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gdb.texinfo (Separate Debug Files): More accurate wording regarding 

build ID and a reference to the ld manual rather than the Fedora wiki.
This commit is contained in:
Eli Zaretskii 2007-09-15 09:49:36 +00:00
parent 821609525d
commit 7e27a47a1e
2 changed files with 26 additions and 22 deletions
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2
gdb/doc/ChangeLog
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@ -2,6 +2,8 @@
* gdb.texinfo (Output): Spell out which features of C's printf are
not supported by GDB's printf.
(Separate Debug Files): More accurate wording regarding build ID
and a reference to the ld manual rather than the Fedora wiki.
2007-09-04 Daniel Jacobowitz <dan@codesourcery.com>
Jim Blandy <jimb@codesourcery.com>

46
gdb/doc/gdb.texinfo
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@ -11933,14 +11933,15 @@ debug link specifies a CRC32 checksum for the debug file, which
came from the same build.
@item
The executable contains a @dfn{build ID}, a unique signature that is
The executable contains a @dfn{build ID}, a unique bit string that is
also present in the corresponding debug info file. (This is supported
only on some operating systems, notably on @sc{gnu}/Linux. For more
details about this feature, see
@uref{http://fedoraproject.org/wiki/Releases/FeatureBuildId, the
Fedora Project's description of the buid ID feature}.) The debug info
file's name is not specified explicitly by the build ID, but can be
computed from the build ID, see below.
only on some operating systems, notably those which use the ELF format
for binary files and the @sc{gnu} Binutils.) For more details about
this feature, see the description of the @option{--build-id}
command-line option in @ref{Options, , Command Line Options, ld.info,
The GNU Linker}. The debug info file's name is not specified
explicitly by the build ID, but can be computed from the build ID, see
below.
@end itemize
Depending on the way the debug info file is specified, @value{GDBN}
@ -11958,14 +11959,14 @@ directories of the executable's absolute file name.
For the ``build ID'' method, @value{GDBN} looks in the
@file{.build-id} subdirectory of the global debug directory for a file
named @file{@var{nn}/@var{nnnnnnnn}.debug}, where @var{nn} are the
first 2 hex characters of the build ID signature, and @var{nnnnnnnn}
are the rest of the signature. (Real signatures are 32 or more
characters, not 10.)
first 2 hex characters of the build ID bit string, and @var{nnnnnnnn}
are the rest of the bit string. (Real build ID strings are 32 or more
hex characters, not 10.)
@end itemize
So, for example, suppose you ask @value{GDBN} to debug
@file{/usr/bin/ls}, which has a @dfn{debug link} that specifies the
file @file{ls.debug}, and a @dfn{build id} whose value in hex is
@file{/usr/bin/ls}, which has a debug link that specifies the
file @file{ls.debug}, and a build ID whose value in hex is
@code{abcdef1234}. If the global debug directory is
@file{/usr/lib/debug}, then @value{GDBN} will look for the following
debug information files, in the indicated order:
@ -12023,14 +12024,15 @@ described above.
@cindex @code{.note.gnu.build-id} sections
@cindex build ID sections
A build ID is a special section of the executable file named
@code{.note.gnu.build-id}. This section contains unique
identification for the built files---it remains the same across
multiple builds of the same build tree. The default algorithm SHA1
produces 160 bits (40 hexadecimal characters) of the content. The
same section with an identical value is present in the original built
binary with symbols, in its stripped variant, and in the separate
debugging information file.
The build ID is a special section in the executable file (and in other
ELF binary files that @value{GDBN} may consider). This section is
often named @code{.note.gnu.build-id}, but that name is not mandatory.
It contains unique identification for the built files---the ID remains
the same across multiple builds of the same build tree. The default
algorithm SHA1 produces 160 bits (40 hexadecimal characters) of the
content for the build ID string. The same section with an identical
value is present in the original built binary with symbols, in its
stripped variant, and in the separate debugging information file.
The debugging information file itself should be an ordinary
executable, containing a full set of linker symbols, sections, and
@ -12039,7 +12041,7 @@ should have the same names, addresses, and sizes as the original file,
but they need not contain any data---much like a @code{.bss} section
in an ordinary executable.
@sc{gnu} binary utilities (Binutils) package includes the
The @sc{gnu} binary utilities (Binutils) package includes the
@samp{objcopy} utility that can produce
the separated executable / debugging information file pairs using the
following commands:
@ -12073,7 +12075,7 @@ the @code{ln -s} command above, together.
Build ID gets embedded into the main executable using @code{ld --build-id} or
the @value{NGCC} counterpart @code{gcc -Wl,--build-id}. Build ID support plus
compatibility fixes for debug files separation are present in @sc{gnu} binary
utilities (Binutils) since version 2.18.
utilities (Binutils) package since version 2.18.
@end itemize
@noindent