[Yaffs] Yaffs with 2k Pages OR Yaffs2

[Charles Manning]

When it comes to back porting, you're pretty much on your own. The mtd fo=
lk=20
get very tied up with what they do so handling backports adds complicatio=
ns.

If you're only wanting to run YAFFS2 on your NAND, then you will probably=
=20
find the backport relatively simple since you don't have to do much. ie. =
it=20
is not really so much a backport as adding a few mods to what you have no=
w.

I'd suggest having a look at the mtd emulation I put in the YAFFS2 source=
=20
tree. THis shows all the functions you need.

-- Charles


On Wednesday 22 December 2004 06:44, Rajiv Dhingra wrote:
> Charles and Thomas:
>
> Thank you very much for your responses.  It will be a while before we m=
ake
> a decision (enjoying the holidays), but for the very reasons that you
> mentioned Charles, it might well be that I end up back-porting mtd to
> 2.4.20.    Any pointers in accomplishing this (in addition to the ones =
that
> you have already mentioned) would be truly appreciated.  Would most of =
the
> modifications be in the nand drivers or the mtd drivers?
>
> Merry Christmas,
>
> Rajiv
>
> >>> "Charles Manning" <Charles.Manning@trimble.co.nz> 12/19/04 11:59AM =
>>>
>
> Rajiv
>
> I've thought about this a bit...
> While Thomas it technically correct that YAFFS2 needs more recent mtd
> (which no longer supports older kernels), I think it rather simple to
> hack the mtd you have to support YAFFS2.
>
> Basically, all you'd need to do is:
> 1) Modify the nand write/read functions to work with 2k pages (change
> the size of the for loop), and a few other minor changes to handle ECC
> etc.
> 2) Add a couple more required fields to the mtd_info structure.
> 3) Add two new functions block_markbad() and block_isbad() for bad bloc=
k
> handling.
>
> Whether it is the right time for you to switch to a newer kernel or not
> is your choice and should not be forced by mtd changes.
>
> -- Charles
>
> > -----Original Message-----
> > From: yaffs-admin@stoneboat.aleph1.co.uk
> > [mailto:yaffs-admin@stoneboat.aleph1.co.uk] On Behalf Of
> > Thomas Gleixner
> > Sent: Thursday, 16 December 2004 9:41 p.m.
> > To: Rajiv Dhingra
> > Cc: YAFFS
> > Subject: Re: [Yaffs] Yaffs with 2k Pages OR Yaffs2
> >
> > On Wed, 2004-12-15 at 15:50 -0800, Rajiv Dhingra wrote:
> > > We were running Linux 2.4.20, Yaffs, and using a NAND
> > > device with 512 byte pages.  Everything was working fine.
> > > Then the hardware guys replaced the 512 byte page NAND
> > > device with a 2k page NAND device.
> > > So, I now have to hack yaffs to support a 2k page size,
> > > or start using Yaffs2.  What would the recommendation
> > > of this newsgroup be?  Would it be easy enough for me
> > > to hack yaffs to start supporting the bigger page size?
> > > Is yaffs2 stable enough and does it run with the 2.4.20
> > > kernel, making it a better option.
> >
> > Be prepared to upgrade your kernel. The MTD NAND layer which
> > has the support for 2k chips is definitely not portable to 2.4.20.
> >
> > Read http://www.linux-mtd.infradead.org/#kernelversions
> >
> > tglx
> >
> >
> >
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