Crosscompiling C++ Ubuntu / Raspberry Pi

I am using Eclipse IDE to crosscomplie C++ code.

When I croosscompile Linux / Ubuntu C++ code for Raspberry Pi 3B (ARM7) I have no issues with actually running the code  on the target.  It all works as expected. I am using just plain "hello word " as test application. No GPIO on 3B.

When I crosscompile identical test code to run on Raspberry Pi Zero -  ARMv6l. The code compiles and runs doing unexpected things

After some research I realized that my "hello word" code does not have a clue about what the target hardware is!

I have no idea where did the "arm7" come from.

After more search I came to conclusion / recommendation to CHANGE the Eclipse default toolset  to toolset specifically build  for ARM processing.

At present I am looking at this developer.arm.com/.../gnu-rm

I am not sure HOW to implement / add this tool to Eclipse.

Not to confuse the issue - I have also found "/tools"  folder in my OS and not really sure which resource should be used in my IDE and how.

I know I am not using correct terminology  but how does GCC / G++ gets involved with ARM options using --buidl, --host, --target?

Any help / references would be greatly appreciated.

Cheers