Re: [Gumstix-users] non-volatile memory?

[Scott K. <sk...@gm...>]

As long as you are not changing anything else on the Gumstix (such as the
package selection, or drivers), it is a lot easier to simply compile
whatever code you are working on and only replacing that.  That way you are
not spending 10-15 minutes every time you upgrade the code you are writing.

Now if you are writing some device drivers or making major changes to the
filesystem, you may want to reflash the entire thing.  However, I found once
I have set up what I need, I don't have to reflash it anymore.  I just copy
my programs (I use a USB stick, you can do it any way you want) over.

On 10/5/07, Julien Lebot <305...@st...> wrote:
>
> Quoting Craig Hughes <cr...@gu...>:
>
> > On Oct 3, 2007, at 8:55 PM, Carl Douglas wrote:
> >
> >> To be more clear, when my application is running it stores data files
> >> containing the addresses of bluetooth devices that have been
> >> discovered.
> >>
> >> When I reflash the gumstix (upgrade the software) it's highly
> >> desirable for the application generated data files to persist.  This
> >> is because new versions of the software will still be able use those
> >> data files.
> >>
> >> Perhaps I have to store that data externally, on a memory card for
> >> example, and then copy the data files over when the gumstix boots?
> >
> > Probably the best/easiest way to do this would be to modify the flash
> > partition structure in linux in drivers/mtd/maps/gumstix-map.c
> > (filename from memory; pretty sure the path's right but my server
> > with my build workdir is inaccessible temporarily).  128kB is
> > probably enough to store whatever you need for these purposes
> > (remember that JFFS2 compresses its content) so allocate 1 sector,
> > probably at the top of flash, just below the uImage space, or
> > something.  Then remember in u-boot to not erase that sector when
> > you're reflashing the rootfs, and in /etc/fstab on your new FS,
> > include a line like
> >
> > # Mount an unerased filesystem for persistance across rootfs reflashes
> > /dev/mtdblock3        /permanent      jffs2   defaults        0 0
> >
> >
> > That will mount that single-sector piece of flash on /permanent
> > (which directory will need to exist in the new rootfs remember).  You
> > can symlink to there from the rest of the rootfs if you need to.
> >
> > C
> >
>
> Doh, forget my previous post, I did not read the whole thread before
> replying.
> Thanks Craig that answered my questions too :)
>
> J.
>
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