Hi,

     we try the following:

1) setup some data in an 8kByte block in RAM
2) frequently modify this data during normal operation
3) on a power fail signal write the block to a file on a NAND flash 
partition
4) recover from the written data after the power cut

   The time between power failure notification and the uP-reset is 
guaranteed by hardware
and is about 20ms.

Simply fsync()ing the file in case of a power cut does not seem 
reliable, for
   - the file system might be full
   - the garbage collector might run to free dirty LEBs and erase the 
corresponding PEBs
The latter overstretching our timing requirements.

This is on an embedded system (i.mx31, arm1136@532MHz) running Linux 
3.something
(we are quite flexible in adapting new kernel versions), currently 
testing on 3.0.45.

Could someone hint the course to follow for this szenario?

Any pointers appreciated,
Helmut
PS: I've already asked the very same question on linux-mtd (more 
specifically about UBIFS) to no avail. I thought YAFFS might be more 
suitable due to its more predictable garbage collector.


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