Self Doubt:Operating System-Threads

Question

User level threads doesnot require context switching- This is a true statement (Because OS cannot recognize user level threads)

Can somebody elaborate more on it??

This given answer is wrong I think:https://gateoverflow.in/290648/made_easy_test_series

Plz check

Comments

I have get idea of user level threads from here and here. But not getting whatever that ans is written

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see this line here

"Creating a new thread, switiching between threads, and synchronizing threads are done via procedure call. i.e no kernel involvement."

context switching is done with the help of procedure calls in ULT.

Operating Systems kernel provides system call to create and manage threads for KLT

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I also didn't understood much from that answer.