[U-Boot] About the variable environment and default_environment when environment is embedded

[Xiaojun Li]

Hi all,

I'm working with the u-boot-2009-08.tar.bz2 and find some code I am not very
clear.
My puzzle is about the extern array "environment[]" which declared in
"env_flash.c" as
an array composed by unsigned char. However, it is defined as a env_t struct
in the
"env_embedded.c".  So the declaration conflicts with definition, but it can
be compiled
normally, does any one tell me why? Thanks.


Here is the code in ./common/env_flash.c and ./common/env_embedded.c

******************************************************************************
/* In file ./common/env_flash.c */

#ifdef ENV_IS_EMBEDDED

extern uchar environment[];
env_t *env_ptr = (env_t *)(&environment[0]);

#ifdef CMD_SAVEENV
/* static env_t *flash_addr = (env_t *)(&environment[0]);-broken on
ARM-wd-*/
static env_t *flash_addr = (env_t *)CONFIG_ENV_ADDR;
#endif

#else /* ! ENV_IS_EMBEDDED */

env_t *env_ptr = (env_t *)CONFIG_ENV_ADDR;
#ifdef CMD_SAVEENV
static env_t *flash_addr = (env_t *)CONFIG_ENV_ADDR;
#endif

******************************************************************************
/* In file ./common/env_embedded.c */

#ifdef ENV_IS_EMBEDDED

  ...

env_t environment __PPCENV__ = {
    ENV_CRC,    /* CRC Sum */
#ifdef CONFIG_SYS_REDUNDAND_ENVIRONMENT
    1,        /* Flags: valid */
#endif
    {
#if defined(CONFIG_BOOTARGS)
    "bootargs="    CONFIG_BOOTARGS            "\0"
#endif
#if defined(CONFIG_BOOTCOMMAND)
    "bootcmd="    CONFIG_BOOTCOMMAND        "\0"
#endif

.....

};

...

#endif
******************************************************************************