| 1 | --- |
| 2 | id: domain |
| 3 | --- |
| 4 | |
| 5 | A tracing _domain_ is the official term the LTTng project uses to |
| 6 | designate a tracer category. |
| 7 | |
| 8 | There are currently three known domains: |
| 9 | |
| 10 | * Linux kernel |
| 11 | * user space |
| 12 | * Java Util Logging (JUL) |
| 13 | |
| 14 | Different tracers expose common features in their own interfaces, but, |
| 15 | from a user's perspective, you still need to target a specific type of |
| 16 | tracer to perform some actions. For example, since both kernel and user |
| 17 | space tracers support named tracepoints (probes manually inserted in |
| 18 | source code), you need to specify which one is concerned when enabling |
| 19 | an event because both domains could have existing events with the same |
| 20 | name. |
| 21 | |
| 22 | Some features are not available in all domains. Filtering enabled |
| 23 | events using custom expressions, for example, is currently not |
| 24 | supported in the kernel domain, but support could be added in the |
| 25 | future. |