[CRIU] [PHAUL] Question Regarding RPC Interface

[John Goen]

I have a question regarding the RPC interfaces with CRIU and their
application to P.Haul.

As of now, it looks like P.Haul does all of its interaction with CRIU
through the RPC interface defined in protocol buffers. However, there seems
to be certain fields/arguments missing from the protobuf interface that
would be necessary to invoke post-copy migration functionality through
P.Haul.

>From what I can understand, these are the steps necessary to conduct proper
post-copy live migration through CRIU:

    - Tell CRIU to perform the initial dump at the source, having the
lazy-pages flag set (this can be easily passed in a criu_req with
lazy_pages=TRUE in the criu_opts protobuf message and with
criu_req_type=DUMP)

    - Bring up the lazy-pages daemon on the destination with the lazy-pages
flag set (currently there seems no means of passing this through the
protobuf RPC interface, though I feel something like having a new
criu_req_type like LP_DAEMON with proper handling on the CRIU side would
work, but I don't know the CRIU side of the code well enough to be sure
this is the case)

    - Call restore with the lazy-pages flag set (much like the initial
dump, this seems to be fully doable through current protobuf RPC interfaces)

Does this sound right to anyone? If so, I'm fully willing to go in and try
adding the RPC protobuf field and interaction necessary to get CRIU to work
in this way, but I'm unsure where exactly this code would need to live or
where to start with it.

Thanks,
John
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