Auxiliary Vector
The auxiliary vector conveys information from the operating system to the application. Only the terminating null auxiliary vector entry is required, but if any other entries are present, they shall be interpreted as follows. This vector is an array of the following structures.
typedef struct
{
long int a_type; /* Entry type */
union
{
long int a_val; /* Integer value */
void *a_ptr; /* Pointer value */
void (*a_fcn) (void); /* Function pointer value */
} a_un;
} auxv_t; |
The application shall interpret the a_un value according to the a_type. Other auxiliary vector types are reserved.
The a_type field shall contain one of the following values:
- AT_NULL
The last entry in the array has type AT_NULL. The value in a_un is undefined.
- AT_IGNORE
The value in a_un is undefined, and should be ignored.
- AT_EXECFD
File descriptor of program
- AT_PHDR
Program headers for program
- AT_PHENT
Size of program header entry
- AT_PHNUM
Number of program headers
- AT_PAGESZ
System page size
- AT_BASE
Base address of interpreter
- AT_FLAGS
Flags
- AT_ENTRY
Entry point of program
- AT_NOTELF
Program is not ELF
- AT_UID
Real uid
- AT_EUID
Effective uid
- AT_GID
Real gid
- AT_EGID
Effective gid
- AT_CLKTCK
Frequency of times()
- AT_PLATFORM
String identifying platform.
- AT_HWCAP
Machine dependent hints about processor capabilities.
- AT_FPUCW
Used FPU control word
- AT_DCACHEBSIZE
Data cache block size
- AT_ICACHEBSIZE
Instruction cache block size
- AT_UCACHEBSIZE
Unified cache block size
 | The auxiliary vector is intended for passing information from the operating system to a program interpreter, such as /lib/ld-lsb-ia64.so.1. |