trace: add "-trace events" argument to control initial state

The "-trace events" argument can be used to provide a file with a list of trace
event names that will be enabled prior to starting execution, thus providing
early tracing.

This saves the user from manually toggling event states through the monitor
interface or whichever backend-specific interface.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>

1 files changed, 3 insertions, 1 deletions

diff --git a/vl.c b/vl.c
index 60322b62a4..c6dc6895b4 100644
--- a/vl.c
+++ b/vl.c
@@ -2137,6 +2137,7 @@ int main(int argc, char **argv, char **envp)
         .realloc = realloc_and_trace,
         .free = free_and_trace,
     };
+    const char *trace_events = NULL;
     const char *trace_file = NULL;
 
     atexit(qemu_run_exit_notifiers);
@@ -2934,6 +2935,7 @@ int main(int argc, char **argv, char **envp)
                 if (!opts) {
                     exit(1);
                 }
+                trace_events = qemu_opt_get(opts, "events");
                 trace_file = qemu_opt_get(opts, "file");
                 break;
             }
@@ -2994,7 +2996,7 @@ int main(int argc, char **argv, char **envp)
         set_cpu_log(log_mask);
     }
 
-    if (!trace_backend_init(trace_file)) {
+    if (!trace_backend_init(trace_events, trace_file)) {
         exit(1);
     }