From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andre Przywara <andre.przywara@arm.com>
Subject: Re: [PATCH 1/7] KVM: api: add kvm_irq_routing_extended_msi
Date: Mon, 6 Jul 2015 17:08:26 +0100
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To: Paolo Bonzini <pbonzini@redhat.com>, Pavel Fedin <p.fedin@samsung.com>, 'Christoffer Dall' <christoffer.dall@linaro.org>
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On 06/07/15 16:54, Paolo Bonzini wrote:
> 
> 
> On 06/07/2015 17:37, Andre Przywara wrote:
>> Wouldn't:
>>     if (kvm_vm_check_extension(s, KVM_CAP_MSI_DEVID)) {
>>         kroute.flags = KVM_MSI_VALID_DEVID;
>>         kroute.u.msi.devid = (pci_bus_num(dev->bus) << 8) | dev->devfn;
>>     }
>>
>> be saner (without a global variable)?
>> That would make the interface more consistent, with a new flag being
>> protected by a new capability.
> 
> I agree that your version is niceer, but you still need to cache the
> kvm_vm_check_extension result... in a global variable. :)

I used a static variable in a wrapper function in kvmtool ;-)
TBH my argument wasn't so much about global variables (just saw that
QEMU seems to use them already), but more about a consistent and
architecture agnostic interface.

Ciao!
Andre.