Re: [Qemu-devel] [PATCH] s390-ccw: Fix alignment for CCW1

[Farhan Ali <alifm@linux.vnet.ibm.com>]

On 08/28/2017 04:22 AM, Cornelia Huck wrote:
> On Fri, 25 Aug 2017 11:05:30 -0400
> Farhan Ali <alifm@linux.vnet.ibm.com> wrote:
>
>> On 08/25/2017 10:04 AM, Cornelia Huck wrote:
>>> On Fri, 25 Aug 2017 09:24:46 -0400
>>> Farhan Ali <alifm@linux.vnet.ibm.com> wrote:
>>>
>>>> The commit 198c0d1f9df8c4 s390x/css: check ccw address validity
>>>> exposes an alignment issue in ccw bios.
>>>>
>>>> According to PoP the CCW must be doubleword aligned. Let's fix
>>>> this in the bios.
>>>>
>>>> Cc: qemu-stable@nongnu.org
>>>> Signed-off-by: Farhan Ali <alifm@linux.vnet.ibm.com>
>>>> Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
>>>> Reviewed-by: Eric Farman <farman@linux.vnet.ibm.com>
>>>> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
>>>> ---
>>>>  pc-bios/s390-ccw/cio.h | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/pc-bios/s390-ccw/cio.h b/pc-bios/s390-ccw/cio.h
>>>> index f5b4549..55eaeee 100644
>>>> --- a/pc-bios/s390-ccw/cio.h
>>>> +++ b/pc-bios/s390-ccw/cio.h
>>>> @@ -133,7 +133,7 @@ struct ccw1 {
>>>>      __u8 flags;
>>>>      __u16 count;
>>>>      __u32 cda;
>>>> -} __attribute__ ((packed));
>>>> +} __attribute__ ((packed, aligned(8)));
>>>>
>>>>  #define CCW_FLAG_DC              0x80
>>>>  #define CCW_FLAG_CC              0x40
>>>
>>> Currently testing.
>>>
>>> This looks obviously right, but did you figure out what the (probably
>>> unrelated) other failure was?
>>>
>>
>> That is still under investigation, for some reason it only fails for an
>> LDL DASD and it works for SCSIs and CDL DASD.
>
> Which are the symptoms of the failure? I'd like to understand this
> before I update the (currently working by accident) bios with an
> updated version.
>
> I'll just apply the patch for now.
>

Well it's seems like the failure for LDL DASD could be a disk setup 
failure. We tried the test on a different environment with LDL disks and 
everything worked fine with the patch applied.