[Letux-kernel] 2GB vs. 4GB Pyra RAM tests

Tony Lindgren tony at atomide.com
Thu Jul 27 16:19:01 CEST 2017


* H. Nikolaus Schaller <hns at goldelico.com> [170727 07:13]:
> Now comes the difficult interpretation.
> * generally this 4GB Pyra is less stable. Could be RAM induced
>   or something else. The test does not give a clear indication.
> * the 2GB Pyra runs stable in all configurations
> * 4GB and LPAE makes Linux boot fail more often
> * it is possible to use the complete 4GB RAM, but not reliably
> So I suspect a mixture of multiple effects. One makes the 4GB
> device I have tested less stable.
> And the other could be an LPAE issue that makes 4GB only useable
> in certain good cases (I could imagine it depends on how the
> virtual paging mechanism randomly allocates RAM). But it could
> still be the 4GB RAM chips or config being less stable due to
> higher noise or power consumption or whatever.
> Attached is an excerpt of the boot log and successful 3GB memtester
> output (the "BUG" occurs for non-lpae kernel as well - so it is not
> influencing the outcome).

Here are two suggestions to try to narrow this down a bit:

1. Try with just 1GB of 4GB enabled instead of 2GB to see if
   that works reliably

2. Revert commit 7abdb0e23e7b ("ARM: OMAP5: Add basic cpuidle
   MPU CSWR support") to see if it's somehow PM related



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