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[alpine-devel] Re: udev replacement on Alpine Linux

From: Jude Nelson <judecn_at_gmail.com>
Date: Sat, 25 Jul 2015 20:51:12 -0400

Hi everyone,


> [vdev] a device manager with an approach a bit different, offers an
> optional filesystem interface that implements a per-process view of
> /dev. Possibly the least simple alternative, but interesting
> nonetheless.
>
>
Thank you for your interest in vdev. I am the principal developer. I hope
you all don't mind me chiming in to provide a little bit more information.

First, I can't emphasize the "optional" qualifier enough regarding the
filesystem component vdevfs. The hotplug daemon vdevd and the
libudev-compat library are meant to replace udevd and libudev respectively;
the filesystem is an add-on that can be used independently of whatever
device manager is running. There are more detailed write-up's on the
design goals for each of the three vdev components in [0] and [1].

Second, I would like to point out that vdevd by itself is not too different
from mdev, nldev, and smdev. The udev-like behavior comes almost entirely
from the shell scripts and auxiliary helper programs it executes in
reaction to device uevents. I bring this up because these scripts and
helper programs could easily be ported to mdev, nldev, and smdev simply by
providing a wrapper that sets the appropriate environment variables (a
listing can be found in Appendix A of [2]).

Third, I would like to point out that libudev-compat is *not* dependent on
vdevd or any device manager. A libudev-compat process receives device
events by watching for new files written into a well-defined directory in a
RAM-backed filesystem. Vdevd simply runs a script to fill in /run/udev and
write device event files in order to communicate with libudev-compat
processes.

I'm happy to help test and evaluate vdev with Alpine. This document [2]
contains a tutorial on how to try it out without installing, and what to
send me if something breaks. We'll be making an alpha branch soon (see
[3]).

[0] http://judecnelson.blogspot.com/2015/01/introducing-vdev.html
[1] https://github.com/jcnelson/vdev/issues/32
[2] https://github.com/jcnelson/vdev/blob/master/how-to-test.md
[3] https://github.com/jcnelson/vdev/issues/33

Thanks,
Jude



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Received on Sat Jul 25 2015 - 20:51:12 GMT