On 11.07.2018 15:50, Maxime Ripard wrote:
On Wed, Jul 11, 2018 at 12:44:23PM +0200, Nicholas wrote:
Maybe a solution could be to have an env_save() function which
acts in a similar way as proposed in my patch and an
env_save_prio() function, which acts like the env_load()
i.e. looking for the best working location instead of relying
on what has been stored into gd-> env_load_location.
I don't really see a use-case for overriding wherever the
environment at the user-level actually. At the board level, for
redundancy or transition, yes, definitely, but we can already do
that.
Well, the use case I saw was that I wanted to test redundant
environment storage. I admit this is not an end user use case but
a developer use case, so I guess you're right.
So after fixing this endless loops I see two questions: - to which
environment do we store if the one in 'env_load_location' fails
to store?
Good question. My opinion is that it strongly depends on what we want
to achieve with the implementation: do we want 1) to keep the
consistency between load and save, or we want 2) to guarantee to be
able to load/save from at least one location?
If 1) then a failure on env_save() simply fails and doesn't store
anything. In other words we are multi-env when loading but single-env
when storing. We are actually binding env_save() to the last
env_load()'s result.
If 2) then a failure on env_save() will try all the available locations
but we are open to misalignments. Here we are full multi-env since
env_save() and env_load() are not bound together.
In that case, we don't want to store to a lower priority, but to a
higher one. Otherwise, the environment will be saved just fine, but
will not be read next time, which will be very confusing to the user.
And with a higher priority, you might end up overwriting something you
weren't expecting to overwrite, so I'd vote 1.
I agree that 1 would be best. But from reading the code, unless I'm
totally wrong, it seems that the patch sent by Nicholas does not suffice:
If no location contained a valid environment (e.g. no environment
written yet), the lowest priority will be written as
'gd->env_load_location' is set to the lowest priority from iterating
locations in 'env_load()'.
So we might have to reset 'gd->env_load_location' to highest prio if
loading the environment fails.
Simon
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