Re: Best way to define flash partitions for an MPC8248

On Feb 13, 2007, at 9:08 AM, Laurent Pinchart wrote:

Hi everybody,

I'm running Linux 2.6.20 on an MPC8248 using arch/ppc/.

The system flash is divided in 5 partitions, which are currently defined in
both U-Boot and in the Linux kernel (hardcoded in platform specific code in
arch/ppc/platforms/). This is error prone, as modifying partition information
requires a change to the U-Boot environment variables and a recompilation of
the Linux kernel.

I would like to get rid of partition data in the kernel. I found 3 ways for
the Linux kernel to get those data from elsewhere:

- command line parsing (using the mtdparts argument)
- redboot partition table parsing
- OF device tree (drivers/mtd/maps/physmap_of.c)

What is the best suited method ? I don't really like the redboot partition
table, is I haven't found any way to write it from U-Boot. Do I need to
switch to arch/powerpc/ to use the OF device tree ? If so, is it possible
today for the MPC8248 processor, or is it still badly supported in
arch/powerpc/ ? Last but not least, is it possible to change the OF device
tree from U-Boot at runtime to resize partitions ?

You'll have to switch to arch/powerpc for using the of device tree parsing.  I believe the 8248/827x are supported under arch/powerpc at this point.

I don't believe its possible to change the OF device tree at runtime currently, you'll have to add code to u-boot to do that.  U-boot does very little with the device tree beyond setting it up and filling in some values that are needed (memory sizes, frequencies, etc.)

- k