Hi Wolfgang,
On Tue, Mar 25, 2008 at 09:16:13PM +0100, Wolfgang Denk wrote:
Quite a number of boards use an embedded environment which gets auto-installed when programming the U-Boot image. And a significant percentage of boards I know use some installation tool that will set up things like serial number, MAC addresses etc. one way or another, andin many cases this includes running "saveenv".
with "installation tool" you mean any kind of interaction from the U-Boot command prompt, correct? (Just for clarification on my side) In my current application there (unfortunately) there is no hardware serial number anyways, and no ethernet, so no data that would have to be set for each device seperately.
I just made this small patch to auto-save the environment if it is not found in flash but am wondering if
- I missed something and such a possibility does already exist?
No, and I strongly discourage it. It just makes detection of certain types of problems / hardware errors etc. more difficult or even impossible.
- something similar might be worth considering as a new regular feature?
I think I would oppose such a change because I consider it really dangerous.
I think I get your point here, and especially as now Markus pointed me to a possible solution just using the command shell I perfectly agree that having it built-in like in my patch is just a source of possible problems, not needed and thus not a good idea.
On the other hand (and taking into account your answer to Markus), sometimes an automatic approach might have its use, too:
On our board we have an FPGA, and for different applications a different FPGA file shall be loaded without updating the firmware. For this, the application has to set an U-Boot environment variable that specifies which FPGA file to load on next boot. But, I do not want the application to mess around with the building the complete environment, instead, it shall just modify the existing variables. So, as I trust U-Boot more than my application, I want U-Boot to always initialize the environment stored in flash, and have the application just update the single variable - but this implies that even if the application failed during updating the environment (be it because of a software fault or power failure or whatever reason), U-Boot has to re-write this on the next power-up in case it detects the flash environment is invalid.
I think there may also be different opinions about which is the best solution here, but especially because the environment holds vital data like bootcmd etc., for me this looks like the most secure solution although I do not know if U-Boot already claims to have a brain. ;-)
Best regards, Wolfgang