Set up a cross compilation toolchain

How to set up a cross compilation toolchain for the Zaurus

Example with the ZEthereal crosscompilation

First read this : Linux Compiler Setup HowTo
Then you can download and install provided RPMs. If you prefer debian packages : use the following source
```
deb http://emdebian.sourceforge.net/emdebian unstable main
```
and install the task-cross-arm task package (if it does not work, read this first). You should then look into /usr/ instead of /opt/Embedix/tools/. Also note that some of what I say latter might not be true for debian packages.
We now have /opt/Embedix/tools/ directory. In the bin/ and lib/, we have gcc cross compilation stuffs. In arm-linux/, we have a whole root file system with libraries, includes, etc. for the ARM architecture. In arm-linux/bin/, we'll find cross compilation tools (links to the gcc stuff), i.e. that work on i386, but produce output for ARM. They are configured to look for includes in /opt/Embedix/tools/arm-linux/include, to link against /opt/Embedix/tools/arm-linux/lib, etc. Now, we will have to cross compile every library we need with these tools and install it in this ARM root file system.

To begin easy : cross compilation and installation of zlib :

wget http://www.gzip.org/zlib/zlib-1.1.4.tar.gz
tar zxf zlib-1.1.4.tar.gz
cd zlib-1.1.4
OPATH=$PATH
export PATH=/opt/Embedix/tools/arm-linux/bin:$PATH

Now, gcc, ld, ar and other tools will be those that output for ARM architecture.
The library will be configured to be installed in our ARM root fs.

./configure --prefix=/opt/Embedix/tools/arm-linux/
make
make install
export PATH=$OPATH

That's it.

More tricky : libpcap. This time the configure script is an autoconf one.
The official way to do that (since autoconf 2.5) is to provide build arch and host (target) arch, like this :
```
./configure --build=i686-pc-linux-gnu --host=armv4l-unknown-linux-gnu
```
But this will work only if the configure script has been designed to cope with cross compilation. Here, it's not the case, so we'll have to hide the cross compilation to it, changing the compiler without informing configure.
Update: use the debian-patched source (apt-get source libpcap) to have a shared library
```
wget http://www.tcpdump.org/release/libpcap-0.7.1.tar.gz
wget http://www.tcpdump.org/release/libpcap-0.7.1.tar.gz.pgp
gpg --verify libpcap-0.7.1.tar.gz.pgp
tar zxf libpcap-0.7.1.tar.gz 
cd libpcap-0.7.1
```
Nothing new until here. The configure script will need to know a lot about the target architecture. It will see that we are using a cross compiler and it won't probe the local host because it is not the target host. Thus, we must provide some additionnal informations. Moreover, the libpcap configure script is not ready to be used for cross compilation. Indeed, nothing is done to provide the target kernel version, and the configure script ends saying it can't determine it.
Let assume your target kernel version is ok and shunt the test providing directly a working value (that's a dirty hack. I'll do a real patch later).
```
--- configure.in~       2001-12-10 09:33:42.000000000 +0100
+++ configure.in        2002-12-27 16:00:47.000000000 +0100
@@ -133,7 +133,7 @@
        AC_MSG_CHECKING(Linux kernel version)
        if test "$cross_compiling" = yes; then
                AC_CACHE_VAL(ac_cv_linux_vers,
-                   ac_cv_linux_vers=unknown)
+                   ac_cv_linux_vers=2)
        else
                AC_CACHE_VAL(ac_cv_linux_vers,
                    ac_cv_linux_vers=`uname -r 2>&1 | \
```
Let's patch configure.in
```
patch
(cut the diff and paste here)
^D
```
Now, we can regenerate the configure script and carry on.
```
autoconf
OPATH=$PATH
export PATH=/opt/Embedix/tools/arm-linux/bin:$PATH
./configure --prefix=/opt/Embedix/tools/arm-linux/ --host=armv4l-unknown-linux-gnu --with-pcap=linux
make
make install
export PATH=$OPATH
```
Done.

Even more dirty : glib. Note that we configure it for a i386 and then make it for the ARM. There were too many things to change in the configure.in file. Happily, i386 and ARM are both little endian :).

wget ftp://ftp.gtk.org/pub/gtk/v1.2/glib-1.2.10.tar.gz
tar zxf glib-1.2.10.tar.gz
cd glib-1.2.10
./configure --prefix=/opt/Embedix/tools/arm-linux/ 
OPATH=$PATH
export PATH=/opt/Embedix/tools/arm-linux/bin:$PATH
make
make install
export PATH=$OPATH

ZEthereal
Let's download the Ethereal-0.9.5 source and cross-compile its objects and libs :

wget http://www.secdev.org/zaurus/ethereal-0.9.5.tar.gz
tar zxf ethereal-0.9.5.tar.gz
cd ethereal-0.9.5
gcc -o rdps rdps.c # this small program is used during the build process. Do not cross-compile!
OPATH=$PATH
export PATH=/opt/Embedix/tools/arm-linux/bin:$PATH
./configure --disable-ethereal --without-ucdsnmp -without-ssl --host=armv4l-unknown-linux-gnu
make

Now, we download zethereal sources in ethereal sources directory, make a big lib with ethereal objects, compile zethereal and link it against the big lib.

wget http://www.secdev.org/zaurus/zethereal-1.0.tar.gz
tar zxf zethereal-1.0.tar.gz
cd qtopia
./mklibzethereal
tmake zethereal.pro > Makefile 
make

That's it!