https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100748
--- Comment #4 from Jeffrey A. Law <law at gcc dot gnu.org> --- Bernd E. analyzed this in the thread referenced in c#1. The test links staticly and we're pulling in the weak definition of pthread_join. I'm not sure why we're linking statically. Reverting to normal dynamic linking would likely fix this problem. If that's not desired, then something like --whole-archive -lpthread --no-whole-archive in the link line will make this work as long as it appears before -lc. Or we could add -Wl,-u,pthread_join to the link line. Or we could hack up the source per Bernd's patch in that thread. No strong opinions here. Just trying to get another failure resolved on our target :-)