[PING*3][PATCH 3/4 v4] gdb/debuginfod: Support on-demand debuginfo downloading

[Aaron Merey <amerey@redhat.com>]

Ping

Thanks,
Aaron

On Mon, Nov 20, 2023 at 1:39 PM Aaron Merey <amerey@redhat.com> wrote:
>
> Ping
>
> Thanks,
> Aaron
>
> On Sun, Nov 12, 2023 at 3:20 PM Aaron Merey <amerey@redhat.com> wrote:
> >
> > Ping
> >
> > Thanks,
> > Aaron
> >
> > On Fri, Oct 27, 2023 at 8:20 PM Aaron Merey <amerey@redhat.com> wrote:
> > >
> > > v3: https://sourceware.org/pipermail/gdb-patches/2023-June/199987.html
> > >
> > > v4 improves testcases when running with --target_board=native-gdbserver.
> > >
> > > v4 also fixes a bug where objfile observers could clear selected_frame
> > > if debuginfo was downloaded during get_selected_frame.
> > >
> > > Commit message:
> > >
> > > At the beginning of a session, gdb may attempt to download debuginfo
> > > for all shared libraries associated with the process or core file
> > > being debugged.  This can be a waste of time and storage space when much
> > > of the debuginfo ends up not being used during the session.
> > >
> > > To reduce the gdb's startup latency and to download only the debuginfo
> > > that is really needed, this patch adds on-demand downloading of debuginfo.
> > >
> > > 'set debuginfo enabled on' now causes gdb to attempt to download a .gdb_index
> > > for each shared library instead of its full debuginfo.  Each corresponding
> > > separate debuginfo will be deferred until gdb needs to expand symtabs
> > > associated with the debuginfo's index.
> > >
> > > Because these indices are significantly smaller than their corresponding
> > > debuginfo, this generally reduces the total amount of data gdb downloads.
> > > Reductions of 80%-95% have been observed when debugging large GUI programs.
> > >
> > >     (gdb) set debuginfod enabled on
> > >     (gdb) start
> > >     Downloading section .gdb_index for /lib64/libcurl.so.4
> > >     [...]
> > >     1826        client->server_mhandle = curl_multi_init ();
> > >     (gdb) step
> > >     Downloading separate debug info for /lib64/libcurl.so.4
> > >     Downloading separate debug info for [libcurl dwz]
> > >     Downloading source file /usr/src/debug/curl-7.85.0-6.fc37.x86_64/build-full/lib/../../lib/multi.c
> > >     curl_multi_init () at ../../lib/multi.c:457
> > >     457     {
> > >     (gdb)
> > >
> > > Some of the key functions below include dwarf2_has_separate_index which
> > > downloads the separate .gdb_index.  If successful, the shared library
> > > objfile owns the index until the separate debug objfile is downloaded
> > > or confirmed to not be available.
> > >
> > > read_full_dwarf_from_debuginfod downloads the full debuginfo and
> > > initializes the separate debug objfile.  It is called by functions
> > > such as dwarf2_gdb_index::expand_symtabs_matching and
> > > dwarf2_base_index_functions::find_pc_sect_compunit_symtab when symtab
> > > expansion is required.
> > > ---
> > >  gdb/dwarf2/frame.c                         |  13 ++
> > >  gdb/dwarf2/frame.h                         |   4 +
> > >  gdb/dwarf2/index-cache.c                   |  33 ++++
> > >  gdb/dwarf2/index-cache.h                   |  13 ++
> > >  gdb/dwarf2/public.h                        |   7 +
> > >  gdb/dwarf2/read-gdb-index.c                | 156 +++++++++++++++--
> > >  gdb/dwarf2/read.c                          | 146 +++++++++++++++-
> > >  gdb/dwarf2/read.h                          |  10 ++
> > >  gdb/dwarf2/section.c                       |   3 +-
> > >  gdb/elfread.c                              |   2 +-
> > >  gdb/frame.c                                |   7 +
> > >  gdb/objfile-flags.h                        |   4 +
> > >  gdb/objfiles.h                             |  20 +++
> > >  gdb/quick-symbol.h                         |   4 +
> > >  gdb/symfile.c                              |  13 +-
> > >  gdb/symtab.c                               |  18 +-
> > >  gdb/testsuite/gdb.debuginfod/libsection1.c |  40 +++++
> > >  gdb/testsuite/gdb.debuginfod/libsection2.c |  37 +++++
> > >  gdb/testsuite/gdb.debuginfod/section.c     |  29 ++++
> > >  gdb/testsuite/gdb.debuginfod/section.exp   | 184 +++++++++++++++++++++
> > >  gdb/testsuite/lib/debuginfod-support.exp   |  27 ++-
> > >  21 files changed, 746 insertions(+), 24 deletions(-)
> > >  create mode 100644 gdb/testsuite/gdb.debuginfod/libsection1.c
> > >  create mode 100644 gdb/testsuite/gdb.debuginfod/libsection2.c
> > >  create mode 100644 gdb/testsuite/gdb.debuginfod/section.c
> > >  create mode 100644 gdb/testsuite/gdb.debuginfod/section.exp
> > >
> > > diff --git a/gdb/dwarf2/frame.c b/gdb/dwarf2/frame.c
> > > index abc8d613482..257f0316731 100644
> > > --- a/gdb/dwarf2/frame.c
> > > +++ b/gdb/dwarf2/frame.c
> > > @@ -1617,6 +1617,19 @@ set_comp_unit (struct objfile *objfile, struct comp_unit *unit)
> > >    return dwarf2_frame_bfd_data.set (abfd, unit);
> > >  }
> > >
> > > +/* See frame.h.  */
> > > +
> > > +void
> > > +dwarf2_clear_frame_data (struct objfile *objfile)
> > > +{
> > > +  bfd *abfd = objfile->obfd.get ();
> > > +
> > > +  if (gdb_bfd_requires_relocations (abfd))
> > > +    dwarf2_frame_objfile_data.clear (objfile);
> > > +  else
> > > +    dwarf2_frame_bfd_data.clear (abfd);
> > > +}
> > > +
> > >  /* Find the FDE for *PC.  Return a pointer to the FDE, and store the
> > >     initial location associated with it into *PC.  */
> > >
> > > diff --git a/gdb/dwarf2/frame.h b/gdb/dwarf2/frame.h
> > > index 5643e557513..2391e313e7c 100644
> > > --- a/gdb/dwarf2/frame.h
> > > +++ b/gdb/dwarf2/frame.h
> > > @@ -238,6 +238,10 @@ void dwarf2_append_unwinders (struct gdbarch *gdbarch);
> > >  extern const struct frame_base *
> > >    dwarf2_frame_base_sniffer (frame_info_ptr this_frame);
> > >
> > > +/* Delete OBJFILEs comp_unit.  */
> > > +
> > > +extern void dwarf2_clear_frame_data (struct objfile * objfile);
> > > +
> > >  /* Compute the DWARF CFA for a frame.  */
> > >
> > >  CORE_ADDR dwarf2_frame_cfa (frame_info_ptr this_frame);
> > > diff --git a/gdb/dwarf2/index-cache.c b/gdb/dwarf2/index-cache.c
> > > index 69f70642dc6..8c969ecd590 100644
> > > --- a/gdb/dwarf2/index-cache.c
> > > +++ b/gdb/dwarf2/index-cache.c
> > > @@ -240,6 +240,33 @@ index_cache::lookup_gdb_index (const bfd_build_id *build_id,
> > >    return {};
> > >  }
> > >
> > > +/* See index-cache.h.  */
> > > +
> > > +gdb::array_view<const gdb_byte>
> > > +index_cache::lookup_gdb_index_debuginfod (const char *index_path,
> > > +                                         std::unique_ptr<index_cache_resource> *resource)
> > > +{
> > > +  try
> > > +    {
