Do not understand use of oobfree

[Philip Rakity]

When reading the documentation for nand flash I realized that there was
an out of band area of some size following each page.  This size could
be say 8, 16 or 64 bytes.  Inside this oob area is stored a bad block
marker.  There may also be stored ecc bytes.  And there is of course
some area not used.

Some Questions:

a) the location and size of the ecc bytes are determined by what ?
.useecc = MTD_NANDECC_AUTOPLACE,

the flash chip -
the nand controller on the flash chip ?
both ??  

b) the oobfree area is specified as a {offset, length) pair.  When this
gets to say the jffs2 file system what does it see.  For example
	.oobfree = { {8, 8} }

it would see 8 bytes starting at offset 8 OR 8 bytes starting at offset
0 and the mtd driver would do the mapping.

more complex example
	.oobfree = { {3, 2}, {6, 2} }

would jffs2 see 4 bytes at offset 0. or 2 sets of data at offset 3 and
offset 6.

I am asking because if I have a flash device that does not map per the
standard includes do I have to touch jffs2 to get things to work. 

regards,

Philip



 
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