Run OFW heat spreader test

James Cameron quozl at
Mon Jan 23 01:58:29 EST 2012

On Mon, Jan 23, 2012 at 05:32:05PM +1100, Sridhar Dhanapalan wrote:
> On 23 January 2012 17:20, James Cameron <quozl at> wrote:
> > I thought you were doing this test to detect early units that may have
> > a failed heat spreader, and you were doing it at the time of reflashing
> > because that's when you had some control.
> Yes, that's the primary reason. Our initial batch of XO-1.5s have an
> inefficient heat spreader. They've been burning out, and replacing the
> motherboards is getting expensive and time consuming. We'd like to
> detect potentially faulty units early, and recommend a heat spreader
> change for them.

I don't think burning out is the right wording.  Perhaps you mean they
have been losing contact with the CPU.

This would be a gradual process, and would be encouraged mostly by
handling, including compression of the case and opening and closing the
lid.  I'm certain fs-update would not affect this process.

> As a thought - maybe we should be identifying the serial number as
> well?

Yes, you should be able to skip the test if the serial number is not in
the range of your initial batch of XO-1.5s.

> > I don't think it is worth doing this test for the purposes of flashing
> > the XOs. ?The built in throttling will work fine. ?If the heat spreader
> > is dodgy, you'll either get a hang during fs-update or it will take much
> > longer.
> Hangs are annoying and don't provide any useful feedback to the user.
> It might be true that the XO can't get damaged from flashing, but the
> symptoms at runtime are random and are difficult to diagnose. I think
> that forcing a heat spreader test can provide a warning to the user
> and allow them to do something before any damage or annoying behaviour
> can begin.

We have long since fixed the problem that led to random symptoms after
boot following an incomplete reflash ... I trust you are using that code
which writes the zero block last in the .zd file?  So unlike your
previous experience I don't expect any random and difficult to diagnose
symptoms.  Perhaps you should test what the result is.  The unit should
fail to boot.  You can simulate a hang during fs-update by forcing the
power off.  The result should be identical.

James Cameron

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