DMAR firmware bug. Broken BIOS?

Solution 1:

DMAR firmware bug. Broken BIOS?

Yes, it is the BIOS that is giving the kernel information that is incorrect (ie. does not follow the specification).

DMAR is mainly used for GPU passthrough to a Windows virtual machine. If you do not use this you can ignore this bug otherwise you will need to look for a BIOS update.

Use 'intremap=no_x2apic_optout' to override the BIOS setting.

Use that and the bug is ignored and no longer shown. Change GRUB_CMDLINE_LINUX_DEFAULT:

sudo vi /etc/default/grub

• add intremap=no_x2apic_optout nox2apic.
• Add acpi=off if the system starts complaining about ACPI.

After editting do

sudo update-grub

and reboot.