Re: [Qemu-devel] What's the intended use of log.h logging? (was: [PATCH 2/3] log: report hmp/qmp command and qmp event)

[Stefan Hajnoczi]

Two useful aspects for observability:

1. Logging

Error messages, rate-limited warnings, and important troubleshooting
information for users.

Audience: Users, system administrators, developers

2. Tracing

Internal state changes and events for performance analysis.

Audience: Developers


DPRINTF() falls under both #1 and #2.  Care needs to be taken to
separate the logging from the tracing when converting DPRINTF().

Side note: we don't have effect "once only" or rate-limiting built into
error_report().  Guest-triggerable errors or warnings should be limited
to prevent log flooding.

It would be nice to unify TCG's "qemu log" and error_report() into a
single logging mechanism that is thread-safe and has rate-limiting.

Stefan