Re: [PATCH 1/2] printk: export pr_flush()

[Esben Haabendal <esben@geanix.com>]

John Ogness <john.ogness@linutronix.de> writes:

> On 2024-04-02, Esben Haabendal <esben@geanix.com> wrote:
>> Outside prinkt users might wan't assure whatever printed has reached
>> its destination before continuing. E.g. during the shutdown-procedure,
>> where printk-buffers aren't emptied before the system goes down.
>
> This is a reposting of:
>
> https://lore.kernel.org/lkml/20231030092432.3434623-1-martin@geanix.com
>
> As I wrote in that thread:
>
> printk() tries to print directly from the calling context. Are you
> experiencing problems where you do not see the restarting message?

Yes, that is exactly what we are seing.

> (If your answer is "yes", please explain the scenario and provide
> information about the console driver you are using.)

It is an i.MX8MP system, and console is attached to ttymxc1
(drivers/tty/serial/imx.c).

Booting up, and simply executing "reboot" command. Without these two
patches, the "reboot: Restarting system" message is not written to
ttymxc1 console. With the patches, it is.

> I assume you have tried the latest RT development version.

I have reproduced the problem with v6.6.23-rt28. I haven't upgraded to
6.7 or 6.8 yet. Do you need me to retest with 6.8?

/Esben