Re: [RESEND RFC PATCH 0/5] Add a hash value for each line in /dev/kmsg

[Joe Perches <joe@perches.com>]

On Thu, 2013-07-25 at 17:37 +0900, Hidehiro Kawai wrote:
> ================
> This patch series adds hash values of printk format strings into
> each line of /dev/kmsg outputs as follows:
> 
>         6,154,325061,-,b7db707c@kernel/smp.c:554;Brought up 4 CPUs
> 
> These hash values allow use space to identify messages easily and
> do valuable things.  There is no guarantee that the hash values
> are unique.  However, user space can know which one collides to
> others from a message-and-hash catalog generated at build time, so
> finally it should be able to identify the messages.  User space
> can also use filename:lineno information to do that, although the
> information is not portable among various kernel versions.
> 
> 
> Background
> ==========
> We sometimes want to identify each kernel message automatically
> because of the following purposes:
> 
> (1) Show more detailed information about the message by cooperating
>     with external system
> (2) Take actions automatically depending on the message, for example
>     trigger a fail over or collect related information to analyze the
>     problem

If there are really "take action" uses, perhaps
it'd be better to mark the specific areas of code
where this needs to be done and add a notifier
function there instead of depending on post effect
processing.