Split test kernel modules to a separate script.

Notice that Python sucks and does SIGPIPE annoyances, for now work around
by grepping the output file...

Fix the exit status read check with 'b', it broke down occasionally with:

UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 1832: invalid start byte

common.py

@@ -310,10 +310,19 @@ def run_cmd(
             del env[key]
     if show_cmd:
         print_cmd(cmd, cmd_file, extra_env=extra_env)
+
     # Otherwise Ctrl + C gives:
     # - ugly Python stack trace for gem5 (QEMU takes over terminal and is fine).
     # - kills Python, and that then kills GDB: https://stackoverflow.com/questions/19807134/does-python-always-raise-an-exception-if-you-do-ctrlc-when-a-subprocess-is-exec
+    sigint_old = signal.getsignal(signal.SIGINT)
     signal.signal(signal.SIGINT, signal.SIG_IGN)
+
+    # Otherwise BrokenPipeError when piping through | grep
+    # But if I do this, my terminal gets broken at the end. Why, why, why.
+    # https://stackoverflow.com/questions/14207708/ioerror-errno-32-broken-pipe-python
+    # Ignoring the exception is not enough as it prints a warning anyways.
+    #sigpipe_old = signal.getsignal(signal.SIGPIPE)
+    #signal.signal(signal.SIGPIPE, signal.SIG_DFL)
     # https://stackoverflow.com/questions/15535240/python-popen-write-to-stdout-and-log-file-simultaneously/52090802#52090802
     with subprocess.Popen(cmd, stdout=stdout, stderr=stderr, env=env, **kwargs) as proc:
         if out_file is not None:
@@ -327,7 +336,8 @@ def run_cmd(
                         logfile.write(byte)
                     else:
                         break
-    signal.signal(signal.SIGINT, signal.SIG_DFL)
+    signal.signal(signal.SIGINT, sigint_old)
+    #signal.signal(signal.SIGPIPE, sigpipe_old)
     return proc.returncode
 
 def setup(parser, **extra_args):