I'm new to trying to use qemu+bt (via btproxy) and haven't managed to get anything working.
btproxy is launched first, then Zephyr launches qemu via it's west tool. The commands look like:
sudo tools/btproxy -u -i 0 -d # in a separate window
x86_64-pokysdk-linux/usr/bin/qemu-system-aarch64 -cpu cortex-a53 -nographic -machine virt -
net none -pidfile qemu.pid -chardev stdio,id=con,mux=on -serial chardev:con -mon chardev=con,mode=readline -serial unix:/tmp/bt-server-bredr -kernel /home/dchristian/share-fb/zephyrproject/zephy
r/build/zephyr/zephyr.elf
It's failing with a device busy when btproxy tries to bind to the adapter. I don't think this is a quemu issue.
Zephyr packages it's own qemu: QEMU emulator version 4.2.0 (v4.2.0-dirty)