How to generate gcc debug symbol outside the build target

Question

I know I can generate debug symbol using -g option  However the symbol is embeded in the target file  Could gcc generate debug symbol outside the result executable library  Like  pdb file of windows VC   compiler did

User · Answer

No answer so far mentions eu-strip --strip-debug -f  lt out debug gt   lt input gt     This is provided by elfutils package   The result will be that  lt input gt  file has been stripped of debug symbols which are now all in  lt out debug gt

User · Answer

You need to use objcopy to separate the debug information   objcopy --only-keep-debug    tostripfile      debugdir    debugfile   strip --strip-debug --strip-unneeded    tostripfile   objcopy --add-gnu-debuglink    debugdir    debugfile      tostripfile     I use the bash script below to separate the debug information into files with a  debug extension in a  debug directory  This way I can tar the libraries and executables in one tar file and the  debug directories in another  If I want to add the debug info later on I simply extract the debug tar file and voila I have symbolic debug information   This is the bash script      bin bash  scriptdir  dirname   0   scriptdir   cd   scriptdir   pwd   scriptname  basename   0    set -e  function errorexit       errorcode   1    shift   echo      exit   errorcode     function usage       echo  USAGE   scriptname   lt tostrip gt      tostripdir  dirname   1   tostripfile  basename   1     if   -z   tostripfile      then   usage   errorexit 0  tostrip must be specified  fi  cd    tostripdir    debugdir  debug debugfile    tostripfile  debug   if     -d    debugdir       then   echo  creating dir   tostripdir    debugdir     mkdir -p    debugdir   fi echo  stripping   tostripfile   putting debug info into   debugfile   objcopy --only-keep-debug    tostripfile      debugdir    debugfile   strip --strip-debug --strip-unneeded    tostripfile   objcopy --add-gnu-debuglink    debugdir    debugfile      tostripfile   chmod -x    debugdir    debugfile

User · Answer

Check out the  --only-keep-debug  option of the strip command   From the link      The intention is that this option will be used in conjunction with --add-gnu-debuglink to create a two part executable  One a stripped binary which will occupy less space in RAM and in a distribution and the second a debugging information file which is only needed if debugging abilities are required

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NOTE  Programs compiled with high-optimization levels  -O3  -O4  cannot generate many debugging symbols for optimized variables  in-lined functions and unrolled loops  regardless of the symbols being embedded  -g  or extracted  objcopy  into a   debug  file   Alternate approaches are    Embed the versioning  VCS  git  svn  data into the program  for compiler optimized executables  -O3  -O4   Build a 2nd non-optimized version of the executable      The first option provides a means to rebuild the production code with full debugging and symbols at a later date   Being able to re-build the original production code with no optimizations is a tremendous help for debugging    NOTE  This assumes testing was done with the optimized version of the program    Your build system can create a  c file loaded with the compile date  commit  and other VCS details   Here is a  make   git  example   program  program o version o   program o  program cpp program h   build version o  build version c      build version c        echo  const char  build1   VCS  Commit    shell git log -1 --pretty  H       gt            echo  const char  build2   VCS  Date    shell git log -1 --pretty  cd       gt  gt            echo  const char  build3   VCS  Author    shell git log -1 --pretty   an  ae        gt  gt            echo  const char  build4   VCS  Branch    shell git symbolic-ref HEAD       gt  gt             TODO  Add compiler options and other build details   TEMPORARY  build version c   After the program is compiled you can locate the original  commit  for your code by using the command  strings -a my program   grep VCS  VCS  PROGRAM NAME my program VCS  Commit 190aa9cace3b12e2b58b692f068d4f5cf22b0145 VCS  BRANCH refs heads PRJ123 feature desc VCS  AUTHOR Joe Developer  joe developer somewhere com VCS  COMMIT DATE 2013-12-19   All that is left is to check-out the original code  re-compile without optimizations  and start debugging

User · Answer

Compile with debug information   gcc -g -o main main c   Separate the debug information   objcopy --only-keep-debug main main debug   or  cp main main debug strip --only-keep-debug main debug   Strip debug information from origin file   objcopy --strip-debug main   or  strip --strip-debug --strip-unneeded main   debug by debuglink mode   objcopy --add-gnu-debuglink main debug main gdb main   You can also use exec file and symbol file separatly   gdb -s main debug -e main   or  gdb  gdb  exec-file main  gdb  symbol-file main debug   For details    gdb  help exec-file  gdb  help symbol-file   Ref  https   sourceware org gdb onlinedocs gdb Files html Files https   sourceware org gdb onlinedocs gdb Separate-Debug-Files html

[gcc] How to generate gcc debug symbol outside the build target?

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