>From looking at the ecclayout on mxc_nd2.c there are only 4 bytes in the oobfree member. How many bytes does yaffs need to store it's tags?
Also, the imx35 uses hw ecc, I've read that mlc nand+hw ecc usually means one cannot really use the oob for anything else, is that true?
Boaz Ben-David <
boaz.bd@wellsense-tech.com> wrote:
I'm using freescale's iMX353 and the nand is Samsung 2GB MLC 4k page with 218 bytes oob.
I was somehow under the impression that writing to the oob area in MLC nand is problematic and thats why I tried using the inband tags option. Isn't it?
Charles Manning <
manningc2@actrix.gen.nz> wrote:
On Friday 14 January 2011 10:59:03 Ross Younger wrote:
> On 13/01/11 17:35, Boaz Ben-David wrote:
> > Well, thanks for everyone for their support.
> > It turns out that all I had to do is mount the partitions with the -o
> > inband-tags flag for YAFFS2 to work correctly on my NAND.
>
> Good to hear you've got it working. However, inband tags reduce both the
> storage capacity of the NAND[0] and the performance you can achieve[1].
> I would recommend regular - out-of-band - tags if possible.
>
> [0] by the size of the packed tags struct (16 bytes) per page; about
> 0.8% of a device with 2k pages.
>
> [1] in cases where YAFFS wants to read only the tags of a page, inband
> mode has to read in the entire page and throw away all but the last 16
> bytes. This adds up fast when mounting following an unclean shutdown,
> when YAFFS has to scan the entire NAND.
Yes, use out of band tags if you can. Inband tags will generally work even if
the mtd driver's oob handling is broken so you're sidestepping the issue
rather than fixing it.
What NAND and NAND controller are you using?
-- CHarles
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