When it comes to back porting, you're pretty much on your own. The mtd folk
get very tied up with what they do so handling backports adds complications.
If you're only wanting to run YAFFS2 on your NAND, then you will probably
find the backport relatively simple since you don't have to do much. ie. it
is not really so much a backport as adding a few mods to what you have now.
I'd suggest having a look at the mtd emulation I put in the YAFFS2 source
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 make
> 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 block
> 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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