slackware11 下gdb 不认得coredump 文件 ？？

tclwp

#gdb ./test2 core.test2
GNU gdb 6.5
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i686-pc-linux-gnu"...Using host libthread_db library "/lib/tls/libthread_db.so.1".

"/root/core.test2" is not a core dump: 不可识别的文件格式
(gdb)
:ask :ask :ask :ask :ask :ask

无论是构造浮点错误还是地址越界的程序，gdb都无法读coredump文件