Linker stage fails with missing reference to _start

RE: Linker stage fails with missing reference to _start

embedded717 — Thu, 22 Jun 2017 22:31:21 GMT

I see

missing reference to _start

error as well and my issue is not the macro expansion. I am really seeing the _start not found.

I do have it crt0.o in the /usr/arm-none-eabi/lib area but how my build does not automatically find it ?

RE: Linker stage fails with missing reference to _start

RK — Mon, 26 Sep 2016 05:41:22 GMT

I use Crossworks, for which I have a personal license which wasn't very expensive (non-commerical). Crossworks can also run in limited size mode for free and Rowley (who make Crossworks) white-box it for Segger where it's called Segger Embedded Studio and is free (for non-commercial use). It's very much the same product simplified so it only supports Segger.

There's a few blog posts on SES, one from the weekend actually. It's been in active development mode so things have been changing, but it's pretty stable now.

If you go to the Blogs section and type 'a week with crossworks' into the search, you'll find the original post I wrote about it a couple of years ago. You have to put a little time into it, new IDEs are always like that, but when you get it, it's very easy to use and the debugging experience is superb.

RE: Linker stage fails with missing reference to _start

Bhaumik — Mon, 26 Sep 2016 05:32:26 GMT

What do you use if not eclipse ? i use mac and I am looking for open source platform (sounds ironic :P).

RE: Linker stage fails with missing reference to _start

RK — Mon, 26 Sep 2016 05:06:02 GMT

nope - don't use eclipse - think it's pretty junky for embedded development for the most part. I'm sure google can help you.

RE: Linker stage fails with missing reference to _start

Bhaumik — Mon, 26 Sep 2016 05:04:25 GMT

Can you explain how to add such rules?

RE: Linker stage fails with missing reference to _start

RK — Sun, 25 Sep 2016 07:18:34 GMT

yes thats the whole point .s files should be compiled WITHOUT the preprocessor, ,S files should have a rule which compiles them WITH the preprocessor. You really want to have two rules, one for each.

RE: Linker stage fails with missing reference to _start

Bhaumik — Sun, 25 Sep 2016 07:11:45 GMT

I actually found the solution: Under your project properties --> C/C++ build -->Settings --> Cross ARM GNU Assembler --> Preprocessor --> Check use preprocessor

This will put everything into perspective and now everything works as expected.

Will give another project a try.

RE: Linker stage fails with missing reference to _start

Bhaumik — Sun, 25 Sep 2016 05:05:34 GMT

Hello RK, Thanks for your response. Your correction are right, I do make my eclipse project compile .s file, by adding the extension as assembly file in my project properties on eclipse. However, your explanation does not help to resolve the issue. It has taken me a week to get this far with SDK v12, in your opinion should i stick with SDK v11?

RE: Linker stage fails with missing reference to _start

RK — Sat, 24 Sep 2016 01:17:07 GMT

You're not reading the error message properly and hence the title of the question is wrong

undefined reference to `__START'

not _start which is defined in crt0.o (not cr0.o) but __START

That shows that the #define in the gcc_startup_nrf52.S file hasn't been expanded in the assembly back to _start, or else you've defined __START as __START which seems unlikely. If you nm the .o file you'll see it needs the symbol __START

and likely this all has something to do with the change from .s to .S files in SDK12, `.S files are supposed to be preprocessed before being assembled but the entire change appears to have borked various things.

I'm actually quite surprised that gcc doesn't complain about the #defines in the .S file if it's not preprocessing it, but it's not.