[Yaffs] Re: yaffs 2.0

[Charles Manning]

Hi

Conceptually, making YAFFS1 work with 2k pages is straight forward, but t=
here=20
are some subtle issues. YAFFS1 uses the stack for pages that it is workin=
g=20
on. The Linux kernel stack is not large, so 2k pages might break.

I would suggest that it makes more sense to wait for YAFFS2. At this stag=
e=20
YAFFS2 is working in yaffs-direct mode on file emulation(that's how I dev=
elop=20
file system algorithms).  I still need to hook up the mtd code to have YA=
FFS2=20
working with 2k pages in the kernel. I expect to have something in CVS wi=
thin=20
2 weeks.

There is also a compatability mode in YAFFS2 so that it will support YAFF=
S1=20
format. The goal of this is that we move all development over to YAFFS2 a=
nd=20
obsolete YAFFS1.

Regards

-- Charles



On Tuesday 19 October 2004 21:21, Li Xin-a16157 wrote:
> Hi Charles,
>
> I am quite new to YAFFS. The flash device on my board is Toshiba 128MB,
> 3.3v, 8bit NAND flash. Its device ID is 0xF1 and has 2KB pages. My
> objective is to run the current YAFFS on my NAND flash. Which files in
> current YAFFS source should be modified to support 2KB page Nand? Will =
this
> kind of modification to support 2KB page need a lot of effort?
>
> Best Regards
> Li Xin
>
>
> -----Original Message-----
> From: Charles Manning [mailto:manningc2@actrix.gen.nz]
> Sent: 2004=C4=EA10=D4=C219=C8=D5 10:08
> To: Li Xin-a16157; Wookey; yaffs@stoneboat.aleph1.co.uk
> Cc: Li Xin-a16157
> Subject: Re: [Yaffs] Re: yaffs 2.0
>
> The major difference in YAFFS2 is the support for flash parts with zero
> rewrite. YAFFS1 keeps track of what data, files etc are deleted by the =
use
> of deletion markers.  Writing the deletion marker has two down-sides: 1=
)
> Some flash parts do not tolerate any rewrites.
> 2) Obviously more writes =3D=3D slower.
>
> YAFFS2 supports page sizes > 512bytes.  You could hack YAFFS1 (ie.=20
> increase chunk size to 2k) to do this too, but YAFFS2 does straight off=
.
>
> Bigger chunks means less chunks per MB which means less RAM footprint.
>
> -- CHarles
>
> On Tuesday 19 October 2004 01:33, Li Xin-a16157 wrote:
> > They are essentially interchangeable, although only YAFFS2 will suppo=
rt
> > newer hardware (2k page size, no page rewriting).
> > -----------------------------------------------------
> >
> > Does this mean the current YAFFS doesn't support 2K page size Nand fl=
ash?
> >
> > Li Xin
> > Best Regards.
> >
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