[Qemu-devel] [very-WIP 0/4] Migration: VMSTATE_WITH_TMP

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Hi,
  I'm interested in comments on the idea here, it's certainly
not ready to go in yet; and VERY untested.

  Here I've added a macro, VMSTATE_WITH_TMP which allows
you to allocate a temporary structure, transmit that with a
VMStateDescription and then free that temporary.
  A pointer to the parent structure is set up in the temporary
allowing the pre_load/pre_save/post_load off the child vmsd
to copy/calculate things to fill in the temporary.

  There are 4 patches:
     a) Add VMSTATE_WITH_TMP
     b) A test for (a)
        An easy read to see how (a) works

     c) Conversion of SLIRPs sbuf structure to a VMState
        This is a nice use of VMSTATE_WITH_TMP since
        it needs to calculate and send a couple of offsets
        based off the contents of the structure but not
        the raw fields.

     d) Conversion of virtio-net to VMState; this is
        pretty hairy, and the previous version I posted
        added a bunch of migration only variables into the
        structure;  here I use 3 VMSTATE_WITH_TMP's to
        avoid it.

   Both (c) & (d) depend on a whole bunch of related
patches I'm still cooking, but they should let people
see how VMSTATE_WITH_TMP is used.

  I think it works OK; it's not exactly compact though,
you often seem to end up with more VMStateDescription
boiler plate and quite a few trivial pre_load/pre_save.

  Note this isn't standalone; it depends on Jianjun's
patches that modify the .get/.put parameters and a bunch
of smaller patches of mine.

  Comments welcome,

Dave

Dr. David Alan Gilbert (7):
  migration: Add VMSTATE_WITH_TMP
  tests/migration: Add test for VMSTATE_WITH_TMP
  virtio/migration: Migrate virtio-net to VMState
  slirp: VMStatify sbuf

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