+USAGE:
+
+ - Create an instrumentation header following the tracepoint examples.
+ See lttng/tracepoint.h, and examples.
+
+ There are 2 ways to compile the Tracepoint Provider with the
+ application: either statically or dynamically. Please follow
+ carefully:
+
+ 1.1) Compile the Tracepoint provider with the application, either
+ directly or through a static library (.a):
+ - Into exactly one object of your application: define
+ "TRACEPOINT_DEFINE" and include the tracepoint provider.
+ - Use "-I." for the compilation unit containing the tracepoint
+ provider include (e.g. tp.c).
+ - Link application with "-ldl".
+ - If building the provider directly into the application,
+ link the application with "-llttng-ust".
+ - If building a static library for the provider, link the static
+ library with "-lllttng-ust".
+ - Include the tracepoint provider header into all C files using
+ the provider.
+ - Example:
+ tests/hello/ hello.c tp.c ust_tests_hello.h Makefile.example
+
+ 2) Compile the Tracepoint Provider separately from the application,
+ using dynamic linking:
+ - Into exactly one object of your application: define
+ "TRACEPOINT_DEFINE" _and_ also define
+ "TRACEPOINT_PROBE_DYNAMIC_LINKAGE", then include the tracepoint
+ provider header.
+ - Include the tracepoint provider header into all instrumented C
+ files that use the provider.
+ - Compile the tracepoint provider with "-I.".
+ - Link the tracepoint provider with "-llttng-ust".
+ - Link application with "-ldl".
+ - Set a LD_PRELOAD environment to preload the tracepoint provider
+ shared object before starting the application when tracing is
+ needed.
+ - Example:
+ - tests/demo/ demo.c tp*.c ust_tests_demo*.h demo-trace
+
+ - Note about dlopen() usage: due to locking side-effects due to the
+ way libc lazily resolves Thread-Local Storage (TLS) symbols when a
+ library is dlopen'd, linking the tracepoint probe or liblttng-ust
+ with dlopen() is discouraged. They should be linked with the
+ application using "-llibname" or loaded with LD_PRELOAD.
+ - Enable instrumentation and control tracing with the "lttng" command
+ from lttng-tools. See lttng-tools doc/quickstart.txt.
+
+ENVIRONMENT VARIABLES:
+
+ - liblttng-ust debug can be activated by setting the environment variable
+ "LTTNG_UST_DEBUG" when launching the application. It can also be enabled
+ at compile-time by compiling libust with -DLTTNG_UST_DEBUG.
+
+ - The environment variable "LTTNG_UST_REGISTER_TIMEOUT" can be used to
+ specify how long the applications should wait for sessiond
+ "registration done" command before proceeding to execute the main
+ program. The default is 3000ms (3 seconds). The timeout value is
+ specified in milliseconds. The value 0 means "don't wait". The value
+ -1 means "wait forever". Setting this environment variable to 0 is
+ recommended for applications with time constraints on the process
+ startup time.