3.6. Working with ELDK

After the initial installation is complete, all you have to do to start working with the ELDK is to set and export the CROSS_COMPILE environment variable. Optionally, you may wish to add the bin and usr/bin directories of your ELDK installation to the value of your PATH environment variable. For instance, a sample ELDK installation and usage scenario looks as follows:

     bash$ export CROSS_COMPILE=ppc_4xxFP-

The value of the CROSS_COMPILE variable must correspond to the target CPU family you want the cross tools to work for. Refer to the table below for the supported CROSS_COMPILE variable values:

3.6.A Table of possible values for $CROSS_COMPILE

CROSS_COMPILE Value Predefined Compiler Flag FPU present or not
ppc_4xx- -mcpu=403 No
ppc_4xxFP- -mcpu=405fp Yes
ppc_6xx- -mcpu=603 Yes
ppc_74xx- -mcpu=7400 Yes
ppc_8xx- -mcpu=860 No
ppc_85xx- -mcpu=8540 Yes
ppc64-linux- -mcpu=powerpc64 Yes
TIP For compatibility with older versions of the ELDK and with other toolkits the following values for $CROSS_COMPILE can be used, too: ppc_7xx- and ppc_82xx-. These are synonyms for ppc_6xx.

3.6.1. Switching Between Multiple Installations

No special actions are required from the user to switch between multiple ELDK installations on the same host system. Which ELDK installation is used is determined entirely by the filesystem location of the binary that is being invoked. This approach can be illustrated using the following example.

Assume the directory /work/denx_tools/usr/bin, where the ppc-linux-gcc compiler binary has been installed, is a part of the PATH environment variable. The user types the command as follows:

$ ppc_8xx-gcc -c myfile.c

To load the correct include files, find the correct libraries, spec files, etc., the compiler needs to know the ELDK root directory. The compiler determines this information by analyzing the shell command it was invoked with ( ppc_8xx-gcc - without specifying the explicit path in this example) and, if needed, the value of the PATH environment variable. Thus, the compiler knows that it has been executed from the /work/denx_tools/usr/bin directory.

Then, it knows that the compiler is installed in the usr/bin subdirectory of the root installation directory, so the ELDK, the compiler is a part of, has been installed in the subdirectories of the /work/denx_tools directory. This means that the target include files are in /work/denx_tools/<target_cpu_variant>/usr/include, and so on.

----- Revision r1.14 - 08 Apr 2009 - 13:12 - WolfgangDenk
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