[crux-devel] udev

Juergen Daubert jue at jue.li
Sat Jun 16 08:34:05 UTC 2012


Hello together,

as you all may have already noticed, as of version 183 the udev sources
has been merged into the systemd sources. 
At the time I read the first announcement from Kay Sievers that doesn't 
sound too bad [1] to me, because I got the impression that it would be easy 
to extract udev from systemd.

Unfortunately in practice the whole thing looks like a big, bad issue.
It's not possible to configure systemd in a way that udev can be build
standalone, but you have to build the complete systemd stuff and manually 
extract what is needed for udev. Kay's comment on to that issue sounds quite 
different than the first announcement to me [2].

In the meantime we can see two attempts of other people to submit patches 
[3][4] to improve the situation, but with no "official" comment yet.

Currently we don't have a practical issue with all of that, because we can
stick with udev 182 for now. You may ask why I wrote all of this, it's just
for your information and to summarize the whole situation. For me the whole 
udev/systemd source merge looks like a crude effort to force people to use 
systemd.

But what can we do? Good question, in the long run it will be impossible
to use udev standalone IMO, so we either have to switch to it or do 
something completely different. One possiblity might be mdev, a dynamic 
device/node creation program that comes with busybox, see [5] for a short 
description, together with devtmpfs which is a kind of devfs, see [6].
Btw, I'm not sure but it looks like our Per had put a comment to that
article ;) [7]

We, that means Jose, Fredrik and me, have done some initial tests with
mdev, it looks not so bad at all. We will continue on testing it and report
here our experiences.


Thanks for the attention and a nice weekend to all.
Juergen

[1] http://article.gmane.org/gmane.linux.hotplug.devel/17392
[2] http://article.gmane.org/gmane.linux.hotplug.devel/17444
[3] http://thread.gmane.org/gmane.linux.hotplug.devel/17478
[4] http://thread.gmane.org/gmane.comp.sysutils.systemd.devel/5330
[5] http://git.busybox.net/busybox/plain/docs/mdev.txt 
[6] http://lwn.net/Articles/331818/
[7] http://lwn.net/Articles/332502/




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