Re: pahole regression: -a no longer works?

[Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>]

Em Sat, Jun 27, 2009 at 11:44:01AM -0400, Samuel Bronson escreveu:
> Speaking of the REDHAT/FEDORA conditional,
> 
>   (a) why doesn't it have a comment explaining what it's for? -- that
> is, what is different on redhat/fedora, and what it does to compensate
> for them
> 
>   (b) why is it *after* the check for the "dwfl_module_build_id"
> symbol, so that the REDHAT/FEDORA stuff can't fix up the missing
> variables and allow the symbol check a chance to run?

Just added comments for both cases, please take a look and see if it
makes it clear for you:

commit f96099b4c519e83ab2421c2e7660e132f63ddec7
Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Date:   Sat Jun 27 13:32:20 2009 -0300

    cmake: Add comments explaining build_id and fedora/rh detection
    
    Suggested-by: Samuel Bronson <naesten@xxxxxxxxx>
    Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

diff --git a/cmake/modules/FindDWARF.cmake b/cmake/modules/FindDWARF.cmake
index 76cdb3f..f4feec4 100644
--- a/cmake/modules/FindDWARF.cmake
+++ b/cmake/modules/FindDWARF.cmake
@@ -47,6 +47,10 @@ if (DWARF_INCLUDE_DIR AND LIBDW_INCLUDE_DIR AND DWARF_LIBRARY AND ELF_LIBRARY AN
 	set(DWARF_LIBRARIES ${DWARF_LIBRARY} ${ELF_LIBRARY} ${EBL_LIBRARY})
 
 	set(CMAKE_REQUIRED_LIBRARIES ${DWARF_LIBRARIES})
+	# check if libdw have the dwfl_module_build_id routine, i.e. if it supports the buildid
+	# mechanism to match binaries to detached debug info sections (the -debuginfo packages
+	# in distributions such as fedora). We do it against libelf because, IIRC, some distros
+	# include libdw linked statically into libelf.
 	check_library_exists(elf dwfl_module_build_id "" HAVE_DWFL_MODULE_BUILD_ID)
 else (DWARF_INCLUDE_DIR AND LIBDW_INCLUDE_DIR AND DWARF_LIBRARY AND ELF_LIBRARY AND EBL_LIBRARY)
 	set(DWARF_FOUND FALSE)
@@ -63,6 +67,9 @@ if (DWARF_FOUND)
 	endif (NOT DWARF_FIND_QUIETLY)
 else (DWARF_FOUND)
 	if (DWARF_FIND_REQUIRED)
+		# Check if we are in a Red Hat (RHEL) or Fedora system to tell
+		# exactly which packages should be installed. Please send
+		# patches for other distributions.
 		find_path(FEDORA fedora-release /etc)
 		find_path(REDHAT redhat-release /etc)
 		if (FEDORA OR REDHAT)
--
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