[U-Boot] user-space ===>> U-Boot ====>> user-space ?

[Wolfgang Denk <wd@denx.de>]

Dear bosmith,

In message <29939469.post@talk.nabble.com> you wrote:
> 
> Is there a simple way to send data from a Linux user-space program to
> U-Boot?
> How about from U-Boot up to a user-space program?

I know of two communication methods:

Using the environment (and fw_printenv/fw_setenv in Linux user space),
and using a shared log buffer (which may be a bit difficult to read /
process in U-Boot if that should be needed).

> The data may change often enough that using fw_printenv and fw_setenv might
> wear out the NAND storage area for the environment.

Then put all this stuff in a UBI partition, and use the "env import" /
"env export" features in U-Boot to access it (or extend the code to
handle environment in a UBI partition directly).

> The use-case is to have two kernel images, two root file systems, and to let
> a user-space application specify which to use and then force a reboot.  The
> system will not lose power during this reboot.

And you think you will switch betweent these two so often that using
the environment would wear out the NAND?  I think you are too
pessimistic.

> This seems like a common enough problem.  Has anyone solved it before?

Most people use the environment for this purpose.

Best regards,

Wolfgang Denk

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