7.4 KiB
| title | TARGET DECK | FILE TAGS | tags | |
|---|---|---|---|---|
| Linkers | Obsidian::STEM | linker |
|
Overview
To build an executable, a linker must perform two main tasks:
- Symbol resolution. The linker phase in which each symbol reference is associated with exactly one symbol definition.
- Relocation. The linker phase in which code and data sections across input modules are combined. Each section, along with the symbols defined in them, are assigned unique run-time memory addresses. Additionally, references to symbols are updated so they point to the correct run-time addresses.
%%ANKI Basic According to Bryant et al., a static linker must perform what two tasks? Back: Symbol resolution and relocation. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic Which of symbol resolution or relocation happens first? Back: Symbol resolution. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic After which linker phase is the size of the code and data sections of each input object module known? Back: Symbol resolution. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic What is the goal of symbol resolution? Back: To associate each symbol reference with exactly one symbol definition. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Cloze The {symbol resolution} phase associates each {symbol reference} with exactly one {symbol definition}. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic What is the goal of relocation? Back: To assign a memory location to each symbol and update references accordingly. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic Why must relocation happen after symbol resolution? Back: We should not assign multiple addresses to the same symbol. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Cloze The {relocation} phase assigns a {memory location} to each symbol and {updates references} accordingly. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic What does it mean for a linker to relocate a code and/or data section? Back: It associates a memory location with each symbol definition and updates references accordingly. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic Which linker phase combines code and data sections of the same type into a new aggregate section? Back: Relocation. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI
Basic
Which linker phase is responsible for building up the .symtab section?
Back: Symbol resolution.
Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Cloze {Relocatable} object files are merged together to make an {executable} object file. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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Object Files
Object files come in three forms:
- relocatable. Contains binary code and data in a form that can be combined with other relocatable object files at compile time.
- Executable object files. Contains binary code and data in a form that can be copied directly into memory and executed.
- Shared object files. A special type of relocatable object file that can be loaded into memory and linked dynamically, at either load time or run time.
An object module is a sequence of bytes whereas an object file is an object module stored on disk.
%%ANKI Basic What are the three types of object files? Back: Relocatable, executable, and shared. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic Executable object files are outputs of which compiler driver component? Back: The linker. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: c17
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%%ANKI Basic Executable object files are inputs into which compiler driver component? Back: N/A. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: c17
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%%ANKI Basic What is an object module? Back: A sequence of bytes. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic In terms of object modules, what is an object file? Back: An object module stored on disk. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic What distinguishes an object module from an object file? Back: An object file is an object module stored on disk. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Basic In what way is the term "object file" misused by Bryant et al.? Back: Technically this term only refers to object modules on disk. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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%%ANKI Cloze A {shared} object file is a special case of a {relocatable} object file. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
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Bibliography
- Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.