Debugging Guest Code
It is possible to attach GDB to any running instance of S2E. S2E relies on the QEMU GDB interface, which can be enabled
-s command line option. This option creates a socket on port number 1234.
./i386-s2e-softmmu/qemu -s2e-config-file config.lua -s
Once the guest is launched and the program is running, attach GDB to it.
gdb /path/to/my/prog target remote localhost:1234 # Use gdb as usual (set breakpoints, source directories, single-step, etc.).
GDB can only manipulate the current path. Use the DFS search strategy to have a coherent debugging experience.
GDB cannot inspect symbolic variables. If you attempt to display a symbolic variable, S2E will concretize it.
You can also debug kernel-mode code.
At any point, if you feel that symbolic execution got stuck, attach GDB to the running S2E instance to check what code is being executed.