On Saturday 26 May 2012 18:38:11 S. K. wrote: > Hello everyone!
> I have already mounted yaffs2 on my ubuntu12.04 with nand simulator .There
> is something not clear to me. Yaffs2 has ECC algorithm but, Where it will
The ECC algorithm is used in different ways depending on configuration
In yaffs1 mode, the ECC is used if use_nand_ecc is NOT selected.
In yaffs2 mode, the ecc is used to protect the tags if no_tags_ecc is NOT set.
> I want to check performance of its ECC algorithm on nand simulator and on
> flash device. can you help me exactly what I have to do?
Without more information it is difficult to advise you.
> and another question: I understood that flash memories can be SLC or MLC.
> SLC uses binary algorithms and MLC uses nonbinary one. Is it correct?
Well all flash cells are really analogue devices - not digitial.
SLC devices store only one bit per cell so they only have one threshold. MLC
devices store multiple bits per cell so have multiple thresholds.
> it influence the ECC algorithm? If yes what is the yaffs ECC
> algorithm?(Hamming or ...) what kind of flashs does yaffs
> support?(simulator and device)
Since MLC has less margin for error, MLC typically requires more robust ECC.
SLC devices will typically use 1-bit ECC using hamming codes (thats what
yaffs_ecc.c does). MLC will typically use BCH codes.
BCH codes are computationally expensive and will often use hardware in the