On Tue, Oct 14, 2008 at 12:40 AM, Duane Ellis <[EMAIL PROTECTED]> wrote:
> David Anders wrote
>
>> the ICEPick works as a JTAG Route Controler(JRC),
>
> [snip]
>
>> due to the number of multi-core arm devices becoming available, a vast
>> majority of the vendors will be providing JRC's as their primary means of
>> jtag.
>
> This is what I think needs to be done to make a beagle board work. (I don't
> have one - so I can't make it happen).
>
> (1) a new "target event" to occur at a specific spot in the reset sequence,
> and/or tap configuration sequence or some where.
> Inserting it is easy - It is the "where to insert it" that I don't know.

A target event wouldn't work terribly well here, as OpenOCD is founded
on the false assumption that the JTAG chain never changes throughout OpenOCDs
lifespan.

My current thinking(and I haven't dived into the problem) is to allow OpenOCD
to have multiple descriptions of JTAG chains and allow switching between these
descriptions(minimally during the reset sequence).

The reset sequence would then talk to the JRC and set it up and switch to the
correct JTAG chain description afterwards.

I don't know what the long term solution will be here. Perhaps this whole bypass
thing is too feeble a concept and something more powerful like JRC needs to
happen during normal operation...

Another trick here is to introduce the *right* amount of complexity to
solve this
problem. Not too much, not too little...

-- 
Øyvind Harboe
http://www.zylin.com/zy1000.html
ARM7 ARM9 XScale Cortex
JTAG debugger and flash programmer

Free eCos workshop in Oslo October 21!
http://www.zylin.com/workshop.html
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