diff -ru xdebug-2.0.5/php_xdebug.h xdebug-2.0.5-modified/php_xdebug.h
--- xdebug-2.0.5/php_xdebug.h	1970-01-01 20:13:08.000000000 +1100
+++ xdebug-2.0.5-modified/php_xdebug.h	2011-03-30 16:05:11.442678999 +1100
@@ -141,6 +141,8 @@
 	FILE         *trace_file;
 	zend_bool     do_trace;
 	zend_bool     auto_trace;
+	zend_bool     trace_enable_trigger;
+	char         *trace_enable_trigger_value;
 	char         *trace_output_dir;
 	char         *trace_output_name;
 	long          trace_options;
@@ -199,6 +201,7 @@
 	char         *profiler_output_dir;
 	char         *profiler_output_name; /* "pid" or "crc32" */
 	zend_bool     profiler_enable_trigger;
+	char         *profiler_enable_trigger_value;
 	zend_bool     profiler_append;
 
 	/* profiler globals */
diff -ru xdebug-2.0.5/xdebug.c xdebug-2.0.5-modified/xdebug.c
--- xdebug-2.0.5/xdebug.c	1970-01-01 20:13:08.000000000 +1100
+++ xdebug-2.0.5-modified/xdebug.c	2011-03-31 17:01:14.885110998 +1100
@@ -253,6 +253,8 @@
 PHP_INI_BEGIN()
 	/* Debugger settings */
 	STD_PHP_INI_BOOLEAN("xdebug.auto_trace",      "0",                  PHP_INI_ALL,    OnUpdateBool,   auto_trace,        zend_xdebug_globals, xdebug_globals)
+	STD_PHP_INI_BOOLEAN("xdebug.trace_enable_trigger", "0",             PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateBool,   trace_enable_trigger, zend_xdebug_globals, xdebug_globals)
+	STD_PHP_INI_ENTRY("xdebug.trace_enable_trigger_value", "",          PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateString,   trace_enable_trigger_value, zend_xdebug_globals, xdebug_globals)
 	STD_PHP_INI_ENTRY("xdebug.trace_output_dir",  "/tmp",               PHP_INI_ALL,    OnUpdateString, trace_output_dir,  zend_xdebug_globals, xdebug_globals)
 	STD_PHP_INI_ENTRY("xdebug.trace_output_name", "trace.%c",           PHP_INI_ALL,    OnUpdateString, trace_output_name, zend_xdebug_globals, xdebug_globals)
 #if ZEND_EXTENSION_API_NO < 90000000
@@ -300,11 +302,12 @@
 	STD_PHP_INI_ENTRY("xdebug.profiler_output_dir",       "/tmp",   PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateString, profiler_output_dir,     zend_xdebug_globals, xdebug_globals)
 	STD_PHP_INI_ENTRY("xdebug.profiler_output_name",      "cachegrind.out.%p",  PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateString, profiler_output_name,    zend_xdebug_globals, xdebug_globals)
 	STD_PHP_INI_BOOLEAN("xdebug.profiler_enable_trigger", "0",      PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateBool,   profiler_enable_trigger, zend_xdebug_globals, xdebug_globals)
+	STD_PHP_INI_ENTRY("xdebug.profiler_enable_trigger_value", "",   PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateString,   profiler_enable_trigger_value, zend_xdebug_globals, xdebug_globals)
 	STD_PHP_INI_BOOLEAN("xdebug.profiler_append",         "0",      PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateBool,   profiler_append,         zend_xdebug_globals, xdebug_globals)
 	STD_PHP_INI_BOOLEAN("xdebug.profiler_aggregate",      "0",      PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateBool,   profiler_aggregate,      zend_xdebug_globals, xdebug_globals)
 
