I'm now using a workaround. I added "module_blacklist=amdgpu" to the kernel command line in /etc/default/grub. The kernel 5.11-series now runs fine, albeit without hybrid amd graphics.
I have put the relevant bit of kern.log when amdgpu is not blacklisted in the attachment. ** Attachment added: "Relevant bit of kern.log when amdgpu is not blacklisted" https://bugs.launchpad.net/ubuntu/+source/linux-meta-hwe-5.11/+bug/1943001/+attachment/5546075/+files/excerpt_kern.log -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-meta-hwe-5.11 in Ubuntu. https://bugs.launchpad.net/bugs/1943001 Title: hwe 20.04 kernel 5.11 series hang at graphical login leaving laptop unusable Status in linux-meta-hwe-5.11 package in Ubuntu: Confirmed Bug description: The 5.11-series 20.04 HWE kernels are not usable on my laptop. They boot up to graphical login. Then the screen goes black for a second every few seconds. When i try to log in the machine seems to hang and the desktop never appears... The kern.log shows a lot of these errors: "[drm:amdgpu_pci_remove [amdgpu]] *ERROR* Hotplug removal is not supported" Many call traces appear as well, involving [amdgpu] and [ttm]. I have reverted to using the 5.8 kernels. ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-generic-hwe-20.04 5.11.0.34.36~20.04.13 ProcVersionSignature: Ubuntu 5.8.0-63.71~20.04.1-generic 5.8.18 Uname: Linux 5.8.0-63-generic x86_64 ApportVersion: 2.20.11-0ubuntu27.18 Architecture: amd64 CasperMD5CheckResult: skip CurrentDesktop: GNOME-Flashback:GNOME Date: Wed Sep 8 09:58:49 2021 InstallationDate: Installed on 2014-07-16 (2610 days ago) InstallationMedia: Ubuntu-GNOME 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.2) SourcePackage: linux-meta-hwe-5.11 UpgradeStatus: Upgraded to focal on 2021-02-24 (195 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-meta-hwe-5.11/+bug/1943001/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
