When a user program calls a system call, let’s say write .

It will cause an interrupt, and transition will happen from user mode to kernel mode, after saving necessary addresses in registers.

In interrupt routine , kernel will perform write for requested system call.

Control would be transferred back to user mode , after completing the activity.
Execution will resume in user mode by getting already saved addresses.

#shorts #linux #os #internals #bydubebox

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