jack-audio-connection-kit doesn't really enable shm when with USE=jack-tmpfs, it only sets the default tmpdir, but doesn't switch the enable configure flag. Here is my patch to the ebuild: if use jack-tmpfs; then - myconf="${myconf} --with-default-tmpdir=/dev/shm" + myconf="${myconf} --with-default-tmpdir=/dev/shm --enable-posix-shm" else myconf="${myconf} --with-default-tmpdir=/var/run/jack" fi Reproducible: Always Steps to Reproduce:
Your patch only toggles between the two types of shm. Without your patch Sysmtem V shm is being used. Run jackd and then check /dev/shm, or read the output of ./configure
But I think there where errors, whitout that patch. I'll test that.