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Date: Mon, 23 Mar 2015 14:34:42 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Petr Mladek <pmladek@suse.cz>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        "David S. Miller" <davem@davemloft.net>,
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        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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* Steven Rostedt <rostedt@goodmis.org> wrote:

> 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?

Even if it was documented (it isn't), it's pretty weird terminology - 
please use clearer formulations, like 'patched function' or 'unpatched 
function' or 'function with pending patch'. No need to redefine 
existing words in a weird fashion just to create the appearance of 
being special ...

Thanks,

	Ingo