running CBE on RAM vfs

Josef Söntgen josef.soentgen at
Fri Oct 8 16:32:11 CEST 2021

Hello Stefan,

> As a precursor of running CBE on our i.MX8 IoT device, I'm trying to run
> CBE entirely from RAM based in a vfs and testing it using the
> block_tester. To achieve this I merged the vfs_cbe_init and vfs_cbe
> runscript using a sequence to run cbe_init before vfs_cbe.
> My problem is that the cbe/current/data device seems to be only 4 KiB or
> 1 block in size, regardless of how I parameterize cbe_init.
> Any ideas on why this happens or how to fix it?

I took your branch and rebased [1] it to pull in CBE commits (which are
now on staging) that are necessary for proper operation of the CBE.


Additionally it contains 3 commits that allow for executing your run
script - I have not checked if the CBE functions correctly though (i.e.,
if the data is properly stored). The 'vfs_block' commit, however, is the
one that solves your problem where the size reported by the CBE's data file
is incorrect. Issuing the explicit sync request will trigger the CBE to
perform any operations necessary to finalize the initialization (the
sync request leads to “freezing” the current state).

At this point the 'file_vault' component is the reference implementation
of a component that manages the CBE. I suggest you look into this component
first. Although it requires a Gui session, which might not work well in
your IoT use-case, and is somewhat extensive, eventually you will need a
management component as well and this one shows you how to operate the CBE


Josef Söntgen
Genode Labs ·
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