 	/* Remote debugger settings */
-	STD_PHP_INI_BOOLEAN("xdebug.remote_enable",   "0",   PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateBool,   remote_enable,     zend_xdebug_globals, xdebug_globals)
+	STD_PHP_INI_BOOLEAN("xdebug.remote_enable",   "0",                  PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateBool,   remote_enable,     zend_xdebug_globals, xdebug_globals)
 	STD_PHP_INI_ENTRY("xdebug.remote_handler",    "dbgp",               PHP_INI_ALL,    OnUpdateString, remote_handler,    zend_xdebug_globals, xdebug_globals)
 	STD_PHP_INI_ENTRY("xdebug.remote_host",       "localhost",          PHP_INI_ALL,    OnUpdateString, remote_host,       zend_xdebug_globals, xdebug_globals)
 	PHP_INI_ENTRY("xdebug.remote_mode",           "req",                PHP_INI_ALL,    OnUpdateDebugMode)
@@ -437,6 +440,9 @@
 		if (strcasecmp(envvar, "profiler_enable_trigger") == 0) {
 			name = "xdebug.profiler_enable_trigger";
 		} else
+		if (strcasecmp(envvar, "trace_enable") == 0) {
+			name = "xdebug.trace_enable";
+		} else
 		if (strcasecmp(envvar, "remote_log") == 0) {
 			name = "xdebug.remote_log";
 		}
@@ -785,11 +791,40 @@
 	XG(remote_enabled) = 0;
 	XG(profiler_enabled) = 0;
 	XG(breakpoints_allowed) = 1;
-	if (XG(auto_trace) && XG(trace_output_dir) && strlen(XG(trace_output_dir))) {
+	if (
+		(
+			XG(auto_trace)
+		 	||
+			(
+				/* Check for special GET/POST parameter to start the trace */
+				XG(trace_enable_trigger) &&
+				(
+					(
+						PG(http_globals)[TRACK_VARS_GET] &&
+						zend_hash_find(PG(http_globals)[TRACK_VARS_GET]->value.ht, "XDEBUG_TRACE", sizeof("XDEBUG_TRACE"), (void **) &dummy) == SUCCESS 
+					) || (
+						PG(http_globals)[TRACK_VARS_POST] &&
+						zend_hash_find(PG(http_globals)[TRACK_VARS_POST]->value.ht, "XDEBUG_TRACE", sizeof("XDEBUG_TRACE"), (void **) &dummy) == SUCCESS
+					) || (
+						PG(http_globals)[TRACK_VARS_COOKIE] &&
+						zend_hash_find(PG(http_globals)[TRACK_VARS_COOKIE]->value.ht, "XDEBUG_TRACE", sizeof("XDEBUG_TRACE"), (void **) &dummy) == SUCCESS
+					)
+				) && (
+					(strlen(XG(trace_enable_trigger_value)) == 0) ||
+					(strcmp(XG(trace_enable_trigger_value), Z_STRVAL_PP(dummy)) == 0)
+				)
+
+			)
+		 ) && XG(trace_output_dir) && strlen(XG(trace_output_dir))) {
+
 		/* In case we do an auto-trace we are not interested in the return
 		 * value, but we still have to free it. */
 		xdfree(xdebug_start_trace(NULL, XG(trace_options) TSRMLS_CC));
 	}
+	php_syslog(LOG_NOTICE, "trace_enable_trigger_value: '%s'", XG(trace_enable_trigger_value));
+	php_syslog(LOG_NOTICE, "dummy: '%s'",	Z_STRVAL_PP(dummy));
+
+
 
 	/* Initialize some debugger context properties */
 	XG(context).program_name   = NULL;
@@ -1494,6 +1529,9 @@
 							PG(http_globals)[TRACK_VARS_COOKIE] && 
 							zend_hash_find(PG(http_globals)[TRACK_VARS_COOKIE]->value.ht, "XDEBUG_PROFILE", sizeof("XDEBUG_PROFILE"), (void **) &dummy) == SUCCESS
 						)
+					) && (
+						(strlen(XG(profiler_enable_trigger_value)) == 0) ||
+						(strcmp(XG(profiler_enable_trigger_value), Z_STRVAL_PP(dummy)) == 0)
 					)
 				)
 			)