Application programs can then use any of the

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Unformatted text preview: e is a sequence of bytes, and an object file is an object module stored on disk in a file. However, we will use these terms interchangeably. 7.4. RELOCATABLE OBJECT FILES 353 Object file formats vary from system to system. The first Unix systems from Bell Labs used the a.out format. (To this day, executables are still referred to as a.out files.) Early versions of System V Unix used the Common Object File format (COFF). Windows NT uses a variant of COFF called the Portable Executable (PE) format. Modern Unix systems — such as Linux, later versions of System V Unix, BSD Unix variants, and Sun Solaris — use the Unix Executable and Linkable Format (ELF). Although our discussion will focus on ELF, the basic concepts are similar, regardless of the particular format. 7.4 Relocatable Object Files Figure 7.3 shows the format of a typical ELF relocatable object file. The ELF header begins with a 16-byte sequence that describes the word size and byte ordering of the system that generated the file. The rest of the ELF header contains information that allows a linker to parse and inte...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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