Re: Questions about initrd environment services and IgnoreOnIsolate

From: Andrei Borzenkov <arvidjaar@xxxxxxxxx>
Sent: Sunday, May 12, 2024 6:44 PM
To: Carolina Jubran <cjubran@xxxxxxxxxx>; systemd-devel@xxxxxxxxxxxxxxxxxxxxx <systemd-devel@xxxxxxxxxxxxxxxxxxxxx>
Subject: Re: Questions about initrd environment services and IgnoreOnIsolate

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On 12.05.2024 18:19, Carolina Jubran wrote:
>> Hello!
>>
>> I need help with a systemd service that loads RDMA and InfiniBand drivers. The service unit specifies DefaultDependencies=no. However, when the service starts in initrd, it gets terminated when initrd-cleanup.service isolates for initrd-switch-root.target in the middle of the initialization.
>>
>
>Then make your service
>
>Before=initrd-switch-root.target

Even with 'Before=initrd-switch-root.target', the service remains susceptible to termination. Hence, I presume 'initrd.target' would be a more appropriate dependency?

>
>assuming it is added to the default transaction. You need to make sure
>your service is not considered started until drives are loaded.
>

What steps can I take to ensure that my service is not considered started until the drivers are loaded?

[Service]

Type=oneshot

RemainAfterExit=yes

ExecStart=/lib/systemd/systemd-modules-load /etc/rdma/modules/%I.conf

TimeoutSec=90s

I attempted to utilize ExecStartPre instead of ExecStart, but systemd indicated that the unit file is missing ExecStart or ExecStop

>> My first question is, what are the correct dependencies required to run this service in the initrd environment? I tried adding IgnoreOnIsolate=true under the Unit section, and it helped, but I'm unsure if that is the correct solution.
>>
>> My second question is, how does IgnoreOnIsolate=true affect the system in initrd? Will this solve the problem, or could it potentially introduce unforeseen issues?
>>
>> Thank you,
>> Carolina Jubran
>>