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How To Fix the DMAR Firmware Bug and Broken BIOS on Ubuntu

Ubuntu 10

In this article, we will walk you through the steps to fix the DMAR Firmware Bug and a broken BIOS on your Ubuntu system. This issue is commonly associated with the error message “DMAR: [Firmware Bug]: No firmware reserved region can cover this RMRR [0x000000008d800000-0x000000008fffffff], contact BIOS vendor for fixes”.

Quick Answer

To fix the DMAR Firmware Bug and broken BIOS on Ubuntu, you can try updating your BIOS or overriding the BIOS setting by adding the "intremap=no_x2apic_optout" parameter to the GRUB_CMDLINE_LINUX_DEFAULT configuration. Running fsck on the problematic device may also help in some cases. However, it’s always recommended to contact your computer manufacturer for further assistance.

Understanding the DMAR Firmware Bug

The Direct Memory Access Remapping (DMAR) feature is a technology used for remapping I/O DMA transfers and interrupt delivery. It’s commonly used for GPU passthrough to a Windows virtual machine. If you’re not using GPU passthrough, you can generally ignore this bug. However, if you’re experiencing other issues like a freezing desktop, sidebar, or top bar, this bug might be the culprit.

Possible Solutions

Updating Your BIOS

One of the most straightforward solutions to this problem is to update your BIOS. BIOS updates often come with fixes for known bugs and issues. Check your computer manufacturer’s website for any available BIOS updates.

Overriding the BIOS Setting

If a BIOS update is not available or doesn’t fix the issue, you can try to override the BIOS setting by adding the “intremap=no_x2apic_optout” parameter to the GRUB_CMDLINE_LINUX_DEFAULT configuration.

Here’s how to do it:

  1. Open the terminal and type sudo vi /etc/default/grub to open the GRUB configuration file with a text editor.
  2. Look for the line that begins with GRUB_CMDLINE_LINUX_DEFAULT and add intremap=no_x2apic_optout nox2apic to the end of the line.
  3. If your system starts complaining about ACPI, you can also add acpi=off to the configuration.
  4. Save the file and exit the text editor.
  5. Run sudo update-grub to update the GRUB bootloader with the new configuration.
  6. Finally, reboot your system.

The intremap=no_x2apic_optout parameter disables the x2APIC opt-out, which is a workaround for systems that have a broken BIOS. The nox2apic parameter disables the x2APIC, which can help to resolve the issue.

The acpi=off parameter disables the Advanced Configuration and Power Interface (ACPI), which is responsible for power management features like hibernation and suspend. Disabling ACPI could potentially impact these functions, so it’s important to weigh the trade-off between resolving the issue and maintaining power management capabilities.

Running FSCK on the Problematic Device

In some cases, running fsck on the problematic device can resolve this issue. fsck is a system utility in Unix and Unix-like operating systems for checking and repairing file systems.

To run fsck, follow these steps:

  1. Open the terminal and type sudo fsck /dev/sda2, replacing /dev/sda2 with the device that’s causing the problem.
  2. Answer “Yes” to all questions.
  3. Reboot your system.

Please note that this solution may not be directly applicable to the DMAR firmware bug, but it has been reported to resolve the issue in some cases.

Conclusion

The DMAR firmware bug and broken BIOS can cause a variety of issues on your Ubuntu system. While this article provides some potential solutions, it’s always recommended to contact your computer manufacturer for further assistance, as they may have specific recommendations or updates related to this BIOS bug.

What is the DMAR Firmware Bug?

The DMAR Firmware Bug is an issue associated with the error message "DMAR: [Firmware Bug]: No firmware reserved region can cover this RMRR [0x000000008d800000-0x000000008fffffff], contact BIOS vendor for fixes". It is related to the Direct Memory Access Remapping (DMAR) feature used for remapping I/O DMA transfers and interrupt delivery.

How do I know if I have the DMAR Firmware Bug?

If you are experiencing issues like a freezing desktop, sidebar, or top bar on your Ubuntu system, the DMAR Firmware Bug might be the cause. Additionally, if you see the error message mentioned in the previous question, it is likely that you are affected by the bug.

What is GPU passthrough?

GPU passthrough is a technology that allows you to dedicate a graphics processing unit (GPU) to a specific virtual machine, typically a Windows virtual machine. It enables better performance and compatibility for running graphics-intensive applications or games within the virtual machine.

What if a BIOS update is not available for my computer?

If a BIOS update is not available for your computer or it doesn’t fix the DMAR Firmware Bug, you can try overriding the BIOS setting by adding the "intremap=no_x2apic_optout" parameter to the GRUB_CMDLINE_LINUX_DEFAULT configuration, as explained in the article.

What are the potential impacts of disabling ACPI?

Disabling ACPI by adding the "acpi=off" parameter to the GRUB configuration can resolve the DMAR Firmware Bug, but it may impact power management features like hibernation and suspend. It’s important to consider the trade-off between resolving the issue and maintaining power management capabilities.

How can running fsck help resolve the DMAR Firmware Bug?

Running fsck on the problematic device can potentially resolve the DMAR Firmware Bug in some cases. fsck is a system utility for checking and repairing file systems. While not directly applicable to the bug, it has been reported to resolve the issue for some users.

Should I contact my computer manufacturer for assistance with the DMAR Firmware Bug?

It is recommended to contact your computer manufacturer for further assistance with the DMAR Firmware Bug and broken BIOS. They may have specific recommendations or updates related to this bug that can help resolve the issue more effectively.

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