manpage: Document probe provider compatibility

[lttng-ust.git] / doc / man / lttng-ust.3

diff --git a/doc/man/lttng-ust.3 b/doc/man/lttng-ust.3
index 3ba5c7cc8e46b2a554957d1fd7b5a99b488925b9..9bad1ecbede318be85d5505bce2da0db85221cdd 100644 (file)
--- a/doc/man/lttng-ust.3
+++ b/doc/man/lttng-ust.3
@@ -257,7 +257,7 @@ carefully:
     - 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".
+      library with "\-llttng-ust".
     - Include the tracepoint provider header into all C files using
       the provider.
     - Example:
@@ -287,6 +287,20 @@ carefully:
     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.
+  - Note for C++ support: although an application instrumented with
+    tracepoints can be compiled with g++, tracepoint probes should be
+    compiled with gcc (only tested with gcc so far).
+
+.fi
+
+.SH "USING LTTNG UST WITH DAEMONS"
+
+.nf
+Some extra care is needed when using liblttng-ust with daemon
+applications that call fork(), clone(), or BSD rfork() without a
+following exec() family system call. The library "liblttng-ust-fork.so"
+needs to be preloaded for the application (launch with e.g.
+LD_PRELOAD=liblttng-ust-fork.so appname).
 
 .fi
 
@@ -312,10 +326,23 @@ startup time.
 .PP
 lttng-gen-tp(1), lttng(1), babeltrace(1), lttng-sessiond(8)
 .PP
+
+.SH "COMPATIBILITY"
+
+.PP
+Older lttng-ust libraries reject more recent, and incompatible, probe
+providers. Newer lttng-ust librairies accept older probe providers, even
+though some newer features might not be available with those providers.
+.PP
+
 .SH "BUGS"
 
 .PP
-No knows bugs at this point.
+LTTng-UST 2.0 and 2.1 lttng-ust libraries do not check for probe
+provider version compatibility. This can lead to out-of-bound accesses
+when using a more recent probe provider with an older lttng-ust library.
+These error only trigger when tracing is active. This issue has been
+fixed in LTTng-UST 2.2.
 
 If you encounter any issues or usability problem, please report it on
 our mailing list <lttng-dev@lists.lttng.org> to help improve this