Of you course you'll need to have a good understanding of the USB concepts, but FreeBSD's USBDI API is well documented and there are many existing drivers that can be taken as examples.

I suppose this would require some effort. And for example I don't understand why _LIB_VERSION would require nl_relocdata, so identifying what needs to be patched isn't clear to me.

I'd prefer that both of you contribute to find out the root cause of the issue.
atiatinini, if you are trying to port SDL programs, you'll probably encounter other conflicts more difficult to identify and work around.

What doesn't make any sense is the size improvement induced by -O3 compared to -Os.

About the freeze at boot time for OS 3.1:
Ndless installs itself in the OS image of the calculator with hard-coded addresses. This OS image will also be read by the hot-run OS at boot time: this will trigger the Ndless hooks, but with a version mismatch.
But it appears it isn't the only issue which avoids booting OS 3.1.

Not all global variables need a special treatment, only those containing string constants and reference to other global elements. nl_relocdata() is documented on Hackspire.
Consider this as a limitation of GCC and not Ndless. GCC doesn't emit relocation information for these variables as it should, and I see no good reason for this.

I think I'll give up with this project, since TI blocked ndless
It would be useless to spend time for this if nobody will use it...
Sorry.

Why can't TI understand that it won't annoy them to allow 3rd party native code ?

Chockosta, please think twice before making such a decision:

 * TI blocking Ndless is not new. Even Ndless v1.1 relied on half a dozen flaws that were all fixed in the next release. Adriweb's exchange with Melendy doesn't tell us much except that they are keeping their initial strategy. Nothing surprising.
 * There have been an update of Ndless for nearly every OS version released by TI. I see no reason why there wouldn't be one for v3.2.
 * I'm really sorry for the delay of Ndless v3.1 release, caused by different reasons (personal issues, wrong initial design choices and CX compatibility). Updating Ndless is a community effort, the more people behind it the faster the releases are updated. Ndless is Open Source for this reason. Don't hesitate to share suggestions or patches if you have any ideas.

The maintenance of Ndless and its SDK directly depends on how it is used by developers. I'll personaly stop any work if Ndless isn't used anymore. So please don't make the community collapse from within and keep up the good work!