linux-kernel - Re: [PATCH v2] printk: allow direct console printing to be enabled always

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Date:   Mon, 20 Jun 2022 09:56:47 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>
Cc:     John Ogness <john.ogness@...utronix.de>,
        Petr Mladek <pmladek@...e.com>, Marco Elver <elver@...gle.com>,
        linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH v2] printk: allow direct console printing to be enabled
 always

Hi Sergey,

On Mon, Jun 20, 2022 at 02:17:36PM +0900, Sergey Senozhatsky wrote:
> On (22/06/20 01:23), John Ogness wrote:
> > I'm wondering if we should output a message here. My suggestion is:
> > 
> > pr_info("printing threads disabled, using direct printing\n");
> > 
> > > +		return 0;
> > > +
> > >  	console_lock();
> > >  	printk_kthreads_available = true;
> > >  	for_each_console(con)
> > 
> > Otherwise it looks OK to me. But you may want to wait on a response from
> > Petr, Sergey, or Steven before sending a v3. You are adding a kernel
> > config and a boot argument. Both of these are sensitive topics that
> > require more feedback from others.
> 
> A tricky situation. I think John already mentioned in another thread
> that any such config/boot param potentially can become a default value
> for some setups; at the same time, well, yeah, I see what commit message
> talks about.

Moving it into the debug section of kconfig hopefully sends the right
message there. Plus the help text makes it clear there are performance
implications and such.

Jason