Programming

13368 readers

2 users here now

All things programming and coding related. Subcommunity of Technology.

This community's icon was made by Aaron Schneider, under the CC-BY-NC-SA 4.0 license.

founded 1 year ago

MODERATORS

alyaza@beehaw.org

Hexorg@beehaw.org

remington@beehaw.org

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

23 comments fedilink hide all child comments

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

you are viewing a single comment's thread
view the rest of the comments

[–] abhibeckert@beehaw.org 2 points 1 year ago* (last edited 1 year ago)

When I last used a computer that had a single mode (about 20 years ago), I was in the habit of saving my work about every 15 seconds and manually backing up my documents (to an offline backup that wasn't physically connected to the computer) multiple times per day.

That's how often the computer crashed. I never had a virus in those days, it was always innocent and unintentional software bugs which would cause your computer to need a reboot regularly and occasionally delete all of your files.

Trust me, things are better now. I still save regularly and maintain backups, but I do it a lot less religiously than I used to, because I've lost my work just once in the last several years. It used to be far more often.