Re: [PATCH 1/7] KVM: api: add kvm_irq_routing_extended_msi

[Andre Przywara <andre.przywara@arm.com>]

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.