linux-kernel - Re: [PATCH 1/2] printk: Unconditionally unregister boot consoles if in init section

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Date:   Fri, 14 Jul 2017 14:58:08 +0100
From:   Matt Redfearn <matt.redfearn@...tec.com>
To:     Petr Mladek <pmladek@...e.com>
CC:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, <linux-serial@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] printk: Unconditionally unregister boot consoles if
 in init section


On 14/07/17 13:40, Petr Mladek wrote:
> On Wed 2017-07-12 13:11:17, Petr Mladek wrote:
>> On Tue 2017-07-11 15:41:50, Matt Redfearn wrote:
>>> On 11/07/17 13:43, Petr Mladek wrote:
>>>> IMHO, the reasonable solution is to move early console code and data
>>>> out of the init sections. We should do this for the early consoles
>>>> where the corresponding real console is registered using a deferred
>>>> probe. Others should be already replaced by the real console when
>>>> printk_late_init() is called. At least this is how I understand it.
>>> This seems like the most reasonable way forward to me as well,
>>> though sadly will lead to some post-init kernel bloat.
>>>
>>> I still think, however, that this patch is a reasonable change to
>>> make.
>> The thing is that this patch "silently" makes the keep_bootcon
>> option almost unusable.
> I was wrong here. I thought that most early consoles used the init
> section. It was mentioned somewhere and I looked a wrong way.
> But this is not true. In fact, it seems that there are
> only few of them. Most early consoles have struct console
> and the write() callback in the normal section that is preserved.
>
> Matt's patch and the keep_bootcon option makes sense to me
> after all. Let me to resend Matt's patch with some small
> improvements and one more patch that improves the check
> of early consoles that use init section. I'll keep Matt
> as the author of the first patch.

Thanks for looking into this and your fix Petr!

Matt

>
> Best Regards,
> Petr
>