Re: [RFC v3] VFIO Migration

[Gerd Hoffmann]

> > In validating QEMU migration compatibility we merely compare the
> > versioned machine type.
> 
> Thinking more about this, maybe the big picture is:
> 
> Today the managment tool controls the variables in the migration (the
> device configuration). It has knowledge of the VMM, can set a machine
> type, apply a device configuration on top, and then migrate safely.
> 
> VFIO changes this model because VMMs and management tools do not have
> knowledge of specific device implementations. The device implementation
> is a new source of variables in the migration and the management tool no
> longer has the full picture.

Well.  We actually have the variables.  They are device properties.
Then the qemu compat properties basically map a machine type to a
set of device properties.  That way we hide the complexity inside
qemu.  The management apps have to deal with the (versioned) machine
type only.

I guess now we have to decide whenever we want expose the individual
variables or whenever we want something like "profiles", i.e. basically
a set of variables with a name attached.

At the end of the day it is a complexity vs. flexibility tradeoff ...

take care,
  Gerd