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

[Cornelia Huck <cohuck@redhat.com>]

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.