I have updated the post with all the suggestions people replied with except this one, because I don't understand it. How do I allocate memory for addressing it with FS/GS? Isn't FS the register pointing to the TLS area - then how is the FS-based access you propose different from how TLS normally works? Isn't GS used "for something" on x86?.. If you could elaborate on this/show some code I would be very grateful!
Note that my question is about shared libraries. If the thread_local is linked into an executable, I guess you could indeed save the offset somewhere and then add the value of %fs to it, though if this is a way to work around the constructor issue, I prefer to not have a constructor. The question is if this sort of direction can help for thread-local storage allocated by a shared library.
Note that my question is about shared libraries. If the thread_local is linked into an executable, I guess you could indeed save the offset somewhere and then add the value of %fs to it, though if this is a way to work around the constructor issue, I prefer to not have a constructor. The question is if this sort of direction can help for thread-local storage allocated by a shared library.