Revision History

First draft published May 14, 1998.

Second draft published May 3, 1999.

• New values introduced for ELF header e_machine field.
• Revised language for EI_OSABI and EI_ABIVERSION fields of the ELF header e_ident array.
• New section flags SHF_MERGE and SHF_STRINGS added.
• New values added to a symbol table entry's st_other field to describe a symbol's visibility.
• New dynamic section tags DT_RUNPATH and DT_FLAGS added. Dynamic section tag DT_RPATH moved to level 2.
• New semantics for shared object path searching, including new ``Substitution Sequences''.

Third draft published May 12, 1999.

• A new symbol type, STT_COMMON, has been added.
• Added language restricting the types of objects that may contain symbols with the section index SHN_COMMON.
• Dynamic section entries DT_SYMBOLIC, DT_TEXTREL and DT_BIND_NOW have been moved to level 2. New DT_FLAGS values DF_SYMBOLIC, DF_TEXTREL and DF_BIND_NOW have been added as replacements.
• New rules for interpreting dynamic section tag encodings have been added.
• The OS and processor specific ranges for DT_FLAGS have been removed.
• The language motivating the use of DF_ORIGIN has been changed.

Fourth draft published July 6, 1999.

• New language has been added warning about the use of WEAK symbols in application programs.
• New rules have been defined for composition of consecutive relocation entries that reference the same location.
• Language has been added clarifying the order of execution for functions specified by initialization and termination arrays.

Fifth draft published July 21, 1999.

• New section types and section names added for init arrays, fini arrays and pre-init arrays.
• An object may now have both DT_INIT and DT_INIT_ARRAY entries (and both DT_FINI and DT_FINI_ARRAY entries). The relative execution order is specified.
• The language describing the order of execution for termination functions has been revised.
• A new pre-initialization mechanism has been added.
• It is now up to the processor supplement for each processor to specify whether the dynamic linker must invoke the executable file's init and fini routines.

Sixth draft published September 14, 1999.

• Changed the numbering of some new section types previously added to account for type numbers already in use in particular vendor implementations.
• Increased the number of section flag bits available in the OS specific range.

Seventh draft published October 4, 1999.

• Changed the values used for some new section attribute flags to accommodate platforms already using previously assigned values.
• Added new section attribute flags SHF_INFO_LINK, SHF_LINK_ORDER and SHF_OS_NONCONFORMING
• Added rules for linkers when linking sections with unrecognized types or flags.

Eighth draft published March 30, 2000.

• Added the concept of section groups.
• Removed the macros for ELF32_ST_OTHER and ELF64_ST_OTHER.

Ninth draft published March 30, 2000.

• Added language clarifying the semantics of symbols marked as STV_PROTECTED.
• Added language clarifying the contents of the initialization and termination arrays.

Tenth draft published 22 June 2000.

• Added a sentence spelling out the behavior when resolving a symbol to a STV_PROTECTED definition from a shared object.
• Added support for more than 65,000 sections in the ELF header, and with SHT_SYMTAB_SHNDX sections, and in symbol tables.

Eleventh draft published 24 April 2001.

• Updated table of EM_* entries.
• Added GRP_MASKOS and GRP_MASKPROC. Changed section group description in a few ways, clarifying some fuzzy points and rewriting the rules for symbols referencing into section groups.
• Changed the warning about using weak to be stronger.
• Reworded the EI_OSABI byte description to make its use clearer.
• Added the table of now generic EI_OSABI values.
• Added SHF_TLS, PT_TLS and its contents, DF_STATIC_TLS, STT_TLS, .tbss, and .tdata.
• Changed the rules for SHT_SYMTAB_SHNDX contents to require 0 when the corresponding st_shndx field is not SHN_XINDEX.

Twelfth draft published 26 March 2007.

• Updated table of EM_* entries.

Thirteenth draft published 03 November 2009.

• Updated table of EM_* entries.
• Added ELFOSABI_FENIXOS to the EI_OSABI values.
• Added ELFOSABI_GNU to the EI_OSABI values; aliased to ELFOSABI_LINUX.

Fourteenth draft published 10 June 2013.

• Added SHF_COMPRESSED to the Section Attribute Flags.
• Updated table of EM_* entries.

Recent Changes

• Clarified the description of SHT_SYMTAB_SHNDX; allow usage with any symbol table section.
• Added DT_SYMTAB_SHNDX to the Dynamic Array Tags.