Hi Scott,
Le 06/02/2012 23:55, Scott Wood a écrit :
On 02/06/2012 04:23 PM, Albert ARIBAUD wrote:
Hi Vaibhav,
Le 06/02/2012 05:57, vaibhav kothari a écrit :
hi albert
Yes,actually there is already support of flash test in POST of latest
uboot.They are testing flash on every power on so am I for my board.But i
don't want to disturb sectors in which uboot code relies. Can you help me
here?
I am no NAND specialist, but I do hope NAND POST tests are pure read
tests and thus are not affected by poweroffs (and can actually test any
part of NAND).
NAND has a property called "read disturb", where excessively reading a
sector without writing to it can eventually cause data loss. U-Boot is
already read once per boot, but reading it a second time could halve the
expected lifetime. Data managed by something like ubi is be scrubbed in
a way that avoids this, but U-Boot itself is not usually managed in this
way (boot hardware/rom does not understand ubi).
I *did* say I am not a NAND expert. :)
Thanks Scott. But then, isn't NAND testing a kind of catch-22, where by
actually tesing if NAND works it one ends up weakening it either through
read disturb, or simply through writes?
-Scott
Amicalement,
--
Albert.
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