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