Re: [PATCH] Documentation: add debugging doc

[Karel Zak <kzak@redhat.com>]

 Semi, could you add howto-debug to your docs branch?

    Karel

On Sat, Aug 06, 2011 at 08:59:32PM -0400, Davidlohr Bueso wrote:
> From: Davidlohr Bueso <dave@gnu.org>
> 
> Layout the base for tips on debugging util-linux programs/wrappers.
> 
> Signed-off-by: Davidlohr Bueso <dave@gnu.org>
> ---
>  Documentation/README.debug |   30 ++++++++++++++++++++++++++++++
>  1 files changed, 30 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/README.debug
> 
> diff --git a/Documentation/README.debug b/Documentation/README.debug
> new file mode 100644
> index 0000000..7ead12f
> --- /dev/null
> +++ b/Documentation/README.debug
> @@ -0,0 +1,30 @@
> +Debugging util-linux programs
> +-----------------------------
> +
> +There are considerations to be made when profiling or debugging some programs found
> +in the util-linux package. Because wrapper scripts are used for the binaries to make
> +sure all library dependencies are met, you cannot use tools such as gdb or valgrind
> +directly with them.
> +
> +Let's take for example the mount command:
> +
> +$> file /path/util-linux/mount/mount
> +mount: Bourne-Again shell script text executable
> +
> +The binary itself is located in the .libs/ dir:
> +
> +$> file /path/util-linux/mount/.libs/mount
> +mount: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, not stripped
> +
> +When this command is run, there's a library dependency error:
> +./mount: /lib/x86_64-linux-gnu/libblkid.so.1: version `BLKID_2.20' not found (required by ./mount)
> +
> +To overcome this we need set the LD_LIBRARY_PATH variable to read the path of the shared lib found in
> +the sources, and not system-wide:
> +
> +$> export LD_LIBRARY_PATH=/path/util-linux/libblkid/src/.libs/:$LD_LIBRARY_PATH
> +
> +Now external debugging tools can be run on the binary.
> +
> +Happy hacking!
> +Davidlohr Bueso, August 2011
> -- 
> 1.7.4.1
> 
> 
> 
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-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com