[systemd-devel] device units rely on udev rules?

[Koen Kooi]

Op 9 mei 2011, om 21:43 heeft Lennart Poettering het volgende geschreven:

> On Mon, 09.05.11 11:53, Scott James Remnant (scott at netsplit.com) wrote:
> 
>> Another question I wasn't able to find an answer to in the documentation
>> I've read so far.
>> 
>> The use of device units seems to very much rely on udevd running on the
>> system, and not only that, udev rules having been parsed for the device and
>> a systemd tag "set" in the udevdb. udev obviously starts after systemd, and
>> systemd starts after the kernel.
> 
> Correct.
> 
>> This means there are a large number of devices already known to the kernel
>> at the point that systemd starts, especially if you build the drivers into
>> the kernel for those devices. It's possible to get going straight away with
>> those devices. But relying on udevd tagging them means you end up waiting
>> around for udevd to start, and worse! since udevd doesn't apply rules to
>> existing devices on startup, you have to wait around for "udevadm trigger"
>> to be run.
> 
> That's actually dead fast

It's still in the 10 second range on a 600MHz cortex-a8 machine booting from an SD card. I need to dig out my 400MHz arm920t to see how long it takes there. So having udev-less operation in systemd would be nice, even if it's only used on 'embedded'

regards,

Koen