Chapter 3Executable and Linking Format
The type of object files created by the SPARC assembler
version for SunOS 5.x are now Executable and Linking Format
(ELF) files. These relocatable ELF files hold code and data suitable for linking
with other object files to create an executable or a shared object file, and
are the assembler normal output. The assembler can also write information
to standard output (for example, under the -S option) and
to standard error (for example, under the -V option). The
SPARC assembler creates a default output file when standard input or multiple
files are used.
This chapter is organized into the following sections:
The ELF object file format consists of:
Header
Sections
Locations
Addresses
Relocation tables
Symbol tables
String tables
For more information, see the System V Application Binary
Interface: SPARC™ Processor Supplement.
3.1 ELF Header
The ELF header is always located at the beginning
of the ELF file. It describes the ELF file organization and contains the actual
sizes of the object file control structures. The initial bytes of an ELF header
specify how the file is to be interpreted.
The ELF header contains the following information:
ehsize ELF header size in bytes.
entry Virtual address at which the process
is to start. A value of 0 indicates no associated entry point.
flag Processor-specific flags associated
with the file.
ident Marks the file as an object file
and provides machine-independent data to decode and interpret the file contents.
machine Specifies the required architecture
for an individual file. A value of 2 specifies SPARC.
phentsize Size in bytes of entries in the
program header table. All entries are the same size.
phnum Number of entries in program header
table. A value of 0 indicates the file has no program header table.
phoff Program header table file offset
in bytes. The value of 0 indicates no program header.
shentsize Size in bytes of the section header.
A section header is one entry in the section header table; all entries are
the same size.
shnum Number of entries in section header
table. A value of 0 indicates the file has no section header table.
shoff Section header table file offset
in bytes. The value of 0 indicates no section header.
shstrndx Section header table index of the
entry associated with the section name string table. A value of SHN_UNDEF indicates the file does not have a section name string
table.
type Identifies the object file type. Table 3-1 describes the reserved object file
types.
version Identifies the object file version.
Table 3-1 shows reserved object
file types:
Table 3-1
Type | Value | Description |
|---|
none | 0 | No file type |
rel | 1 | Relocatable file |
exec | 2 | Executable file |
dyn | 3 | Shared object file |
core | 4 | Core file |
loproc | 0xff00 | Processor-specific |
hiproc | 0xffff | Processor-specific |
| 
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