Re: [PATCH 4/4] s390x: Beautify machine reset

[David Hildenbrand <david@redhat.com>]

On 22.11.19 13:22, Janosch Frank wrote:
> On 11/22/19 1:10 PM, Cornelia Huck wrote:
>> On Fri, 22 Nov 2019 12:47:44 +0100
>> David Hildenbrand <david@redhat.com> wrote:
>>
>>> On 22.11.19 12:46, Janosch Frank wrote:
>>>> On 11/22/19 11:59 AM, David Hildenbrand wrote:
>>>>> On 22.11.19 08:52, Janosch Frank wrote:
>>>>>> * Add comments that tell you which diag308 subcode caused the reset
>>>>>> * Sort by diag308 reset subcode
>>>>>>
>>>>>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>>>>>> ---
>>>>>>     hw/s390x/s390-virtio-ccw.c | 20 ++++++++++----------
>>>>>>     1 file changed, 10 insertions(+), 10 deletions(-)
>>>>>>
>>>>>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>>>>>> index c1d1440272..88f7758721 100644
>>>>>> --- a/hw/s390x/s390-virtio-ccw.c
>>>>>> +++ b/hw/s390x/s390-virtio-ccw.c
>>>>>> @@ -330,15 +330,7 @@ static void s390_machine_reset(MachineState *machine)
>>>>>>         s390_cmma_reset();
>>>>>>     
>>>>>>         switch (reset_type) {
>>>>>> -    case S390_RESET_EXTERNAL:
>>>>>> -    case S390_RESET_REIPL:
>>>>>> -        qemu_devices_reset();
>>>>>> -        s390_crypto_reset();
>>>>>> -
>>>>>> -        /* configure and start the ipl CPU only */
>>>>>> -        run_on_cpu(cs, s390_do_cpu_ipl, RUN_ON_CPU_NULL);
>>>>>> -        break;
>>>>>> -    case S390_RESET_MODIFIED_CLEAR:
>>>>>> +    case S390_RESET_MODIFIED_CLEAR: /* Subcode 0 */
>>>>>
>>>>> IMHO "Subcode X" isn't of much help here. We're out of diag handling.
>>>>>
>>>>> I'd suggest to just document the subcodes along with the definitions, if
>>>>> really needed, and drop this patch, at least I don't quite see the value
>>>>> of moving code around here... or is the code shuffling of any value on
>>>>> your prot virt patches?
>>>>>   
>>>>
>>>> It keeps me from consulting the POP every time I need to change things
>>>> in the machine resets. This is basically a 1:1 mapping of diag 308
>>>> subcodes to machine resets, so why don't we want to make that obvious
>>>> and order them by the subcodes?
>>>>    
>>>
>>> Because it is not a 1:1 mapping: S390_RESET_EXTERNAL
>>>
>>
>> Tack the explanation onto the definitions of S390_RESET_, then?
>> Probably still quicker than consulting the POP :)
>>
> 
> Does it really bother you that much, that I add some explanations to the
> things we're doing. The external reset also gets a comment so Conni
> won't need that much coffee anymore to understand the code :-)
> 

I'm really sorry, but I fail to see how "Subcode 0" is *any* better than 
S390_RESET_MODIFIED_CLEAR (and avoids consulting the PoP) and why the 
order should matter at all here to make it easier to understand.

I don't NACK this, I just find it *completely* useless :)

-- 

Thanks,

David / dhildenb