From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:53727)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <david@redhat.com>) id 1eLuyP-0008Uq-Kk
	for qemu-devel@nongnu.org; Mon, 04 Dec 2017 12:56:10 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <david@redhat.com>) id 1eLuyL-0005En-MQ
	for qemu-devel@nongnu.org; Mon, 04 Dec 2017 12:56:09 -0500
References: <20171204125505.29203-1-david@redhat.com>
	<20171204125505.29203-6-david@redhat.com>
	<20171204182244.2b789717.cohuck@redhat.com>
	<8904d9e3-990f-46e1-49d1-9d37533d025e@redhat.com>
	<20171204185352.39f2b131.cohuck@redhat.com>
From: David Hildenbrand <david@redhat.com>
Message-ID: <51a752c1-994e-e57a-8fce-1e2afcc2092c@redhat.com>
Date: Mon, 4 Dec 2017 18:56:00 +0100
MIME-Version: 1.0
In-Reply-To: <20171204185352.39f2b131.cohuck@redhat.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v1 for-2.12 5/5] s390x/tcg: wire up STORE
 CHANNEL REPORT WORD
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Cornelia Huck <cohuck@redhat.com>
Cc: qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Christian Borntraeger <borntraeger@de.ibm.com>, Richard Henderson <rth@twiddle.net>, Alexander Graf <agraf@suse.de>, Thomas Huth <thuth@redhat.com>

On 04.12.2017 18:53, Cornelia Huck wrote:
> On Mon, 4 Dec 2017 18:34:36 +0100
> David Hildenbrand <david@redhat.com> wrote:
> 
>> On 04.12.2017 18:22, Cornelia Huck wrote:
>>> On Mon,  4 Dec 2017 13:55:05 +0100
>>> David Hildenbrand <david@redhat.com> wrote:
>>>   
>>>> We somehow missed that, new kernels require it.  
>>>
>>> Why _new_ kernels? I think we have unconditionally issued stcrw since
>>> back in 2.2?  
>>
>> Okay, the problem is then rather related to my setup. No ccw devices ->
>> no stcrw.
>>
>> How could we ever add ccw devices to a TCG guest then?
> 
> Hotplug never worked before your patches. Coldplug does not create
> machine checks and thus does not trigger the guest to do STCRW. (Only
> STSCH, in keeping with "all channel I/O acronyms look the same".)
> 

But booting Fedora 26/27 without any involved hotplugs (therefore
machine checks) triggers a STCRW.

That's how I originally found it. (I started playing with machine checks
after I had fedora 26/27 running)

-- 

Thanks,

David / dhildenb