FCB support for non-0xFF flash erase values

[de-nordic]

Is your enhancement proposal related to a problem? Please describe.
Currently FCB is able to work with flash devices that erase to 0xFF values.
Since it's implementation new devices have appeared that use non-0xFF erase values (0x00), which is not supported
by the FCB as it relies on 0xFF as an erased/empty value in some cases.

Describe the solution you'd like
Make FCB flash erase value independent.

Describe alternatives you've considered
There is none as long as FCB is to be used.

Additional context
The flash API now supports flash_get_parameters that returns flash_parameters structure that has erase_value member, which is initialized by driver with the erase value.

[nvlsianpu]

Also newly proposed flash_area_ersed_val() might be usefull.

[utzig]

Also we should consider importing fcb2 from Mynewt, it was huge improvement over fcb.

[de-nordic]

Also we should consider importing fcb2 from Mynewt, it was huge improvement over fcb.

Does the fcb2 support the original fcb or this is parallel?

[utzig]

Also we should consider importing fcb2 from Mynewt, it was huge improvement over fcb.

Does the fcb2 support the original fcb or this is parallel?

fcb2 originated from refactoring fcb but it ended up with a slightly different metadata formats AFAIR, so not compatible, you have to use one or the other from the beginning.

[de-nordic]

fcb2 originated from refactoring fcb but it ended up with a slightly different metadata formats AFAIR, so not compatible, you have to use one or the other from the beginning.

OK then, we will have to add it as an alternative. Do you want me to create enhancement request for importing fcb2 or do you want to post the request yourself?

[utzig]

fcb2 originated from refactoring fcb but it ended up with a slightly different metadata formats AFAIR, so not compatible, you have to use one or the other from the beginning.

OK then, we will have to add it as an alternative. Do you want me to create enhancement request for importing fcb2 or do you want to post the request yourself?

Please go ahead and do it! :-)

[nvlsianpu]

^^ Please count benefits of having fcb2 in compassion to FCB and NVS.