How to set up Byteman support in Systemtap
==========================================

Systemtap now contains support for probing Java methods using the
Byteman tool from JBoss as a backend. In order to make use of it, two
things are required.

(1) Environment variable BYTEMAN_HOME must point to a valid Byteman installation.

Byteman can be obtained at http://www.jboss.org/byteman; alternately,
it can be installed through your distribution's package manager.
Either way, double-check that this enviroment variable is configured
correctly.

(2) libHelperSDT_*.so and HelperSDT.jar must be installed into the
local JDK that you are planning to probe.

Unless you are installing systemtap from the RPM package on a system
with OpenJDK 1.6.0+ (in which case the following step is done for
you), the current systemtap makefile makes no effort to install
libHelperSDT_*.so and HelperSDT.jar where the JDK install can detect
them, instead putting them in PREFIX/libexec/systemtap. You must
copy/link these files to the JDK install's extension directories
yourself.

For example, if you have systemtap installed under /usr and an OpenJDK
install under /usr/lib/jvm/java on a x86_64 machine, you can create
symlinks as follows:

  # ln -s /usr/libexec/systemtap/libHelperSDT_amd64.so /usr/lib/jvm/java/jre/lib/amd64/libHelperSDT_amd64.so
  # ln -s /usr/libexec/systemtap/HelperSDT.jar /usr/lib/jvm/java/jre/lib/ext/HelperSDT.jar

Other JDK versions may have a different placement for their extension
directories; consult the corresponding JDK's documentation as
appropriate.
