Date: Wed, 14 Sep 2005 13:00:49 -0700
From: Mike Bell <mike@mikebell.org>
To: Greg KH <gregkh@suse.de>
Cc: Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org
Subject: Re: [GIT PATCH] Remove devfs from 2.6.13
Message-ID: <20050914200048.GB15017@mikebell.org>
Mail-Followup-To: Mike Bell <mike@mikebell.org>, Greg KH <gregkh@suse.de>,
	Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>,
	linux-kernel@vger.kernel.org
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On Sat, Sep 10, 2005 at 10:09:06PM -0700, Greg KH wrote:
> Said people who like devfs are lazy and don't like running userspace
> programs. 

I hardly consider myself lazy or a hater of user space programs. I've
been an early adopter running unstable series kernels and testing out
new features since long before devfs went into the kernel. In the past
I've been quick to switch over to new ways of doing things as they came
into the kernel, even when it required a fair bit of time and effort to
migrate.

What I don't like is when someone arbitrarily declares that their
half-finished project obsoletes a working one, and yet even a full year
later with a massive development community using the latest kernel
features (sometimes added specifically for that project) it isn't a full
replacement for a project that has been - in your own words -
unmaintained for years and years.

> They pretty much also are pretty restricted to embedded systems.
> That's all I have been able to determine so far.  Care to help flush
> this profile out some?

Probably because they're the people building linux systems from scratch
and caring about the size and speed of the result?

> My applogies, I used the OSS compatible module for ALSA when I tested
> this out. 

And while some input subsystem users force you to specify a device node,
this method is incompatible with hotplugging so the more advanced ones
rely on finding the input device nodes where they're supposed to be, as
they should.

> Hm, ok, ALSA will not work.  Can you point to anything else? 

See above. And of course ndevfs doesn't create the device nodes that udev
doesn't support (yes, even in 2.6.12 devfs still supported more devices
than udev on my test system). Those are just the things that bit me on
the one system I tried ndevfs on before deciding there was no way to
make it work without adding sysfs attributes.

> Who cares about sound on embedded systems anyway...

People who make audio players, SIP phones, PMPs, multimedia displays,
information kiosks, set top boxes, security monitoring devices and PA
systems, to give just a few examples of embedded systems that need sound
and are currently made with linux. And even though embedded linux is
still in its infancy, I would guess that it's responsible for more linux
systems in people's hands than most distributions.

> I'm claiming that the people who insisted that keeping the devfs
> patchset outside of the mainline kernel was impossible.  I show how to
> do this with 3 calls to "add a node" and three calls to "remove a node",
> in a total of only 2 different kernel files.  Such a patch is _easily_
> maintainable for pretty much forever outside the kernel tree.  Distros
> maintain patches _way_ more complex and rough than that all the time.

How is that anything of the sort? ndevfs doesn't work, and isn't even
remotely compatible with devfs. Yes, ndevfs is easy to maintain out of
the kernel tree. But since ndevfs has absolutely nothing to do with
devfs, that doesn't change the fact that devfs can't be maintained out
of the kernel tree. Your reasoning makes no sense.

Anyway, if things continue the way they are with intentional
devfs-breakage having moved from out-of-tree drivers to in-tree drivers,
you'll get your wish soon enough when backhanded devfs removal makes the
in-tree version useless.
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