Re: [qemu-s390x] [PATCH v4 3/3] s390x/sclp: extend SCLP event masks to 64 bits

[Christian Borntraeger]

On 03/05/2018 04:27 PM, Cornelia Huck wrote:
> On Fri, 2 Mar 2018 10:44:46 +0100
> Christian Borntraeger <address@hidden> wrote:
> 
>> On 02/23/2018 06:42 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         | 56 
>>> ++++++++++++++++++++++++++++++---------
>>>  include/hw/s390x/event-facility.h |  2 +-
>>>  2 files changed, 45 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/hw/s390x/event-facility.c b/hw/s390x/event-facility.c
>>> index e04ed9f..c3e39ee 100644
>>> --- a/hw/s390x/event-facility.c
>>> +++ b/hw/s390x/event-facility.c
>>> @@ -30,7 +30,7 @@ struct SCLPEventFacility {
>>>      SysBusDevice parent_obj;
>>>      SCLPEventsBus sbus;
>>>      /* guest's receive mask */
>>> -    sccb_mask_t receive_mask;
>>> +    uint32_t receive_mask_pieces[2];  
>>
>>
>> Before the change, we basically use be32_to_cpu to transfer the byte field 
>> into a cpu
>> endianess value. In the end it is actually a bitfield, but for compat we 
>> need to keep
>> he reversal. So it will be hard to get this fixed without some kind of 
>> ugliness.
> 
> Could we also use a compat mask callback/handler for older machines and
> switch to 64 bit handlers for the default case? Probably would be even
> more ugly, though.

Claudio had a version with a pre/post/load/save handler. Claudio can you repost 
this
version so that we can have a look what is "less ugly"?