[U-Boot-Users] U-Boot environment for NAND booting scheme

[Leonid]

Hi:

If CPU boot from NAND (at least for AMCC Sequoia board) u-boot
environment is part of u-boot image itself, see extraction from sequia.h
file:

#ifdef CFG_ENV_IS_IN_NAND
/*
 * For NAND booting the environment is embedded in the U-Boot image.
Please take
 * look at the file board/amcc/sequoia/u-boot-nand.lds for details.
 */
#define CFG_ENV_SIZE		CFG_NAND_BLOCK_SIZE
#define CFG_ENV_OFFSET		(CFG_NAND_U_BOOT_OFFS + CFG_ENV_SIZE)
#define CFG_ENV_OFFSET_REDUND	(CFG_ENV_OFFSET + CFG_ENV_SIZE)
#endif

Such layout supported by u-boot-nand.lds as comment suggests:

    /* WARNING - the following is hand-optimized to fit within  */
    /* the sector layout of our flash chips!    XXX FIXME XXX   */

    cpu/ppc4xx/start.o  (.text)

    /* Align to next NAND block */
    . = ALIGN(0x4000);
    common/environment.o  (.ppcenv)
    /* Keep some space here for redundant env and potential bad env
blocks */
    . = ALIGN(0x10000);

The problem is that any time u-boot image is updated, its environment is
lost which is not convenient if the environment differs from default one
significantly.

Can I put environment elsewhere on NAND flash and what is bad in doing
so?

Thanks,

Leonid.