At some point in the 18.04 cycle, /sys/bus/iio has disappeared from my system

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apport-collect 1807250

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Right, I understand fully what the bot is asking for, but it's not exactly relevant here. We are seeing (on at least two systems) a lack of IIO device discovery. If I modprobe all the iio modules, I do get a /sys/bus/iio, but no devices in it. So it feels like something is missing, but I don't know where.

I just tried booting into 4.15.0-20 as the release pocket has it still and it also failed to work. So now I'm wondering if/when it did work. I will try and narrow it down in the next few days.

Yeah, so this is like the person who started complaining about this stuff which was totally confirmed by nacc.

Exceedingly fun fact: current bionic userspace/install booted with debian stable kernel 4.9, debian testing kernel 4.18 and ye olde xenial 4.4.0-134 is working just fine *indicating* that support for an entire bus class has been missing/faulty in ubuntu >=4.15 since bionic launch like way back before everyone knew the name Cambridge Analytica and that girl with the weird teeth from "Smallville" was charged with human trafficking or whatever. I realize that people have selfies to take and like totally have to spend a lot of time placating their friends about their issues and stuff but that no one noticed this until now is kinda disturbing and I like totally have to resist the urge to somehow implicate Kylie Jenner in this.

The reason for the attitude is that i had to complete a friggin js-required Scroogle puzzle to state the obvious.

https://news.ycombinator.com/item?id=18711970

The sad state of being able to use Ubuntu on touch devices (hint: you can't)

 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1807250

So, apparently support for an entire bus class has been missing since ubuntu bionic (18.04 LTS) was released in april. Using kernels from other distros or ubuntus old xenial 4.4.0-134 all provide access to sensor data, suggesting the issue is with current (and shipped) kernels. Three weeks into this not much is happening even though the issue also affect canonical-specific 4,18 kernels.

This all suggests that pretty much no one has been using ubuntu on touch devices otherwise i wouldn't be the first one to notice this. Now that the devs know this they have no time for it...

The issue now appears resolved with hwe-18.04/4.18.0-13, /sys/bus/iio is now present and the functionality has been restored.

Summary:
/sys/bus/iio appears to be missing on all the bionic 4.15.* kernel releases (including 4.15.0-43) but is present on xenial 4.4 and cosmic 4.18 (at least as of 4.18.0-13). Here is to hoping there is not a similar kerfuffle with RNGs and stuff :P

Please find the first -rc kernel that fixes the issue between v4.15 and v4.18.
Kernels can be downloaded at [1].

[1] https://kernel.ubuntu.com/~kernel-ppa/mainline/

Incomplete: Someone please answer comment #7.

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[Expired for linux-hwe (Ubuntu) because there has been no activity for 60 days.]