debug dongle

[John Watlington]

On Dec 12, 2011, at 10:37 AM, Marek Vasut wrote:

>> On Dec 12, 2011, at 10:13 AM, Marek Vasut wrote:
>> What exactly do you want to do ?
> 
> Port u-boot to the device.

I'm sorry to hear that.   We have no interest in running u-boot
on our hardware.

Open Firmware isn't just boot firmware.   It is involved
in the entire life cycle of the laptop.   The firmware shipped on
the laptop is used in the factory to test the bare motherboards,
and also for functional tests of the assembled laptops.   Once
delivered to users, OFW both a quick way for users to check
the hardware functionality and tools for repair shops to diagnose
problems.    OFW also supports mass reflashing of laptops
via WiFi multicast.

Type "menu" at the OFW prompt to see some of the diagnostics
for the current stage of your laptop's life.

>> In general, we use Open Firmware to completely re-install the OS onto the
>> laptop (as in "I just hosed the kernel on the eMMC and it refuses to
>> boot.)
> 
> Exactly, I'd prefer to replace the software from bottom up.

Learn about Open Firmware.   It has GREATLY increased my productivity
as a hardware debugger, and as mentioned earlier, is integrated into the
entire life cycle, not just booting an OS.

>> You can copy a new kernel into the boot directory in the boot partition
>> using Open Firmware, although it is much easier to do this from Linux.
> 
> It's not about kernel, I like to do lowlevel stuff.

Then you will love OFW.   And it is all open source.   You can see the
current OFW source running on your laptop at:
http://code.coreboot.org/p/openfirmware/source/tree/HEAD/

> Also, if I was able to debug 
> the thing via OpenOCD, that'd be cool. I added PXA3xx support to OpenOCD, I see 
> no reason why I won't be able to support A610.

Supporting OpenOCD on the 1.75 might get you that JTAG interface dongle.
Do you already have the Marvell JTAG "black box" ?
Or if you use your own JTAG interface device, the JTAG pinouts on XO-1.75
are documented at:    http://wiki.laptop.org/go/XO_1.75_B1#Documentation

Cheers,
wad