From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christian Borntraeger <borntraeger@de.ibm.com>
Subject: Re: [Qemu-devel] [PATCH v5 11/17] target-s390x: Add KVM VM attribute
 interface for S390 CPU models
Date: Mon, 27 Apr 2015 12:52:54 +0200
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Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org,
	linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
	Eduardo Habkost <ehabkost@redhat.com>,
	Gleb Natapov <gleb@kernel.org>, Alexander Graf <agraf@suse.de>,
	Daniel Hansel <daniel.hansel@linux.vnet.ibm.com>,
	"Jason J. Herne" <jjherne@linux.vnet.ibm.com>,
	Cornelia Huck <cornelia.huck@de.ibm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Richard Henderson <rth@twiddle.net>,
	Andreas Faerber <afaerber@suse.de>
To: Michael Mueller <mimu@linux.vnet.ibm.com>
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Am 27.04.2015 um 11:43 schrieb Michael Mueller:
> On Mon, 27 Apr 2015 10:15:47 +0200
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> 
>> Am 13.04.2015 um 15:56 schrieb Michael Mueller:
>> [...]
>>> +static int cpu_model_get(KVMState *s, uint64_t attr, uint64_t addr)
>>> +{
>>> +    int rc = -ENOSYS;
>>> +    struct kvm_device_attr dev_attr = {
>>> +        .group = KVM_S390_VM_CPU_MODEL,
>>> +        .attr = attr,
>>> +        .addr = addr,
>>
>> Would it make sense to do the cast here....
> 
> cpu_model_get/set() is used to handle both attributes,
> KVM_S390_VM_CPU_MACHINE and KVM_S390_VM_CPU_PROCESSOR.
> Both require a different type in the signature, (S390ProcessorProps*)
> and (S390MachineProps*). Adding both as parameters seems to be odd
> and would require additionally logic in the function.
> Thus I think doing the cast outside is just the right thing to do.

So what about a void pointer then as parameter?
I prefer a pointer for qemu process memory over uint64_t as part of the 
function interface. This makes it somewhat clearer that this is an
address within QEMU. Both ways will certainly work, though.

Conny, I guess you will pick up the patches. Any preference?

Christian