[Qemu-devel] Re: [PATCH V3] floppy: save and restore DIR register

[Juan Quintela]

Jason Wang <address@hidden> wrote:
> Paolo Bonzini writes:
>  > On 04/01/2011 08:22 AM, Jason Wang wrote:
>  > > +
>  > > +    if (drive->bs == NULL) {
>  > > +        return 1;
>  > 
>  > Is it okay to return 1 here?  Have you tested the case when both the 
>  > source and the target drives have no floppy?
>  > 
>
> Thanks for the reminding, and it could be fixed by put all pre/post callbacks
> into the subsections.
>
>  > (The "media_changed == 2" in my sample code was basically a way to save 
>  > the "media present" state of the drive on the source).
>  > 
>
> Right, but it would make subsection saving be the common case (consider most 
> of
> the vm may just have one floppy but we have two drives). A better solution 
> maybe:
>
> 1 Set default_migration_media_changed be 0 for 0.15 and 1 for elder
> 2 Unconditiaonlly send subsection when it was 0, and do not send subsection 
> when
> it was 1

If you do this, you are just removing the capability of migrating to
older versions.  If you need to send a subsection unconditionlly, then
just upgrade the version of the device, it is going to give the same result.

Later, Juan.