> > > +      /* Try to map that file.  */
> > > +      index_cache_resource_mmap *mmap_resource
> > > +       = new index_cache_resource_mmap (index_path);
> > > +
> > > +      /* Hand the resource to the caller.  */
> > > +      resource->reset (mmap_resource);
> > > +
> > > +      return gdb::array_view<const gdb_byte>
> > > +         ((const gdb_byte *) mmap_resource->mapping.get (),
> > > +          mmap_resource->mapping.size ());
> > > +    }
> > > +  catch (const gdb_exception_error &except)
> > > +    {
> > > +      warning (_("Unable to read %s: %s"), index_path, except.what ());
> > > +    }
> > > +
> > > +  return {};
> > > +}
> > > +
> > >  #else /* !HAVE_SYS_MMAN_H */
> > >
> > >  /* See dwarf-index-cache.h.  This is a no-op on unsupported systems.  */
> > > @@ -251,6 +278,12 @@ index_cache::lookup_gdb_index (const bfd_build_id *build_id,
> > >    return {};
> > >  }
> > >
> > > +gdb::array_view<const gdb_byte>
> > > +index_cache::lookup_gdb_index_debuginfod (const char *index_path,
> > > +                                         std::unique_ptr<index_cache_resource> *resource)
> > > +{
> > > +  return {};
> > > +}
> > >  #endif
> > >
> > >  /* See dwarf-index-cache.h.  */
> > > diff --git a/gdb/dwarf2/index-cache.h b/gdb/dwarf2/index-cache.h
> > > index cfa45435fbd..9d18717fe56 100644
> > > --- a/gdb/dwarf2/index-cache.h
> > > +++ b/gdb/dwarf2/index-cache.h
> > > @@ -90,6 +90,19 @@ class index_cache
> > >    lookup_gdb_index (const bfd_build_id *build_id,
> > >                     std::unique_ptr<index_cache_resource> *resource);
> > >
> > > +  /* Look for an index file located at INDEX_PATH in the debuginfod cache.
> > > +     Unlike lookup_gdb_index, this function does not exit early if the
> > > +     index cache has not been enabled.
> > > +
> > > +     If found, return the contents as an array_view and store the underlying
> > > +     resources (allocated memory, mapped file, etc) in RESOURCE.  The returned
> > > +     array_view is valid as long as RESOURCE is not destroyed.
> > > +
> > > +     If no matching index file is found, return an empty array view.  */
> > > +  gdb::array_view<const gdb_byte>
> > > +  lookup_gdb_index_debuginfod (const char *index_path,
> > > +                              std::unique_ptr<index_cache_resource> *resource);
> > > +
> > >    /* Return the number of cache hits.  */
> > >    unsigned int n_hits () const
> > >    { return m_n_hits; }
> > > diff --git a/gdb/dwarf2/public.h b/gdb/dwarf2/public.h
> > > index 0e74857eb1a..4a44cdbc223 100644
> > > --- a/gdb/dwarf2/public.h
> > > +++ b/gdb/dwarf2/public.h
> > > @@ -40,4 +40,11 @@ extern void dwarf2_initialize_objfile (struct objfile *objfile);
> > >
> > >  extern void dwarf2_build_frame_info (struct objfile *);
> > >
> > > +/* Query debuginfod for the .gdb_index associated with OBJFILE.  If
> > > +   successful, create an objfile to hold the .gdb_index information
> > > +   and act as a placeholder until the full debuginfo needs to be
> > > +   downloaded.  */
> > > +
> > > +extern bool dwarf2_has_separate_index (struct objfile *);
> > > +
> > >  #endif /* DWARF2_PUBLIC_H */
> > > diff --git a/gdb/dwarf2/read-gdb-index.c b/gdb/dwarf2/read-gdb-index.c
> > > index e789e9c2654..da88a8b405c 100644
> > > --- a/gdb/dwarf2/read-gdb-index.c
> > > +++ b/gdb/dwarf2/read-gdb-index.c
> > > @@ -139,6 +139,7 @@ struct dwarf2_gdb_index : public dwarf2_base_index_functions
> > >       gdb.dwarf2/gdb-index.exp testcase.  */
> > >    void dump (struct objfile *objfile) override;
> > >
> > > +  /* Calls do_expand_matching_symbols and downloads debuginfo if necessary.  */
> > >    void expand_matching_symbols
> > >      (struct objfile *,
> > >       const lookup_name_info &lookup_name,
> > > @@ -146,6 +147,14 @@ struct dwarf2_gdb_index : public dwarf2_base_index_functions
> > >       int global,
> > >       symbol_compare_ftype *ordered_compare) override;
> > >
> > > +  void do_expand_matching_symbols
> > > +    (struct objfile *,
> > > +     const lookup_name_info &lookup_name,
> > > +     domain_enum domain,
> > > +     int global,
> > > +     symbol_compare_ftype *ordered_compare);
> > > +
> > > +  /* Calls do_expand_symtabs_matching and downloads debuginfo if necessary.  */
> > >    bool expand_symtabs_matching
> > >      (struct objfile *objfile,
> > >       gdb::function_view<expand_symtabs_file_matcher_ftype> file_matcher,
> > > @@ -155,8 +164,59 @@ struct dwarf2_gdb_index : public dwarf2_base_index_functions
> > >       block_search_flags search_flags,
> > >       domain_enum domain,
> > >       enum search_domain kind) override;
> > > +
> > > +  bool do_expand_symtabs_matching
> > > +    (struct objfile *objfile,
> > > +     gdb::function_view<expand_symtabs_file_matcher_ftype> file_matcher,
> > > +     const lookup_name_info *lookup_name,
> > > +     gdb::function_view<expand_symtabs_symbol_matcher_ftype> symbol_matcher,
> > > +     gdb::function_view<expand_symtabs_exp_notify_ftype> expansion_notify,
> > > +     block_search_flags search_flags,
> > > +     domain_enum domain,
> > > +     enum search_domain kind);
> > > +
> > > +  /* Calls dwarf2_base_index_functions::expand_all_symtabs and downloads
> > > +     debuginfo if necessary.  */
> > > +  void expand_all_symtabs (struct objfile *objfile) override;
> > > +
> > > +  /* Calls dwarf2_base_index_functions::find_last_source_symtab and downloads
> > > +     debuginfo if necessary.  */
> > > +  struct symtab *find_last_source_symtab (struct objfile *objfile) override;
> > >  };
> > >
> > > +void
> > > +dwarf2_gdb_index::expand_all_symtabs (struct objfile *objfile)
> > > +{
> > > +  try
> > > +    {
> > > +      dwarf2_base_index_functions::expand_all_symtabs (objfile);
> > > +    }
> > > +  catch (const gdb_exception &e)
> > > +    {
> > > +      if ((objfile->flags & OBJF_DOWNLOAD_DEFERRED) == 0)
> > > +       exception_print (gdb_stderr, e);
> > > +      else
> > > +       read_full_dwarf_from_debuginfod (objfile, this);
> > > +    }
> > > +}
> > > +
> > > +struct symtab *
> > > +dwarf2_gdb_index::find_last_source_symtab (struct objfile *objfile)
> > > +{
> > > +  try
> > > +    {
> > > +      return dwarf2_base_index_functions::find_last_source_symtab (objfile);
> > > +    }
> > > +  catch (const gdb_exception &e)
> > > +    {
> > > +      if ((objfile->flags & OBJF_DOWNLOAD_DEFERRED) == 0)
> > > +       exception_print (gdb_stderr, e);
> > > +      else
> > > +       read_full_dwarf_from_debuginfod (objfile, this);
> > > +      return nullptr;
> > > +    }
> > > +}
> > > +
> > >  /* This dumps minimal information about the index.
