[U-Boot-Users] Redundant environment expected behavior vs current

[Wolfgang Denk]

In message <444E7C7D.2060106 at orkun.us> you wrote:
> 
> I've found that redundant environment does not really create an exact 
> duplicate environment (as far as environment variables are concerned). 
> Instead, the active environment is rotated each save and only the new 
> active environment copy contains the changes to the environment.

Correct. That's how it is supposed to work.

> So, at this stage if your active environment is lost/corrupted your 
> latest changes to the environment is lost as well which might be 
> important to boot your system. The idea behind redundancy (IMHO) is such 
> that if one environment is lost the backup can provide all that was in 
> active but in current implementation it is not be possible simply using 
> one saveenv command. To get truly redundant environment that is exactly 
> duplicate, you are supposed to save the environment twice.

Corruption happens usually only because you  have  a  power  loss  or
reset  or  crash  when  writing the new environment. In this case you
keep the old, known to be working state.

Redundant   environment   implements   something   like   an   atomic
transaction.

> I personally think this is not quite how redundant environment should be 
> implemented. I think once the update of one environment is completed, 
> second environment should be updated with the same. What do you think? 

If you want this behaviour, then just use it. All you need to  do  is
typing "saveenv;saveenv". Next question, please.

> Am I the only one that expect complete sync of both sectors? Should I 
> submit a patch?

No. Nothing is broken.

> Other cosmetic issues noticed:
> 
> 1) Defining CFG_ENV_ADDR_REDUND or CFG_ENV_OFFSET_REDUND results in 
> definition of CFG_REDUNDAND_ENVIRONMENT. I might be nitpicking but the 
> correct spelling should have been CFG_REDUNDANT_ENVIRONMENT

Typo. Submit a patch.

> 2) The output of saveenv intermixed with output from flash driver is 
> looking rather untidy and confusing. For example, ". done" below is 
> coming from "driver/cfi_flash.c". We get ". done" right after "Saving 
> Environment to Flash..." message and other messages follow. However, the 
> first ". done" was really for unprotect which is reported after. I think 
> like U-Boot does for Erasing part, we should announce the operation 
> first (i.e. Un-protecting ...  Protecting...) so flash driver output can 
> match the current operation properly.

The CFI driver is a bit noisy, indeed.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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