Sometimes customers have a crash and can provide you a core file and everything you ask for, but gdb shows nothing but "???". Here's the instruction how fix the problem and debug the core file.

1. Request for core file and tarantool binary.
2. Run 'gdb ' and type 'info sharedlibrary'
3. Request for all libraries listed in (2) and place it to, for instance, 'lib' folder near core and binary. Use subfolders (e.g. ./lib/lib64) for libraries that listed with subfolders (e.g. /lib64/libc.so.6)
4. Run 'gdb' without parameters and type a script:

set solib-absolute-prefix ./lib
file <binary>
core <core>
bt