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Date:   Tue, 22 Dec 2020 13:11:02 +0200
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     David Gow <davidgow@google.com>
Cc:     Brendan Higgins <brendanhiggins@google.com>,
        Petr Mladek <pmladek@suse.com>,
        Shuah Khan <skhan@linuxfoundation.org>,
        linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kunit: tool: Force the use of the 'tty' console for UML
Message-ID: <20201222111102.GC4077@smile.fi.intel.com>
References: <20201222073900.3490607-1-davidgow@google.com>
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Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
Precedence: bulk

On Mon, Dec 21, 2020 at 11:39:00PM -0800, David Gow wrote:
> 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=757055ae8dedf5333af17b3b5b4b70ba9bc9da4e

Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Thanks!

> Signed-off-by: David Gow <davidgow@google.com>
> Fixes: 757055ae8ded ("init/console: Use ttynull as a fallback when there is no console")


> ---
>  tools/testing/kunit/kunit_kernel.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
> index 57c1724b7e5d..698358c9c0d6 100644
> --- a/tools/testing/kunit/kunit_kernel.py
> +++ b/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'])
> -- 
> 2.29.2.729.g45daf8777d-goog
> 

-- 
With Best Regards,
Andy Shevchenko