Known differences between dbus1 and kdbus:

- NameAcquired/NameLost is gone entirely on kdbus backends if

libsystemd is used. It is still added in by systemd-bus-proxyd

for old dbus1 clients, and it is available if libsystemd is used

against the classic dbus1 daemon. If you want to write compatible

code with libsystem-bus you need to explicitly subscribe to

NameOwnerChanged signals and just ignore NameAcquired/NameLost

- Applications have to deal with spurious signals they didn't expect,

due to the probabilistic bloom filters. They need to handle this

anyway, given that any client can send anything to arbitrary clients

anyway, even in dbus1, so not much changes.

- clients of the system bus when kdbus is used must roll their own

security. Only legacy dbus1 clients get the old XML policy enforced,

which is implemented by systemd-bus-proxyd.

- Serial numbers of synthesized messages are always (uint32_t) -1.

- NameOwnerChanged is a synthetic message, generated locally and not

by the driver. On dbus1 only the Disconnected message was

synthesized like this.

- There's no standard per-session bus anymore. Only a per-user bus.