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Re: [PATCH 4/7] pc-bios: s390x: Rework data initialization
From: |
Janosch Frank |
Subject: |
Re: [PATCH 4/7] pc-bios: s390x: Rework data initialization |
Date: |
Mon, 20 Jul 2020 14:10:50 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 |
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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- Re: [PATCH 6/7] pc-bios: s390x: Use PSW constants in start.S, (continued)
[PATCH 5/7] pc-bios: s390x: Replace lowcore offsets with pointers in dasd-ipl.c, Janosch Frank, 2020/07/15
[PATCH 4/7] pc-bios: s390x: Rework data initialization, Janosch Frank, 2020/07/15
[PATCH 2/7] pc-bios: s390x: Cleanup jump to ipl code, Janosch Frank, 2020/07/15