> > >     It is called via "mt print objfiles".
> > >     One use is to verify .gdb_index has been loaded by the
> > > @@ -318,7 +378,7 @@ dw2_symtab_iter_next (struct dw2_symtab_iterator *iter,
> > >  }
> > >
> > >  void
> > > -dwarf2_gdb_index::expand_matching_symbols
> > > +dwarf2_gdb_index::do_expand_matching_symbols
> > >    (struct objfile *objfile,
> > >     const lookup_name_info &name, domain_enum domain,
> > >     int global,
> > > @@ -356,6 +416,29 @@ dwarf2_gdb_index::expand_matching_symbols
> > >      }, per_objfile);
> > >  }
> > >
> > > +void
> > > +dwarf2_gdb_index::expand_matching_symbols
> > > +  (struct objfile *objfile,
> > > +   const lookup_name_info &lookup_name,
> > > +   domain_enum domain,
> > > +   int global,
> > > +   symbol_compare_ftype *ordered_compare)
> > > +{
> > > +  try
> > > +    {
> > > +      do_expand_matching_symbols (objfile, lookup_name, domain,
> > > +                                 global, ordered_compare);
> > > +    }
> > > +  catch (const gdb_exception &e)
> > > +    {
> > > +      if ((objfile->flags & OBJF_DOWNLOAD_DEFERRED) == 0)
> > > +       exception_print (gdb_stderr, e);
> > > +      else
> > > +       read_full_dwarf_from_debuginfod (objfile, this);
> > > +      return;
> > > +    }
> > > +}
> > > +
> > >  /* Helper for dw2_expand_matching symtabs.  Called on each symbol
> > >     matched, to expand corresponding CUs that were marked.  IDX is the
> > >     index of the symbol name that matched.  */
> > > @@ -458,7 +541,7 @@ dw2_expand_marked_cus
> > >  }
> > >
> > >  bool
> > > -dwarf2_gdb_index::expand_symtabs_matching
> > > +dwarf2_gdb_index::do_expand_symtabs_matching
> > >      (struct objfile *objfile,
> > >       gdb::function_view<expand_symtabs_file_matcher_ftype> file_matcher,
> > >       const lookup_name_info *lookup_name,
> > > @@ -507,6 +590,39 @@ dwarf2_gdb_index::expand_symtabs_matching
> > >    return result;
> > >  }
> > >
> > > +bool
> > > +dwarf2_gdb_index::expand_symtabs_matching
> > > +    (struct objfile *objfile,
> > > +     gdb::function_view<expand_symtabs_file_matcher_ftype> file_matcher,
> > > +     const lookup_name_info *lookup_name,
> > > +     gdb::function_view<expand_symtabs_symbol_matcher_ftype> symbol_matcher,
> > > +     gdb::function_view<expand_symtabs_exp_notify_ftype> expansion_notify,
> > > +     block_search_flags search_flags,
> > > +     domain_enum domain,
> > > +     enum search_domain kind)
> > > +{
> > > +  if (objfile->flags & OBJF_READNEVER)
> > > +    return false;
> > > +
> > > +  try
> > > +    {
> > > +      return do_expand_symtabs_matching (objfile, file_matcher, lookup_name,
> > > +                                        symbol_matcher, expansion_notify,
> > > +                                        search_flags, domain, kind);
> > > +    }
> > > +  catch (const gdb_exception &e)
> > > +    {
> > > +      if ((objfile->flags & OBJF_DOWNLOAD_DEFERRED) == 0)
> > > +       {
> > > +         exception_print (gdb_stderr, e);
> > > +         return false;
> > > +       }
> > > +
> > > +      read_full_dwarf_from_debuginfod (objfile, this);
> > > +      return true;
> > > +    }
> > > +}
> > > +
> > >  quick_symbol_functions_up
> > >  mapped_gdb_index::make_quick_functions () const
> > >  {
> > > @@ -842,28 +958,32 @@ dwarf2_read_gdb_index
> > >
> > >    /* If there is a .dwz file, read it so we can get its CU list as
> > >       well.  */
> > > -  dwz = dwarf2_get_dwz_file (per_bfd);
> > > -  if (dwz != NULL)
> > > +  if (get_gdb_index_contents_dwz != nullptr)
> > >      {
> > >        mapped_gdb_index dwz_map;
> > >        const gdb_byte *dwz_types_ignore;
> > >        offset_type dwz_types_elements_ignore;
> > > +      dwz = dwarf2_get_dwz_file (per_bfd);
> > >
> > > -      gdb::array_view<const gdb_byte> dwz_index_content
> > > -       = get_gdb_index_contents_dwz (objfile, dwz);
> > > -
> > > -      if (dwz_index_content.empty ())
> > > -       return 0;
> > > -
> > > -      if (!read_gdb_index_from_buffer (bfd_get_filename (dwz->dwz_bfd.get ()),
> > > -                                      1, dwz_index_content, &dwz_map,
> > > -                                      &dwz_list, &dwz_list_elements,
> > > -                                      &dwz_types_ignore,
> > > -                                      &dwz_types_elements_ignore))
> > > +      if (dwz != nullptr)
> > >         {
> > > -         warning (_("could not read '.gdb_index' section from %s; skipping"),
> > > -                  bfd_get_filename (dwz->dwz_bfd.get ()));
> > > -         return 0;
> > > +         gdb::array_view<const gdb_byte> dwz_index_content
> > > +           = get_gdb_index_contents_dwz (objfile, dwz);
> > > +
> > > +         if (dwz_index_content.empty ())
> > > +           return 0;
> > > +
> > > +         if (!read_gdb_index_from_buffer (bfd_get_filename
> > > +                                            (dwz->dwz_bfd.get ()),
> > > +                                          1, dwz_index_content, &dwz_map,
> > > +                                          &dwz_list, &dwz_list_elements,
> > > +                                          &dwz_types_ignore,
> > > +                                          &dwz_types_elements_ignore))
> > > +           {
> > > +             warning (_("could not read '.gdb_index' section from %s; skipping"),
> > > +                      bfd_get_filename (dwz->dwz_bfd.get ()));
> > > +               return 0;
> > > +           }
> > >         }
> > >      }
> > >
> > > diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
> > > index ea0b2328a3e..0c5689c63ef 100644
> > > --- a/gdb/dwarf2/read.c
> > > +++ b/gdb/dwarf2/read.c
> > > @@ -34,6 +34,7 @@
> > >  #include "dwarf2/attribute.h"
> > >  #include "dwarf2/comp-unit-head.h"
> > >  #include "dwarf2/cu.h"
> > > +#include "dwarf2/frame.h"
> > >  #include "dwarf2/index-cache.h"
> > >  #include "dwarf2/index-common.h"
> > >  #include "dwarf2/leb.h"
> > > @@ -95,6 +96,8 @@
> > >  #include "split-name.h"
> > >  #include "gdbsupport/parallel-for.h"
> > >  #include "gdbsupport/thread-pool.h"
> > > +#include "inferior.h"
> > > +#include "debuginfod-support.h"
> > >
> > >  /* When == 1, print basic high level tracing messages.
