On Wed, Jan 6, 2021 at 3:52 AM Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote: > > On 1/5/21 11:57 AM, Andy Shevchenko wrote: > > On Tue, Jan 05, 2021 at 09:34:33AM -0700, Shuah Khan wrote: > >> On 1/5/21 9:21 AM, Petr Mladek wrote: > >>> On Mon 2021-01-04 09:23:57, Shuah Khan wrote: > >>>> On 12/22/20 4:11 AM, Andy Shevchenko wrote: > >>>>> 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@xxxxxxxxxxxxxxx> > >>>>> Tested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > >>>>> > >>>> > >>>> Thank you all. Now in linux-kselftest kunit-fixes branch. > >>>> > >>>> Will send this up for rc3. > >>>> > >>>> Sorry for the delay - have been away from the keyboard for a > >>>> bit. > >>> > >>> JFYI, I am not sure that this is the right solution. I am > >>> looking into it, see > >>> https://lore.kernel.org/linux-kselftest/X%2FSRA1P8t+ONZFKb@alley/ > >>> for more details. > >>> > >> > >> Thanks Petr. I will hold off on sending the patch up to Linus and > >> let you find a the right solution. > > > > Please. leave it in Linux Next at least. Otherwise kunit will be broken for a > > long time which is not good. > > > > > > Yes. That is the plan. It will be in there until real fix comes in. > Thanks, Shuah. Personally, I think that this patch makes some sense to keep even if the underlying issue with ttynull is resolved. Given that kunit.py requires the console output, explicitly stating we want console=tty set is probably worth doing rather than relying on it being the default. That being said, I definitely agree that this patch doesn't fix the underlying issue with UML/ttynull: it just makes the kunit.py script less sensitive to such changes (which, while unlikely, could potentially occur legitimately down the track). Cheers, -- David
