[Yaffs] ECC byte ordering (Possibly: SIGH, AGAIN?)

Charles Manning Charles.Manning@trimble.co.nz
Thu, 10 Feb 2005 09:09:34 +1300


Thanx for pointing that out. Sometimes it is easy to forget the
assumptions.



> -----Original Message-----
> From: yaffs-admin@stoneboat.aleph1.co.uk=20
> [mailto:yaffs-admin@stoneboat.aleph1.co.uk] On Behalf Of Steve Wahl
> Sent: Thursday, 10 February 2005 8:16 a.m.
> To: Steve Wahl
> Cc: yaffs@stoneboat.aleph1.co.uk
> Subject: Re: [Yaffs] ECC byte ordering (Possibly: SIGH, AGAIN?)
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>=20
> Hi, again,
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> I'm committing the wonderful sin of replying to my own=20
> message!  But thinking about this from a newbie's point of=20
> view, it occured to me that my fundamental disconnect was in=20
> not recognizing that "Steven Hill's nand_ecc.c" *IS* the "ECC=20
> functions of the generic MTD-NAND driver", as referred to in=20
> the original help docs for these two options.
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> To try and connect the two phrases is probably the biggest=20
> motivation for me in suggesting changes (repeated below) to=20
> the Kconfig help strings.
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> Again, thanks for listening.
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> --> Steve Wahl
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> On Wed, Feb 09, 2005 at 10:57:38AM -0600, Steve Wahl wrote:
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> > ----------------------Cut here--------------------------------------
> >  +config YAFFS_USE_NANDECC
> >  +	bool "Use ECC functions of the generic MTD-NAND driver"
> >  +	depends on YAFFS_FS
> >  +	default y
> >  +	help
> >  +	  This enables the ECC functions of the generic MTD-NAND driver.
> >  +	  This will not work if you are using the old mtd.
> >  +
> >  +	  NB Use NAND ECC does not work at present with yaffsram.
> > ++
> > ++	  NB Use NAND ECC has a different ECC byte order than the
> > ++	  normal yaffs_ecc.c, and the resulting filesystem format is
> > ++	  binary incompatible with a previously existing yaffs=20
> filesystem.
> > ++	  (This different ordering is the same as yaffs_ecc.c generates
> > ++	  when ECC_WRONG_ORDER is turned on.)
> >  +
> >  +	  If unsure, say Y.
> >  +
> >  +config YAFFS_ECC_WRONG_ORDER
> >  +	bool "Use the same ecc byte order as Steven Hill's nand_ecc.c"
> >  +	depends on YAFFS_FS
> >  +	help
> >  +	  This makes yaffs_ecc.c use the same ecc byte order as
> > -+	  Steven Hill's nand_ecc.c. If not set, then you get the
> > -+	  same ecc byte order as SmartMedia.
> > ++	  Steven Hill's nand_ecc.c (part of the MTD-NAND driver).
> > ++	  If not set, then you get the same ecc byte order as=20
> SmartMedia.
> >  +
> >  +	  If unsure, say N.
> >  +
> > ----------------------Cut here--------------------------------------
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