we don't need to support format command for PT ctrl as we don't support other commands such create_sq/cq.I don't understand why we don't limit a regular ctrl to single access and we do it for the PT ctrl.
I guess the block layer helps to sync between multiple access in parallel but we can do it as well.
Also, let's say you limit the access to this subsystem to 1 user, the bdev is still accessibly for local user and also you can create a different subsystem that will use this device (PT and non-PT ctrl).
can you explain the trouble you meant and how this limitation solve it ?
Its different to emulate the controller with all its admin
commands vs. passing it through to the nvme device.. (think of format nvm)