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| author | mo khan <mo@mokhan.ca> | 2021-02-08 13:33:22 -0700 |
|---|---|---|
| committer | mo khan <mo@mokhan.ca> | 2021-02-08 13:33:22 -0700 |
| commit | 3728acea49328d6b8932275f582b81dcf2356df2 (patch) | |
| tree | 705bcbc476a5a97a387a5722e517800743008c11 | |
| parent | e81a5139ef85bf4dfef2fc47ffa057fd76dfec91 (diff) | |
descibe system calls and user/kernel mode
| -rw-r--r-- | doc/assignment1.md | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/doc/assignment1.md b/doc/assignment1.md index 539c936..aaf1e0e 100644 --- a/doc/assignment1.md +++ b/doc/assignment1.md @@ -255,6 +255,28 @@ Instructions: Please answer the following questions in about 1-2 pages each. [source][geeks-von-neumann] 1. Define system call, and list the main types of system calls. Elaborate on how a system call interacts with a standard C library and hardware under a dual-mode operating system environment. (10 marks) + + The two types of systems call modes are kernel mode and user mode. + With a mode bit we are able to determine if a task is being executed on behalf o + the operating system or the user. A user may request a service from the + operating system via a system call. In this case the system call + will transition from user mode to kernel mode to perform the request then + transition back to user mode once the request has been fulfilled. + + ```plaintext + user + [process] -> [system call] [return from system call] + | | + (user mode) (user mode) + -------------------V------------------ A----------------- + -------------------V------------------ A----------------- + kernel | | + (kernel mode) | + | | + [execute system call]-| + ``` + + 1. Describe the overall structure of virtual machines, and compare VMware and JVM. (15 marks) # Sources: |