On 04/09/15 09:01, David Gibson wrote:
> On Thu, Aug 06, 2015 at 10:57:15AM +0530, Bharata B Rao wrote:
>> QEMU currently supports CPU topologies where there can be cores
>> which are not completely filled with all the threads as per the
>> specifed SMT mode.
>>
>> Restore support for such topologies (Eg -smp 15,cores=4,threads=4)
>> The last core will always have the deficit even when -device options are
>> used to cold-plug the cores.
>>
>> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> 
> Is there a reason to support these silly toplogies, or should we just
> error out if this is specified?

FYI, I've recently submitted a patch that tries to catch such illegal
SMP configurations and simply errors out in that case:

http://lists.nongnu.org/archive/html/qemu-devel/2015-07/msg04549.html

It's not upstream yet, but already in Eduardo's x86 branch. I think this
will reject the bad topology from your example, too.

 Thomas