GDB remote protocol: how to analyse packets?

I have: - A proprietary prototype ARM board (Cortex-M3 based) with eCos OS - The board has the programmed RedBoot bootloader - Serial line (RS-232) - GDB debugger for ARM (arm-eabi-gdb) - Host OS is Windows/Cygwin and/or Linux (actually, doesn't matter) Problem: GDB debugger cannot connect to the target over the serial line. What I want: is to sniff the packets of the GDB remote protocol in order to undestand whether the GDB stub on the target is alive and operating. Details: RedBoot has an option to pass the target's control to the built-in GDB stub. I know that the RedBoot is alive, I can connect to it and send it commands over the serial line. The RedBoot manual says that the switch to the GDB stub can be made by typing $ or + symbols (which are actually the prefixes of the GDB remote protocol packets). It seems to work for when I send those symbols the terminal dies. But I'm not sure if the RedBoot was compiled with the GDB stub support (don't ask me why :-)). Then, when I try to connect to the board with my GDB debugger I get the following picture (on Windows): ``` (gdb) target remote COM3 Remote debugging using COM3 Ignoring packet error, continuing... Ignoring packet error, continuing... Ignoring packet error, continuing... Ignoring packet error, continuing... ``` The port is correct, the baudrate as well. Actually the same output I get if I try to do the same with another serial port which is not connected with anything. What I want to know is does GDB stub send back anything or not? Intuitively I thought that probably ``` set verbose on ``` would help, but GDB manual says it has very a limited effect and my case is beyond it. May be it is possible to compile GDB debugger with a macro which enables debug logging?