> > >     When > 1, be more verbose.
> > > @@ -3188,7 +3191,7 @@ dwarf2_base_index_functions::find_per_cu (dwarf2_per_bfd *per_bfd,
> > >  }
> > >
> > >  struct compunit_symtab *
> > > -dwarf2_base_index_functions::find_pc_sect_compunit_symtab
> > > +dwarf2_base_index_functions::do_find_pc_sect_compunit_symtab
> > >       (struct objfile *objfile,
> > >        struct bound_minimal_symbol msymbol,
> > >        CORE_ADDR pc,
> > > @@ -3219,6 +3222,32 @@ dwarf2_base_index_functions::find_pc_sect_compunit_symtab
> > >    return result;
> > >  }
> > >
> > > +struct compunit_symtab *
> > > +dwarf2_base_index_functions::find_pc_sect_compunit_symtab
> > > +     (struct objfile *objfile,
> > > +      struct bound_minimal_symbol msymbol,
> > > +      CORE_ADDR pc,
> > > +      struct obj_section *section,
> > > +      int warn_if_readin)
> > > +{
> > > +  if (objfile->flags & OBJF_READNEVER)
> > > +    return nullptr;
> > > +
> > > +  try
> > > +    {
> > > +      return do_find_pc_sect_compunit_symtab (objfile, msymbol, pc,
> > > +                                             section, warn_if_readin);
> > > +    }
> > > +  catch (const gdb_exception &e)
> > > +    {
> > > +      if ((objfile->flags & OBJF_DOWNLOAD_DEFERRED) == 0)
> > > +       exception_print (gdb_stderr, e);
> > > +      else
> > > +       read_full_dwarf_from_debuginfod (objfile, this);
> > > +      return nullptr;
> > > +    }
> > > +}
> > > +
> > >  void
> > >  dwarf2_base_index_functions::map_symbol_filenames
> > >       (struct objfile *objfile,
> > > @@ -3375,6 +3404,29 @@ get_gdb_index_contents_from_cache_dwz (objfile *obj, dwz_file *dwz)
> > >    return global_index_cache.lookup_gdb_index (build_id, &dwz->index_cache_res);
> > >  }
> > >
> > > +/* Query debuginfod for the .gdb_index matching OBJFILE's build-id.  Return the
> > > +   contents if successful.  */
> > > +
> > > +static gdb::array_view<const gdb_byte>
> > > +get_gdb_index_contents_from_debuginfod (objfile *objfile, dwarf2_per_bfd *per_bfd)
> > > +{
> > > +  const bfd_build_id *build_id = build_id_bfd_get (objfile->obfd.get ());
> > > +  if (build_id == nullptr)
> > > +    return {};
> > > +
> > > +  gdb::unique_xmalloc_ptr<char> index_path;
> > > +  scoped_fd fd = debuginfod_section_query (build_id->data, build_id->size,
> > > +                                          bfd_get_filename
> > > +                                            (objfile->obfd.get ()),
> > > +                                          ".gdb_index",
> > > +                                          &index_path);
> > > +  if (fd.get () < 0)
> > > +    return {};
> > > +
> > > +  return global_index_cache.lookup_gdb_index_debuginfod
> > > +    (index_path.get (), &per_bfd->index_cache_res);
> > > +}
> > > +
> > >  static quick_symbol_functions_up make_cooked_index_funcs ();
> > >
> > >  /* See dwarf2/public.h.  */
> > > @@ -3440,10 +3492,102 @@ dwarf2_initialize_objfile (struct objfile *objfile)
> > >        return;
> > >      }
> > >
> > > +  if ((objfile->flags & OBJF_DOWNLOAD_DEFERRED)
> > > +      && dwarf2_read_gdb_index (per_objfile,
> > > +                               get_gdb_index_contents_from_debuginfod,
> > > +                               nullptr))
> > > +    {
> > > +      dwarf_read_debug_printf ("found .gdb_index from debuginfod");
> > > +      objfile->qf.push_front (per_bfd->index_table->make_quick_functions ());
> > > +      objfile->qf.begin ()->get ()->from_separate_index = true;
> > > +      return;
> > > +    }
> > > +
> > >    global_index_cache.miss ();
> > >    objfile->qf.push_front (make_cooked_index_funcs ());
> > >  }
> > >
> > > +/* See read.h.  */
> > > +
> > > +void
> > > +read_full_dwarf_from_debuginfod (struct objfile *objfile,
> > > +                                dwarf2_base_index_functions *fncs)
> > > +{
> > > +  gdb_assert (objfile->flags & OBJF_DOWNLOAD_DEFERRED);
> > > +
> > > +  const struct bfd_build_id *build_id = build_id_bfd_get (objfile->obfd.get ());
> > > +  const char *filename;
> > > +  gdb_bfd_ref_ptr debug_bfd;
> > > +  gdb::unique_xmalloc_ptr<char> symfile_path;
> > > +  scoped_fd fd;
> > > +
> > > +  if (build_id == nullptr)
> > > +    goto unset;
> > > +
> > > +  filename = bfd_get_filename (objfile->obfd.get ());
> > > +  fd = debuginfod_debuginfo_query (build_id->data, build_id->size,
> > > +                                  filename, &symfile_path);
> > > +  if (fd.get () < 0)
> > > +    goto unset;
> > > +
> > > +  /* Separate debuginfo successfully retrieved from server.  */
> > > +  debug_bfd = symfile_bfd_open (symfile_path.get ());
> > > +  if (debug_bfd == nullptr
> > > +      || !build_id_verify (debug_bfd.get (), build_id->size, build_id->data))
> > > +    {
> > > +      warning (_("File \"%s\" from debuginfod cannot be opened as bfd"),
> > > +              filename);
> > > +      goto unset;
> > > +    }
> > > +
> > > +  /* Clear frame data so it can be recalculated using DWARF.  */
> > > +  dwarf2_clear_frame_data (objfile);
> > > +
> > > +  /* This may also trigger a dwz download.  */
> > > +  symbol_file_add_separate (debug_bfd, symfile_path.get (),
> > > +                            current_inferior ()->symfile_flags, objfile);
> > > +
> > > +unset:
> > > +  objfile->remove_deferred_status ();
> > > +}
> > > +
