+ If compiling from the git repository, run ./bootstrap before running
+ the configure script, to generate it.
+
+ Note that configure sets '/usr/local' as the default prefix for files it
+ installs. However, this path is not part of most distributions' default
+ library path which will cause builds depending on liblttng-ust to fail unless
+ '-L/usr/local/lib' is added to LDFLAGS. You may provide a custom prefix to
+ configure by using the --prefix switch. Note that LTTng-UST needs to
+ be a shared library, even if the tracepoint probe provider is statically
+ linked into the application.
+
+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" on Linux, with "-lc" on BSD.
+ - 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 "-llttng-ust".
+ - Include the tracepoint provider header into all C files using
+ the provider.
+ - Examples:
+ - doc/examples/easy-ust/ sample.c sample_component_provider.h
+ tp.c Makefile
+ - doc/examples/hello-static-lib/ hello.c tp.c ust_test_hello.h
+ Makefile
+
+ 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" on Linux, "-lc" on BSD.
+ - Set a LD_PRELOAD environment to preload the tracepoint provider
+ shared object before starting the application when tracing is
+ needed. Another way is to dlopen the tracepoint probe when needed
+ by the application.
+ - Example:
+ - doc/examples/demo demo.c tp*.c ust_tests_demo*.h demo-trace Makefile
+
+ - Note about dlclose() usage: it is not safe to use dlclose on a
+ provider shared object that is being actively used for tracing due
+ to a lack of reference counting from lttng-ust to the used shared
+ object.
+ - Enable instrumentation and control tracing with the "lttng" command
+ from lttng-tools. See lttng-tools doc/quickstart.txt.
+ - Note for C++ support: since LTTng-UST 2.3, both tracepoints and
+ tracepoint probes can be compiled in C++. To compile tracepoint probes
+ in C++, you need g++ >= 4.7 or Clang.
+
+
+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.
+
+ - The compilation flag "-DLTTNG_UST_DEBUG_VALGRIND" should be enabled
+ at build time to allow liblttng-ust to be used with valgrind
+ (side-effect: disables per-cpu buffering).