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Why do we have two modes in cpu(user and kernel) since we still can still easily harm computer with userland programs? (lemm.ee)

submitted 1 year ago* (last edited 1 year ago) by SmoothSurfer@lemm.ee to c/programming@beehaw.org

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I have never dug into low level things like cpu architectures etc. and decided to give it a try when I learned about cpu.land.

I already was aware of the existence of user and kernel mode but while I was reading site it came to me that "I still can harm my system with userland programs so what does it mean to switch user mode for almost everything other than kernel and drivers?" also we still can do many things with syscalls, what is that stopping us(assuming we want to harm system of course) from damaging our system.

[edit1]: grammar mistakes

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[–] jarfil@beehaw.org 5 points 1 year ago

classic “hackers can turn your computer into a bomb” advertisement

Somewhat ironically, with hardware allowing drivers to overclock their speed, voltage, cooling, and thus temperature and heat output... which drivers allow userland software with cool visuals to tweak at will... and laptops with high energy density lithium batteries... that would be more plausible today than at the time of those advertisements.

(except for some CPUs that used to burn a hole in the motherboard if cooling stopped... but those didn't explode; some PSUs exploded, but back then were not controllable by software)