> > > +/* See public.h.  */
> > > +
> > > +bool
> > > +dwarf2_has_separate_index (struct objfile *objfile)
> > > +{
> > > +  if (objfile->flags & OBJF_DOWNLOAD_DEFERRED)
> > > +    return true;
> > > +  if (objfile->flags & OBJF_MAINLINE)
> > > +    return false;
> > > +  if (!IS_DIR_SEPARATOR (*objfile_filename (objfile)))
> > > +    return false;
> > > +
> > > +  gdb::unique_xmalloc_ptr<char> index_path;
> > > +  const bfd_build_id *build_id = build_id_bfd_get (objfile->obfd.get ());
> > > +
> > > +  if (build_id == nullptr)
> > > +    return false;
> > > +
> > > +  scoped_fd fd = debuginfod_section_query (build_id->data,
> > > +                                          build_id->size,
> > > +                                          bfd_get_filename
> > > +                                            (objfile->obfd.get ()),
> > > +                                          ".gdb_index",
> > > +                                          &index_path);
> > > +
> > > +  if (fd.get () < 0)
> > > +    return false;
> > > +
> > > +  /* We found a separate .gdb_index file so a separate debuginfo file
> > > +     should exist, but we don't want to download it until necessary.
> > > +     Attach the index to this objfile and defer the debuginfo download
> > > +     until gdb needs to expand symtabs referenced by the index.  */
> > > +  objfile->flags |= OBJF_DOWNLOAD_DEFERRED;
> > > +  dwarf2_initialize_objfile (objfile);
> > > +  return true;
> > > +}
> > > +
> > >
> > >
> > >  /* Build a partial symbol table.  */
> > > diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h
> > > index dc7abf23ba4..6ed0be7203b 100644
> > > --- a/gdb/dwarf2/read.h
> > > +++ b/gdb/dwarf2/read.h
> > > @@ -883,6 +883,10 @@ struct dwarf2_base_index_functions : public quick_symbol_functions
> > >       CORE_ADDR pc, struct obj_section *section, int warn_if_readin)
> > >         override final;
> > >
> > > +  struct compunit_symtab *do_find_pc_sect_compunit_symtab
> > > +    (struct objfile *objfile, struct bound_minimal_symbol msymbol,
> > > +     CORE_ADDR pc, struct obj_section *section, int warn_if_readin);
> > > +
> > >    struct compunit_symtab *find_compunit_symtab_by_address
> > >      (struct objfile *objfile, CORE_ADDR address) override
> > >    {
> > > @@ -959,4 +963,10 @@ extern bool read_addrmap_from_aranges (dwarf2_per_objfile *per_objfile,
> > >                                        dwarf2_section_info *section,
> > >                                        addrmap *mutable_map);
> > >
> > > +/* If OBJFILE contains information from a separately downloaded .gdb_index,
> > > +   attempt to download the full debuginfo.  */
> > > +
> > > +extern void read_full_dwarf_from_debuginfod (struct objfile *,
> > > +                                            dwarf2_base_index_functions *);
> > > +
> > >  #endif /* DWARF2READ_H */
> > > diff --git a/gdb/dwarf2/section.c b/gdb/dwarf2/section.c
> > > index 1235f293f45..b674103c72f 100644
> > > --- a/gdb/dwarf2/section.c
> > > +++ b/gdb/dwarf2/section.c
> > > @@ -54,7 +54,8 @@ dwarf2_section_info::get_bfd_owner () const
> > >        section = get_containing_section ();
> > >        gdb_assert (!section->is_virtual);
> > >      }
> > > -  gdb_assert (section->s.section != nullptr);
> > > +  if (section->s.section == nullptr)
> > > +    error (_("Can't find owner of DWARF section."));
> > >    return section->s.section->owner;
> > >  }
> > >
> > > diff --git a/gdb/elfread.c b/gdb/elfread.c
> > > index 7900dfbc388..5c89598eee7 100644
> > > --- a/gdb/elfread.c
> > > +++ b/gdb/elfread.c
> > > @@ -1235,7 +1235,7 @@ elf_symfile_read_dwarf2 (struct objfile *objfile,
> > >             symbol_file_add_separate (debug_bfd, debugfile.c_str (),
> > >                                       symfile_flags, objfile);
> > >         }
> > > -      else
> > > +      else if (!dwarf2_has_separate_index (objfile))
> > >         {
> > >           has_dwarf2 = false;
> > >           const struct bfd_build_id *build_id
> > > diff --git a/gdb/frame.c b/gdb/frame.c
> > > index 7077016ccba..00dbffed1ef 100644
> > > --- a/gdb/frame.c
> > > +++ b/gdb/frame.c
> > > @@ -1892,6 +1892,13 @@ get_selected_frame (const char *message)
> > >         error (("%s"), message);
> > >
> > >        lookup_selected_frame (selected_frame_id, selected_frame_level);
> > > +
> > > +      /* It is possible for lookup_selected_frame to cause a new objfile
> > > +        to be loaded.  Some objfile observers may choose to clear
> > > +        selected_frame when an objfile is loaded.  Work around this by
> > > +        calling lookup_selected_frame again if the first try failed.  */
> > > +      if (selected_frame == nullptr)
> > > +       lookup_selected_frame (selected_frame_id, selected_frame_level);
> > >      }
> > >    /* There is always a frame.  */
> > >    gdb_assert (selected_frame != NULL);
> > > diff --git a/gdb/objfile-flags.h b/gdb/objfile-flags.h
> > > index 9dee2ee51a0..fb3f741c899 100644
> > > --- a/gdb/objfile-flags.h
> > > +++ b/gdb/objfile-flags.h
> > > @@ -60,6 +60,10 @@ enum objfile_flag : unsigned
> > >      /* User requested that we do not read this objfile's symbolic
> > >         information.  */
> > >      OBJF_READNEVER = 1 << 6,
> > > +
> > > +    /* A separate .gdb_index has been downloaded for this objfile.
