android13/art/tools/jvmti-agents/enable-vlog/README.md

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# enablevlog
enablevlog is a JVMTI agent designed for changing the VLOG options of a
running process. Currently it only allows one to turn vlog options 'on'.
# Usage
### Build
> `m libenablevlog`
The libraries will be built for 32-bit, 64-bit, host and target. Below
examples assume you want to use the 64-bit version.
Use `libenablevlogs` if you wish to build a version without non-NDK dynamic
dependencies.
### Command Line
The agent is loaded using -agentpath like normal. It takes arguments in the
following format:
`[vlog1[,vlog2[,...]]]`
It will cause the runtime to act as though you had passed these after the
`-verbose:[...]` argument to `dalvikvm`.
#### Supported events
At the time of writing, the following events may be listened for with this agent
* `class`
* `collector`
* `compiler`
* `deopt`
* `gc`
* `heap`
* `interpreter`
* `jdwp`
* `jit`
* `jni`
* `monitor`
* `oat`
* `profiler`
* `signals`
* `simulator`
* `startup`
* `third-party-jni`
* `threads`
* `verifier`
* `verifier-debug`
* `image`
* `systrace-locks`
* `plugin`
* `agents`
* `dex`
These are not particularly stable and new options might get added. Examine
the LogVerbosity struct definition and the parser for a up-to-date list.
#### ART
> `art -Xplugin:$ANDROID_HOST_OUT/lib64/libopenjdkjvmti.so '-agentpath:libenablevlog.so=class,profiler' -cp tmp/java/helloworld.dex -Xint helloworld`
* `-Xplugin` and `-agentpath` need to be used, otherwise the agent will fail during init.
* If using `libartd.so`, make sure to use the debug version of jvmti.
> `adb shell setenforce 0`
>
> `adb push $ANDROID_PRODUCT_OUT/system/lib64/libenablevlog.so /data/local/tmp/`
>
> `adb shell am start-activity --attach-agent /data/local/tmp/libenablevlog.so=class,jit some.debuggable.apps/.the.app.MainActivity`