Looking in to the build log a little more, it seems that the gcc linker thinks the path to the lwip_lowpan6.o file contains .../lwi-interface... rather than ../lwip-interface/.. as it should be. It is randomly dropping characters from the object paths.

I then found these similar issues online that indicate that its not the linker, but a limitation of the Windows cmd.exe. You cannot pass in more than 8191 characters per command.

1. https://stackoverflow.com/questions/20777521/linker-dropping-characters-on-object-files-passed-into-it
2. http://asf.atmel.com/bugzilla/show_bug.cgi?id=1965

Since the mbed-cli automatically generated makefile linker command has well in excess of 8191 characters with all the mbed-os object files that are being passed in, I'm willing to bet this is the issue.

However, the Windows mbed-cli "compile" command manages to get around this. Presumably because it calls the linker via Python rather than Windows cmd.exe?

Are there any ways around this limitation?

Thanks

Paul

Actually we get around it by placing all of the command line arguments into a file and having the linker read its arguments from that file.

Other things to note: when exporting to GNU ARM Eclipse, mbed CLI and the mbed OS tools do not geterata a Makefile. Instead they generate a GNU ARM Eclipse managed project. The GNU ARM Eclipse plugin is what is generating your makefile here.

I make this distinction because there is another exporter, eclipse_gcc_arm, that exports an unmanaged project. For this exporter mbed CLI and the mbed OS tools generate the Makefile.