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Subject: Re: Re: printk meeting at LPC
To:     John Ogness <john.ogness@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Steven Rostedt <rostedt@goodmis.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Petr Mladek <pmladek@suse.com>,
        Andrea Parri <parri.andrea@gmail.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Brendan Higgins <brendanhiggins@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Theodore Ts'o <tytso@mit.edu>, Paul Turner <pjt@google.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Prarit Bhargava <prarit@redhat.com>,
        Jeff Moyer <jmoyer@redhat.com>,
        David Lehman <dlehman@redhat.com>
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From:   Tony Asleson <tasleson@redhat.com>
Organization: Red Hat
Message-ID: <30f29fe6-8445-0016-8cdc-3ef99d43fbf5@redhat.com>
Date:   Fri, 4 Oct 2019 09:48:24 -0500
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On 9/13/19 8:26 AM, John Ogness wrote:
> 9. Support for printk dictionaries will be discontinued. I will look
> into who is using this and why. If printk dictionaries are important for
> you, speak up now!

I think this functionality is important.

I've been experimenting with a change which adds dictionary data to
storage related printk messages so that a persistent durable id is
associated with them for filtering, eg.

$ journalctl -r _KERNEL_DURABLE_NAME=naa.0000000000bc614e

This has the advantage that when the device attachment changes across
reboots or detach/reattach cycles you can easily find its messages
throughout it's recorded history.

Other reasons were outlined when introduced, ref.
https://lwn.net/Articles/490690/

I believe this functionality hasn't been leveraged to its full potential
yet.

-Tony