Yes, but in order to do this you need to make a few modifications, then rebuild the project with "make DEBUG=1".
As an example, you can run design example 4 (de4) using the GDB debugger as follows:
1. FWX_SERIAL_EEPROM in fwxcfg.h must be undefined. In order to use the debugger, this must not be defined. This is described in the Frameworks Reference Guide.
2. The de4.ld file must be modified to change the org point to 0x1000. This will allow room for the GDB stub to be loaded into memory.
Also, you will have to run the debug session through the serial port instead of the USB port because design example 4 takes over control from the BIOS for the USB port on SIE2.