Re: [Qemu-devel] S390 bios breaks in qemu 2.10.rc3

From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: Farhan Ali <alifm@linux.vnet.ibm.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	Thomas Huth <thuth@redhat.com>,
	David Hildenbrand <david@redhat.com>,
	Halil Pasic <pasic@linux.vnet.ibm.com>,
	QEMU Developers <qemu-devel@nongnu.org>,
	"Collin L. Walling" <walling@linux.vnet.ibm.com>
Subject: Re: [Qemu-devel] S390 bios breaks in qemu 2.10.rc3
Date: Fri, 25 Aug 2017 10:21:58 +0200	[thread overview]
Message-ID: <d3e9d032-fd2e-6126-1774-cb8a86a219f4@de.ibm.com> (raw)
In-Reply-To: <20170825092008.12484e6a.cohuck@redhat.com>

On 08/25/2017 09:20 AM, Cornelia Huck wrote:
> On Thu, 24 Aug 2017 20:14:06 +0200
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> 
>> On 08/24/2017 07:38 PM, Farhan Ali wrote:
>>>
>>>
>>> On 08/24/2017 12:07 PM, Peter Maydell wrote:  
>>>> On 24 August 2017 at 16:53, Farhan Ali <alifm@linux.vnet.ibm.com> wrote:  
>>>>>
>>>>>
>>>>> On 08/24/2017 11:50 AM, Thomas Huth wrote:  
>>>>>> True, so that could still be an issue. Looking at the cio.h in the
>>>>>> kernel, they define the struct like this:
>>>>>>
>>>>>> struct ccw1 {
>>>>>>         __u8  cmd_code;
>>>>>>         __u8  flags;
>>>>>>         __u16 count;
>>>>>>         __u32 cda;
>>>>>> } __attribute__ ((packed,aligned(8)));
>>>>>>
>>>>>> So I guess adding the aligned(8) is the right way to go?  
>>>>  
>>>>> This was my initial fix and it works on my system. But for some reason this
>>>>> fix does not work on my colleague's system. So I am hesitant about
>>>>> submitting this fix  
>>>>
>>>> It seems like it ought to be the obvious fix, so I would double
>>>> check that on your colleague's system the change really did
>>>> get recompiled and it's actually using the new version (that
>>>> sort of mistake can be easy to make and very confusing...)  
>>
>>>>
>>>> thanks
>>>> -- PMM
>>>>  
>>>
>>> So after trying again with the fix, it seems to work on my colleague's system for most cases. It fails for LDL DASD boot case.... we are still investigating it.  
>>
>> So chances are that this is an independent problem, I guess?
>>
> 
> OK, to recap:
> 
> - the current pre-built bios seems fine
> - rebuilding the bios may yield a version that fails on some systems
>   (different compiler?)
> - adding aligned(8) looks like the right thing to do
> - it seems to fix the problem, but on at least one system something
>   still seems off (under investigation)

Yes. I am out of office today, so for any aligned(8) patch
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
even for 2.10.