OoO En cette fin de matinée radieuse du dimanche 29 avril 2012, vers
11:25, Svante Signell <svante.signell@telia.com> disait :
>> But that's the whole point : new hardware pops up while booting. See for
>> example a server that will need a 3G connection. The 3G connection will
>> be done by some classic USB key. When the USB key is detected, udev
>> triggers a script asking the USB key (which defaults to a mass storage
>> device) to switch to "modem mode". Once it becomes a modem, the 3G
>> connection can be initialized. Turning the USB key into a modem is
>> taking some time. The USB key will be "disconnected", then
>> "reconnected". SO, "found new hardware". ifupdown scripts were already
>> run and filed with "interface not found".
> Nice description, thanks. However, this is not necessarily part of the
> _boot_ process!! This could/should happen _after_ the computer is up and
> running, e.g. when starting X. You are not able to use your USB modem
> until then anyway, and boot times should be as short as possible, not
> having to wait for a dongle to connect to the wireless network.
There is no X. It is a _server_. Its only available network connection
is through this 3G usb dongle. If it does not happen on boot, it never
happens.
>> udev can run simple actions when a device appears but cannot run a chain
>> of dependencies (start the 3G connection, run some daemon that needs
>> Internet which in turn will trigger some client to this daemon to
>> run). The solution is an event-based init. We want a reliable boot.
> Then the functionality of udev should be extended, not dragging the
> init scripts into this udev<->Linux kernel interaction. I think it
> would be much better to isolate these two instead of having a third
> (potentially buggy) software included.
The functionality of udev should be extended to manage dependencies
between system daemons? Isn't the job of init?
--
Vincent Bernat ☯ http://vincent.bernat.im
Format a program to help the reader understand it.
- The Elements of Programming Style (Kernighan & Plauger)
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