[U-Boot] u-boot boot sequence
Wolfgang Denk
wd at denx.de
Mon Sep 27 09:25:36 CEST 2010
Dear Marcel,
In message <201009270011.32850.korgull at home.nl> you wrote:
>
> I do however have some questions about the u-boot startup behaviour.
Please read the manual; it should cover most of your questions.
> What I want to create is the following :
>
> 1) u-boot starts and checks if it can start my application (either CRC check
> or whatever). This is the first thing u-boot should do.
> 2) if it can't boot it will listen on USB or ethernet for someone to upload a
> valid image or boot via NFS or whatever has been configured.
This is standard behaviour. See 7.4. Boot Arguments Unleashed etc.,
http://www.denx.de/wiki/view/DULG/LinuxBootArgs
> 3) If it can boot, it will boot immediately (there may be a GPIO pin to
> override this behaviour)
setenv bootdelay 0
> 4) once within the application (linux or whatever) I must be able to set a flag
> that lets u-boot wait for uploading a new image file when I soft-reset my
> device. This is needed for firmware upgrading of course. I still need to check
> if this flag is supported by the CPU or needs other support (eeprom perhaps).
see tools/env for tools to read and write the U-Boot environment
settings from Linux. This can be used to change the boot command, boot
delay etc.
> 5) After uploading an image the soft-reset is cleared and the whole sequence
> start over again, so it should boot the new image.
You can script all these things in U-Boot.
> I know it's possible to do this but I wonder if it has been done before and if
> there any examples of it ?
There is all kinds of more or less complext stuff around. Read the
manual. Read the default configurations set in other board config
files. Read the code available in board/*/auto_update.c etc.
Best regards,
Wolfgang Denk
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
The first 90% of a project takes 90% of the time, the last 10% takes
the other 90% of the time.
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