acpi(probably) random hang on boot

[Marcin Tanasiewicz]

This happens on a fresh installation of Ubuntu 18.04.02 on a brand new Asus UX433FN ultrabook.

Ubuntu randomly hangs on boot, during the first black screen that appears. Sometimes it boots normally, but shows couple acpi errors for a second. I can boot successfuly after couple attempts usually. Sometimes the system boots successfully for couple times in a row.

Sometimes it hangs on displaying a line: laoding initial ramdisk...

Usually I have to force shut down the system, and start it again to boot. I haven't noticed any recurrence in those behaviours it just happens randomly.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.18.0-20-generic 4.18.0-20.21~18.04.1
ProcVersionSignature: Ubuntu 4.18.0-20.21~18.04.1-generic 4.18.20
Uname: Linux 4.18.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.6
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon May 20 19:59:39 2019
EcryptfsInUse: Yes
InstallationDate: Installed on 2019-05-18 (2 days ago)
InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
SourcePackage: linux-signed-hwe
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Lei Zhao (leizmonk)]

Seems like this bug could be related to: https://bugs.launchpad.net/ubuntu/+bug/1829735?

[Mark (markthecodehamster)]

Most likely duplicate of https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1829620
where we found the culpit (intel-microcode) and have a workaround.

[Marcin Tanasiewicz (mtanas)]

Thanks Mark, it looks like it is a duplicate of https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1829620

The temporary solution seems to resolve the problem for now. I added dis_ucode_ldr parameter to grub, and the system booted normally 3 times in a row, although still it shows ACPI errors in logs. Will keep updated if something more happens.