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I installed Kubuntu 20.04 to my new machine with CPU AMD Ryzen 5 4500Uļ¼Œ unfortunately, the GPU failed to function properly to adjust the display lightness.

Friends guided me that the kernel 5.4 released earlier than AMD Ryzen 5ļ¼Œ so updating kernel to latest 5.8 might be a decent solution.

I followed the instruction How to Install Linux Kernel 5.8 in Ubuntu

cd /tmp/
wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8/amd64/linux-headers-5.8.0-050800_5.8.0-050800.202008022230_all.deb
wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8/amd64/linux-headers-5.8.0-050800-generic_5.8.0-050800.202008022230_amd64.deb
wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8/amd64/linux-image-unsigned-5.8.0-050800-generic_5.8.0-050800.202008022230_amd64.deb
wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8/amd64/linux-modules-5.8.0-050800-generic_5.8.0-050800.202008022230_amd64.deb

sudo dpkg -i *.deb

However, after restart it report error:

error: /boot/vmlinuz-5.8.0-050800-generic has invalid signature.
error: you need to load the kernel first
Press any key to continue...

I re-installed the kernel 5.8 more than twice, it report such the identical error.

How could solve the problem?

Wizard
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  • File a bug report with super-specific detail about the hardware that is not recognized...since the kernel developer who reads it won't have access to your hardware. ā€“ user535733 Aug 15 '20 at 21:57
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    The 5.8 kernel is not officially supported by Ubuntu. But your problem looks like a Secure Boot issue. Disable it. Instead of using an unsupported kernel, it is better to use drivers from AMD site and the 5.4 kernel. ā€“ Pilot6 Aug 16 '20 at 08:37

1 Answers1

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The kernel is not signed. Turning off secure-boot in your bios could help. This could be the same issue.

MaxSilvester
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