> > > +       Debuginfo for this objfile can be downloaded when required.  */
> > > +    OBJF_DOWNLOAD_DEFERRED = 1 << 7,
> > >    };
> > >
> > >  DEF_ENUM_FLAGS_TYPE (enum objfile_flag, objfile_flags);
> > > diff --git a/gdb/objfiles.h b/gdb/objfiles.h
> > > index c20b63ceadf..ea9bd2157dc 100644
> > > --- a/gdb/objfiles.h
> > > +++ b/gdb/objfiles.h
> > > @@ -612,6 +612,26 @@ struct objfile
> > >    /* See quick_symbol_functions.  */
> > >    void require_partial_symbols (bool verbose);
> > >
> > > +  /* Indicate that the aquisition of this objfile's separate debug objfile
> > > +     is no longer deferred.  Used when the debug objfile has been aquired
> > > +     or could not be found.  */
> > > +  void remove_deferred_status ()
> > > +  {
> > > +    flags &= ~OBJF_DOWNLOAD_DEFERRED;
> > > +
> > > +    /* Remove quick_symbol_functions derived from a separately downloaded
> > > +       index.  If available the separate debug objfile's index will be used
> > > +       instead, since that objfile actually contains the symbols and CUs
> > > +       referenced in the index.
> > > +
> > > +       No more than one element of qf should have from_separate_index set
> > > +       to true.  */
> > > +    qf.remove_if ([&] (const quick_symbol_functions_up &qf_up)
> > > +      {
> > > +       return qf_up->from_separate_index;
> > > +      });
> > > +  }
> > > +
> > >    /* Return the relocation offset applied to SECTION.  */
> > >    CORE_ADDR section_offset (bfd_section *section) const
> > >    {
> > > diff --git a/gdb/quick-symbol.h b/gdb/quick-symbol.h
> > > index a7fea2ccb49..e7163503e39 100644
> > > --- a/gdb/quick-symbol.h
> > > +++ b/gdb/quick-symbol.h
> > > @@ -225,6 +225,10 @@ struct quick_symbol_functions
> > >    virtual void read_partial_symbols (struct objfile *objfile)
> > >    {
> > >    }
> > > +
> > > +  /* True if this quick_symbol_functions is derived from a separately
> > > +     downloaded index.  */
> > > +  bool from_separate_index = false;
> > >  };
> > >
> > >  typedef std::unique_ptr<quick_symbol_functions> quick_symbol_functions_up;
> > > diff --git a/gdb/symfile.c b/gdb/symfile.c
> > > index eebc5ea44b9..0491a33e8f5 100644
> > > --- a/gdb/symfile.c
> > > +++ b/gdb/symfile.c
> > > @@ -991,6 +991,10 @@ syms_from_objfile (struct objfile *objfile,
> > >  static void
> > >  finish_new_objfile (struct objfile *objfile, symfile_add_flags add_flags)
> > >  {
> > > +  struct objfile *parent = objfile->separate_debug_objfile_backlink;
> > > +  bool was_deferred
> > > +    = (parent != nullptr) && (parent->flags & OBJF_DOWNLOAD_DEFERRED);
> > > +
> > >    /* If this is the main symbol file we have to clean up all users of the
> > >       old main symbol file.  Otherwise it is sufficient to fixup all the
> > >       breakpoints that may have been redefined by this symbol file.  */
> > > @@ -1001,7 +1005,8 @@ finish_new_objfile (struct objfile *objfile, symfile_add_flags add_flags)
> > >
> > >        clear_symtab_users (add_flags);
> > >      }
> > > -  else if ((add_flags & SYMFILE_DEFER_BP_RESET) == 0)
> > > +  else if ((add_flags & SYMFILE_DEFER_BP_RESET) == 0
> > > +          && !was_deferred)
> > >      {
> > >        breakpoint_re_set ();
> > >      }
> > > @@ -1122,6 +1127,12 @@ symbol_file_add_with_addrs (const gdb_bfd_ref_ptr &abfd, const char *name,
> > >    if (objfile->sf != nullptr)
> > >      finish_new_objfile (objfile, add_flags);
> > >
> > > +  /* Remove deferred status now in case any observers trigger symtab
> > > +     expansion.  Otherwise gdb might try to read parent for psymbols
> > > +     when it should read the separate debug objfile instead.  */
> > > +  if (parent != nullptr && (parent->flags & OBJF_DOWNLOAD_DEFERRED))
> > > +    parent->remove_deferred_status ();
> > > +
> > >    gdb::observers::new_objfile.notify (objfile);
> > >
> > >    bfd_cache_close_all ();
> > > diff --git a/gdb/symtab.c b/gdb/symtab.c
> > > index 5ec56f4f2af..bd01a75189d 100644
> > > --- a/gdb/symtab.c
> > > +++ b/gdb/symtab.c
> > > @@ -2925,14 +2925,30 @@ find_pc_sect_compunit_symtab (CORE_ADDR pc, struct obj_section *section)
> > >    if (best_cust != NULL)
> > >      return best_cust;
> > >
> > > +  int warn_if_readin = 1;
> > > +
> > >    /* Not found in symtabs, search the "quick" symtabs (e.g. psymtabs).  */
> > >
> > >    for (objfile *objf : current_program_space->objfiles ())
> > >      {
> > > +      bool was_deferred = objf->flags & OBJF_DOWNLOAD_DEFERRED;
> > > +
> > >        struct compunit_symtab *result
> > > -       = objf->find_pc_sect_compunit_symtab (msymbol, pc, section, 1);
> > > +       = objf->find_pc_sect_compunit_symtab (msymbol, pc, section,
> > > +                                             warn_if_readin);
> > > +
> > >        if (result != NULL)
> > >         return result;
> > > +
> > > +      /* If objf's separate debug info was just acquired, disable
> > > +        warn_if_readin for the next iteration of this loop.  This prevents
> > > +        a spurious warning in case an observer already triggered expansion
> > > +        of the separate debug objfile's symtabs.  */
> > > +      if (was_deferred && objf->separate_debug_objfile != nullptr
> > > +         && (objf->flags & OBJF_DOWNLOAD_DEFERRED) == 0)
> > > +       warn_if_readin = 0;
> > > +      else if (warn_if_readin == 0)
> > > +       warn_if_readin = 1;
> > >      }
> > >
> > >    return NULL;
> > > diff --git a/gdb/testsuite/gdb.debuginfod/libsection1.c b/gdb/testsuite/gdb.debuginfod/libsection1.c
> > > new file mode 100644
> > > index 00000000000..60824b415c6
> > > --- /dev/null
> > > +++ b/gdb/testsuite/gdb.debuginfod/libsection1.c
> > > @@ -0,0 +1,40 @@
> > > +/* This testcase is part of GDB, the GNU debugger.
> > > +
> > > +   Copyright 2023 Free Software Foundation, Inc.
> > > +
> > > +   This program is free software; you can redistribute it and/or modify
> > > +   it under the terms of the GNU General Public License as published by
> > > +   the Free Software Foundation; either version 3 of the License, or
> > > +   (at your option) any later version.
