUILD environment
variables.

* The <toplevel>/make/ directory hierarchy is not treated correctly.