[RFC] Debugging techniques for GeodeLX-based platforms

[llandre]

Hi all,

I'm going to start my first Geode-based project. I was googling around 
to understand which debugging techniques are available for this processor.
So far I found:
* (old fashioned) burn boot flash and see what happens (flash 
programming can be performed with external programmer or via JTAG)
* ROM emulator (see for example 
http://wiki.laptop.org/go/ROM_Emulators_for_OLPC or 
http://www.tech-tools.com/er3.htm)

I'm wondering if it is possible to avoid the long burn-debug-recode cycle.
For example, in case JTAG debugger is available, I should be possible to 
download the boot code in RAM (on-chip or external) and execute it under 
debugger control (I often used this technique in ARM/PowerPC-based 
embedded systems).
I was having a look at Geode LX databook and I found that the GeodeLink 
Control Processor provides 1KB SRAM that could be suitable for this 
purpose. Anybody implemented such solution?
Any comment or advice will be appreciated.

TIA,
llandre

DAVE Electronics System House - R&D Department
web:   http://www.dave.eu
email: r&[e-mail]

Debugging techniques for GeodeLX-based platforms

[Jordan Crouse]

On 21/04/08 15:17 +0200, llandre wrote:
> Hi all,
>
> I'm going to start my first Geode-based project. I was googling around 
> to understand which debugging techniques are available for this processor.
> So far I found:
> (old fashioned) burn boot flash and see what happens (flash
>
> programming can be performed with external programmer or via JTAG)
> ROM emulator (see for example
>
> http://wiki.laptop.org/go/ROM_Emulators_for_OLPC or 
> http://www.tech-tools.com/er3.htm)
>
> I'm wondering if it is possible to avoid the long burn-debug-recode cycle.
> For example, in case JTAG debugger is available, I should be possible to 
> download the boot code in RAM (on-chip or external) and execute it under 
> debugger control (I often used this technique in ARM/PowerPC-based 
> embedded systems).
> I was having a look at Geode LX databook and I found that the GeodeLink 
> Control Processor provides 1KB SRAM that could be suitable for this 
> purpose. Anybody implemented such solution?
> Any comment or advice will be appreciated.

The quickest and best option is a ROM emulator - I recommend the Artec
dongle, which was actually developed for a Geode platform:

http://www.coreboot.org/Artecgroup_programmable_LPC_dongle

Using a good ROM emulator results in a faster turn around cycle then JTAG,
and is more reliable too.

Jordan