Added support to access native posix flash via host file system

[vanwinkeljan]

Add support to access native posix flash device via host file system.
The flash device is mapped into the host file system by means of the FUSE library.

These changesets where original part of PR #12503

edit: actually only access to FS partitions is provided

[zephyrbot]

All checks are passing now.

Review history of this comment for details about previous failed status.
Note that some checks might have not completed yet.

[aescolar]

Please move the code, kconfig and cmake into drivers/flash
The Kconfig can be into drivers/flash/Kconfig.native_posix
The cmake chunk into drivers/flash/CMakeLists.txt
The code could be just named drivers/flash/fuse_native_posix.c or so

[vanwinkeljan]

Please move the code, kconfig and cmake into drivers/flash

I did try this but it is not an option as the compiler flags need to be changed to make use of FUSE and there is a conflict with the flags used in the zephyr flash library.

[dbkinder]

Thanks for adding the documentation. I've got a few recommended edits.

[aescolar]

there is a conflict with the flags used in the zephyr flash library.

@vanwinkeljan Would declaring the fuse part as a separate library do the trick? (even if it is in the same folder as the other flash drivers)

[vanwinkeljan]

Would declaring the fuse part as a separate library do the trick? (even if it is in the same folder as the other flash drivers)

Yes it does, moved the code to subsys/fs

[vanwinkeljan]

Renamed fuse_flash to fuse_fs_access as the code actually only provides access to the FS partitions

Addressed

[aescolar]

@vanwinkeljan I guess you have tested that it works nicely?
You may want to add a line in CODEOWNERS for this new fuse file assigned to yourself.
If you commit to maintain/support this new functionality I think it should be ok to merge it, as there is very little risk, this being a new optional feature.
Regarding the new fs function, I hope @nvlsianpu has taken a look(?) and is ok with it

[aescolar]

@vanwinkeljan Apart from those minor issues I'm ok with this, and can approve it after you fixed them

[dbkinder]

one fix to remove the doc-build warning...

[vanwinkeljan]

You may want to add a line in CODEOWNERS for this new fuse file assigned to yourself.

Done

If you commit to maintain/support this new functionality I think it should be ok to merge it,

No problem with that, I think it is an added value for zephyr

[dbkinder]

The Makefile in the Zephyr root has this htmldocs-fast target.

[nvlsianpu]

Any chance that this will work on widowns?

[vanwinkeljan]

@nvlsianpu

Any chance that this will work on widowns?

No currently this not possible due to 2 limitations:

• Fuse is not suported on windows
• The WSL layer does not support 32-bit application, and native_posix is a 32-bit appilcation

Now it looks that both issues will be solved by introduction of WSL2, an initial build of WSL2 would be available by end of June for people with access to WIndows Insider.
https://devblogs.microsoft.com/commandline/announcing-wsl-2/

[dbkinder]

docs LGTM, thanks!