Thanks a lot to all for your answers and that you want to help me.
But I have difficulties to understand what you mean, because I'm an absolute beginner on Linux and on cross-compiling.
I'd recommend using a separate fpc.cfg and a completely separate directory structure independent from the installed OS that contains the libraries you need for cross-compilation.
I thought I did this by using fpcupdeluxe to create a separate Lazarus installation with its own fpc.cfg and its own library folder <install_folder>/cross/lib/i386-linux/
What else must I do?
In setup+ , you can choose your os and cpu in "Custom tools location ..."
And enter your location where to find the bins and the libs.
In setup+ , I first set "Search options" to custom and then enter the lib-Path in "Libraries" and the bin-Path in "Tools"?
But which lib-Path must I use? You recommended /lib32, but WayneSherman wrote that they are in /lib/i386-linux-gnu and /usr/lib/i386-linux-gnu. What must I use?
And which bin-Path must I use? I don't know it. Please, how can I find this out?
Sorry, that for me things are very difficult because everything is new and unknown for me.
Thanks again for your help.