[arch-general] usbmuxd with systemd

[Ray Kohler]

On Sun, Jul 29, 2012 at 9:38 PM, Zhengyu Xu <xzy3186 at gmail.com> wrote:
> Hello to All,
>
> I have a question relating to the new usbmuxd in the testing repo.
>
> Actually I have been bothered for months by the fact that udev failed to
> start usbmuxd automatically after plugging my iphone into lattop since I
> switched to systemd. In order to work it around, I did some trials to
> compare the configuration of my laptop, which running archlinux, with
> another desktop of Fedora 16 in which usbmuxd can be started
> automatically with systemd as service manager. From the files
> "85-usbmuxd.rules" and systemd services, especially the ones related to
> udev, started on both machines, I can not find any difference but the
> results of connecting iphone to each are completely different.
>
> After today's update, the usbmuxd in my laptop worked automatically
> again and I noticed a new file called "usbmuxd.service" in the package,
> which definitely has something to do with systemd. My question is why
> this file is necessary in archlinux. This does not make sense to me
> because I can not find such thing in Fedora 16 that still work fine with
> my iphone.

It's likely that the difference is because Fedora 16 (and still on F17
now) runs a much older version of systemd than Arch does. There have
been some changes to systemd (and udev) in the meantime. In
particular, it's no longer legal for udev rules to start long-running
daemons - systemd will kill such daemons if this happens now. While
I'm not familiar with this particular udev rule, it's likely that it
was doing such a thing, and now the new service file will start it
"the right way".