> > > +
> > > +   This program is distributed in the hope that it will be useful,
> > > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > +   GNU General Public License for more details.
> > > +
> > > +   You should have received a copy of the GNU General Public License
> > > +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> > > +
> > > +#include <stdio.h>
> > > +#include <pthread.h>
> > > +#include <unistd.h>
> > > +
> > > +extern void libsection2_test ();
> > > +extern void *libsection2_thread_test (void *);
> > > +
> > > +void
> > > +libsection1_test ()
> > > +{
> > > +  pthread_t thr;
> > > +
> > > +  printf ("In libsection1\n");
> > > +  libsection2_test ();
> > > +
> > > +  pthread_create (&thr, NULL, libsection2_thread_test, NULL);
> > > +
> > > +  /* Give the new thread a chance to actually enter libsection2_thread_test.  */
> > > +  sleep (3);
> > > +  printf ("Cancelling thread\n");
> > > +
> > > +  pthread_cancel (thr);
> > > +}
> > > diff --git a/gdb/testsuite/gdb.debuginfod/libsection2.c b/gdb/testsuite/gdb.debuginfod/libsection2.c
> > > new file mode 100644
> > > index 00000000000..629a67f94a5
> > > --- /dev/null
> > > +++ b/gdb/testsuite/gdb.debuginfod/libsection2.c
> > > @@ -0,0 +1,37 @@
> > > +/* This testcase is part of GDB, the GNU debugger.
> > > +
> > > +   Copyright 2023 Free Software Foundation, Inc.
> > > +
> > > +   This program is free software; you can redistribute it and/or modify
> > > +   it under the terms of the GNU General Public License as published by
> > > +   the Free Software Foundation; either version 3 of the License, or
> > > +   (at your option) any later version.
> > > +
> > > +   This program is distributed in the hope that it will be useful,
> > > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > +   GNU General Public License for more details.
> > > +
> > > +   You should have received a copy of the GNU General Public License
> > > +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> > > +
> > > +#include <stdio.h>
> > > +
> > > +void
> > > +libsection2_test ()
> > > +{
> > > +  printf ("In libsection2\n");
> > > +}
> > > +
> > > +void *
> > > +libsection2_thread_test (void *arg)
> > > +{
> > > +  (void) arg;
> > > +
> > > +  printf ("In thread test\n");
> > > +
> > > +  while (1)
> > > +    ;
> > > +
> > > +  return NULL;
> > > +}
> > > diff --git a/gdb/testsuite/gdb.debuginfod/section.c b/gdb/testsuite/gdb.debuginfod/section.c
> > > new file mode 100644
> > > index 00000000000..d391a8f898e
> > > --- /dev/null
> > > +++ b/gdb/testsuite/gdb.debuginfod/section.c
> > > @@ -0,0 +1,29 @@
> > > +/* This testcase is part of GDB, the GNU debugger.
> > > +
> > > +   Copyright 2023 Free Software Foundation, Inc.
> > > +
> > > +   This program is free software; you can redistribute it and/or modify
> > > +   it under the terms of the GNU General Public License as published by
> > > +   the Free Software Foundation; either version 3 of the License, or
> > > +   (at your option) any later version.
> > > +
> > > +   This program is distributed in the hope that it will be useful,
> > > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > +   GNU General Public License for more details.
> > > +
> > > +   You should have received a copy of the GNU General Public License
> > > +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> > > +
> > > +#include <stdio.h>
> > > +
> > > +extern void libsection1_test ();
> > > +
> > > +int
> > > +main()
> > > +{
> > > +  libsection1_test ();
> > > +  printf ("in section exec\n");
> > > +
> > > +  return 0;
> > > +}
> > > diff --git a/gdb/testsuite/gdb.debuginfod/section.exp b/gdb/testsuite/gdb.debuginfod/section.exp
> > > new file mode 100644
> > > index 00000000000..ff57c6e32b7
> > > --- /dev/null
> > > +++ b/gdb/testsuite/gdb.debuginfod/section.exp
> > > @@ -0,0 +1,184 @@
> > > +# Copyright 2023 Free Software Foundation, Inc.
> > > +
> > > +# This program is free software; you can redistribute it and/or modify
> > > +# it under the terms of the GNU General Public License as published by
> > > +# the Free Software Foundation; either version 3 of the License, or
> > > +# (at your option) any later version.
> > > +#
> > > +# This program is distributed in the hope that it will be useful,
> > > +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > +# GNU General Public License for more details.
> > > +#
> > > +# You should have received a copy of the GNU General Public License
> > > +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> > > +
> > > +# Test debuginfod functionality
> > > +
> > > +standard_testfile
> > > +
> > > +load_lib debuginfod-support.exp
> > > +
> > > +require allow_debuginfod_tests
> > > +
> > > +set sourcetmp [standard_output_file tmp-${srcfile}]
> > > +set outputdir [standard_output_file {}]
> > > +
> > > +# SECTEXEC is an executable which calls a function from LIB_SL1.
> > > +set sectfile "section"
> > > +set sectsrc $srcdir/$subdir/section.c
> > > +set sectexec [standard_output_file $sectfile]
> > > +
> > > +# Solib LIB_SL1 calls functions from LIB_SL2.
> > > +set libfile1 "libsection1"
> > > +set libsrc1 $srcdir/$subdir/$libfile1.c
> > > +set lib_sl1 [standard_output_file $libfile1.sl]
> > > +
> > > +set libfile2 "libsection2"
> > > +set libsrc2 $srcdir/$subdir/$libfile2.c
> > > +set lib_sl2 [standard_output_file $libfile2.sl]
> > > +
> > > +set lib_opts1 [list debug build-id shlib=$lib_sl2]
> > > +set lib_opts2 [list debug build-id]
> > > +set exec_opts [list debug build-id shlib=$lib_sl1 shlib=$lib_sl2]
> > > +
> > > +clean_restart
> > > +
> > > +if {[enable_section_downloads] == 0} {
> > > +    untested "GDB does not support debuginfod section downloads"
> > > +    return -1
> > > +}
> > > +
> > > +# Compile SECTEXEC, LIB_SL1 and LIB_SL2.
> > > +if { [gdb_compile_shlib $libsrc2 $lib_sl2 $lib_opts2] != "" } {
> > > +    untested "failed to compile $libfile2"
> > > +    return -1
> > > +}
> > > +
> > > +if { [gdb_compile_shlib_pthreads $libsrc1 $lib_sl1 $lib_opts1] != "" } {
> > > +    untested "failed to compile $libfile1"
> > > +    return -1
> > > +}
> > > +
> > > +if { [gdb_compile $sectsrc $sectexec executable $exec_opts] != "" } {
> > > +    untested "failed to compile $sectfile"
> > > +    return -1
> > > +}
> > > +
> > > +# Add .gdb_index to solibs.
