Syminfo Table (Linker and Libraries Guide)

Linker and Libraries Guide

Syminfo Table

This section contains multiple entries of the type Elf32_Syminfo or Elf64_Syminfo. There is one entry in the .SUNW_syminfo section for every entry in the associated symbol table (sh_link).

If this section is present in an object, additional symbol information is to be found by taking the symbol index from the associated symbol table and using that to find the corresponding Elf32_Syminfo or Elf64_Syminfo entry in this section. The associated symbol table and the Syminfo table will always have the same number of entries.

Index 0 is used to store the current version of the Syminfo table, which will be SYMINFO_CURRENT. Since symbol table entry 0 is always reserved for the UNDEF symbol table entry, this does not pose any conflicts.

An Symfino entry has the following format:

typedef struct {
        Elf32_Half      si_boundto;
        Elf32_Half      si_flags;
} Elf32_Syminfo;

typedef struct {
        Elf64_Half      si_boundto;
        Elf64_Half      si_flags;
} Elf64_Syminfo;

si_flags: This is a bit-field that can have flags set, as shown in the following table.

Table 7-26 Syminfo flags


Name	Value	Meaning
`SYMINFO_FLG_DIRECT`	`0x01`	This symbol has a direct reference to an external object.
`SYMINFO_FLG_COPY`	`0x04`	This symbol is the result of a copy-relocation.
`SYMINFO_FLG_LAZYLOAD`	`0x08`	This symbol has a reference to an external, lazy loadable object.

si_boundto: Index to an entry in the .dynamic section identified by the sh_info field. This entry will identify a DT_* (DT_NEEDED) entry which will identify a dynamic object associated with the Syminfo entry. The entries that follow are reserved values for si_boundto.

Table 7-27 si_boundto reserved values


Name	Value	Meaning
`SYMINFO_BT_SELF`	`0xffff`	Symbol bound to self
`SYMINFO_BT_PARENT`	`0xfffe`	Symbol bound to parent. The parent is the first object to cause this dynamic object to be loaded.