"Robert P. J. Day" rpjday@crashcourse.ca writes:
oh, wait, i think i just answered some of my questions based on this snippet from common/env_nvram.c:
/*
- Initialize Environment use
- We are still running from ROM, so data use is limited
*/ int env_init(void) { #if defined(CONFIG_SYS_NVRAM_ACCESS_ROUTINE) ulong crc; uchar data[ENV_SIZE];
nvram_read(&crc, CONFIG_ENV_ADDR, sizeof(ulong)); nvram_read(data, CONFIG_ENV_ADDR + sizeof(ulong), ENV_SIZE); if (crc32(0, data, ENV_SIZE) == crc) { gd->env_addr = (ulong)CONFIG_ENV_ADDR + sizeof(long);#else if (crc32(0, env_ptr->data, ENV_SIZE) == env_ptr->crc) { gd->env_addr = (ulong)&env_ptr->data; #endif gd->env_valid = 1; } else { gd->env_addr = (ulong)&default_environment[0]; gd->env_valid = 0; }
return 0;}
so if there is a valid environment at the address specified by the board header file, it's used, otherwise fall back to default_environment[]. i had suspected it was something like that, i just hadn't found the code yet.
is this written up somewhere?
Looks like you found your answer, at least in part. The environment is stored in one of many possible locations, see the various env_*.c files. Which one is used is determined by the board configuration.
p.s. how does the default environment get to the CONFIG_ENV_ADDR defined in the board header file? is that done automatically when u-boot starts to run and notices that there is no valid environment info at that address, and therefore copies it for you?
If the stored environment is invalid (e.g. uninitialised), the built-in default is used. Nothing is written until you issue a saveenv command. This saves a copy of the live environment to the configured location.