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Date: Wed, 16 May 2018 17:52:43 +0200
From: Cornelia Huck <cohuck@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH RFC 1/2] vfio-ccw: forward halt/clear to
 device if supported
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To: Pierre Morel <pmorel@linux.ibm.com>
Cc: Dong Jia Shi <bjsdjshi@linux.ibm.com>, Halil Pasic <pasic@linux.ibm.com>, linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, qemu-s390x@nongnu.org, qemu-devel@nongnu.org

On Wed, 16 May 2018 15:53:48 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> On 15/05/2018 18:01, Cornelia Huck wrote:
> > On Fri, 11 May 2018 11:53:52 +0200
> > Pierre Morel <pmorel@linux.ibm.com> wrote:

> >> Couldn't we introduce ABI versioning ?  
> > Can you elaborate what you're referring to?
> >
> > If you mean checking capabilities of the kernel or so: If we can avoid
> > that and just try (and stop if it does not work), I'd prefer that (no
> > dependencies).  
> 
> VFIO_CHECK_EXTENSION is already used in different drivers
> for this kind of interface extension.
> We could use it to setup appropriate callbacks for scsh/csch/xsch/hsch
> depending on the extension argument.

Hm, this might be useful for things like xsch that aren't really well
served by the current interface. Or we could try using the
device-specific capability interface.

Let me think and play with this a bit.