Hello,
This patch series adds the notifications of 'trace-started' and
'trace-stopped', which are emitted when
1) trace is started or stopped by commands in GDB,
2) trace is stopped due to some reasons in the remote stub, such as
trace buffer full.
With these notifications, MI front-end can show the status of trace
up to date.
Patch 1/3 is to address #1, adding new MI notifications and
notifying observers when the commands are called. #2 needs more work
here, because GDB doesn't know the trace is stopped in the remote
stub. So we need an async remote notification 'Trace' to tell GDB.
That is what patch 2/3 about. Patch 3/3 is to use this async remote
notification 'Trace' and notify trace_stopped observer.