Re: [PATCH 4/7] pc-bios: s390x: Rework data initialization

[Janosch Frank <frankja@linux.ibm.com>]

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On 7/20/20 1:56 PM, Thomas Huth wrote:
> On 15/07/2020 11.40, Janosch Frank wrote:
>> Sometimes a memset is nicer to read than multiple struct->data = 0;
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>  pc-bios/s390-ccw/dasd-ipl.c | 7 ++-----
>>  1 file changed, 2 insertions(+), 5 deletions(-)
>>
>> diff --git a/pc-bios/s390-ccw/dasd-ipl.c b/pc-bios/s390-ccw/dasd-ipl.c
>> index e8f2846740..0543334ed4 100644
>> --- a/pc-bios/s390-ccw/dasd-ipl.c
>> +++ b/pc-bios/s390-ccw/dasd-ipl.c
>> @@ -167,16 +167,13 @@ static void ipl1_fixup(void)
>>      ccwSeek->cda = ptr2u32(seekData);
>>      ccwSeek->chain = 1;
>>      ccwSeek->count = sizeof(*seekData);
>> -    seekData->reserved = 0x00;
>> -    seekData->cyl = 0x00;
>> -    seekData->head = 0x00;
>> +    memset(seekData, 0, sizeof(*seekData));
> 
> Sounds ok for me if the whole struct gets cleared (though I wonder
> whether this is really worth the effort)...
> 
>>      ccwSearchID->cmd_code = CCW_CMD_DASD_SEARCH_ID_EQ;
>>      ccwSearchID->cda = ptr2u32(searchData);
>>      ccwSearchID->chain = 1;
>>      ccwSearchID->count = sizeof(*searchData);
>> -    searchData->cyl = 0;
>> -    searchData->head = 0;
>> +    memset(searchData, 0, sizeof(*searchData));
>>      searchData->record = 2;
> 
> ... but that looks rather worse to me, and the generated code will
> likely also be slightly worse (since ->record is cleared first and then
> set to 2 again).
> 
> Maybe rather drop this patch?

Sure, I'm definitely not hard set on this patch :)

> 
>  Thomas
> 
> 



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