sim,python: add activate option and method

With --debug-activate option, user can add the target names into
activate list of debug log.

For example, with "--debug-activate=system.AAA.bus --debug-flags=IOXBar"
We can enable the logs of a specified bus.

Change-Id: I89ce87d784ae9736708bbc976a6bad58732bd5da
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/70618
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>

src/python/m5/main.py

@@ -275,6 +275,13 @@ def parse_options():
         help="Sets the output file for debug. Append '.gz' to the name for it"
         " to be compressed automatically [Default: %default]",
     )
+    option(
+        "--debug-activate",
+        metavar="EXPR[,EXPR]",
+        action="append",
+        split=",",
+        help="Activate EXPR sim objects",
+    )
     option(
         "--debug-ignore",
         metavar="EXPR",
@@ -557,6 +564,10 @@ def main():
 
     trace.output(options.debug_file)
 
+    for activate in options.debug_activate:
+        _check_tracing()
+        trace.activate(activate)
+
     for ignore in options.debug_ignore:
         _check_tracing()
         trace.ignore(ignore)

src/python/m5/trace.py

@@ -25,4 +25,4 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 # Export native methods to Python
-from _m5.trace import output, ignore, disable, enable
+from _m5.trace import output, activate, ignore, disable, enable