Re: [qemu-s390x] [PATCH v5 1/1] s390x/sclp: extend SCLP event masks to 64 bits

[Christian Borntraeger]

On 03/08/2018 11:02 AM, Claudio Imbrenda wrote:
> On Thu, 8 Mar 2018 08:41:47 +0100
> Christian Borntraeger <address@hidden> wrote:
> 
>> On 03/07/2018 04:10 PM, Claudio Imbrenda wrote:
>>> Extend the SCLP event masks to 64 bits.
>>>
>>> Notice that using any of the new bits results in a state that
>>> cannot be migrated to an older version.
>>>
>>> Signed-off-by: Claudio Imbrenda <address@hidden>
>>> ---
>>>  hw/s390x/event-facility.c         | 49
>>> ++++++++++++++++++++++++++++++++-------
>>> include/hw/s390x/event-facility.h |  2 +- 2 files changed, 41
>>> insertions(+), 10 deletions(-)
>>>
>>> diff --git a/hw/s390x/event-facility.c b/hw/s390x/event-facility.c
>>> index e04ed9f..c166e0a 100644
>>> --- a/hw/s390x/event-facility.c
>>> +++ b/hw/s390x/event-facility.c
>>> @@ -30,7 +30,10 @@ struct SCLPEventFacility {
>>>      SysBusDevice parent_obj;
>>>      SCLPEventsBus sbus;
>>>      /* guest's receive mask */
>>> -    sccb_mask_t receive_mask;
>>> +    union {
>>> +        uint32_t receive_mask_pieces[2];
>>> +        sccb_mask_t receive_mask;
>>> +    };  
>>
>> Would it work to make sccb_mask_t a union instead?
> 
> yes, but then a lot of other code should be changed: we use sccb_mask_t
> as scalar everywhere.
> 
> also, we only need the pieces when migrating the state, never during
> normal operation

ok, makes sense.