Part of the development flow using
devtool
of course involves updating
your source files.
Several opportunities exist in the workflow to extract and
work on the files.
For now, just realize that you need to be able to have
access to and edit files.
One obvious solution is to initially extract the code into an
isolated area in preparation for modification.
Another option is to use the
devtool modify
command.
This command makes use of a "workspace" layer where much of
the transitional work occurs, which is needed for setting up
Metadata used by the OpenEmbedded build system that lets you
build your software.
Options (i.e. "-x") exist using devtool
that enable you to use the tool to extract source code.