Lpc2000

On Friday 28 May 2004 20:30, Micron Engineering wrote:
> I have a simple question: is it possible debug a program running from
> flash with gdb and a jtag interface? If yes, please tell me the
> configuration and/or where I may download gdb and/or the gdb stub.
> Best regards,
> Massimo Manca, Micron Engineering

I don't think jtag +flash really works via a gdbstub, but I could be wrong.

The jtag EmbeddedICE interface uses special debug registers in the core 
which, AFAIK, are not visible from code space which means that the gdbstub 
cannot access them. AFAIK gdbstub only works for executing programs in RAM.

Some JTAG debuggers (eg. bdi2000) emulate the gdb remote interface and 
convert the gdbremote commands into their corresponding JTAG embedded ICE 
commands.

There are two ways of trapping code in the EmbeddedICE(ie for breakpoints and 
single stepping). One is to trap on a specific pattern (software breakpt) and 
the other is to trap at a specific address (hardware breakpt). When debugging 
a RAM program we can trap on specific patterns and can have (almost) 
unlimited breakpoints by just setting those patterns in RAM at the breakpoint 
addresses. Since we can't easily modify code in flash we have to use the trap 
on address approach which means we can only set one or two breakpoints.

-- CHarles