[U-Boot-Users] Question about CFG_ENV_ADDR during RAMBOOT

Ladislav Michl ladis at linux-mips.org
Wed May 30 14:16:08 CEST 2007

On Wed, May 30, 2007 at 01:34:19PM +0200, Ulf Samuelsson wrote:
> => We also need to understand if we are talking
> about the same thing.
> I have this feeling that
> mtdparts exist to divide
> the rootfs into several
> areas while the dataflash
> partioning is there purely
> for U-boot purposes.

Hmm, does it mean that you do not want to share dataflash partitioning
between U-Boot nad Linux?

> The partion use is:
> 1) AT91 bootstrap.
> 2) U-boot environment
> 3) U-boot image.
> 4) Kernel image
> 5) Root FS.
> The sum of 1+2+3 is
> always 256kB due to
> df sector size.
> The only programmable value
> is the kernel size.

There are constrains I'd like to see implemented some generic way as

> Nothing is ever written to
> the dataflash to indicate
> partion info and nothing
> is passed to Linux 
> except rootfs start adress in
> bootargs.

Partitioning is stored inside U-Boot environment. In case this is
written into dataflash, the above will not be true. Also Linux will
share this partition map, but can be told to not do so and also some
partitions can be read-only for Linux.

> The df partion is just for setttins protection
> and (in my 1 year+ old patch)
> sets a few environment
> variables to contain the
> start adress of kernel &
> rootfs.
> Can someone confirm that
> mtdparts is the right way
> to go?

It will definitely work for me the way I'm used to use it. I do not know
what is "the right way" in your mind, but I will try to answer your
questions as well as I can do.

(all my boards are using redundand environment which can be read and
written also from Linux - for firmware upgrading purposes)

Best regards,

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