10.3 Linkers and Loaders

Question 1

What is the relationship between a compiler, assembler, linker and assmebly / high level programs

Answer 1

Following shows how they relate:

Note: Sometimes compiler may use assembler, other times could go straight to source

Question 2

What are object files (what do they relate to and what do they reference)

Answer 2

• Machine code for one part of program (ie single file)
• References to external files
• Object files are generated from translation units (preprocessed source file)

Question 3

What is a linker (and what does it do)

Answer 3

• Links the separated object files, into one consistent instruction stream
• Converts the object files into an executable or library file (exe, dll)

Question 4

What is the loader responsible for

Answer 4

• Loading the executable file (on disk) to memory (ram)

Question 5

What is dynamic linking (DLL: dynamic linking loader)

Answer 5

• Allows for references to be resolved at runtime
• Useful for system calls (don’t want to link entire system), or to decide on different libraries / versions (at runtime)

Question 6

What does an executable look like when loaded into memory

Answer 6

• Each executable has own stack, program, data strcutures etc.