How do you investigate the cause of total hang? Is there some information that I should pay attention to in order to get some hint?

[åäé sunshilong]

Hi, list

My x86 machine(linux4.19) sometimes hangs, suddenly not responding in
any way to the mouse or the keyboard.

How can I investigate why it hung up? Is there extra information I can
find for a clue? Is there anything less drastic than power-off to get
some kind of action, if only some limited shell or just beeps,
but might give a clue?

Thank you for your attention to this matter.