On 5/27/20 10:50 AM, Christian Borntraeger wrote:
>
>
> On 27.05.20 09:49, Janosch Frank wrote:
>> If we have a lowcore struct that has members for offsets that we want
>> to touch, why not use it?
>>
>> Signed-off-by: Janosch Frank <fran...@linux.ibm.com>
>> Reviewed-by: David Hildenbrand <da...@redhat.com>
>> ---
>> pc-bios/s390-ccw/cio.h | 17 +++++++++++------
>> pc-bios/s390-ccw/main.c | 8 +++-----
>> 2 files changed, 14 insertions(+), 11 deletions(-)
>>
>> diff --git a/pc-bios/s390-ccw/cio.h b/pc-bios/s390-ccw/cio.h
>> index aaa432dedd..1e5d4e92e1 100644
>> --- a/pc-bios/s390-ccw/cio.h
>> +++ b/pc-bios/s390-ccw/cio.h
>> @@ -122,12 +122,17 @@ typedef struct schib {
>> } __attribute__ ((packed, aligned(4))) Schib;
>>
>> typedef struct subchannel_id {
>> - __u32 cssid:8;
>> - __u32:4;
>> - __u32 m:1;
>> - __u32 ssid:2;
>> - __u32 one:1;
>> - __u32 sch_no:16;
>> + union {
>> + struct {
>> + __u16 cssid:8;
>> + __u16 reserved:4;
>> + __u16 m:1;
>> + __u16 ssid:2;
>> + __u16 one:1;
>> + };
>> + __u16 sch_id;
>> + };
>> + __u16 sch_no;
>> } __attribute__ ((packed, aligned(4))) SubChannelId;
>> > struct chsc_header {
>> diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
>> index 4e65b411e1..8b912454c9 100644
>> --- a/pc-bios/s390-ccw/main.c
>> +++ b/pc-bios/s390-ccw/main.c
>> @@ -36,11 +36,9 @@ LowCore *lowcore; /* Yes, this *is* a pointer to address
>> 0 */
>> */
>> void write_subsystem_identification(void)
>> {
>> - SubChannelId *schid = (SubChannelId *) 184;
>> - uint32_t *zeroes = (uint32_t *) 188;
>> -
>> - *schid = blk_schid;
>> - *zeroes = 0;
>> + lowcore->subchannel_id = blk_schid.sch_id;
>> + lowcore->subchannel_nr = blk_schid.sch_no;
>> + lowcore->io_int_parm = 0;
>> }
>>
>> void write_iplb_location(void)
>
> As an alternative, why not change the definition of Lowcore and replace both
> 16bit
> fields lowcore->subchannel_id and lowcore->subchannel_nr with SubChannelID.
> You can then simply assign lowcore->schid= blk_schid;
>
> ?
>
I think Pierre voted against that in the internal review if I remember
correctly.
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