Abstract
- Built on top of System Call (系统调用)
- Some written in Assembly language
- Can be traced by
lstrace
Privilege Mode
Doesn’t switch to Kernel Mode, always runs in User Mode
Abstraction
Make it possible to make System Call (系统调用) from user program written in languages like Java and C via an unified interface without considering the underlying Instruction Set Architecture (ISA)
One example is POSIX
Library Procedure
- The underlying codes that carry out Library Call