Your BIOS is broken; bad RMRR -- since I upgraded to Ubuntu 22.04.1 LTS

user2587106

11/22/23, 12:13 PM

I can still boot the machine and use it. Yet since the upgrade from version 20, only the US keyboard layout works reliably. Sometimes I can switch keyboard layouts, but most of the times I cannot.

This is the OS Release I am on now:

$ cat /etc/os-release 
PRETTY_NAME="Ubuntu 22.04.1 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.1 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy

And here is where ubuntu complains about my BIOS being broken:

$ sudo dmesg > dmesg.$(timestamp).txt
$ cat --number dmesg.20221122T114716Z0000.txt | less
...
       267  [    0.139631] DMAR: [Firmware Bug]: No firmware reserved region can cover this RMRR [0x0000000078800000-0x000000007affffff], contact BIOS vendor for fixes
       268  [    0.139636] DMAR: [Firmware Bug]: Your BIOS is broken; bad RMRR [0x0000000078800000-0x000000007affffff]
       269                 BIOS vendor: American Megatrends Inc.; Ver: GL752VW.303; Product Version: 1.0
...

I then checked with my hardware vendor, to make sure that I am using the most recent available BIOS version. The BIOS dates from April 2019, which is not that old.

Before the ubuntu upgrade, I still had a BIOS version from 2014 in place. But ubuntu did not complain before the upgrade ... it should have checked for what it needs to succeed. So this makes it a bug in the upgrade process.

The root cause seems to be a kernel bug. It looks like it can't deal with a BIOS version from 2019 (less than five years old, and actually I expect to be able to use a machine I buy for about ten years).

876

0 + 6

upgrade

boot

user2587106

11/26/23, 3:08 PM

https://www.kernel.org/doc/html/latest/x86/iommu.html?highlight=rmrr says that RMRR means "Intel Reserved Memory Region Reporting Structure"

user2587106

11/26/23, 3:10 PM

https://www.kernel.org/doc/html/latest/x86/iommu.html?highlight=rmrr#what-is-intel-rmrr says: There are some devices the BIOS controls, for e.g USB devices to perform PS2 emulation. The regions of memory used for these devices are marked reserved in the e820 map. When we turn on DMA translation, DMA to those regions will fail. Hence BIOS uses RMRR to specify these regions along with devices that need to access these regions. OS is expected to setup unity mappings for these regions for these devices to access these regions.

user2587106

11/26/23, 3:12 PM

Judging from this, it looks like the problem I face is a kernel bug.

user2587106

11/29/23, 9:31 AM

https://www.kernel.org/doc/html/latest/admin-guide/reporting-issues.html#make-sure-you-re-using-the-upstream-linux-kernel effectively says, that reporting a bug on a kernel in some distro to the kernel developers is pointless. Do you agree?

user2587106

11/29/23, 9:40 AM

The upgrade procedure should have checked the BIOS first, before making changes that cannot be easily reversed. In that respect, I consider the upgrade procedure to be broken.

user2587106

11/29/23, 9:42 AM

A reinstall of Ubuntu 20 on the existing file systems, do you think that would be worth a try, or is that doomed to fail? I have a backup of all files that are of value to me on a separate system.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Your BIOS is broken; bad RMRR -- since I upgraded to Ubuntu 22.04.1 LTS

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