DWARF Standard


HOME
SPECIFICATIONS
FAQ
ISSUES



040308.1 Jason Molenda Version Numbering Clarification Accepted with modifications Jason Molenda


Jason Molenda
Ron Brender
Todd Allen
David Anderson

had a long email discussion titled
	CFI parsing questions

and a clear outcome of that discussion was
a reminder that version numbering is difficult to find in the
document.


PROPOSAL:

Add a new appendix, informative,

Appendix F     Version Numbering

Dwarf2 and dwarf 3 sections have a 'version number' embedded
so consumer code can tell what it is reading.
Version numbers are 2 byte unsigned integers.

This table shows what version numbers are in use for each section.
The version number changes where there is an 'incompatible change
in layout' so that a consumer can correctly determine the contents.

dwarf2: July 1993 public review document
dwarf3: Draft 8, Nov 2001
	- means a version number is not applicable.
	x means that section was not defined
	  (so a version number is not applicable)

                      dwarf2     dwarf3
                        ver       ver
 .debug_info             2         3
 .debug_abbrev           -         -
 .debug_frame            1         3
 .debug_str              -         -
 .debug_loc              -         -
 .debug_line             2         3
 .debug_aranges          2         2
 .debug_ranges           x         -
 .debug_pubtypes         x         2
 .debug_pubnames         2         2
 .debug_macinfo          -         -

For .debug_frame, version 2 is unused.
Higher numbers are reserved  for future use.

========================================================================

Revised text:

Version Numbering

Most Dwarf sections have a version number in the section header.   This
version number is not tied to the Dwarf standard revision  numbers, but 
instead is incremented when incompatible changes to that  section are made.  
The Dwarf standard that a producer is generating  to is not explicitly encoded 
in the file.  Version numbers in the  section headers are represented as two 
byte unsigned integers.  This  table shows what version numbers are in use 
for each section.

There are sections with no version number encoded in them; they are  only 
accessed via the .debug_info section and so an incompatible  change in 
those sections' format would be represented by  the .debug_info's version 
number changing.

"dwarf2" is the July 1993 public review document.  "dwarf3" is the  DWARF 3 
standard.

"-" means that a version number is not applicable (the section's  header 
does not include a version).
"x" means that the section was not defined in that version of the  Dwarf 
standard.

                      dwarf2     dwarf3
                        ver       ver
 .debug_info             2         3
 .debug_abbrev           -         -
 .debug_frame            1         3
 .debug_str              -         -
 .debug_loc              -         -
 .debug_line             2         3
 .debug_aranges          2         2
 .debug_ranges           x         -
 .debug_pubtypes         x         2
 .debug_pubnames         2         2
 .debug_macinfo          -         -

For .debug_frame, version 2 is unused.
Higher numbers are reserved  for future use. 


All logos and trademarks in this site are property of their respective owner.
The comments are property of their posters, all the rest © 2007-2017 by DWARF Standards Committee.