Re: how to debug mips or arm platform applications by cgdb

[Duane Ellis <duane at duaneellis dot com>]

loody wrote:
> Hi:
>
> 2009/6/7 Duane Ellis <duane@duaneellis.com>:
>   
loody> Would someone tell me how to debug mips or arm applications by CGDB.

duane> You need to describe your target better.

[... snip ...]

[answer: Basically a standalone board, NO OS]

duane> ....
> > In this case, 2 options:
> >
> > (a) A serial rom monitor that talks the GDB protocol (very rare these days,
> > most people use jtag).
> >
> > (b) A JTAG dongle, and software for that jtag dongle that understands the
> > GDB protocol.
> >
> > You'll need to *PURCHASE* a jtag dongle (or make one) - I highly recommend a
> > "USB based ftdi-2232 based dongle", and *STRONGLY* do not recommend a
> > "printer-port" solution.
> >
> > The "jtag dongle method" - is 80% identical to the GDBREMOTE example above -
> > but is more complicated (20%) because you have to create an initialization
> > script to setup your target board, program the cpu clocks, erase & program
> > the flash memory, stuff like that.
> >
> > A *VERY* common JTAG solution (de-facto for ARM) is:  "openocd" - see:
> >  http://openocd.berlios.de/web
> >
> > In the JTAG dongle case, GDB talks "target remote" to a
> > GDB server program running on Linux, or Windows, or in some cases the DONGLE is really a tiny
> > computer that talks the GDBSERVER protocol over Ethernet (the Zylin zy1000
> > is an example, it actually runs OpenOCD inside).
> >     
>
>   

loody> ...
> from the case you mention above, there seems a gdbserver running on
> the dongle not on the target board such that
> when we send gdb protocol from host to the dongle, it can translate it
> to the proper jtag instructions to handle the target board.
>
> Is my assumption correct?
> Thanks for your help,
>   

Yes, exactly.  Some are standalone and self contained "dongles" - ie: 
ZYLIN Z1000 (it has an Ethernet connector). Others are a cheap piece of 
hardware (few chips) and the software runs on your PC under windoze, or 
Linux (ie: OpenOCD is an example of that).

If the GDB server runs on the target (with no operating system present) 
- it is most typically a ROM monitor of some sort. The problem with this 
sort of platform is this: If your program goes off into the weeds - so 
might your ROM monitors ability to respond to GDB requests.  Example: 
You are using a serial port to respond to GDB requests. If your program 
*disables* interrupts and gets hung up, there will be no more serial 
port interrupts. GDB will be ignored.

Another variant of this is a commercial product. In the past I used the 
"ARM" version of the "EPI TOOLS" majic debugger. Which, is/was a 
fantastic package with fantastic support. Today, they are owned by 
Mentor. I have no experience since Mentor's acquisition, nor their MIPS 
variant of their debuggers. My experience with Mentor though has always 
been very positive.

   http://www.mentor.com/products/embedded_software/majic-jtag-probe/

Another variant is offered by "Green Hills Software".
And another is Lauterbach software.
(They also often include/require use of their compiler and/or tools).

-Duane.









Be