python: Automatically disable listeners in batch setups

Determine if gem5 is running in a batch environment by checking if
STDIN is wired to a TTY or not. If the simulator is running in a batch
environment, disable all listeners by default. This behavior can be
overridden using the --enable-listeners option.

Change-Id: I404c709135339144216bf08a2769c016c543333c
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Sean McGoogan <sean.mcgoogan@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2322
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

src/python/m5/main.py

@@ -1,3 +1,15 @@
+# Copyright (c) 2016 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
 # Copyright (c) 2005 The Regents of The University of Michigan
 # All rights reserved.
 #
@@ -48,6 +60,8 @@ def parse_options():
     option = options.add_option
     group = options.set_group
 
+    listener_modes = ( "on", "off", "auto" )
+
     # Help options
     option('-B', "--build-info", action="store_true", default=False,
         help="Show build information")
@@ -67,6 +81,10 @@ def parse_options():
         help="Filename for -r redirection [Default: %default]")
     option("--stderr-file", metavar="FILE", default="simerr",
         help="Filename for -e redirection [Default: %default]")
+    option("--listener-mode", metavar="{on,off,auto}",
+        choices=listener_modes, default="auto",
+        help="Port (e.g., gdb) listener mode (auto: Enable if running " \
+        "interactively) [Default: %default]")
     option('-i', "--interactive", action="store_true", default=False,
         help="Invoke the interactive interpreter after running the script")
     option("--pdb", action="store_true", default=False,
@@ -179,7 +197,7 @@ def main(*args):
     import stats
     import trace
 
-    from util import fatal
+    from util import inform, fatal, panic, isInteractive
 
     if len(args) == 0:
         options, arguments = parse_options()
@@ -321,6 +339,19 @@ def main(*args):
     # set stats options
     stats.addStatVisitor(options.stats_file)
 
+    # Disable listeners unless running interactively or explicitly
+    # enabled
+    if options.listener_mode == "off":
+        m5.disableAllListeners()
+    elif options.listener_mode == "auto":
+        if not isInteractive():
+            inform("Standard input is not a terminal, disabling listeners.")
+            m5.disableAllListeners()
+    elif options.listener_mode == "on":
+        pass
+    else:
+        panic("Unhandled listener mode: %s" % options.listener_mode)
+
     # set debugging options
     debug.setRemoteGDBPort(options.remote_gdb_port)
     for when in options.debug_break:

src/python/m5/util/__init__.py

@@ -1,3 +1,15 @@
+# Copyright (c) 2016 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
 # Copyright (c) 2008-2009 The Hewlett-Packard Development Company
 # Copyright (c) 2004-2006 The Regents of The University of Michigan
 # All rights reserved.
@@ -195,3 +207,8 @@ def makeDir(path):
             raise AttributeError, "%s exists but is not directory" % path
     else:
         os.mkdir(path)
+
+def isInteractive():
+    """Check if the simulator is run interactively or in a batch environment"""
+
+    return sys.__stdin__.isatty()