Applying images

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The page describes thoughts about how to take an existing process and apply images into it, instead of turn CRIU process into target one.

What for[edit]

This feature is useful for

Reverting to snapshot
In case process keep running after a snapshot, reverting back might be faster if not restoring from images, but applying those directly on the running tasks
FT case
In fault tolerant systems master node would send updates to slave one(s) and the latter guys would benefit from ability to "add" the snapshot update onto existing tasks

Problem[edit]

There's a technical problem in it -- currently CRIU restores data from images into itself. Only a small portion of code is executed in a PIE mode (called "restorer context") and that is run in a target task environment. In apply-images mode we'd have to push parasite into target task and run all the restoration code in it. This is a lot of patching.