Re: [Gumstix-users] How is jffs2 made?

[David F. <dav...@ya...>]

"Wear-leveling is an intrinsic part of the
Erase-Pooling functionality of SD using NAND
memory". SanDisk

SD cards are no worse off using JFFS2 that
NAND devices are.

David.

--- David Farrell <dav...@ya...> wrote:

> Thanks, I got that impression from several
> threads
> I read but I didn't trust it.  Ok I wrote a
> program to create 128MB of FF's as a file and
> dd'd it to the mmc card. Put the card in,
> loaded
> the blkmtd.ko module, mounted and bingo.
> 
> I am not conviced wear levelling in two places
> is
> a problem.  As I understand it the levelling
> just
> spreads out the writes.  If the levelling on
> the
> card never sees writes to the same location, it
> wont do anything.  I am testing big writes now,
> I look at the SanDisk spec about levelling to
> see if I am overlooking something.
> 
> Maybe you have a better suggestion for a fs
> that
> supports links and uid/gid.  I don't expect
> that
> I will be the only person who cares about this.
> 
> David.
> 
> 
> 
> --- Craig Hughes <cr...@hu...>
> wrote:
> 
> > A completely erased mtd device is a valid
> JFFS2
> > image.  So to make a 
> > blank jffs2 filesystem, erase your mtd block
> > device, then mount it -t 
> > jffs2 and you should be able to write to it. 
> I
> > would suspect that 
> > using jffs2 on an MMC card is probably not a
> > great way to go -- the 
> > wear levelling stuff in jffs2 when combined
> > with the wear-levelling 
> > that the MMC card probably does internally
> > might end up doing bizarre 
> > stuff.
> > 
> > C
> > 
> > On Feb 25, 2005, at 5:01 PM, David Farrell
> > wrote:
> > 
> > > In my quest for another filesystem on mmc
> > cards
> > > I tried ext2, it works but I really don't
> > want
> > > it.
> > >
> > > Now I am trying jffs2 using the mtdblock
> > driver.
> > > I build the mtdblock module, mknod the
> > mtdblock3
> > > device, loaded the module, looks
> promising..
> > > fdisk the new mtd device, good.
> > >
> > > build a filesystem, oops, no mkfs.jffs2 ok
> > I'll
> > > build one on Fedora, oops, no mkfs. Now
> wait
> > a
> > > minute isn't root_fs_arm a jffs2 image?
> > > How is jffs2 built for the root_fs_arm?
> > >
> > > On to enabling jffs in busybox...
> > >
> > > David.
> > >
> > >
> > >
> > >
> > >
> >
>
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