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Date: Sun, 18 Nov 2007 13:05:03 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Helge Deller <deller@gmx.de>
Cc: linux-kernel@vger.kernel.org, Theodore Tso <tytso@mit.edu>
Subject: Re: [PATCH] Time-based RFC 4122 UUID generator
Message-Id: <20071118130503.7d5ec842.akpm@linux-foundation.org>
In-Reply-To: <200711182038.22055.deller@gmx.de>
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On Sun, 18 Nov 2007 20:38:21 +0100 Helge Deller <deller@gmx.de> wrote:

> Title: Add time-based RFC 4122 UUID generator
> 
> The current Linux kernel currently contains the generate_random_uuid() 
> function, which creates - based on RFC 4122 - truly random UUIDs and 
> provides them to userspace through /proc/sys/kernel/random/boot_id and 
> /proc/sys/kernel/random/uuid.
> 
> This patch additionally adds the "Time-based UUID" variant of RFC 4122, 
> with which userspace applications can easily get real unique time-based 
> UUIDs through /proc/sys/kernel/random/uuid_time.
> A new /proc/sys/kernel/random/uuid_time_clockseq sysfs entry is available,
> so that the clock_seq value can be retained across system bootups (which
> is required by RFC 4122).
> 
> The attached implementation uses getnstimeofday() to get very fine-grained
> granularity. This helps, so that userspace tools can get a lot more UUIDs 
> (if needed) per time than before.
> A mutex takes care of the proper locking against a mistaken double creation 
> of UUIDs for simultanious running processes.

Who will use this feature, and for what?

(In fact, who uses the existing UUID generators, and for what?)

Thanks.