linux-kernel - Re: [PATCH] printk: Make CONSOLE_LOGLEVEL

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Date:   Wed, 20 Jun 2018 15:43:09 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] printk: Make CONSOLE_LOGLEVEL_QUIET configurable

Hi,

On 20-06-18 13:24, Sergey Senozhatsky wrote:
> On (06/20/18 13:03), Petr Mladek wrote:
>>> This commit makes CONSOLE_LOGLEVEL_QUIET configurable.
>>>
>>> This for example will allow distros which want quiet to really mean quiet
>>> to set CONSOLE_LOGLEVEL_QUIET so that only messages with a higher severity
>>> then KERN_ERR (CRIT, ALERT, EMERG) get printed, avoiding an endless game
>>> of whack-a-mole silencing harmless error messages.
>>
>> I find it a bit confusing that "quiet" would mean something different
>> on different systems.
> 
> Good that you brought this up. I had similar feelings but then the
> patch looked rather simple and I kinda agreed with it. If we can come
> up with alternative solution (you mentioned some) then it would be
> great.

I guess with my downstream hat on that we could live with silent,
but I would much prefer changing quiet, also so that we can lower
the firehose of mostly false-positive bugs coming in because of this.
Here is a short list from quick search which in no way is complete
(tip of the iceberg really):

   1413342 - Linux 4.9.3: ACPI Error: [_OSI] Namespace lookup failure, AE_NOT_FOU
   1415853 - ACPI Error: Namespace lookup failure, AE_NOT_FOUND (20160831/psargs-
   1514937 - ACPI Error: AE_NOT_FOUND
   1527870 - ACPI Error: [\_SB_.PCI0.SAT1] Namespace lookup failure, AE_NOT_FOUND
   1552580 - ACPI Error: Method parse/execution failed
   1553320 - Kernel errors at bootup -- system runs okay
   1556967 - ACPI Error: [SMIC] Namespace lookup failure, AE_ALREADY_EXISTS
   1582825 - ACPI Error: Method parse/execution failed
   https://bugzilla.kernel.org/show_bug.cgi?id=109511
   https://bugzilla.kernel.org/show_bug.cgi?id=194687

If we change quiet to filter these out, all of these will go away, if
we add a new silent option then only fresh installs will get the
new silent option and the benefit will be much reduced.

Besides that we would also need to make e.g. arch/x86/boot/edd.c
check for both quiet and silent and of course init/main.c and probably
others too, so form a code complexity pov the Kconfig way seems better too.

Regards,

Hans