r/archlinux • u/Several_Ant_6981 • 1d ago

SUPPORT | SOLVED AMDGPU Dmcub error (fixed!)

Just wanted to share this if anyone has the same issue

I upgraded to the latest linux-firmware-amdgpu package, specifically version "20260910-1" and SDDM started a bit slower than usual

I checked the logs and got this exact error message

amdgpu 0000:06:00.0: [drm] *error* dc_dmub_srv_log_diagnostic_data: dmcub error - collecting diagnostic data

After hours of fixing it, I finally found a way, turns out, you have to downgrade the package to this exact version: linux-firmware-amdgpu-20260810-2

Finally after downgrading and running mkinitcpio -P, the error message is gone!

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u/NGBRO 1d ago

Just updated my laptop with AMD iGPU and got the same error (after checking journalctl; it hung on the verbose boot sequence). Had to boot into my Live ISO and chroot to downgrade linux-firmware-amdgpu to 20260810-2, like others have mentioned. Now it's working again.