tests/debug-info-data/README.md

   1 debug-info-data
   2 ==============
   3
   4 This directory contains pre-generated ELF and DWARF files used to test
   5 the debug info analysis feature, including lookup of DWARF debugging
   6 information via build ID and debug link methods, as well as the source
   7 files used to generate them.
   8
   9 The generated files are:
  10
  11 * `ARCH/dwarf_full/libhello_so` (ELF and DWARF)
  12 * `ARCH/elf_only/libhello_so` (ELF only)
  13 * `ARCH/build_id/libhello_so` (ELF with separate DWARF via build ID)
  14 * `ARCH/build_id/.build-id/cd/d98cdd87f7fe64c13b6daad553987eafd40cbb.debug` (DWARF for build ID)
  15 * `ARCH/debug_link/libhello_so` (ELF with separate DWARF via debug link)
  16 * `ARCH/debug_link/libhello_so.debug` (DWARF for debug link)
  17
  18 We use a suffix of "_so" instead of ".so" since some distributions
  19 build systems will consider ".so" files as artifacts from a previous
  20 build that were "left-over" and will remove them prior to the build.
  21
  22 All files are generated from the four (4) following source files:
  23
  24 * libhello.c
  25 * libhello.h
  26 * tp.c
  27 * tp.h
  28
  29 The generated executables were built using a native GNU toolchain on either
  30 Ubuntu 16.04 or 18.04 depending on the architecture.
  31
  32 To regenerate them, you can use the included Makefile or follow these steps:
  33
  34 ## Generate the object files
  35
  36     $ gcc -gdwarf -fdebug-prefix-map=$(pwd)=. -fPIC -c -I. tp.c libhello.c
  37
  38 ## Combined ELF and DWARF
  39
  40     $ build_id_prefix=cd
  41     $ build_id_suffix=d98cdd87f7fe64c13b6daad553987eafd40cbb
  42     $ build_id="$build_id_prefix$build_id_suffix"
  43     $ mkdir dwarf_full
  44     $ gcc -shared -g -llttng-ust -ldl -Wl,-soname,libhello.so -Wl,--build-id=0x$build_id -o dwarf_full/libhello_so tp.o libhello.o
  45
  46 ## ELF only
  47
  48     $ mkdir elf_only
  49     $ objcopy -g dwarf_full/libhello_so elf_only/libhello_so
  50     $ objcopy --remove-section=.note.gnu.build-id elf_only/libhello_so
  51
  52 ## ELF and DWARF with Build ID
  53
  54     $ mkdir -p build_id/.build-id/$build_id_prefix
  55     $ objcopy --only-keep-debug dwarf_full/libhello_so build_id/.build-id/$build_id_prefix/$build_id_suffix.debug
  56     $ objcopy -g dwarf_full/libhello_so build_id/libhello_so
  57
  58 ##  ELF and DWARF with Debug Link
  59
  60     $ mkdir debug_link
  61     $ objcopy --remove-section=.note.gnu.build-id dwarf_full/libhello_so debug_link/libhello_so
  62     $ objcopy --only-keep-debug debug_link/libhello_so debug_link/libhello_so.debug
  63     $ objcopy -g debug_link/libhello_so
  64     $ cd debug_link && objcopy --add-gnu-debuglink=libhello_so.debug libhello_so && cd ..
  65
  66
  67 Test program
  68 ------------
  69 An executable linked to this library can be compiled from the `main.c` source file.
  70 To compile it, you can do:
  71
  72     $ ln -s libhello_so libhello.so
  73     $ gcc -I. -o test main.c -L. -lhello_build_id -llttng-ust -ldl -Wl,--rpath=.
  74
  75 The trace provided in this directory was generated with lttng-ust running this
  76 program and stripped to contain only the bare minimum. When running babeltrace
  77 with the `--debug-info-target-prefix` option pointing to the source tree of
  78 Babeltrace, the `my_provider:my_first_tracepoint` events should contain this
  79 information:
  80
  81     debug_info = { bin = "libhello_so+0x166b", func = "baz+0x9c", src = "libhello.c:20" } }