[systemd-devel] systemd unit review requested

[Lennart Poettering]

On Wed, 11.12.13 12:34, Peter Hutterer (peter.hutterer at who-t.net) wrote:

> > If a module exposes those alias lines then the module is auto-loaded by
> > udev as soon as matching hardware shows up. That's the preferable way to
> > load kernel modules these days, instead of loading them explicitly they
> > way you are doing it.
> > 
> > Of course, what's behind an rs232 port is generally not automatically
> > discoverable, that's why Kay was asking whether the modalias line is
> > insufficient.
> 
> ok, after spending half the day going down the most likely wrong track: are
> we talking about auto-loading the module once inputattach is launched, or
> dropping the need for inputattach?
> 
> because if it's the former then yes, I can confirm that works and the module
> is loaded correctly so the modalias seems to work here. we can drop the kmod
> from the udev rule.

Well, it's udev that loads the kmod as the hw shows up, not inputattach
that triggers the loading. inputattach comes later...

> > It sounds like a good idea to get rid of the explicit module loading and
> > simply rely on the modalias stuff for that. Then, if your program really
> > only does what you list above (i.e. nothing that can block for longer or
> > that needs to stay around during runtime), then you could just do this
> > synchronously as part of an udev rule, no?
> 
> sorry, I wasn't clear enough. inputattach does the above and then just sits
> with a 0-byte read() to keep the line open. as soon as inputattach finishes
> the device will revert back to just being a serial device.
> so it's definitely not a one-shot, we need it to sit there.

OK, then doing this as systemd service is the right thing.

Lennart

-- 
Lennart Poettering, Red Hat