[maemo-developers] [maemo-developers] Hints for using Valgrind tools in Scratchbox

[From: Eero Tamminen]

Hi,

Some additional things to remember when using Valgrind/gdb/etc.
in Scratchbox and with Maemo...

For them to find debug symbols packages in Scratchbox, you need
to do something like following:
--- symlinks for debug symfiles in sbox -----
#!/bin/sh
mkdir -p /usr/lib/debug/targets
cd /usr/lib/debug/targets
ln -sf /usr/lib/debug $(sh -c '. /targets/links/scratchbox.config;echo $SBOX_TARGET_NAME')
---------------------------------------------

This is because when Gdb uses "realpath" on libraries in Sbox it
gets a path starting with /targets/<target-name>/...  You can see
the effect of this if you "strace" Valgrind (or Gdb).


When using Valgrind, you need to remember to use:
	export G_SLICE="always-malloc"
Otherwise Valgrind will report bogus leaks (see Gnome Bugzilla
for more information on Glib Gslice and Valgrind).


Another thing to remember about Gdb is that the Maemo Sbox cross-gdb
cannot debug ARM (EABI) core dumps.  You need target Gdb for this.
However, because Sbox will use the host (cross-gdb) binary if
it exists, you need to tell Sbox to ignore that:
------ using native gdb in sbox -------
#!/bin/sh
# use native Gdb in Scratchbox
SBOX_REDIRECT_IGNORE=/usr/bin/gdb /usr/bin/gdb $*
---------------------------------------

You can check which Gdb is used with "gdb -v".  If it says
"--host=i686-pc-linux-gnu" on ARM target, it's a cross-gdb.


	- Eero

PS. Even if there would be ARM version of Valgrind, it would
be useless.  Even on >2GHz PC, programs are run under Valgrind
(memcheck tool) slower than on 770. Valgrind also takes several
times more memory than is available on the target.  However,
on PC target it's very nice as you can:
- check for memory access errors and leaks (--tool=memcheck)
- get time memory usage graph and backtraces (--tool=massif)
- profile code (--tool=callgrind)