Is there a non-systemd alternative to systemd-utils udev?

[lars_the_bear]

Hi folks

I've only been looking at this forum for a couple of months, but I've already seen a couple of threads (maybe more) from people who are confused about why they have bits of systemd in their installation, when they thought they weren't using it. Or from people who have used PACKAGE_MASK to eliminate any residual bits of systemd, and ended up with a non-working system because there's no udev.

To be fair, the situation with udev is well-documented. Nevertheless, I suspect that many people come to Gentoo with the express intention of avoiding systemd (although I appreciate that isn't a universal goal). It surprises me that there isn't a workable, non-systemd version of udev. Or, if there is, it's not very prominent.

I found a file under /var/db called "2021-08-24-eudev-retirement.en.txt", which explains why eudev is no longer maintained. It suggests "sys-fs/udev" as the alternative, but sys-fs/udev does not seem to exist. I'm guessing the sys-fs/udev is now systemd-utils, or part of it.

There do seem to be 3rd-party overlays that still have sys-fs/eudev. There's also mdev from Busybox, but I'm not sure how practical it is.

To be clear: it doesn't bother me that there are files and directories in my installation with 'systemd' in the name. Nor am I much concerned that there might be other unused bits of systemd lurking about. I'm more concerned that system-utils udev is part of the sytemd project, and has had ten years of tinkering from the systemd maintainers. The implications of this tinkering are hard (for me) to assess but, on balance, I would prefer not to use it at all.

So: is there really no way to run Gentoo practically, without using software that is part of the systemd effort?

BR, Lars.

[sMueggli]

The short answer: systemd-utils is the non-systemd udev alternative.

It is like in programming. The hard thing is not to programm (create the logic) but naming the things. Whether you are naming a variable "username" or "a9382593" does not change anything to the interpreted or compiled code. For 99% of the code readers the first variant is better and clearer, but for 1% the latter is preferable (for whatever esoteric reason).

[lars_the_bear]

[sMueggli]

If you look at the ebuild, you will see

[Zucca]

systemd devs have made few of the systemd utilities totally independent from systemd.
udev and tmpfiles are few examples.

I've personally had incompability issues with other udev implementations when I've tested my own udev rules with those, so I've kept using udev from systemd.

Despite of all this, if you're adventurous, you can try mdev for example.
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[pa4wdh]

I've also been searching for alternatives to udev. Apart from the association with systemd i also don't like the way you have to configure it and it's network interface renaming.

If you really want to be independent of systemd i think mdev is the closest you van get: https://wiki.gentoo.org/wiki/Mdev
However, it's limitations (especially with it comes to devicemapper) make it unusable for my use cases.

I also just found mdevd, a mdev compatible daemon separate from the busybox project. I haven't looked enough into this to see it that fits my use cases.
https://skarnet.org/software/mdevd/
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[lars_the_bear]

[Zucca]

[lars_the_bear]

[Zucca]

[lars_the_bear]

[Chiitoo]

[lars_the_bear]

[pa4wdh]

[elbci]

I have this trolling medical condition. Once every two or so yrs I go to internet, post a few off-topic rants, see how things got worse in the mean time and go back to my dogs and too-big-for-me-backyard. So... here we go...

[logrusx]

[Zucca]

@elbci "nice story bro", but we've had conversations like this before. Let's not derail this topic any more than it needs to be.
Currently we're exploring the possibilities of replacing only systemd-udev.
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Gentoo IRC channels reside on Libera.Chat.
--

[lars_the_bear]

It's a shame that it's impossible to discuss any aspect of systemd without provoking a heated response. I'm not a fan of systemd, but I hope I am at least able to discuss it without frothing at the mouth.

My concern about systemd_udevd is that it doesn't really seem to be independent of the rest of systemd. Looking at the source code, I see many calls to bus_connect_system_systemd() which connects to systemd via a socket at /run/systemd/private. I don't know enough about systemd to know whether these operations are, or could be, problematic on a non-systemd system. They all seem to fail gracefully, and clearly systemd_udevd does work right now without systemd.

My worry is that, in the longer term, integration between systemd_udevd and the rest of systemd will become tighter. That integration is already there, even if it's not yet problematic. Whatever else can be said about systemd, I'm fairly sure that modularity of the different components is the maintainers' number one design priority. Sooner or later, systemd_udevd might not work without the rest of systemd.

Then what? I guess what I'll do is fall back on all-manual device management, although it's a pain. I wondered what the few other non-systemd Linux distros do in this area, but all I find is confusion there as well. The lack of a non-systemd udevd seems to be a serious problem for everybody who doesn't want to buy into systemd.

Having said that, I don't have the time to write and maintain one. I fully understand that it's not the job of the Gentoo maintainers to fix this mess, even if they had the resources; but I can't think of anybody else who will :/

BR, Lars.

[GDH-gentoo]

[logrusx]

[lars_the_bear]

[elbci]

Final notes:

[CaptainBlood]

Maybe off topic...
Using without-systemd overlay here:
No systemd-utils installed.

Thks 4 ur attention, interest & support.
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[eschwartz]

[lars_the_bear]