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Date: Wed, 09 Sep 2009 09:57:54 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: [Qemu-devel] Re: The State of the SaveVM format
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To: Juan Quintela <quintela@redhat.com>
Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>

Juan Quintela wrote:
>>    if (version_id == 3)
>>        s->scancode_set=qemu_get_be32(f);
>>    else
>>        s->scancode_set=2;
>>     
>
> Problem here is this value, there is no way to set default values
> different of zero.  That is why there is still the old function.
>   

We do this with qdev properties, certainly we could do it with savevm too?

The advantage of doing this with savevm is that it potentially allows 
for the init and the reset functions to be simplified/eliminated.  Even 
fields that are present in all versions should have the ability to have 
default values.

In fact, semantically, a field should be zero unless a default value is 
specified.

>> I think the discussion around optional features is orthogonal to how
>> to support older savevm formats so let's keep it separate.  I
>> generally share your concern about test matrix explosion.
>>     
>
> Ok. I am trying to port all the pc.c stuff to new VMState without adding
> more marshaling (we already have the old load functions).  After I
> finish with that, we can look at the remaining cases and look at a
> course of action?
>   

Sounds good to me.

Regards,

Anthony Liguori