linux-kernel - Re: [PATCH 0/8] Rework KERN

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Date:	Wed, 6 Jun 2012 02:28:39 +0200
From:	Kay Sievers <kay@...y.org>
To:	Joe Perches <joe@...ches.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-arm-kernel@...ts.infradead.org, linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
	alsa-devel@...a-project.org
Subject: Re: [PATCH 0/8] Rework KERN_<LEVEL>

On Wed, Jun 6, 2012 at 2:19 AM, Joe Perches <joe@...ches.com> wrote:
> On Wed, 2012-06-06 at 02:13 +0200, Kay Sievers wrote:
>> The question is what happens if you inject your new binary two-byte
>> prefix, like:
>>   echo -e "\x01\x02Hello" > /dev/kmsg
>
> It's not a 2 byte binary.
> It's a leading ascii SOH and a standard ascii char
> '0' ... '7' or 'd'.
>
> #define KERN_EMERG      KERN_SOH "0"    /* system is unusable */
> #define KERN_ALERT      KERN_SOH "1"    /* action must be taken immediately */
> etc...

Ok.

>> And if that changes the log-level to "2" instead of the default "4"?
>
> No it doesn't.

So:
   echo -e "\x012Hello" > /dev/kmsg
is still level 4? Sounds all fine then.

> It's not triggering that because devkmsg_writev does
> prefix parsing only on the old "<n>" form.

Yeah, but printk_emit() will not try to parse it? I did not check, but
with your change, the prefix parsing in printk_emit() is still skipped
if a level is given as a parameter to printk_emit(), right?

Kay
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