Hello,

from the JFFS2 documentation I have this:

http://sourceware.org/jffs2/jffs2-html/node3.html

"The original JFFS simply assumed that any block which appeared at first scan 
to contain 0xFF in every byte was free, and would select the longest run of 
apparently free space at mount time to be the space between the head and tail 
of the log. Unfortunately, extensive power fail testing on JFFS proved this to 
be unwise. For many types of flash chips, if power is lost during an erase 
operation, some bits may be left in an unstable state, while most are reset to 
a logical one. If the initial scan happens to read all ones and treat a block 
containing such unstable bits as usable, then data may be lost -- and such data 
loss may not even be avoidable by the naïve method of verification by reading 
back data immediately by writing, because the bit may just happen to return the 
correct value when read back for verification.

Empirical results showed that even rereading the entire contents of the block 
multiple times in an attempt to detect unstable bits was not sufficiently 
reliable to avoid data loss, so an alternative approach was required. The 
accepted solution was to write the marker node to the flash block immediately 
after successful completion of an erase operation. Upon encountering flash 
blocks which do not appear to contain any valid nodes, JFFS2 will trigger an 
erase operation and subsequently write the appropriate marker node to the 
erased block."

Has YAFFS2 a similar mechanism to prevent usage of blocks which had a power 
down during an erase operation?

Best regards,
	Sebastian

-- 
Sebastian Huber, embedded brains GmbH

Address : Obere Lagerstr. 30, D-82178 Puchheim, Germany
Phone   : +49 89 18 90 80 79-6
Fax     : +49 89 18 90 80 79-9
E-Mail  : sebastian.huber@embedded-brains.de
PGP     : Public key available on request.

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