Debugging MIPS cpu with a probe, how?

Debugging MIPS cpu with a probe, how?

[TriKri]

Hello!

I have an embedded system, a box, with a MIPS processor on it, which I need
to debug (stop and start the processor, tell what instructions it has
previously executed, etc.). I also have an EJTAG probe, which I have
connected between the computer's usb and the box, and written software for
it. The software can communicate with the probe, which in its own turn can
communicate with the box through the tap (test access port), by giving the
tap certain instructions. It can also, through the tap, feed the MIPS
processor with instructions, and read/write data from processor registers.

The question is now, how can debug the processor? How do I stop it, do I
have to send any certain instructions to it? How can I set a breakpoint
(which I understand is a quite crucial point)? Can I use GDB with my
software to help debug the processor and how do I do that?

Thank you in advance!
/Kristofer Krus
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Re: Debugging MIPS cpu with a probe, how?

[Markus Gothe]

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See: http://www.linux-mips.org/wiki/JTAG for references...

//Markus

TriKri wrote:
> Hello!
>
> I have an embedded system, a box, with a MIPS processor on it,
> which I need to debug (stop and start the processor, tell what
> instructions it has previously executed, etc.). I also have an
> EJTAG probe, which I have connected between the computer's usb and
> the box, and written software for it. The software can communicate
> with the probe, which in its own turn can communicate with the box
> through the tap (test access port), by giving the tap certain
> instructions. It can also, through the tap, feed the MIPS processor
> with instructions, and read/write data from processor registers.
>
> The question is now, how can debug the processor? How do I stop it,
> do I have to send any certain instructions to it? How can I set a
> breakpoint (which I understand is a quite crucial point)? Can I use
> GDB with my software to help debug the processor and how do I do
> that?
>
> Thank you in advance! /Kristofer Krus
- --

_______________________________________

Mr Markus Gothe
Software Engineer

Phone: +46 (0)13 21 81 20 (ext. 1046)
Fax: +46 (0)13 21 21 15
Mobile: +46 (0)70 348 44 35
Diskettgatan 11, SE-583 35 Linköping, Sweden
www.27m.com
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Re: Debugging MIPS cpu with a probe, how?

[Johannes Stezenbach]

On Tue, Aug 05, 2008, TriKri wrote:
> 
> I have an embedded system, a box, with a MIPS processor on it, which I need
> to debug (stop and start the processor, tell what instructions it has
> previously executed, etc.). I also have an EJTAG probe, which I have
> connected between the computer's usb and the box, and written software for
> it. The software can communicate with the probe, which in its own turn can
> communicate with the box through the tap (test access port), by giving the
> tap certain instructions. It can also, through the tap, feed the MIPS
> processor with instructions, and read/write data from processor registers.
> 
> The question is now, how can debug the processor? How do I stop it, do I
> have to send any certain instructions to it? How can I set a breakpoint
> (which I understand is a quite crucial point)? Can I use GDB with my
> software to help debug the processor and how do I do that?

I looked for Open Source EJTAG software a while ago and found
two projects which may be of interest to you:

http://svn.berlios.de/svnroot/repos/openocd/branches/mips/
http://www.totalembedded.com/open_source/jtag/mips32_ejtag/

But I didn't try to use any of it so far.


Johannes