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Date: Thu, 07 Apr 2011 07:43:55 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: tip: New "Link:" tag to replace "LKML-Reference:"
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On 04/07/2011 07:08 AM, Peter Zijlstra wrote:
> 
> OK, so I fixed my scripts to match this and it all seems to work, except
> for the:
> 
>  LKML-Reference: <new-submission>
> 
> case, where the tip-bot would mail it out for me. While I try not to use
> it too much its convenient for quick fixes etc. Will the absence of a
> Link tag suffice or is there more to it?
> 

OK, I have asked for a long time that we do not use <new-submission>.

The recommended pattern has been:

LKML-Reference: <tip-*@git.kernel.org>

... which at least indicates to the user how the message-ID is to be
generated (* being a placeholder for the commit SHA1).

The only think I can think of for how to make Link: work would be to
recognize a pattern that the tip-bot would use as its own Message-ID
*instead* of the commit SHA1 pattern that it would normally use.  There
are disadvantages to every approach, of course.

We have a couple of alternatives:

a) Continue to use "LKML-Reference: <tip-*@git.kernel.org>"
   + At least gives a hint how to find the newly-formed LKML thread
   - Not a clickable link
   - Somewhat noisy
b) Just Cc: everything to LKML regardless of tag
   + Easy
   - No way to *not* post everything to LKML
   - No way to locate the thread without knowing the magic
c) A recognizable pattern with a unique pattern *generated by the
   committer*, something like:
   Link: http://lkml.kernel.org/r/tip-`uuidgen -r`@git.kernel.org
   + Clickable link
   - Long (the above is 86 characters wide)
   - Message-IDs of a nonstandard form
   - Bad things will happen if someone re-uses an identifier
   - String has to be generated by machine at commit time

[Using ranpwd instead of uuidgen allows for a more compact random string
by using a wider character set.  For example:

Link: http://lkml.kernel.org/r/tip-`ranpwd -l 24`@git.kernel.org

... has the same entropy but is 74 characters wide.]

Thoughts?

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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