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title TARGET DECK FILE TAGS tags
Relocatable Object Files Obsidian::STEM linker
linker

Overview

Relocatable object files are those, typically ending with a .o suffix, produced by the assembler. They contain binary code and data in a form that can be combined with other relocatable object files at compile time. The following diagram shows how one looks like when formatted using elf:

!elf.png

%%ANKI Basic Relocatable object files are outputs of which compiler driver component? Back: The assembler. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: c17

END%%

%%ANKI Basic Relocatable object files are inputs into 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

END%%

%%ANKI Basic A relocatable object file is typically broken up into what three regions? Back: The header, sections, and the section header table. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: linker::elf

END%%

%%ANKI Basic In a relocatable object file, what exists between the header and section header table? Back: The sections. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: linker::elf

END%%

%%ANKI Cloze A relocatable object file consists of a {header}, {sections}, and a {section header table}, in that order. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: linker::elf

END%%

%%ANKI Basic Where in a relocatable object file does the section header table exist? Back: At the end. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: linker::elf

END%%

Symbols

Every relocatable object module m has a [[elf#.symtab|symbol table]] that contains information about the symbols defined and referenced by m. In the context of a linker, there are three different kinds of symbols:

  1. Global symbols defined by m and that can be referenced by other modules.
  2. Global symbols referenced by m but defined by another module.
  3. Local symbols defined and referenced exclusively by m.

%%ANKI Basic With respect to linkers, how many kinds of symbols are there? Back: Three. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.

END%%

%%ANKI Basic With respect to linkers, what are the three kinds of symbols? Back: Global (defined), global (referenced), and local. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.

END%%

%%ANKI Basic What distinguishes the two types of global symbols a linker understands? Back: Whether or not the symbol is defined within the module in question. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.

END%%

%%ANKI Basic With respect to linkers, a global (defined) symbol corresponds to what kind of C construct? Back: A nonstatic function or global variable defined in the given module. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: c17

END%%

%%ANKI Basic With respect to linkers, a global (referenced) symbol corresponds to what kind of C construct? Back: A nonstatic function or global variable defined in a different module. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: c17

END%%

%%ANKI Basic With respect to linkers, a local symbol corresponds to what kind of C construct? Back: A static function or global variable defined in the given module. Reference: Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016. Tags: c17

END%%

Bibliography

  • Bryant, Randal E., and David O'Hallaron. Computer Systems: A Programmer's Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.