On 2011-03-23 17:27, Anthony Liguori wrote: > On 03/23/2011 10:00 AM, Peter Maydell wrote: >> On 23 March 2011 14:52, Anthony Liguori<anth...@codemonkey.ws> wrote: >>> I think we ought to merge VMStateDescription into DeviceInfo. For >>> compatibility, we probably need a vmstate_alias name since the device names >>> don't always map 1-1 with the qdev names. But this should eliminate the >>> problem of reusing VMStateDescriptions for multiple devices. >> That's a feature, not a bug. Consider eg hw/pl110.c -- there >> are two different DeviceInfo devices but since the underlying >> implementation is the same you definitely don't want to have >> two separate VMStateDescription structures to get out of sync. > > No, it's a bug. > > Migration uses the VMStateDescription name as a section identifier. The > section identifiers MUST be unique for a given device. Otherwise, if > both devices are present, migration fails miserably. It also means that > if the wrong devices are created on the destination, instead of > predictable failure, you get unpredictable guest corruption.
This is true for incompatible devices, but not for those that are perfectly exchangeable (like in-kernel vs. user-space irqchip). Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux
