Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 46912513283232 (LWP 13447)]
0x000000000050ee13 in _php_stream_write (stream=0x0, buf=0x985678 "give me a crash", count=15)
at /usr/src/debug/php-5.1.2/main/streams/streams.c:1012
1012 if (buf == NULL || count == 0 || stream->ops->write == NULL) {
(gdb) bt
#0 0x000000000050ee13 in _php_stream_write (stream=0x0, buf=0x985678 "give me a crash", count=15)
at /usr/src/debug/php-5.1.2/main/streams/streams.c:1012
#1 0x0000000000487a45 in zif_spl_SplFileObject_fwrite (ht=<value optimized out>, return_value=0x985578,
return_value_ptr=<value optimized out>, this_ptr=<value optimized out>, return_value_used=<value optimized out>)
at /usr/src/debug/php-5.1.2/ext/spl/spl_directory.c:1861
0000002 0x00002aaaabb16e46 in xdebug_execute_internal (current_execute_data=0x7fffffca0860, return_value_used=0)
at /home/cristian/xdebug/xdebug.c:1428
0000003 0x000000000055a1d7 in zend_do_fcall_common_helper_SPEC (execute_data=0x7fffffca0860) at zend_vm_execute.h:202
0000004 0x0000000000559993 in execute (op_array=0x983aa8) at zend_vm_execute.h:92
0000005 0x00002aaaabb16b05 in xdebug_execute (op_array=0x983aa8) at /home/cristian/xdebug/xdebug.c:1366
0000006 0x000000000053d23c in zend_execute_scripts (type=8, retval=<value optimized out>, file_count=3)
at /usr/src/debug/php-5.1.2/Zend/zend.c:1109
0000007 0x00000000004ff84c in php_execute_script (primary_file=0x7fffffca2fc0) at /usr/src/debug/php-5.1.2/main/main.c:1732
0000008 0x00000000005ce045 in main (argc=2, argv=0x7fffffca3178) at /usr/src/debug/php-5.1.2/sapi/cli/php_cli.c:1092

don't know if it is related , but I opened a PHP bug due to other issue with
SplTempFileObject (xdebug unloaded)

http://bugs.php.net/bug.php?id=37257

fixed the mentioned PHP bug, I recompiled PHP. and without xdebug it works as expected now.

but stills segfaults with xdebug loaded. :-(

Fixed in CVS. The cause was that Xdebug didn't understand the EH_THROW error mode yet.