microcodeIntel update makes ASUS UX305CA unbootable

[NeQuissimus]

Describe the bug
Computer shows GRUB boot menu, upon selection of NixOS entry, the screen stays blank indefinitely.

To Reproduce

1. Buy ASUS UX305CA laptop
2. Update to NixOS 20.09 (any commit since c89ffdc) OR NixOS unstable (any commit since a79902f)
3. Reboot

Expected behavior
The OS should be able to boot

Additional context
I spent a bit of time reducing this to a single commit. I have this issue on master and release-20.09.
The Intel microcode updates in the above commits seem to cause the issue.

Notify maintainers
@mweinelt

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
  - microcodeIntel
# a list of nixos modules affected by the problem
module:

[mweinelt]

There was a regression, which should be fixed with microcodeIntel 20201118. I forgot to backport them to 20.03 and 20.09, I did that just now. #104303 (comment)

Buy ASUS UX305CA laptop

😄

[NeQuissimus]

😄

I had already tried cherry-picking onto 20.09, does not seem to help.
I'd say we keep this issue open and I'll report back at some point.
For now, I am trying my luck with an overlay that uses 20200616

[Shados]

Oh, this is why my laptop won't boot... 20201118 does not fix it, I am able to boot fine with 20200616.

[NeQuissimus]

I believe the upstream issue to be intel/Intel-Linux-Processor-Microcode-Data-Files#31 btw (intel/Intel-Linux-Processor-Microcode-Data-Files#31 (comment) mentions the m3 CPU specifically)

[mweinelt]

This is just sad. I wonder whether we should revert to 20200616 then. Can you check for open issues over at https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues?

…

On Wed, Dec 09, 2020 at 01:31:21AM -0800, Alexei Robyn wrote: Oh, *this* is why my laptop won't boot... `20201118` does not fix it, I am able to boot fine with `20200616`. -- You are receiving this because you were mentioned. Reply to this email directly or view it on GitHub: #105172 (comment)

[NeQuissimus]

And for others, that come across this issue, here is an overlay that downgrades the derivation:

https://github.com/NeQuissimus/DevSetup/blob/8803c4443ea0ff76b333f76796cbc60c4bc1b708/ux305c.nix#L37-L39
https://github.com/NeQuissimus/DevSetup/blob/8803c4443ea0ff76b333f76796cbc60c4bc1b708/ux305c-overlay.nix

[mweinelt]

I believe the upstream issue to be intel/Intel-Linux-Processor-Microcode-Data-Files#31 btw (intel/Intel-Linux-Processor-Microcode-Data-Files#31 (comment) mentions the m3 CPU specifically)

Though that comment is from June and does not feel actionable to me. Better to create something new relating to the november series of microcode releases.

[stale]

I marked this as stale due to inactivity. → More info

[Shados]

Still matters to me. I'll test whether or not the current, more recent microcode (20210216) still breaks booting on this laptop, though.

[Shados]

Yeah, still broken with 20210216. I might do some digging and see if I can narrow things down any.

[Shados]

Boots OK with the even-newer microcode-20210608 files.

[NeQuissimus]

@Shados Awesome, I can confirm my laptop boots with 20210608. I created #126888 to update the version in nixpkgs

[mweinelt]

Fixed in #126291. Backports to release branches will be up soon.