linux-kernel - Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test

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Date:   Sun, 9 Apr 2017 11:57:32 +0200
From:   Pavel Machek <pavel@....cz>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Jan Kara <jack@...e.cz>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Ye Xiaolong <xiaolong.ye@...el.com>,
        Petr Mladek <pmladek@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Len Brown <len.brown@...el.com>,
        linux-kernel@...r.kernel.org, lkp@...org
Subject: Re: [printk]  fbc14616f4:
 BUG:kernel_reboot-without-warning_in_test_stage

On Fri 2017-04-07 10:29:17, Steven Rostedt wrote:
> On Fri, 7 Apr 2017 10:14:49 +0200
> Pavel Machek <pavel@....cz> wrote:
> 
> > > serial console can be quite slow. and port->lock, that is acquired by
> > > console_unlock()->call_console_drivers()->write(), is also accessible
> > > by serial driver's IRQ handler, and this lock may be busy long
> > > enough -- as long as that IRQ handler transmits/receives chars. but
> > > that's not the point.  
> > 
> > Well. This is what we had for 20 years.
> 
> But for the last 20 years we were not booting on machines with over 200
> CPUs. Well, we were, but those had custom kernels (which probably
> dismantled printk).

Well, not a problem. Just find a solution that works for dual core
machines as well as it did for 20 years.

2 seconds timeout as proposed earlier should work well for big
machines, and with no regressions on small machines.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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