[systemd-devel] Use a specific device ?

[Harald Hoyer]

On 05.06.2015 15:28, Mantas Mikulėnas wrote:
> On Fri, Jun 5, 2015 at 4:22 PM, Harald Hoyer <harald.hoyer at gmail.com
> <mailto:harald.hoyer at gmail.com>> wrote:
> 
>     On 05.06.2015 15:09, poma wrote:
>     > On 05.06.2015 14:14, Jean-Christian de Rivaz wrote:
>     >> Le 05. 06. 15 13:18, Aleksander Morgado a écrit :
>     >>> On Tue, May 26, 2015 at 12:19 AM, Jean-Christian de Rivaz <jc at eclis.ch
>     <mailto:jc at eclis.ch>> wrote:
>     >>>> I have a system where the modem have multiple /dev/ttyACMx ports where
>     x is
>     >>>> not constant because of the dynamic nature of others serial devices.
>     >>> It may be worth noting that a very similar issue with the one faced
>     >>> here is the one with network interface names, where interface names
>     >>> were created as kernel drivers probed the different interfaces, ending
>     >>> up with "eth0", "eth1" and so on. Then, there would be network
>     >>> interface configurations for each network interface based on the name,
>     >>> but no one really ensured that the name was the same upon reboots. The
>     >>> solution provided by systemd to ensure that the proper configuration
>     >>> is applied always to the proper interface is to make the device names
>     >>> "predictable", see:
>     >>>
>     http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
>     >>>
>     >>> This solution avoids the need of any other udev rules to e.g. create
>     >>> network interface names containing the device MAC address or what not.
>     >>>
>     >>> I'm wondering whether the same could be applied not only to network
>     >>> interfaces, but also to ttyACMs, ttyUSBs and cdc-wdms, and end up
>     >>> having predictable tty names like e.g. /dev/ttyACMp0s20u4i0. Sure,
>     >>> those names are a nightmare to type, but they are predictable (e.g. in
>     >>> this case by including the physical location of the connector of the
>     >>> hardware).
>     >>>
>     >>
>     >> This would be a wonderful solution. The only problem is when will this
>     >> feature be available in a stable Linux kernel widely used by all majors
>     >> distributions? Until this dream happens (probably not before severals
>     >> years I guess), an other option must be implemented.
>     >>
>     >> Jean-Christian
>     >
>     >
>     > Face your broadband modem, live your dreams?
>     >
>     > Kay, when this would happen - Predictable Broadband Modem Interface Names?
>     >
> 
>     Wouldn't it be nicer to have symlinks like in /dev/disk ?
>     /dev/tty/by-path/....
> 
> 
> 60-serial.rules:16:ENV{ID_PATH}=="?*", ENV{.ID_PORT}=="",
> SYMLINK+="serial/by-path/$env{ID_PATH}"
> 60-serial.rules:17:ENV{ID_PATH}=="?*", ENV{.ID_PORT}=="?*",
> SYMLINK+="serial/by-path/$env{ID_PATH}-port$env{.ID_PORT}" 
> 
> -- 
> Mantas Mikulėnas <grawity at gmail.com <mailto:grawity at gmail.com>>

There we go.. already implemented :)