[Qemu-devel] early_savevm (was: [PATCH V2 5/5] vga-cirrus: Workaround during restore when using Xen.)

[Stefano Stabellini]

On Mon, 12 Dec 2011, Stefano Stabellini wrote:
> > Really, I think this is something inherently incompatible with the
> > current memory API. If Xen has this unfixable special "requirement"
> > (it's rather a design issue IMHO), adjust the API and adapt all devices.
> > Hot-fixing only a single one this way is no good idea long term.
> 
> Fair enough.
> What about introducing a type of savevm state that is going to be
> restored before machine->init?
> This way we could save and restore our physmap and we could handle
> memory maps and allocations transparently.
> 

A bit more context to my suggestion:

- we open the save state file and check the magic number and the
version number before machine->init();

- we add a new set of entries to the save state file that contains
early_savevm functions: they are called before machine->init();

- after reaching the end of the early_savevm functions we stop parsing
the save state file and we call machine->init();

- after machine->init() is completed we continue parsing the save state
file as usual.