> > > +if { [have_index $lib_sl1] != "gdb_index"
> > > +     && [add_gdb_index $lib_sl1] == 0 } {
> > > +    untested "failed to add .gdb_index to $libfile1"
> > > +    return -1
> > > +}
> > > +
> > > +if { [have_index $lib_sl2] != "gdb_index"
> > > +     && [add_gdb_index $lib_sl2] == 0 } {
> > > +    untested "failed to add .gdb_index to $libfile2"
> > > +    return -1
> > > +}
> > > +
> > > +# Strip solib debuginfo into separate files.
> > > +if { [gdb_gnu_strip_debug $lib_sl1 ""] != 0} {
> > > +   fail "strip $lib_sl1 debuginfo"
> > > +   return -1
> > > +}
> > > +
> > > +if { [gdb_gnu_strip_debug $lib_sl2 ""] != 0} {
> > > +   fail "strip $lib_sl2 debuginfo"
> > > +   return -1
> > > +}
> > > +
> > > +# Move debuginfo files into directory that debuginfod will serve from.
> > > +set debugdir [standard_output_file "debug"]
> > > +set debuginfo_sl1 [standard_output_file $libfile1.sl.debug]
> > > +set debuginfo_sl2 [standard_output_file $libfile2.sl.debug]
> > > +
> > > +file mkdir $debugdir
> > > +file rename -force $debuginfo_sl1 $debugdir
> > > +file rename -force $debuginfo_sl2 $debugdir
> > > +
> > > +# Restart GDB and clear the debuginfod client cache. Then load BINFILE into
> > > +# GDB and start running it.  Match output with pattern RES and use TESTNAME
> > > +# as the test name.
> > > +proc_with_prefix clean_restart_with_prompt { binfile res testname } {
> > > +    global cache
> > > +
> > > +    # Delete client cache so debuginfo downloads again.
> > > +    file delete -force $cache
> > > +    clean_restart
> > > +
> > > +    gdb_test "set debuginfod enabled on" "" "clean_restart enable $testname"
> > > +    gdb_load $binfile
> > > +
> > > +    if {![runto_main]} {
> > > +       return
> > > +    }
> > > +}
> > > +
> > > +# Tests with no debuginfod server running.
> > > +proc_with_prefix no_url { } {
> > > +    global sectexec libfile1 libfile2
> > > +
> > > +    gdb_load $sectexec
> > > +    if {![runto_main]} {
> > > +       return
> > > +    }
> > > +
> > > +    # Check that no section is downloaded and no debuginfo is found.
> > > +    gdb_test "info sharedlibrary" ".*Yes \\(\\*\\).*$libfile1.*" \
> > > +            "found no url lib1"
> > > +    gdb_test "info sharedlibrary" ".*Yes \\(\\*\\).*$libfile2.*" \
> > > +            "found no url lib2"
> > > +}
> > > +
> > > +# Tests with a debuginfod server running.
> > > +proc_with_prefix local_url { } {
> > > +    global sectexec
> > > +    global libsrc1 lib_sl1 libfile1
> > > +    global libsrc2 lib_sl2 libfile2
> > > +    global debugdir db
> > > +
> > > +    set url [start_debuginfod $db $debugdir]
> > > +    if { $url == "" } {
> > > +       unresolved "failed to start debuginfod server"
> > > +       return
> > > +    }
> > > +
> > > +    # Point GDB to the server.
> > > +    setenv DEBUGINFOD_URLS $url
> > > +
> > > +    # Download .gdb_index for solibs.
> > > +    set res ".*section \.gdb_index for $lib_sl1.*\
> > > +       section \.gdb_index for $lib_sl2.*"
> > > +    clean_restart_with_prompt $sectexec $res "index"
> > > +
> > > +    # Download debuginfo when stepping into a function.
> > > +    set res ".*separate debug info for $lib_sl1.*\"In ${libfile1}\\\\n\".*"
> > > +    gdb_test "step" $res "step"
> > > +
> > > +    clean_restart_with_prompt $sectexec "" "break"
> > > +
> > > +    # Download debuginfo when setting a breakpoint.
> > > +    set res "Download.*separate debug info for $lib_sl2.*"
> > > +    gdb_test "br libsection2_test" $res "break set"
> > > +
> > > +    # Hit the breakpoint.
> > > +    set res ".*Breakpoint 2, libsection2_test.*\"In ${libfile2}\\\\n\".*"
> > > +    gdb_test "c" $res "break continue"
> > > +
> > > +    # Check that download progress message is correctly formatted
> > > +    # during backtrace.
> > > +    set res ".*debug info for $lib_sl1\.\.\.\r\n\#1.*"
> > > +    gdb_test "bt" $res "break backtrace"
> > > +}
> > > +
> > > +# Create CACHE and DB directories ready for debuginfod to use.
> > > +prepare_for_debuginfod cache db
> > > +
> > > +with_debuginfod_env $cache {
> > > +    no_url
> > > +    local_url
> > > +}
> > > +
> > > +stop_debuginfod
> > > diff --git a/gdb/testsuite/lib/debuginfod-support.exp b/gdb/testsuite/lib/debuginfod-support.exp
> > > index 50a8b512a4a..e0b3dc39f51 100644
> > > --- a/gdb/testsuite/lib/debuginfod-support.exp
> > > +++ b/gdb/testsuite/lib/debuginfod-support.exp
> > > @@ -113,6 +113,8 @@ proc with_debuginfod_env { cache body } {
> > >  proc start_debuginfod { db debugdir } {
> > >      global debuginfod_spawn_id spawn_id
> > >
> > > +    set logfile [standard_output_file "server_log"]
> > > +
> > >      # Find an unused port.
> > >      set port 7999
> > >      set found false
> > > @@ -127,7 +129,8 @@ proc start_debuginfod { db debugdir } {
> > >             set old_spawn_id $spawn_id
> > >         }
> > >
> > > -       spawn debuginfod -vvvv -d $db -p $port -F $debugdir
> > > +       spawn sh -c "debuginfod -vvvv -d $db -p $port -F $debugdir 2>&1 \
> > > +               | tee $logfile"
> > >         set debuginfod_spawn_id $spawn_id
> > >
> > >         if { [info exists old_spawn_id] } {
> > > @@ -194,3 +197,25 @@ proc stop_debuginfod { } {
> > >         unset debuginfod_spawn_id
> > >      }
> > >  }
> > > +
> > > +# Return 1 if gdb is configured to download ELF/DWARF sections from
> > > +# debuginfod servers.  Otherwise return 0.
> > > +proc enable_section_downloads { } {
> > > +    global gdb_prompt
> > > +
> > > +    set cmd "maint set debuginfod download-sections on"
> > > +    set msg "enable section downloads"
> > > +
> > > +    gdb_test_multiple $cmd $msg {
> > > +       -re -wrap ".*not compiled into GDB.*" {
> > > +           return 0
> > > +       }
> > > +       -re -wrap "^" {
> > > +           return 1
> > > +       }
> > > +       -re -wrap "" {
> > > +           fail "$gdb_test_name (unexpected output)"
> > > +           return 0
> > > +       }
> > > +    }
> > > +}
> > > --
> > > 2.41.0
> > >