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;
?
