PATCH: Update NEWS/texinfo with compressed debug sections info

[csilvers at google dot com (Craig Silverstein)]

I took a stab (no pun intended) at documenting the
compressed-debug-section patch, which I submitted earlier this
evening.  I'm not really sure what information is appropriate to
include, or where to put it; any suggestions on this patch are
appreciated.

craig

--cut here--

      * NEWS (Changes since GDB 6.8): Add information on compressed
      debug sections.
      * doc/gdb.texinfo (Requirements): Add an optional requirement
      on zlib.
      * doc/gdbint.texinfo (Debugging File Formats): Add new
      subsection for Compressed DWARF 2.

Index: NEWS
===================================================================
RCS file: /cvs/src/src/gdb/NEWS,v
retrieving revision 1.264
diff -u -r1.264 NEWS
--- NEWS	4 Apr 2008 15:51:15 -0000	1.264
+++ NEWS	19 Apr 2008 05:50:35 -0000
@@ -3,11 +3,14 @@
 
 *** Changes since GDB 6.8
 
+* gdb can now read compressed debug sections, as produced by GNU gold
+with the --compress-debug-sections=zlib flag.
+
 * Watchpoints can now be set on unreadable memory locations, e.g. addresses
 which will be allocated using malloc later in program execution.
 
 * The qXfer:libraries:read remote procotol packet now allows passing a
-  list of section offsets.
+list of section offsets.
 
 * New features in the GDB remote stub, gdbserver
 
Index: doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.481
diff -u -r1.481 gdb.texinfo
--- doc/gdb.texinfo	16 Apr 2008 13:14:18 -0000	1.481
+++ doc/gdb.texinfo	19 Apr 2008 05:50:38 -0000
@@ -22732,6 +22732,17 @@
 MS-Windows shared libraries (@pxref{Shared Libraries})
 @end itemize
 
+@item zlib
+@value{GDBN} will use the zlib library, if available, to read
+compressed debug sections.  Some linkers, such GNU gold, are capable
+of producing binaries with compressed debug sections.  If @value{GDBN}
+is compiled with zlib, it will be able to read the debug information
+in such binaries.
+
+The zlib library is likely included with your operating system
+distribution; if it is not, you can get the latest version from
+@url{http://zlib.net}.
+
 @end table
 
 @node Running Configure
Index: doc/gdbint.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdbint.texinfo,v
retrieving revision 1.280
diff -u -r1.280 gdbint.texinfo
--- doc/gdbint.texinfo	13 Feb 2008 05:05:29 -0000	1.280
+++ doc/gdbint.texinfo	19 Apr 2008 05:50:39 -0000
@@ -2201,6 +2201,29 @@
 
 The DWARF 2 reader is in @file{dwarf2read.c}.
 
+@subsection Compressed DWARF 2
+
+@cindex Compressed DWARF 2 debugging info
+Compressed DWARF 2 is not technically a separate debugging format, but
+merely DWARF 2 debug information that has been compressed.  In this
+format, every object-file section holding DWARF 2 debugging
+information is compressed and prepended with a header.  (The section
+is also typically renamed, so a section called @code{.debug_info} in a
+DWARF 2 binary would be called @code{.zdebug_info} in a compressed
+DWARF 2 binary.)  The header is 12 bytes long:
+
+@itemize @bullet
+@item
+4 bytes: the literal string ``ZLIB''
+@item
+8 bytes: the uncompressed size of the section, in big-endian byte
+order.
+@end itemize
+
+The same reader is used for both compressed an normal DWARF 2 info.
+Section decompression is done in @code{zlib_decompress_section} in
+@file{dwarf2read.c}.
+
 @subsection SOM
 
 @cindex SOM debugging info