XO 1.75 hangs on countdown

James Cameron quozl at laptop.org
Mon Mar 18 22:14:31 EDT 2013

On Mon, Mar 18, 2013 at 06:10:42PM -0700, Sameer Verma wrote:
> On Mon, Mar 18, 2013 at 5:59 PM, James Cameron <quozl at laptop.org> wrote:
> > A hang at the number "10" means that Open Firmware did not continue
> > past the point of setting up the page (section) table and turning on
> > the MMU and caches.
> >
> > http://tracker.coreboot.org/trac/openfirmware/browser/cpu/arm/olpc/resetvec.fth#L144
> > is where the "10" is shown.  The "11" is just beyond, a few lines
> > down.
> >
> > My guesses are:
> >
> > - faulty memory,
> >
> > - faulty processor,
> >
> > - fault in wiring between processor and memory,
> >
> > - incorrect firmware version for the memory, (some memory required a
> >   specific version),
> >
> > - corrupt SPI FLASH.
> >
> > Have you any further history on this laptop?
> Fresh out of the box. SKU 213
> Box id: BCL201208280039C16


The possibilities are; the fault developed during shipment, or
developed after testing, or the testing was insufficient, or the
testing failed to detect the fault (a test escape).

Further diagnosis is possible, but will cost you some time and risk.

You should choose whether you want to go through this route.  If
anybody is going to do failure analysis, they will want the unit in
pristine condition.

SKU213 included Q4D18.  The switch of memory vendor required Q4D22.
The unit should not have the newer memory, but on the off chance it
does: if you have the unit open already, please photograph one of the
memory chips.

It may be possible to upgrade the firmare despite the problem you see,
but this requires a serial adapter and opening the unit.  I can guide
you through this process, but it would invalidate failure analysis.

This is not to say this memory vendor switch is a likely cause, it is
only that I am primed for this particular cause, and it is something I
can help with.  A bias.  Other causes are more likely, and I can't
help with them.

A dislodged piece of metal, such as a screw, or solder, might also
cause this if it became lodged near the memory chips.

James Cameron

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