UBIFS Corrupt during power failure

Eric Holmberg Eric_Holmberg at Trimble.com
Wed Apr 15 12:32:24 EDT 2009

> Is this really different from NAND and it's page writes?
> Do the CFI block writes have to be aligned (to 64 bytes) offset, or
> can the 64 bytes start at any word position?

Looking through the data sheet again, it looks like there is the concept
of a page for block writes in this particular NOR flash where a page
starts on any address evenly divisible by 0x20 (32-byte block).  The CFI
driver handles this when splitting up the blocks.

Here's the datasheet for reference:
 * http://www.spansion.com/datasheets/s29gl-p_00_a11_e.pdf?page=28

Thinking about it, this shouldn't affect the maximum possible corruption
count, since a fully-aligned write buffer is the worst case (a possible
of a <=64-byte corruption).  If the block is split between pages, then
32-bytes would occur in the first write and 32-bytes in the second
write, so the maximum corruption would be <=32 bytes.

Does this match with your thoughts?


P.S.  I'm working on applying the latest patches and running a
corruption test where I limit the write-buffer size of 8 bytes.  So far,
so good.

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