[Techtalk] understanding udev

[Marize Pommot-Maia]

On 12/24/06, Akkana Peck <akkana at shallowsky.com> wrote:
> I've been fighting with a new Ubuntu Edgy install on my laptop --
> I'm having trouble getting my PCMCIA wi-fi card to be configured
> automatically (yes, I already added "allow-hotplug eth0" in
> /etc/network/interfaces), and getting /dev/sda1 to be created so
> that I can read cards in the built-in memory stick reader.
>
> This all boils down to Edgy's elimination of the hotplug and
> pcmcia-cs systems in favor of doing everything through udev and
> a udev helper called pccardctl. In previous Ubuntu releases it was
> pretty easy to tweak the udev and hotplug systems to work together:
> /etc/hotplug was all scripts so I could put in debugging lines
> to figure out how control passed from one script to another,
> but /lib/udev is all binaries so that's no longer an option.
>
> I've done lots of googling and reading man pages, but the udev man
> pages are pretty minimal, and everything I've found on the web
> describes older versions of the system and references programs that
> no longer exist, or udev configuration lines that no longer work.
> Questions like: How is a device supposed to get recognized as it
> passes through the various udev layers? How do pcmcia devices work,
> and at what point is a network suppose to get configured? How does a
> program like hal tell udev to create a new device node, and how
> could I do that myself?
>
> Anybody have a clue how to find more information about udev, or how
> to debug udev problems?  I'm getting a bit tired of having to run
> "ifdown eth0; ifup eth0" every time I resume from suspend, or having
> to stop and start udev any time I need to read a memory stick.
>
>         ...Akkana
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Hi,

You may want to read this document:
http://www.reactivated.net/writing_udev_rules.html

The following is Gentoo-centric but it shows an example of such a rule:
http://gentoo-wiki.com/UDEV

HTH,
-- 
Marize Pommot-Maia
marize at gmail.com