The kernel developer decided to change the default for intel_iommu.
Some machines have problems after the update. Either not booting at all or throwing messages like these around:
Oct 08 13:26:28 eigen kernel: DMAR: DRHD: handling fault status reg 3 Oct 08 13:26:28 eigen kernel: DMAR: [DMA Write] Request device [00:02.0] fault addr 3a87000 [fault reason 23] Unknown Oct 08 13:26:28 eigen kernel: DMAR: DRHD: handling fault status reg 3 Oct 08 13:26:28 eigen kernel: DMAR: [DMA Write] Request device [00:02.0] fault addr 3a84000 [fault reason 23] Unknown Oct 08 13:26:28 eigen kernel: DMAR: DRHD: handling fault status reg 3 Oct 08 13:26:28 eigen kernel: DMAR: [DMA Read] Request device [00:02.0] fault addr 7ea000 [fault reason 23] Unknown Oct 08 13:26:31 eigen kernel: [drm:fw_domains_get [i915]] *ERROR* render: timed out waiting for forcewake ack to clear.
or
Oct 08 13:49:23 eigen kernel: DMAR: DRHD: handling fault status reg 3 Oct 08 13:49:23 eigen kernel: DMAR: [DMA Write] Request device [00:02.0] fault addr 3568000 [fault reason 23] Unknown Oct 08 13:49:23 eigen kernel: DMAR: DRHD: handling fault status reg 3 Oct 08 13:49:23 eigen kernel: DMAR: [DMA Write] Request device [00:02.0] fault addr 35aa000 [fault reason 23] Unknown Oct 08 13:49:23 eigen kernel: DMAR: DRHD: handling fault status reg 2 Oct 08 13:49:23 eigen kernel: DMAR: [DMA Write] Request device [00:02.0] fault addr 35ec000 [fault reason 23] Unknown Oct 08 13:49:32 eigen kernel: [drm] GPU HANG: ecode 8:0:0x85dffffb, in chromium [1112], reason: Hang on rcs0, action: reset Oct 08 13:49:32 eigen kernel: [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace. Oct 08 13:49:32 eigen kernel: [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel Oct 08 13:49:32 eigen kernel: [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue. Oct 08 13:49:32 eigen kernel: [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it. Oct 08 13:49:32 eigen kernel: [drm] GPU crash dump saved to /sys/class/drm/card0/error Oct 08 13:49:32 eigen kernel: drm/i915: Resetting chip after gpu hang Oct 08 13:49:32 eigen systemd[1]: Starting autorandr execution hook... Oct 08 13:49:40 eigen kernel: drm/i915: Resetting chip after gpu hang
I found a hint on how to fix this issue in the Archlinux forums.
Try booting linux with intel_iommu=off or intel_iommu=igfx_off (in the grub
menu hit e to edit the boot command)
To make it permanent add the respective flag to /etc/default/grub and run:
sudo grub-mkconfig -o /boot/grub/grub.cfg
This should fix the issue.