This is actually a bug in mesa. See https://bugs.freedesktop.org/show_bug.cgi?id=107012 .
- Bug#902247: glxgears crashes with SIGSEGV on ppc64el with ... Timothy Pearson
- Bug#902247: Acknowledgement (glxgears crashes with SI... Timothy Pearson
This is actually a bug in mesa. See https://bugs.freedesktop.org/show_bug.cgi?id=107012 .