On XO-1.5 with 11.3.0/11.3.1 -- hang during shutdown?

[James Cameron]

On Thu, Jun 14, 2012 at 12:03:39PM +0530, Anish Mangal wrote:
> FYI, The testing efforts (with old v new SD cards are being recorded
> at http://dev.laptop.org.au/issues/1323)

I've found microSD card performance can change slightly as a result of
a reflash.  On #1323 it seems an fs-update was done prior to the test.

If you wish to keep analysing it to look at the differences between
microSD cards, then:

- make the same number of shutdown tests for both the original microSD
  card and the different microSD card, so that the difference can be
  established statistically.

- restrict the testing to microSD cards from OLPC that we have
  qualified.

- widen the testing to microSD cards from OLPC that have had little use.

- look for difference in behaviour with the microSD card written to in
  one laptop and used in another ... 'cause I'd hate to find that this
  was due to fs-update.

I predict that this is a race condition during shutdown, which may
yield better to analysis with serial port attached.  The 11.3.x builds
maintain a getty and shell on the serial port, if I recall correctly,
and this may still be responsive at the time of the hang.  Using that
shell it may be possible to find what processes are happening.  If
that shell isn't available, try adding it.

As to what is causing the different timing between different laptops,
I predict that this is dependent on microSD card performance
variation.  These cards contain a FLASH translation layer that
processes SD commands and manages the remapping from virtual blocks to
physical cells.  Their performance can vary.

I did consider the possibility of power cycling timing during
fs-update, but in the XO-1.5 units you have the microSD power is
managed by the embedded controller.  The SD card is power cycled by
Open Firmware, but not the microSD card.

Another thing you might try is run a microSD card in an SD card
adapter, see if there is a difference.

#1323 needs a pointer to your earlier work on #1033.  I found it in
mail, but I shouldn't have had to.  ;-}

-- 
James Cameron
http://quozl.linux.org.au/