linux-kernel - Re: [RFC PATCH] cmdline: Hide "debug" from /proc/cmdline

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Date:	Thu, 3 Apr 2014 08:17:33 -0700
From:	Tim Bird <tbird20d@...il.com>
To:	Måns Rullgård <mans@...sr.com>
Cc:	Jiri Kosina <jkosina@...e.cz>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Mateusz Guzik <mguzik@...hat.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
	Ingo Molnar <mingo@...nel.org>, Mel Gorman <mgorman@...e.de>,
	Kay Sievers <kay@...y.org>
Subject: Re: [RFC PATCH] cmdline: Hide "debug" from /proc/cmdline

On Thu, Apr 3, 2014 at 4:25 AM, Måns Rullgård <mans@...sr.com> wrote:
> Jiri Kosina <jkosina@...e.cz> writes:
>
>> On Wed, 2 Apr 2014, Linus Torvalds wrote:
>>
>>> Steven, Borislav, one thing that strikes me might be a good idea is to
>>> limit the amount of non-kernel noise in dmesg. We already have the
>>> concept of rate-limiting various spammy internal kernel messages for
>>> when device drivers misbehave etc. Maybe we can just add rate-limiting
>>> to the interfaces that add messages to the kernel buffers, and work
>>> around this problem that way instead while waiting for Gregs fix to
>>> percolate? Or are the systemd debug messages going to so many other
>>> places too that that wouldn't really help?
>>
>> I think that it's in principle a good idea, however ... the in-kernel
>> ratelimiting always happens per sourcecode location, but this will be
>> rather hard to achieve with interface such as /dev/kmsg.
>>
>> If /dev/kmsg is going to be ratelimited as a whole, it might potentially
>> create a severely unfair situation between individual userspace programs
>> trying to do logging (although there is apparently only one userspace
>> service doing any logging through this interface whatsoever, right?).
>
> The point is that /dev/kmsg is *not* intended as a syslog replacement.

Agreed in general for many systems.  I'll just point out that for ultra-tiny
(i.e. embedded) systems, it's nice to only have one logging implementation
in the system.

I had no idea systemd was so verbose and was abusing the kernel
log buffers so badly.  I'm not a big fan of the rate-limiting, as this just
seems to encourage this kind of abuse.

 -- Tim Bird
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