linux-kernel - Re: [PATCH v3 1/5] panic: clean up code for console replay

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Message-ID: <aHWwL7TdabnGna3D@U-2FWC9VHC-2323.local>
Date: Tue, 15 Jul 2025 09:34:39 +0800
From: Feng Tang <feng.tang@...ux.alibaba.com>
To: Askar Safin <safinaskar@...omail.com>
Cc: akpm <akpm@...ux-foundation.org>, corbet <corbet@....net>,
	"john.ogness" <john.ogness@...utronix.de>,
	"lance.yang" <lance.yang@...ux.dev>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	paulmck <paulmck@...nel.org>, pmladek <pmladek@...e.com>,
	rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH v3 1/5] panic: clean up code for console replay

On Tue, Jul 15, 2025 at 05:18:10AM +0400, Askar Safin wrote:
>  ---- On Tue, 15 Jul 2025 04:49:12 +0400  Feng Tang <feng.tang@...ux.alibaba.com> wrote --- 
>  > Thanks for trying the patch! 
> I didn't try it. :) I merely run normal mainline or distro kernel in qemu.
> 
>  > My understanding is, 'console' have kind of different meaning in kernel
>  > space than just /dev/console. In printk.c, you can see 'console' is
>  > used everywhere,  which are mostly bound to kernel message.like
>  > console_try_replay_all(), console_flush_all(), console_flush_on_panic(),
>  > which are consistent with the new name suggested by Petr.
> Okay, I agree.
> 
> But I still kindly ask you to revert changes to Documentation/admin-guide/kernel-parameters.txt .
> Previous documentation is better.
> admin-guide is written for admins, not for kernel developers. And they understand "console" as /dev/console .
> 
> I run kernel with panic_print=32 in hope that this will flush console (i. e. /dev/console), because this is how I interpreted
> your patched documentation. And I got different effect.

I see. How about changing the patch to: 

-			bit 5: print all printk messages in buffer
+			bit 5: replay all kernel messages on consoles at the end of panic

Thanks,
Feng

> 
> --
> Askar Safin
> https://types.pl/@safinaskar