google/veyron: How to use emulator for development?

[Paul Menzel]

Dear coreboot folks,

I’d like to run upstream coreboot on the MEDION AKOYA S2013 
(google/veyron_jaq) [1].

As I have access to a DediProg EM100Pro [1] including a 10-Pin Split 
Cable with a grabber on the hold pin [2], and a clip, I was wondering if 
I can hook it up without soldering to boot from (like an external chip). 
On some boards, the wiring does not support In-system programming (ISP), 
as some other parts would for example be powered.

I couldn’t find the schematics. It’d be great if somebody with access 
could check that.

Kind regards,

Paul

[1]: 
https://www.chromium.org/chromium-os/developer-information-for-chrome-os-dev...
[2]: https://www.dediprog.com/product/EM100Pro-G2
[3]: https://www.dediprog.com/product/EM-SP-CB

[Julius Werner]

> As I have access to a DediProg EM100Pro [1] including a 10-Pin Split
> Cable with a grabber on the hold pin [2], and a clip, I was wondering if
> I can hook it up without soldering to boot from (like an external chip).
> On some boards, the wiring does not support In-system programming (ISP),
> as some other parts would for example be powered.

I mean... I can at least tell you that we do this in practice all the
time (with generally no issues). The SPI flash is not electrically
isolated, so yes, you're gonna leak some current into the SoC when you
do this (there are 100Ohm limiting series resistors so it's not a
complete short). I've never heard of a Chromebook board dying from
this but I can't legally guarantee you anything, of course.

[Peter Stuge]

Julius Werner wrote:
> > As I have access to a DediProg EM100Pro [1] including a 10-Pin Split
> > Cable with a grabber on the hold pin [2], and a clip, I was wondering if
> > I can hook it up without soldering to boot from (like an external chip).
>
> I mean... I can at least tell you that we do this in practice all the
> time (with generally no issues). The SPI flash is not electrically
> isolated, so yes, you're gonna leak some current into the SoC when you
> do this (there are 100Ohm limiting series resistors so it's not a
> complete short). I've never heard of a Chromebook board dying from
> this but I can't legally guarantee you anything, of course.

I don't think there can be a problem with current leaking, but on some
boards HOLD is tied directly to VCC, without a pullup.

In that case there's no way to work with a clip, the whole chip or at
least the HOLD pin has to be disconnected from the board, and HOLD
tied low instead.

//Peter