Dear Bo Shen,
In message 5208DE04.1000405@gmail.com you wrote:
At first glance of CONFIG_ENV_IS_NOWHERE, I think no need to define the CONFIG_ENV_SIZE, actually, it needs to define the CONFIG_ENV_SIZE. So, I think add a default value will be better (Maybe another choice to add a description in README file to specify how to use CONFIG_ENV_IS_NOWHERE).
I cannot see in which way the required environment size in this case is different from all other cases. To me, a default size makes little sense - it is just a chance to miss setting a suitable value, so it bites you later (at run time) instead of earlyin development.
In any cse, the needed environment seize if a pretty board specific thing, and I think it makes sense to let the user define it.
Yes, the environment size is a pretty board specific thing. So, in this patch, there is an option for user to define it.
I think the user should always set this to a useful (for him) value. For example, you think 1 KiB is a useful size, I would think it is too small. Ask two other people, and you will hear three other different numbers.
Best regards,
Wolfgang Denk