Issues with static libraries

[franky47]

Hello,

I'm trying to add LUFA to a firmware that is built using several modules, each built in a separate static library, and linked together to produce the final elf file, but I encounter a link error with CALLBACK_USB_GetDescriptor. In order to keep it simple, I tried to replicate the project's structure using the ClassDriver MIDI Device demo in your repository, using my build system (based on CMake).

The whole project looks like this:

• LUFA, where only the sources from LUFA/Drivers/USB are compiled.
• lufa-demo-core, which contains the Descriptors and MIDI files from the demo, with the following modifications:
  • The main function has been removed from MIDI.c, and its contents have been spread out to two functions, init and process (one to be called before the loop, and the other one within).
  • The appropriate declarations for init and process have been added in MIDI.h
• lufa-demo-firmware, which contains a single main.c file, implementing the main function calling init and process as described.

LUFA and lufa-demo-core each compile to liblufa.a and liblufa-demo-core.a, C static libraries.

lufa-demo-firmware links against these static libs to produce the final elf, but fails to find the CALLBACK_USB_GetDescriptor symbol, implemented in Descriptors.c, from its usage in USB_Device_ProcessControlRequest in the file DeviceStandardReq.c.

All LUFA components use the same LUFAConfig.h file (the one from the demo), and the signature for CALLBACK_USB_GetDescriptor matches in both the implementation and the call (so it's not a signature issue).

Please note that when building the demo files as-is in a single executable target, the link step succeeds.

I can't attach archives on GitHub, so here's a link to the modified demo files: https://drive.google.com/file/d/0B7AbgN8zxRh0SmE0UDBoV0dWQTA/view?usp=sharing

More details if it helps:

• Building with avr-gcc 4.8.3 on Mac OS X 10.9.5, avr-libc version 1.8.1
• Building for ATmega32U4 (Arduino Leonardo), 16MHz for both F_CPU & F_USB.

Any insight would be most welcome !

Best regards, Francois.

[franky47]

I just found that if I merge Descriptors and MIDI files together (in the MIDI file), it links alright. That's odd..

[abcminiuser]

Oops. I'm guessing this is now solved (or you've long since given up and decided I was a fool) - please re-open if not and I'll help out ASAP.

[franky47]

Yep my "fix" in the second comment is fine enough for my use. Thanks for a very cool library !