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Date: Mon, 23 Mar 2015 09:30:13 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Petr Mladek <pmladek@suse.cz>
Cc: Ingo Molnar <mingo@kernel.org>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        "David S. Miller" <davem@davemloft.net>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
        Ananth NMavinakayanahalli <ananth@in.ibm.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Ingo Molnar <mingo@redhat.com>, Jiri Kosina <jkosina@suse.cz>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] kprobes: Disable Kprobe when ftrace arming fails
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On Mon, 23 Mar 2015 13:39:55 +0100
Petr Mladek <pmladek@suse.cz> wrote:


> > wth is a 'universe' in this context?
> 
> We use the term "universe" to define whether the system or task uses
> original or patched functions. It is especially important for patches
> that modify semantic of functions. They need more complex consistency
> model. It defines when it is safe time for the system or task to start
> using the new functions (switch to the new universe).
> 
> In theory, different tasks might be in more universes if more patches are
> being applied. In practice, we deal with only two universes. The trick is
> that we allow to add new patch only when the whole system has switched
> to the previous one.
> 

Is this terminology documented anywhere upstream yet?

-- Steve