Hello everyone,
I have been trying to instrument the Apache web server, the latest version (2.4.7 from the URL http://httpd.apache.org/download.cgi#apache24) for LTTng UST tracing
1. To start with the simplest case, I created a *.tp file named smallestTracePoint.tp with the content below
    TRACEPOINT_EVENT(
    mk,
    apache_process_entry,
    TP_ARGS(),
    TP_FIELDS()
  )

2. Then I ran the following
   lttng-gen-tp smallestTracePoint.tp -o smallestTracePoint.h -o smallestTracePoint.c

3. Then, I put the smallestTracePoint.h and smallestTracePoint.c in httpd-2.4.7/server directory,

included  smallestTracePoint.h in the main.c  file and added trace points in the int main(int argc, const char * const argv[]) and *init_process(int *argc, const char * const * *argv) functions.

   

5. Then, from the /httpd-2.4.7 directory, I ran the following command to configure the installation, it completed without any error.
    ./configure --libdir=/usr/lib/usr/lib/liblttng-ust.so --with-included-apr

6. When I ran the command 'make', I get the following error after a while
...
make[1]: Entering directory `/root/httpd-2.4.7'
/root/httpd-2.4.7/srclib/apr/libtool --silent --mode=compile gcc -std=gnu99  -g -O2 -pthread      -DLINUX -D_REENTRANT -D_GNU_SOURCE     -I. -I/root/httpd-2.4.7/os/unix -I/root/httpd-2.4.7/include -I/root/httpd-2.4.7/srclib/apr/include -I/root/httpd-2.4.7/srclib/apr-util/include -I/root/httpd-2.4.7/srclib/apr-util/xml/expat/lib -I/root/httpd-2.4.7/modules/aaa -I/root/httpd-2.4.7/modules/cache -I/root/httpd-2.4.7/modules/core -I/root/httpd-2.4.7/modules/database -I/root/httpd-2.4.7/modules/filters -I/root/httpd-2.4.7/modules/ldap -I/root/httpd-2.4.7/modules/loggers -I/root/httpd-2.4.7/modules/lua -I/root/httpd-2.4.7/modules/proxy -I/root/httpd-2.4.7/modules/session -I/root/httpd-2.4.7/modules/ssl -I/root/httpd-2.4.7/modules/test -I/root/httpd-2.4.7/server -I/root/httpd-2.4.7/modules/arch/unix -I/root/httpd-2.4.7/modules/dav/main -I/root/httpd-2.4.7/modules/generators -I/root/httpd-2.4.7/modules/mappers  -prefer-non-pic -static -c modules.c && touch modules.lo
gcc -std=gnu99  -g -O2 -pthread      -DLINUX -D_REENTRANT -D_GNU_SOURCE     -I. -I/root/httpd-2.4.7/os/unix -I/root/httpd-2.4.7/include -I/root/httpd-2.4.7/srclib/apr/include -I/root/httpd-2.4.7/srclib/apr-util/include -I/root/httpd-2.4.7/srclib/apr-util/xml/expat/lib -I/root/httpd-2.4.7/modules/aaa -I/root/httpd-2.4.7/modules/cache -I/root/httpd-2.4.7/modules/core -I/root/httpd-2.4.7/modules/database -I/root/httpd-2.4.7/modules/filters -I/root/httpd-2.4.7/modules/ldap -I/root/httpd-2.4.7/modules/loggers -I/root/httpd-2.4.7/modules/lua -I/root/httpd-2.4.7/modules/proxy -I/root/httpd-2.4.7/modules/session -I/root/httpd-2.4.7/modules/ssl -I/root/httpd-2.4.7/modules/test -I/root/httpd-2.4.7/server -I/root/httpd-2.4.7/modules/arch/unix -I/root/httpd-2.4.7/modules/dav/main -I/root/httpd-2.4.7/modules/generators -I/root/httpd-2.4.7/modules/mappers  -c /root/httpd-2.4.7/server/buildmark.c
/root/httpd-2.4.7/srclib/apr/libtool --silent --mode=link gcc -std=gnu99  -g -O2 -pthread         -o httpd  modules.lo buildmark.o -export-dynamic server/libmain.la modules/core/libmod_so.la modules/http/libmod_http.la server/mpm/event/libevent.la os/unix/libos.la -L/usr/lib/x86_64-linux-gnu -lpcre     /root/httpd-2.4.7/srclib/apr-util/libaprutil-1.la /root/httpd-2.4.7/srclib/apr-util/xml/expat/libexpat.la /root/httpd-2.4.7/srclib/apr/libapr-1.la -luuid -lrt -lcrypt -lpthread -ldl
server/.libs/libmain.a(main.o): In function `main':
/root/httpd-2.4.7/server/main.c:443: undefined reference to `__tracepoint_mk___apache_process_entry'
server/.libs/libmain.a(main.o): In function `init_process':
/root/httpd-2.4.7/server/main.c:284: undefined reference to `__tracepoint_mk___apache_process_entry'
server/.libs/libmain.a(main.o): In function `__tracepoint_cb_mk___apache_process_entry':
/root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to `tracepoint_dlopen'
/root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to `__tracepoint_mk___apache_process_entry'
/root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to `tracepoint_dlopen'
/root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to `tracepoint_dlopen'
/root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to `tracepoint_dlopen'
/root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to `__tracepoint_mk___apache_process_entry'
/root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to `tracepoint_dlopen'
/root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to `tracepoint_dlopen'
collect2: ld returned 1 exit status
make[1]: *** [httpd] Error 1
make[1]: Leaving directory `/root/httpd-2.4.7'
make: *** [all-recursive] Error 1

I have tried including the smallestTracePoint.c file in the local makefile (/root/httpd-2.4.7/MakeFile)... didn't do me any good.