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NAND Flash filesystem


On 09/10/2010 06:10 AM, Mick Davis wrote:
> I'm looking at implementing a NAND flash filesystem for the
> at91sam9263-ek, and hoped there might be some advice available.
> The raw flash chip is connected to the processor's on-chip static memory
> controller.
> I'm not keen to use GPL sources, but I can share my own results.
> JFFS2 has a license exception which might make it OK, but porting it
> away from Linux seems like an excessive amount of work. Has anyone
> succeeded with this?   I'd want it to integrate with RTEMS for use with
> ordinary system calls.

This sounds interesting.  I was not aware that JFFS2 is under a GPL with the
following exception (http://ecos.sourceware.org/license-overview.html):

  As a special exception, if other files instantiate templates or use macros
  or inline functions from this file, or you compile this file and link it
  with other works to produce a work based on this file, this file does not by
  itself cause the resulting work to be covered by the GNU General Public
  License. However the source code for this file must still be made available
  in accordance with section (3) of the GNU General Public License.

  This exception does not invalidate any other reasons why a work based on
  this file might be covered by the GNU General Public License.

I order to port this to RTEMS, I see the following tasks:

1. Implement all services provided by the Linux kernel to JFFS2 via RTEMS means.
2. Create a mapping from the RTEMS file system interface to the JFFS2 interface.
3. Provide the MTD interface and a driver for your NAND flash.  I looked in
some random MTD files, it seems that they use a pure GPL license.  So we cannot
use it directly.

All in all not something you do in 5 minutes.

Does someone know if the BSD community has plans for a flash file system?

Have a nice day!

Sebastian Huber, embedded brains GmbH

Address : Obere Lagerstr. 30, D-82178 Puchheim, Germany
Phone   : +49 89 18 90 80 79-6
Fax     : +49 89 18 90 80 79-9
E-Mail  : sebastian.huber at embedded-brains.de
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