Re: [Qemu-devel] [PATCH 09/26] ehci: Use uframe precision for interrupt threshold checking

[Gerd Hoffmann]

On 12/17/12 15:23, Hans de Goede wrote:
> Hi,
> 
> On 12/17/2012 02:16 PM, Gerd Hoffmann wrote:
>> On 12/14/12 14:35, Hans de Goede wrote:
>>> Note that a shadow variable is used instead of changing frindex to
>>> uframe accuracy because we must send a frindex which is a multiple of 8
>>> during migration for migration compatibility, and rounding it down to
>>> a multiple of 8 pre-migration, can lead to frindex going backwards from
>>> the guest pov.
>>
>> Jumping forward instead?
> 
> You mean rounding the send frindex up pre-migration, I didn't really
> consider
> that as it will cause us skipping processing an entry in the periodic frame
> list. I guess doing that on migration isn't too bad. OTOH giving the guest
> only frame accuracy like we've been doing till now also works fine...
> 
> Your choice :)

I'm looking for a way to avoid the shadow variable, but of course
without breaking migration.  giving the guest only frame accuracy looks
good to me.

cheers,
  Gerd