On 27/06/2016 09:20, Amit Shah wrote:
> On (Mon) 20 Jun 2016 [16:33:26], Paolo Bonzini wrote:
>> Commit 926cde5 ("scsi: esp: make cmdbuf big enough for maximum CDB size",
>> 2016-06-16) changed the size of a migrated field. Split it in two
>> parts, and only migrate the second part in a new vmstate version.
>
> With this patch, the static checker fails in this way:
>
> Section "esp", Description "esp": expected field "cmdlen", got "cmdbuf";
> skipping rest
> Section "dc390", Description "esp": expected field "cmdlen", got "cmdbuf";
> skipping rest
> Section "am53c974", Description "esp": expected field "cmdlen", got "cmdbuf";
> skipping rest
>
> Note it doesn't complain about the version numbers. That's because:
>
>> const VMStateDescription vmstate_esp = {
>> .name ="esp",
>> - .version_id = 3,
>> + .version_id = 4,
>> .minimum_version_id = 3,
>
> this suggests older versions can still be accepted for incoming
> migration, which isn't true.
Sure they can:
- VMSTATE_BUFFER(cmdbuf, ESPState),
+ VMSTATE_PARTIAL_BUFFER(cmdbuf, ESPState, 16),
+ VMSTATE_BUFFER_START_MIDDLE_V(cmdbuf, ESPState, 16, 4),
2.6 is transmitting version 3 and a 16-byte buffer.
2.7 is transmitting version 4, a first 16-byte buffer, and a second
16-byte buffer that is skipped when receiving version 3.
So it seems like a static checker limitation.
Paolo
