Paolo,
commit 41fc57e44ed64cd4ab5393d83624afd897dabd4f
trace: split trace_init_file out of trace_init_backends
causes hangs for libvirt when checking the daemonized process,
if the qemu was build with trace-backend=simple.
Also calling
qemu-system-s390x -machine accel=kvm -S -no-user-config -nodefaults -nographic
-M none -qmp unix:/var/lib/libvirt/qemu/capabilities.monitor.sock,server,nowait
-pidfile /var/lib/libvirt/qemu/capabilities.pidfile -daemonize
just hangs
without "trace-backend=simple"
things are fine.