https://askubuntu.com/questions/1288395/system-is-unusable-after-upgrade-to-20-10-i915-gpu-hang
Having updated to 20.10, it now boots okay and the login screen appears normal. The desktop is fine until I try to open any application. The application name appears at the top, and then the desktop completely freezes. In some cases the app icon in the dock becomes pixelated. Sometimes a portion of the desktop flickers to solid black.
The mouse still moves occasionally, and I can CTRL+ALT+F3 to a command line.
Various searches suggest a graphics driver problem. It's an Intel Haswell graphics chip.
I've tried both the Ubuntuand Ubuntu on Wayland options at log in, both give the same results.
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https://software.intel.com/content/www/us/en/develop/documentation/vtune-help/top/installation/set-up-system-for-gpu-analysis/rebuild-and-install-i915-module-ubuntu.html
https://linuxreviews.org/Linux_Kernel_5.5_Will_Not_Fix_The_Frequent_Intel_GPU_Hangs_In_Recent_Kernels
这个问题直到linux内核5.9版本都没有解决！
2021年4月 升级至5.8.0-51-generic内核，貌似问题解决，继续观察中...