MMIO Stale Data CPU bug

[Divemaskstrap]

Hi you all,

I am using Endeavour OS for a while now, and because of plymouth I never payed a lot of attention to boot messages.

But recently I was checking them via demesg and I saw this message passing by:

0.176838] MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html for more details.

I wanted to solve this by adding this to my systemdboot config:

mds=full,nosmt

But doesn’t seem to work.

I have searched the Arch wiki for systemd-boot options, but I couldn’t find something similar that would solve this.

Do you guys have an idea?

Thanks a lot!

[kmonster]

Are you sure that you are affected by this bug? If not, you can just ignore that warning instead of putting effort to solve a nonexistent problem.
And how do you know your mitigation is in working or not? If you want to switch off SMT you can do this in BIOS.

[Divemaskstrap]

@kmonster , thanks for this reply!
I will ignore it then if this is just a warning.

Cheers!

[yum13241]

You must execute sudo reinstall-kernels every time you make a change to /etc/kernel/cmdline.

[kmonster]

grub-mkconfig is sufficient, if you use grub. BTW on my system there is no file /etc/kernel/cmdline with this name, the kernel command line is in /etc/default/grub. Are you using systemd-boot maybe?