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Re: Re: your mail -->fs for NAND



On Tue, 18 Mar 2003 01:41, Thomas Gleixner wrote:
> On Monday 17 March 2003 12:28, David Woodhouse wrote:
> > On Mon, 2003-03-17 at 11:11, jimzeus@xxxxxxx.com wrote:
> > > > In some parts of the world that's patented and may only be used on
> > > > DiskOnChip hardware.
> > > >
> > > > Why on earth would you want to put FAT on NAND flash? Seems like a
> > > > really bizarre idea to me. What's wrong with just putting a proper
> > > > file system on it which is actually designed for flash?
> > >
> > > Because I want windows to identify the NAND Flash.
> >
> > You'll presumably have to write a driver for Windows _anyway_. And hence
> > I'd be inclined to suggest that you might as well use YAFFS or JFFS2,
> > and port it to Windows rather than implementing a 'translation layer'
> > and porting that to Windows.
>
> YAFFS is already ported to windows, at least to Windows CE, AFAIK

Yes, YAFFS is shipping on WinCE devices (both CE3 and CE4). WinCE file 
systems have a different interface to Windows fs, however the WinCE FSD (file 
system driver) does wrap stuff up in a way that would likely be close to 
Windows. Bear in mind though that every Windows version (CE, ME, 98, 
2000,XP...) have different OS interfaces in places.

The easiest way to incorporate NAND into a Windows system is to use 
SmartMedia. However, this is not a very healthy way to make a robust system 
(Smartmedia is OK to use for data you do not care about much).  If you really 
want a robust solution you need a journaling fs (something like YAFFS or 
JFFS2).

Getting a solid NAND file system going is trickier than it seems and is 
probably close to impossible with FAT. One company tried three different 
commercially available "solutions" using FAT and gave up on these because of 
both robustness and speed. They switched to YAFFS and are more than happy. 
This is only one of such cases.


-- CHarles

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