Entry symbol in binary not found

Hello,

I'm trying to convert a .out file to a .bin file which I can start from u-boot bootloader.

I'm using arm objcopy to generate the binary. The strange thing is that the .bin file is way smaller than the .out file (180kB vs 3,6 MB), which means to me that objcopy strips some sections and further more the entry symbol (as written in the map-file) would lie somewhere after the binary.
How can I either tell objcopy to leave all sections in the .bin file (as starting point) or (for proper setup) find my entry point in the binary and pass it to u-boot?

I played around a bit with a linker script, mapping the entry symbol right at the beginning, but this did not show the desired effect.

Might it be a problem with any linker setting?

Regards,
Rene