[U-Boot] U-boot -Modifying boot sequence on a ARM based board

[Wolfgang Denk]

Dear alfred steele,

In message <528f13590908200918s6f1a00d4v294867f350037551 at mail.gmail.com> you wrote:
>
> What is the general boot sequence for u-boot. IIRC, its the cpu
> specific start followed by board specfic stuff, then general init
> stuff (like misc_init_f) and then the common stuff.

Not really. First low level intialization gets done, needed to set up
a reasonable C execution environment; then all initialization running
from  flash  gets  done,  RAM  initalization  included;  then  U-Boot
relocates  to  RAM  and initializes flash end the rest of the system.
There are CPU resp. board specific and common parts in all  of  these
steps, or at least there may be.

> The reason i am asking this i want to inject my own boot path based on
> the presence of certain boot peripherals. I want to override the
> "boot_args" with my custom-defined bootargs and then execute "bootm"
> from a predefined RAM address.

No need to change any code then. Just define the needed environment
variables to contain the commands you want.

> I want to know which is the most appropriate place for soing this. I
> was initilally thinking it would end up in the board specific
> code(board/<boardname>.c) but  i am a bit confused when i read the
> main/common code.

Don't change any code. Use the scripting capabilities of U-Boot's
environment variables.

Best regards,

Wolfgang Denk

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