diff --git a/contrib/trace/trace.awk b/contrib/trace/trace.awk
index 8c8854a90..6bd5b10a5 100755
--- a/contrib/trace/trace.awk
+++ b/contrib/trace/trace.awk
@@ -44,6 +44,8 @@ BEGIN {
     indents[">",i-1] = indents[">",i-1] " "
     indents["<",i] = indents["<",i-1] "  "
     indents["<",i-1] = indents["<",i-1] " "
+    indents[" ",i] = indents[" ",i-1] "##"
+    indents[" ",i-1] = indents[" ",i-1] " "
   }
 }
 
@@ -61,7 +63,13 @@ function getptr(ptr)
 }
 
 {
-  # input format: <timestamp> <level> <caller> <dir> <callee>
+  # input format: <timestamp> <level> <caller> <dir> <callee> [<ret>|<args>...]
+  if ($3 == "#") { # this is a trace comment
+    printf "%s %s  ", $1, indents[" ",$2]
+    $1=""; $2=""; $3=""
+    print substr($0,4)
+    next
+  }
   getptr($3); caller_loc=loc; caller_name=name
   getptr($5); callee_loc=loc; callee_name=name
   printf "%s %s  %s %s %s [%s:%s] %s [%s:%s]\n",
diff --git a/include/common/standard.h b/include/common/standard.h
index 535efa736..18d90566d 100644
--- a/include/common/standard.h
+++ b/include/common/standard.h
@@ -1105,6 +1105,10 @@ char *env_expand(char *in);
  */
 void debug_hexdump(FILE *out, const char *pfx, const char *buf, unsigned int baseaddr, int len);
 
+/* this is used to emit traces when building with TRACE=1 */
+__attribute__((format(printf, 1, 2)))
+void trace(char *fmt, ...);
+
 /* used from everywhere just to drain results we don't want to read and which
  * recent versions of gcc increasingly and annoyingly complain about.
  */
diff --git a/src/standard.c b/src/standard.c
index 174edd2cc..db312dd18 100644
--- a/src/standard.c
+++ b/src/standard.c
@@ -3880,6 +3880,12 @@ void debug_hexdump(FILE *out, const char *pfx, const char *buf,
 	}
 }
 
+/* do nothing, just a placeholder for debugging calls, the real one is in trace.c */
+__attribute__((weak,format(printf, 1, 2)))
+void trace(char *msg, ...)
+{
+}
+
 /*
  * Local variables:
  *  c-indent-level: 8
diff --git a/src/trace.c b/src/trace.c
index 4bbbc302a..9425be9f7 100644
--- a/src/trace.c
+++ b/src/trace.c
@@ -29,11 +29,20 @@
  *
  * where <dir> is '>' when entering a function and '<' when leaving.
  *
+ * It is also possible to emit comments using the trace() function which uses
+ * the printf() format. Such comments are then inserted by replacing the caller
+ * pointer with a sharp ('#') like this :
+ *
+ *   <sec.usec> <level> # <comment>
+ *  or :
+ *   <tsc> <level> # <comment>
+ *
  * The article below is a nice explanation of how this works :
  *   http://balau82.wordpress.com/2010/10/06/trace-and-profile-function-calls-with-gcc/
  */
 
 #include <sys/time.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -229,3 +238,33 @@ void __cyg_profile_func_exit(void *to,  void *from)
 	if (!disabled)
 		return make_line(from, to, level--, '<');
 }
+
+/* the one adds comments in the trace above. The output format is :
+ * <timestamp> <level> # <string>
+ */
+__attribute__((format(printf, 1, 2)))
+void trace(char *fmt, ...)
+{
+	va_list ap;
+
+	if (unlikely(!log) && !open_trace())
+		return;
+
+	if (unlikely(!fast_time))
+		gettimeofday(now_ptr, NULL);
+
+	if (!use_tsc)
+		fprintf(log, "%u.%06u %d # ",
+			(unsigned int)now_ptr->tv_sec,
+			(unsigned int)now_ptr->tv_usec,
+			level + 1);
+	else
+		fprintf(log, "%llx %d # ",
+			rdtsc(), level + 1);
+
+	va_start(ap, fmt);
+	vfprintf(log, fmt, ap);
+	va_end(ap);
+	fputc('\n', log);
+	fflush(log);
+}