From: "Henrik Rydberg" <rydberg@euromail.se>
Date: Sun, 26 Feb 2012 11:47:01 +0100
To: Bobby Powers <bobbypowers@gmail.com>
Cc: "Ted Ts'o" <tytso@mit.edu>, Greg KH <gregkh@linuxfoundation.org>,
        Guenter Roeck <guenter.roeck@ericsson.com>,
        Jidong Xiao <jidong.xiao@gmail.com>,
        Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: Can we move device drivers into user-space?
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> > The main issue that set me off has been sufficiently diluted in the
> > (selective) discussion so as to no longer make sense as a reply: At
> > some point, in-tree or out-of-tree will no longer be distinguishable,
> 
> Please explain how you would be unable to distinguish between a driver
> that lives in the kernel source tree, and one that does not.

The SUD pointed to in the beginning of the thread is an example of
this, but I was not thinking of it in quite so literal terms. Rather,
I was imagining that as the kernel grows and the in-kernel interfaces
matures, the amount of actual communication between different portions
of the code diminishes. Code on opposite sides of a stable interface
is, for all practical purposes, separated. Whether that code lives
in-tree or out-of tree is then of little consequence.

To try to prevent another flame war, let's make it clear that I am not
saying that the most powerful in-kernel argument, that code can be
changed, is unimportant. Maybe code, like so many other things,
arranges itself in a scale-free critical fashion, which would forever
warrant a monolithic approach. Maybe it would even make sense to have
userspace join the same tree as well. There is however a frofoundly
political aspect here, which cannot be expressed in terms of
code. Also, in practise, breaking things down into manageable chunks
is usually a good idea in the end.

Thanks,
Henrik
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