Using avr-gcc and attempting to reduce size of binary using -ffunction-sections and -fdata-sections when compiling and linking with --gc-sections. The .lds file contains nothing:

SECTIONS { }

This error occurs when partial linking many .o's into a .a, which will then be used later to complete the build.

I've read through some other posts that discuss these options, but nothing that clarifies the ENTRY() issue. Their doesn't seem to be a need for it at the partial stage before trying to reduce code size(pre-existing linker script clearly doesn't use it).

Documentation states : --gc-sectionts

"This option can be set when doing a partial link (enabled with option '-r'). In this case the root of symbols kept must be explicitly specified either by an '--entry' or `--undefined' option or by a ENTRY command in the linker script."

This is where I'm lost. Would greatly appreciate some more explanation of how to use --undefined, --entry, or ENTRY cmd in linker script to resolve this issue.