== Linux ==
-* Run the application you want to trace as
+Run the application you want to trace as
LD_PRELOAD=/path/to/glxtrace.so /path/to/application
directory. You can specify the written trace filename by setting the
TRACE_FILE envirnment variable before running.
-* View the trace with
+View the trace with
/path/to/tracedump application.trace | less -R
-* Replay the trace with
+Replay the trace with
/path/to/glretrace application.trace
+The LD_PRELOAD mechanism should work with most applications. There are some
+applications, e.g., Unigine Heaven, which global function pointers with the
+same name as GL entrypoints, living in a shared object that wasn't linked with
+-Bsymbolic flag, so relocations to those globals function pointers get
+overwritten with the address to our wrapper library, and the application will
+segfault when trying to write to them. For these applications it is possible
+to trace by using glxtrace.so as an ordinary libGL.so and injecting into
+LD_LIBRARY_PATH:
+
+ ln -s glxtrace.so libGL.so
+ ln -s glxtrace.so libGL.so.1
+ ln -s glxtrace.so libGL.so.1.2
+ export LD_LIBRARY_PATH=/path/to/directory/where/glxtrace/is:$LD_LIBRARY_PATH
+ export TRACE_LIBGL=/path/to/real/libGL.so.1
+ /path/to/application
+
+
== Windows ==
* Copy opengl32.dll, d3d8.dll, or d3d9.dll from build/wrappers directory to the
print r'''
+/*
+ * Handle to the true libGL.so
+ */
static void *libgl_handle = NULL;
handle = __dlopen(filename, flag);
- if (filename && handle) {
+ const char * libgl_filename = getenv("TRACE_LIBGL");
+
+ if (filename && handle && !libgl_filename) {
if (0) {
OS::DebugMessage("warning: dlopen(\"%s\", 0x%x)\n", filename, flag);
}
// FIXME: handle absolute paths and other versions
if (strcmp(filename, "libGL.so") == 0 ||
strcmp(filename, "libGL.so.1") == 0) {
+
// Use the true libGL.so handle instead of RTLD_NEXT from now on
libgl_handle = handle;
if (!libgl_handle) {
/*
- * Try to use whatever libGL.so the library is linked against.
+ * The app doesn't directly link against libGL.so, nor does it directly
+ * dlopen it. So we have to load it ourselves.
*/
- result = dlsym(RTLD_NEXT, symbol);
- if (result) {
- libgl_handle = RTLD_NEXT;
- return result;
+
+ const char * libgl_filename = getenv("TRACE_LIBGL");
+
+ if (!libgl_filename) {
+ /*
+ * Try to use whatever libGL.so the library is linked against.
+ */
+
+ result = dlsym(RTLD_NEXT, symbol);
+ if (result) {
+ libgl_handle = RTLD_NEXT;
+ return result;
+ }
+
+ libgl_filename = "libGL.so.1";
}
/*
- * The app doesn't directly link against libGL.so, nor does it directly
- * dlopen it. So we have to load it ourselves.
+ * It would have been preferable to use RTLD_LOCAL to ensure that the
+ * application can never access libGL.so symbols directly, but this
+ * won't work, given libGL.so often loads a driver specific SO and
+ * exposes symbols to it.
*/
- libgl_handle = __dlopen("libGL.so", RTLD_LAZY | RTLD_LOCAL);
+
+ libgl_handle = __dlopen(libgl_filename, RTLD_GLOBAL | RTLD_LAZY);
if (!libgl_handle) {
OS::DebugMessage("error: couldn't find libGL.so\n");
return NULL;