Re: [PATCH] expand-on-first-boot: wait for udev to create symlink

["Roberto A. Foglietta" <roberto.foglietta@gmail.com>]

On Fri, 9 Dec 2022 at 11:51, Schaffner, Tobias
<tobias.schaffner@siemens.com> wrote:
>
>
> The problem appears if this systemd unit is not up yet when we try to
> use systemd-growfs by hand.
>
> Therefore a udevadm trigger/settle would also most probably hit too early.
>

Dear Tobias,

 I am not an expert of udev because I never investigated its code.
However, for the little I did with it, udevadm is the main tool to
interact with udev. In particular udevadm trigger --action=add is
exactly the request we send in order to push udev to register devices.
Because this registration is not immediate, udevadm settle is a good
way to wait for it finishes. Probably --type=subsystems
--subsystems-type=block could be better address the initial trigger
request. In my case, it seems not appropriate but further
investigation may worth a little of time. The settle could have a
timeout and in such a case a loop of pooling for the device should
run. In my specific case, udevadm also terminate udev because the
initial instance at boot time would not collide with system instance
called later. I hope this helps.

 Best regards, R-