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