As it turns out, with HAVE_THREAD_LOCAL_VARIABLE defined, you end up with a g2c binary that doesn't run: fn@lunix:~/goo-0_155-any-dev$ c/g2c/g2c c/g2c/g2c: relocation error: c/g2c/g2c: undefined symbol: tregs fn@lunix:~/goo-0_155-any-dev$ Unfortunately, I don't have a fix for this...