kunit: tool: Force the use of the 'tty' console for UML

kunit_tool relies on the UML console outputting printk() output to the
tty in order to get results. Since the default console driver could
change, pass 'console=tty' to the kernel.

This is triggered by a change[1] to use ttynull as a fallback console
driver which -- by chance or by design -- seems to have changed the
default console output on UML, breaking kunit_tool. While this may be
fixed, we should be less fragile to such changes in the default.

[1]:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=757055ae8dedf5333af17b3b5b4b70ba9bc9da4eSigned-off-by: David Gow <davidgow@google.com>
Fixes: 757055ae ("init/console: Use ttynull as a fallback when there is no console")
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/kunit/kunit_kernel.py

@@ -198,7 +198,7 @@ class LinuxSourceTree(object):
 		return self.validate_config(build_dir)
 
 	def run_kernel(self, args=[], build_dir='', timeout=None):
-		args.extend(['mem=1G'])
+		args.extend(['mem=1G', 'console=tty'])
 		self._ops.linux_bin(args, timeout, build_dir)
 		outfile = get_outfile_path(build_dir)
 		subprocess.call(['stty', 'sane'])